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Calculate the price of your order Type of paper needed:. Pages: words. You will get a personal manager and a discount. Academic level:. We'll send you the first draft for approval by September 11, at AM. Total price:. Activiti runs on a JDK higher than or equal to version 7. There are installation instructions on that page as well. To verify that your installation was successful, run java -version on the command line. That should print the installed version of your JDK. Activiti development can be done with the IDE of your choice.
Download the eclipse distribution of your choice from the Eclipse download page. Unzip the downloaded file and then you should be able to start it with the eclipse file in the directory eclipse. Further in this user guide, there is a section on installing our eclipse designer plugin. Every self-respecting developer should have read How to ask questions the smart way. All classes that have. However, if the user guide mentions those classes as configuration values, they are supported and can be considered stable.
In the jar file, all classes in packages that have. No stability guarantees are given on classes or interfaces that are in implementation classes.
After downloading the Activiti UI WAR file from the Activiti website , follow these steps to get the demo setup running with default settings. But we test on Tomcat primarily. Login with admin and password test. The Activiti UI application uses an in-memory H2 database by default, if you want to use another database configuration please read the longer version.
The way to do this depends on your operating system. By default the UI application runs with an in-memory database. The process engine user console. Use this tool to start new processes, assign tasks, view and claim tasks, etc. Note that the Activiti UI app demo setup is a way of showing the capabilities and functionality of Activiti as easily and as fast as possible. This does however, not mean that it is the only way of using Activiti.
Or you could very well choose to run Activiti as a typical, standalone BPM server. If it is possible in Java, it is possible with Activiti! As said in the one minute demo setup, the Activiti UI app runs an in-memory H2 database by default. To run the Activiti UI app with a standalone H2 or another database the activiti-app. To include the Activiti jar and its dependent libraries, we advise using Maven or Ivy , as it simplifies dependency management on both our and your side a lot.
The Activiti download zip contains a folder libs which contain all the Activiti jars and the source jars. The dependencies are not shipped this way. The required dependencies of the Activiti engine are generated using mvn dependency:tree :. Note: the mail jars are only needed if you are using the mail service task. All the dependencies can easily be downloaded using mvn dependency:copy-dependencies on a module of the Activiti source code.
Playing around with the Activiti UI web application is a good way to get familiar with the Activiti concepts and functionality. However, the main purpose of Activiti is of course to enable powerful BPM and workflow capabilities in your own application. The following chapters will help you to get familiar with how to use Activiti programmatically in your environment:. The chapter on configuration will teach you how to set up Activiti and how to obtain an instance of the ProcessEngine class which is your central access point to all the engine functionality of Activiti.
These services offer the Activiti engine functionality in a convenient yet powerful way and can be used in any Java environment. Then continue on to the BPMN 2. The Activiti process engine is configured through an XML file called activiti. The easiest way to obtain a ProcessEngine , is to use the org.
ProcessEngines class:. This will look for an activiti. The following snippet shows an example configuration. The following sections will give a detailed overview of the configuration properties.
Note that the configuration XML is in fact a Spring configuration. This does not mean that Activiti can only be used in a Spring environment!
We are simply leveraging the parsing and dependency injection capabilities of Spring internally for building up the engine. The ProcessEngineConfiguration object can also be created programmatically using the configuration file. It is also possible to use a different bean id e. It is also possible not to use a configuration file, and create a configuration based on defaults see the different supported classes for more information.
All these ProcessEngineConfiguration. After calling the buildProcessEngine operation, a ProcessEngine is created:. The activiti.
This bean is then used to construct the ProcessEngine. There are multiple classes available that can be used to define the processEngineConfiguration. These classes represent different environments, and set defaults accordingly. The following classes are currently available more will follow in future releases :.
StandaloneProcessEngineConfiguration : the process engine is used in a standalone way. Activiti will take care of the transactions. By default, the database will only be checked when the engine boots and an exception is thrown if there is no Activiti schema or the schema version is incorrect. An H2 in-memory database is used by default.
The database will be created and dropped when the engine boots and shuts down. When using this, probably no additional configuration is needed except when using for example the job executor or mail capabilities. SpringProcessEngineConfiguration : To be used when the process engine is used in a Spring environment.
See the Spring integration section for more information. There are two ways to configure the database that the Activiti engine will use.
The first option is to define the JDBC properties of the database:. The data source that is constructed based on the provided JDBC properties will have the default MyBatis connection pool settings.
The following attributes can optionally be set to tweak that connection pool taken from the MyBatis documentation :. Default is Default is 20 seconds. Our benchmarks have shown that the MyBatis connection pool is not the most efficient or resilient when dealing with a lot of concurrent requests. As such, it is advised to us a javax. Note that Activiti does not ship with a library that allows to define such a data source.
So you have to make sure that the libraries are on your classpath. The following properties can be set, regardless of whether you are using the JDBC or data source approach:. Should only be specified in case automatic detection fails. See the supported databases section for an overview of which types are supported. By default, the database configuration for Activiti is contained within the db. By using JNDI Java Naming and Directory Interface to obtain the database connection, the connection is fully managed by the Servlet Container and the configuration can be managed outside the war deployment.
This also allows more control over the connection parameters than what is provided by the db. Configuration of the JNDI datasource will differ depending on what servlet container application you are using.
The instructions below will work for Tomcat, but for other container applications, please refer to the documentation for your container app.
The default context is copied from the Activiti war file when the application is first deployed, so if it already exists, you will need to replace it. Default is "true". Add an Activiti configuration file activiti. However, often only database administrators can execute DDL statements on a database. On a production system, this is also the wisest of choices.
The scripts are also in the engine jar activiti-engine-x. The SQL files are of the form. Where db is any of the supported databases and type is. These tables are optional and should be used when using the default identity management as shipped with the engine. Optional: not needed when history level is set to none. Note that this will also disable some features such as commenting on tasks which store the data in the history database.
When using the DDL file approach, both a regular version and a special file with mysql55 in it are available this applies on anything lower than 5. This latter file will have column types with no millisecond precision in it. DDL files available look for files containing mysql It is advised to upgrade to a newer database version anyway. DDL files for mysql 5. DDL files available default file containing mysql.
The second part is a two-character identification of the use case of the table. This use case will also roughly match the service API. Tables with this prefix contain static information such as process definitions and process resources images, rules, etc. These are the runtime tables that contain the runtime data of process instances, user tasks, variables, jobs, etc.
Activiti only stores the runtime data during process instance execution, and removes the records when a process instance ends. This keeps the runtime tables small and fast. These tables contain identity information, such as users, groups, etc. These are the tables that contain historic data, such as past process instances, variables, tasks, etc.
Make sure you make a backup of your database using your database backup capabilities before you run an upgrade. By default, a version check will be performed each time a process engine is created.
This typically happens once at boot time of your application or of the Activiti webapps. If the Activiti library notices a difference between the library version and the version of the Activiti database tables, then an exception is thrown. To upgrade, you have to start with putting the following configuration property in your activiti. Also, include a suitable database driver for your database to the classpath.
Upgrade the Activiti libraries in your application. Or start up a new version of Activiti and point it to a database that contains an older version.
With databaseSchemaUpdate set to true , Activiti will automatically upgrade the DB schema to the newer version the first time when it notices that libraries and DB schema are out of sync.
As an alternative you can also run the upgrade DDL statements. The async executor of Activiti 5 is the only available job executor in Activiti 6 as it is a more performant and more database friendly way of executing asynchronous jobs in the Activiti Engine.
The old job executor of Activiti 5 is removed. More information can be found in the advanced section of the user guide. In order to enable them, the thread factory should be passed in the configuration as follows:. The managed implementation fall back to their default counterparts if the thread factory is not specified. The AsyncExecutor is a component that manages a thread pool to fire timers and other asynchronous tasks.
Other implementations are possible for example using a message queue, see the advanced section of the user guide. By default, the AsyncExecutor is not activated and not started. With the following configuration the async executor can be started together with the Activiti Engine. The property asyncExecutorActivate instructs the Activiti Engine to startup the Async executor at startup. Configuring a mail server is optional.
Activiti supports sending e-mails in business processes. To actually send an e-mail, a valid SMTP mail server configuration is required.
See the e-mail task for the configuration options. Customizing the configuration of history storage is optional. This allows you to tweak settings that influence the history capabilities of the engine. See history configuration for more details. By default, all beans that you specify in the activiti.
If you want to limit the visibility of beans in your configuration file, you can configure a property called beans in your process engine configuration. The beans property in ProcessEngineConfiguration is a map. When you specify that property, only beans specified in that map will be visible to expressions and scripts. The exposed beans will be exposed with the names as you specify in that map. By default, there is no limit on this cache. To limit the process definition cache, add following property.
Setting this property will swap the default hashmap cache with a LRU cache that has the provided hard limit. Of course, the best value of this property depends on the total amount of process definitions stored and the number of process definitions actually used at runtime by all the runtime process instances.
You can also inject your own cache implementation. This must be a bean that implements the org. DeploymentCache interface:. There is a similar property called knowledgeBaseCacheLimit and knowledgeBaseCache for configuring the rules cache. This is only needed when you use the rules task in your processes. By default no SFL4J-binding jar is present in the activiti-engine dependencies, this should be added in your project in order to use the logging framework of your choice.
If no implementation jar is added, SLF4J will use a NOP-logger, not logging anything at all, other than a warning that nothing will be logged. With Maven, add for example a dependency like this here using log4j , note that you still need to add a version:. The activiti-ui and activiti-rest webapps are configured to use Log4j-binding. These basic information are passed to the underlying logger along with what is going to be logged:.
None of these information are logged by default. The logger can be configured to show them in desired format, extra to the usual logged messages. For example in Log4j the following sample layout definition causes the logger to show the above mentioned information:.
This is useful when the logs contain information that needs to checked in real time, by means of a log analyzer for example. The event mechanism in the Activiti engine allows you to get notified when various events occur within the engine.
Take a look at all supported event types for an overview of the events available. You can either add engine-wide event listeners through the configuration , add engine-wide event listeners at runtime using the API or add event-listeners to specific process definitions in the BPMN XML. All events dispatched are a subtype of org. Certain events contain additional context related to the event that occurred, additional information about additional payload can be found in the list of all supported event types.
The only requirement an event-listener has, is to implement org. Below is an example implementation of a listener, which outputs all events received to the standard-out, with exception of events related to job-execution:.
The isFailOnException method determines the behaviour in case the onEvent.. In case false is returned, the exception is ignored. When true is returned, the exception is not ignored and bubbles up, effectively failing the current ongoing command. In case the event was part of an API-call or any other transactional operation, e. There are a few base implementations provided by Activiti to facilitate common use cases of event-listeners. These can be used as base-class or as an example listener implementation:.
BaseEntityEventListener : An event-listener base-class that can be used to listen for entity-related events for a specific type of entity or for all entities. It hides away the type-checking and offers 4 methods that should be overridden: onCreate.. For all other entity-related events, the onEntityEvent.. If an event-listener is configured in the process engine configuration, it will be active when the process engine starts and will remain active after subsequent reboots of the engine.
The property eventListeners expects a list of org. ActivitiEventListener instances. As usual, you can either declare an inline bean definition or use a ref to an existing bean instead.
The snippet below adds an event-listener to the configuration that is notified when any event is dispatched, regardless of its type:. To get notified when certain types of events get dispatched, use the typedEventListeners property, which expects a map. The key of a map-entry is a comma-separated list of event-names or a single event-name. The value of a map-entry is a list of org. The snippet below adds an event-listener to the configuration, that is notified when a job execution was successful or failed:.
The order of dispatching events is determined on the order the listeners were added. First, all normal event-listeners are called eventListeners property in the order they are defined in the list. After that, all typed event listeners typedEventListeners properties are called, if an event of the right type is dispatched. Please note that the listeners added at runtime are not retained when the engine is rebooted.
The listeners will only be called for events related to the process definition and to all events related to process instances that are started with that specific process definition.
The snippet below adds 2 listeners to a process-definition. The first listener will receive events of any type, with a listener implementation based on a fully-qualified class name. The second listener is only notified when a job is successfully executed or when it failed, using a listener that has been defined in the beans property of the process engine configuration.
The snippet below shows how this can be achieved. It can be used along for ALL entity-events first example or for specific event types only second example. Supported values for the entityType are: attachment , comment , execution , identity-link , job , process-instance , process-definition , task. Another way of handling events being dispatched is to throw a BPMN event.
Please bear in mind that it only makes sense to throw BPMN-events with certain kinds of Activiti event types. For example, throwing a BPMN event when the process-instance is deleted will result in an error. The snippet below shows how to throw a signal inside process-instance, throw a signal to an external process global , throw a message-event inside the process-instance and throw an error-event inside the process-instance.
Instead of using the class or delegateExpression , the attribute throwEvent is used, along with an additional attribute, specific to the type of event being thrown. SignalThrowingEventListenerTest , org. MessageThrowingEventListener and org. Event-listeners can only be declared on the process element, as a child-element of the extensionElements. Listeners cannot be defined on individual activities in the process. Expressions used in the delegateExpression do not have access to the execution-context, as other expressions e.
They can only reference beans defined in the beans property of the process engine configuration or when using spring and the beans property is absent to any spring-bean that implements the listener interface. When using the class attribute of a listener, there will only be a single instance of that class created.
When an illegal event-type is used in the events attribute or illegal throwEvent value is used, an exception will be thrown when the process-definition is deployed effectively failing the deployment. When an illegal value for class or delegateExecution is supplied either a nonexistent class, a nonexistent bean reference or a delegate not implementing listener interface , an exception will be thrown when the process is started or when the first valid event for that process-definition is dispatched to the listener.
Make sure the referenced classes are on the classpath and that the expressions resolve to a valid instance. We opened up the event-dispatching mechanism through the API, to allow you to dispatch custom events to any listeners that are registered in the engine.
Dispatching the event can be done using the RuntimeService :. Listed below are all event types that can occur in the engine. Each type corresponds to an enum value in the org. The process-engine this listener is attached to, has been created and is ready for API-calls. The process-engine this listener is attached to, has been closed.
API-calls to the engine are no longer possible. A new entity has been created and is fully initialized. An existing entity is suspended. The suspended entity is contained in the event. An existing entity is activated. The activated entity is contained in the event. A job has been executed successfully. The event contains the job that was executed. The execution of a job has failed. The event contains the job that was executed and the exception.
The number of job retries have been decremented due to a failed job. The event contains the job that was updated. A job has been canceled. The event contains the job that was canceled.
Job can be canceled by API call, task was completed and associated boundary timer was canceled, on the new process definition deployment.
An activity is going to be cancelled. An activity received a message. Dispatched before the activity receives the message. An activity has received an error event. Dispatched before the actual error has been handled by the activity. An uncaught BPMN error has been thrown. The process did not have any handlers for that specific error.
An activity is about to be compensated. The event contains the id of the activity that is will be executed for compensation. A variable has been created. The event contains the variable name, value and related execution and task if any.
An existing variable has been updated. The event contains the variable name, updated value and related execution and task if any. An existing variable has been deleted. The event contains the variable name, last known value and related execution and task if any. A task has been created.
In case the task is part of a process, this event will be fired before the task listeners are executed. A task has been completed. A process has been completed. Process is completed when it reaches state in which process instance does not have any transition to take. A process has been cancelled. Dispatched before the process instance is deleted from runtime. A user has been added to a group. The event contains the ids of the user and group involved. A user has been removed from a group.
All members will be removed from a group. The event is thrown before the members are removed, so they are still accessible. The list below show an overview of what entity-events are dispatched for which entities:. Only listeners are notified in the engine the events are dispatched from. So in case you have different engines - running against the same database - only events that originated in the engine the listener is registered for, are dispatched to that listener.
The events that occur in the other engine are not dispatched to the listeners, regardless of the fact they are running in the same JVM or not. Certain event-types related to entities expose the targeted entity. Depending on the type or event, these entities cannot be updated anymore e. If possible, use the EngineServices exposed by the event to interact in a safe way with the engine. No entity-events are dispatched related to history, as they all have a runtime-counterpart which have their events dispatched.
The engine API is the most common way of interacting with Activiti. The central starting point is the ProcessEngine , which can be created in several ways as described in the configuration section. ProcessEngine and the services objects are thread safe.
So you can keep a reference to 1 of those for a whole server. Proper creation and closing of all process engines can be done with ProcessEngines. The ProcessEngines class will scan for all activiti. For all activiti. For all activiti-context. All services are stateless. This means that you can easily run Activiti on multiple nodes in a cluster, each going to the same database, without having to worry about which machine actually executed previous calls.
Any call to any service is idempotent regardless of where it is executed. The RepositoryService is probably the first service needed when working with the Activiti engine.
This service offers operations for managing and manipulating deployments and process definitions. It is a representation of the structure and behaviour of each of the steps of a process. A deployment is the unit of packaging within the Activiti engine. A deployment can contain multiple BPMN 2. The choice of what is included in one deployment is up to the developer.
It can range from a single process BPMN 2. The RepositoryService allows to deploy such packages. Deploying a deployment means it is uploaded to the engine, where all processes are inspected and parsed before being stored in the database. From that point on, the deployment is known to the system and any process included in the deployment can now be started.
Suspend and activate deployments as a whole or specific process definitions. Suspending means no further operations can be done on them, while activation is the opposite operation. Retrieve various resources such as files contained within the deployment or process diagrams that were auto generated by the engine.
Retrieve a POJO version of the process definition which can be used to introspect the process using Java rather than xml. While the RepositoryService is rather about static information i. It deals with starting new process instances of process definitions. As said above, a process definition defines the structure and behaviour of the different steps in a process. A process instance is one execution of such a process definition. For each process definition there typically are many instances running at the same time.
The RuntimeService also is the service which is used to retrieve and store process variables. This is data which is specific to the given process instance and can be used by various constructs in the process e. The Runtimeservice also allows to query on process instances and executions. Executions are a representation of the 'token' concept of BPMN 2.
Basically an execution is a pointer pointing to where the process instance currently is. Lastly, the RuntimeService is used whenever a process instance is waiting for an external trigger and the process needs to be continued. A process instance can have various wait states and this service contains various operations to signal the instance that the external trigger is received and the process instance can be continued. Tasks that need to be performed by actual human users of the system are core to a BPM engine such as Activiti.
Everything around tasks is grouped in the TaskService , such as. Creating new standalone tasks. These are tasks that are not related to a process instances. Manipulating to which user a task is assigned or which users are in some way involved with the task.
Claiming and completing a task. Claiming means that someone decided to be the assignee for the task, meaning that this user will complete the task. Completing means doing the work of the tasks. Typically this is filling in a form of sorts. The IdentityService is pretty simple. For example, a task could be assigned to any user, but the engine does not verify if that user is known to the system.
The FormService is an optional service. Meaning that Activiti can perfectly be used without it, without sacrificing any functionality. This service introduces the concept of a start form and a task form. A start form is a form that is shown to the user before the process instance is started, while a task form is the form that is displayed when a user wants to complete a form.
Activiti allows to define these forms in the BPMN 2. This service exposes this data in an easy way to work with. The HistoryService exposes all historical data gathered by the Activiti engine. When executing processes, a lot of data can be kept by the engine this is configurable such as process instance start times, who did which tasks, how long it took to complete the tasks, which path was followed in each process instance, etc.
This service exposes mainly query capabilities to access this data. The ManagementService is typically not needed when coding custom application using Activiti. It allows to retrieve information about the database tables and table metadata. Furthermore, it exposes query capabilities and management operations for jobs.
Later on, these topics will be discussed in more detail. The DynamicBpmnService can be used to change part of the process definition without needing to redeploy it. You can for example change the assignee definition for a user task in a process definition, or change the class name of a service task. For more detailed information on the service operations and the engine API, see the javadocs.
The base exception in Activiti is the org. ActivitiException , an unchecked exception. This exception can be thrown at all times by the API, but expected exceptions that happen in specific methods are documented in the the javadocs. For example, an extract from TaskService :. In the example above, when an id is passed for which no task exists, an exception will be thrown.
Also, since the javadoc explicitly states that taskId cannot be null, an ActivitiIllegalArgumentException will be thrown when null is passed. Even though we want to avoid a big exception hierarchy, the following subclasses were added which are thrown in specific cases. ActivitiWrongDbException : Thrown when the Activiti engine discovers a mismatch between the database schema version and the engine version.
ActivitiOptimisticLockingException : Thrown when an optimistic locking occurs in the data store caused by concurrent access of the same data entry. ActivitiClassLoadingException : Thrown when a class requested to load was not found or when an error occurred while loading it e. ActivitiObjectNotFoundException : Thrown when an object that is requested or action on does not exist.
As described above, the way to interact with the Activiti engine is through the services exposed by an instance of the org. ProcessEngine class. The following code snippets assume you have a working Activiti environment, i. If you simply want to try out the code below, you can download or clone the Activiti unit test template , import it in your IDE and add a testUserguideCode method to the org.
MyUnitTest unit test. The end goal of this little tutorial will be to have a working business process which mimics a simplistic vacation request process at a company:. Everything that is related to static data such as process definitions are accessed through the RepositoryService. Conceptually, every such static piece of data is content of the repository of the Activiti engine.
Create a new xml file VacationRequest. Please read the BPMN 2. To make this process known to the Activiti engine, we must deploy it first. Deploying means that the engine will parse the BPMN 2. This way, when the engine reboots, it will still know all of the deployed processes:. After deploying the process definition to the Activiti engine, we can start new process instances from it.
For each process definition, there are typically many process instances. The process definition is the blueprint , while a process instance is a runtime execution of it. Everything related to the runtime state of processes can be found in the RuntimeService.
There are various way to start a new process instance. In the following snippet, we use the key we defined in the process definition xml to start the process instance.
Process variables are commonly used because they give meaning to the process instances for a certain process definition. Typically, the process variables are what make process instances differ from one another.
When the process starts, the first step will be a user task. This is a step that must be performed by a user of the system. Typically, such a user will have an inbox of tasks which lists all the tasks that need to be done by this user. Following code snippet shows how such a query might be performed:.
To continue the process instance, we need to finish this task. For the Activiti engine, this means you need to complete the task. Following snippet shows how this is done:. The process instance will now continue to the next step. In this example, the next step allows the employee to complete a form that adjusts their original vacation request. The employee can resubmit the vacation request which will cause the process to loop back to the start task.
Suspending the process definition is done through the RepositoryService :. To reactivate a process definition, simply call one of the repositoryService. When suspended, the process cannot be continued e. Suspending a process instance can be done by calling the runtimeService. Activating the process instance again is done by calling the runtimeService. We will expand these sections further in the future with additional coverage of the Activiti API.
Of course, as with any open source project, the best way to learn is to inspect the code and read the Javadocs! There are two ways of querying data from the engine: The query API and native queries. You can add various conditions to your queries all of which are applied together as a logical AND and precisely one ordering. The following code shows an example:.
Sometimes you need more powerful queries, e. For these cases, we introduced native queries, which allow you to write your own SQL queries. The return type is defined by the Query object you use and the data is mapped into the correct objects, e. Since the query will be fired at the database you have to use table and column names as they are defined in the database; this requires some knowledge about the internal data structure and it is recommended to use native queries with care.
The table names can be retrieved via the API to keep the dependency as small as possible. Every process instance needs and uses data to execute the steps it exists of. In Activiti, this data is called variables , which are stored in the database. Variables can be used in expressions for example to select the correct outgoing sequence flow in an exclusive gateway , in java service tasks when calling external services for example to provide the input or store the result of the service call , etc.
A process instance can have variables called process variables , but also executions which are specific pointers to where the process is active and user tasks can have variables. A process instance can have any number of variables. Any of the startProcessInstanceXXX methods have an optional parameters to provide the variables when the process instance is created and started.
For example, from the RuntimeService :. Note that variables can be set local for a given execution remember a process instance consists of a tree of executions.
The variable will only be visible on that execution, and not higher in the tree of executions. Variables can also be fetched again, as shown below.
Note that similar methods exist on the TaskService. This means that tasks, like executions, can have local variables that are alive just for the duration of the task. Variables are often used in Java delegates , expressions , execution- or tasklisteners, scripts, etc. The simplest methods are these:. For historical and backwards compatible reasons , when doing any of the calls above, behind the scenes actually all variables will be fetched from the database. This means that if you have 10 variables, and only get one through getVariable "myVariable" , behind the scenes the other 9 will be fetched and cached.
This is not bad, as subsequent calls will not hit the database again. For example, when your process definition has three sequential service tasks and thus one database transaction , using one call to fetch all variables in the first service task might be better then fetching the variables needed in each service task separately. Note that this applies both for getting and setting variables. Of course, when using a lot of variables or simply when you want tight control on the database query and traffic, this is not appropriate.
Since Activiti 5. When using true for the parameter fetchAllVariables , the behaviour will be exactly as described above: when getting or setting a variable, all other variables will be fetched and cached. However, when using false as value, a specific query will be used and no other variables will be fetched nor cached.
Only the value of the variable in question here will be cached for subsequent use. Transient variables are variables that behave like regular variables, but are not persisted. Typically, transient variables are used for advanced use cases i. Like regular variables, transient variables are put on the highest parent when set.
This means that when setting a variable on an execution, the transient variable is actually stored on the process instance execution. Like regular variables, a local variant of the method exists if the variable should be set on the specific execution or task. A transient variable can only be accessed until the next wait state in the process definition.
After that, they are gone. The wait state means here the point in the process instance where it is persisted to the data store. Note that an async activity also is a wait state in this definition! Transient variables can only be set by the setTransientVariable name, value , but transient variables are also returned when calling getVariable name a getTransientVariable name also exists, that only checks the transient variables. The reason for this is to make the writing of expressions easy and existing logic using variables works for both types.
A transient variable shadows a persistent variable with the same name. This means that when both a persistent and transient variable is set on a process instance and the getVariable "someVariable" is used, the transient variable value will be returned.
Also, these config parameters are not important for historical audit purposes, so we pass them as transient variables:. Note that the variables will be available until the user task is reached and persisted to the database. For example, in the Additional Work user task they are not available anymore. The Process Data would get the response transient variable, parse it and store the relevant data in real process variables as we need them later.
The condition on the sequence flow leaving the exclusive gateway are oblivious to whether persistent or transient variables are used in this case the status transient variable :. Activiti uses UEL for expression-resolving. Although there are 2 types of expressions, value-expression and method-expression, Activiti abstracts this so they can both be used where an expression is needed.
Value expression : resolves to a value. By default, all process variables are available to use. Also all spring-beans if using Spring are available to use in expressions. Some examples:. Method expression : invokes a method, with or without parameters. When invoking a method without parameters, be sure to add empty parentheses after the method-name as this distinguishes the expression from a value expression.
The passed parameters can be literal values or expressions that are resolved themselves. Note that these expressions support resolving primitives incl. On top of all process variables, there are a few default objects available to be used in expressions:. Note: Only works in expressions evaluated from task listeners. If no user is authenticated, the variable is not available.
Business processes are an integral part of software projects and they should be tested in the same way normal application logic is tested: with unit tests. Since Activiti is an embeddable Java engine, writing unit tests for business processes is as simple as writing regular unit tests. Activiti supports both JUnit versions 3 and 4 styles of unit testing.
In the JUnit 3 style, the org. ActivitiTestCase must be extended. This will make the ProcessEngine and the services available through protected member fields. In the setup of the test, the processEngine will be initialized by default with the activiti. To specify a different configuration file, override the getConfigurationResource method. Process engines are cached statically over multiple unit tests when the configuration resource is the same.
By extending ActivitiTestCase , you can annotate test methods with org. Before the test is run, a resource file of the form testClassName. At the end of the test, the deployment will be deleted, including all related process instances, tasks, etc. The Deployment annotation also supports setting the resource location explicitly. See the class itself for more information. To get the same functionality when using the JUnit 4 style of writing unit tests, the org. ActivitiRule Rule must be used.
Through this rule, the process engine and services are available through getters. As with the ActivitiTestCase see above , including this Rule will enable the use of the org. Deployment annotation see above for an explanation of its use and configuration and it will look for the default configuration file on the classpath. Process engines are statically cached over multiple unit tests when using the same configuration resource.
The following code snippet shows an example of using the JUnit 4 style of testing and the usage of the ActivitiRule. When using the in-memory H2 database for unit tests, the following instructions allow to easily inspect the data in the Activiti database during a debugging session. The screenshots here are taken in Eclipse, but the mechanism should be similar for other IDEs.
Suppose we have put a breakpoint somewhere in our unit test. In Eclipse this is done by double-clicking in the left border next to the code:.
If we now run the unit test in debug mode right-click in test class, select Run as and then JUnit test , the test execution halts at our breakpoint, where we can now inspect the variables of our test as shown in the right upper panel. Now select Display or execute the shortcut instead of right-clicking. You can now see the Activiti data and use it to understand how and why your unit test is executing your process in a certain way.
The ProcessEngine is a thread-safe class and can easily be shared among multiple threads. In a web application, this means it is possible to create the process engine once when the container boots and shut down the engine when the container goes down. The following code snippet shows how you can write a simple ServletContextListener to initialize and destroy process engines in a plain Servlet environment:. The contextInitialized method will delegate to ProcessEngines. That will look for activiti.
If you have multiple such resource files on the classpath, make sure they all have different names. When the process engine is needed, it can be fetched using. Of course, it is also possible to use any of the variants of creating a process engine, as described in the configuration section.
The contextDestroyed method of the context-listener delegates to ProcessEngines. That will properly close all initialized process engines. The ProcessEngine can be configured as a regular Spring bean. The starting point of the integration is the class org.
That bean takes a process engine configuration and creates the process engine. This means that the creation and configuration of properties for Spring is the same as documented in the configuration section. For Spring integration the configuration and engine beans will look like this:.
Note that the processEngineConfiguration bean now uses the org. SpringProcessEngineConfiguration class. Below is the Spring configuration file that we use in this example you can find it in SpringTransactionIntegrationTest-context. The section shown below contains the dataSource, transactionManager, processEngine and the Activiti Engine services. This is done to make sure the SQL connections retrieved from the DataSource and the Spring transactions play well together.
In this case no additional wrapping will occur. First the application context is created with any of the Spring ways to do that. In this example you could use a classpath XML resource to configure our Spring application context:. Then we can get the service beans and invoke methods on them.
The ProcessEngineFactoryBean will have added an extra interceptor to the services that applies Propagation. So, for example, we can use the repositoryService to deploy a process like this:. The other way around also works. In this case, the Spring transaction will be around the userBean. The UserBean looks like this. Remember from above in the Spring bean configuration we injected the repositoryService into the userBean.
How To Pattern Fill with Affinity Designer.
I recommend watching this video before moving on to the other tutorials showcased here. Serif also has a more extensive collection of tutorials that cover specific tools and features.
There is an excellent series of tutorials from the YouTube channel Detour Shirts. These videos were created specifically for anyone who is new to Affinity Designer. Each one is between 15 — 25 minutes long. There are a lot of ways you could use the techniques covered in this video. This video covers the process of creating an awesome vector illustration from scratch. This is a long almost two hours in-depth tutorial that walks through the entire process of creating this character rendering.
If you really want to learn and master the techniques, the tutorial is worth the time. Learn how to create this awesome wallpaper illustration. Here is a great wallpaper design tutorial that features nature and silhouettes. You can use the same techniques to create a variety of different nature-inspired scenes and designs. This minute character design tutorial is ideal for someone who has a little bit of experience with the software.
This text-based tutorial shows how to create a simple and fun character illustration. You can apply these techniques to your own designs by getting creative. In less than 20 minutes, you can follow along and learn how to create a deer logo.
Emojis seem to be everywhere these days, so why not create your own? This is an icon that could prove to be used in a lot of different projects and applications. Use simple shapes to create this back to school icon. Again, this is a good tutorial for anyone who is new to the software. This is excellent for anyone who sells stock graphics as a way to generate passive income.
Of course, you could take the concepts from this tutorial and adapt the specifics to create a unique design or a different style of car or vehicle. If you design graphics to be sold at stock marketplaces, the vector illustration created in this tutorial is the style of something you could design specifically to upload to stock sites. Here is a tutorial for a totally different style of character design. Affinity Designer can also be used for print design projects. Mandalas can be used for a lot of different purposes, including uploading at stock marketplaces as a way to make money with your design skills.
This video tutorial shows how to create your own unique mandalas in Affinity Designer. Patterns are extremely useful, both in your own projects and as a stock resource to sell. Of course, as with any open source project, the best way to learn is to inspect the code and read the Javadocs! There are two ways of querying data from the engine: The query API and native queries. You can add various conditions to your queries all of which are applied together as a logical AND and precisely one ordering.
The following code shows an example:. Sometimes you need more powerful queries, e. For these cases, we introduced native queries, which allow you to write your own SQL queries. The return type is defined by the Query object you use and the data is mapped into the correct objects, e.
Since the query will be fired at the database you have to use table and column names as they are defined in the database; this requires some knowledge about the internal data structure and it is recommended to use native queries with care. The table names can be retrieved via the API to keep the dependency as small as possible.
Every process instance needs and uses data to execute the steps it exists of. In Activiti, this data is called variables , which are stored in the database. Variables can be used in expressions for example to select the correct outgoing sequence flow in an exclusive gateway , in java service tasks when calling external services for example to provide the input or store the result of the service call , etc. A process instance can have variables called process variables , but also executions which are specific pointers to where the process is active and user tasks can have variables.
A process instance can have any number of variables. Any of the startProcessInstanceXXX methods have an optional parameters to provide the variables when the process instance is created and started. For example, from the RuntimeService :. Note that variables can be set local for a given execution remember a process instance consists of a tree of executions. The variable will only be visible on that execution, and not higher in the tree of executions.
Variables can also be fetched again, as shown below. Note that similar methods exist on the TaskService. This means that tasks, like executions, can have local variables that are alive just for the duration of the task.
Variables are often used in Java delegates , expressions , execution- or tasklisteners, scripts, etc. The simplest methods are these:. For historical and backwards compatible reasons , when doing any of the calls above, behind the scenes actually all variables will be fetched from the database. This means that if you have 10 variables, and only get one through getVariable "myVariable" , behind the scenes the other 9 will be fetched and cached. This is not bad, as subsequent calls will not hit the database again.
For example, when your process definition has three sequential service tasks and thus one database transaction , using one call to fetch all variables in the first service task might be better then fetching the variables needed in each service task separately.
Note that this applies both for getting and setting variables. Of course, when using a lot of variables or simply when you want tight control on the database query and traffic, this is not appropriate. Since Activiti 5. When using true for the parameter fetchAllVariables , the behaviour will be exactly as described above: when getting or setting a variable, all other variables will be fetched and cached.
However, when using false as value, a specific query will be used and no other variables will be fetched nor cached. Only the value of the variable in question here will be cached for subsequent use. Transient variables are variables that behave like regular variables, but are not persisted. Typically, transient variables are used for advanced use cases i.
Like regular variables, transient variables are put on the highest parent when set. This means that when setting a variable on an execution, the transient variable is actually stored on the process instance execution. Like regular variables, a local variant of the method exists if the variable should be set on the specific execution or task. A transient variable can only be accessed until the next wait state in the process definition.
After that, they are gone. The wait state means here the point in the process instance where it is persisted to the data store. Note that an async activity also is a wait state in this definition! Transient variables can only be set by the setTransientVariable name, value , but transient variables are also returned when calling getVariable name a getTransientVariable name also exists, that only checks the transient variables.
The reason for this is to make the writing of expressions easy and existing logic using variables works for both types. A transient variable shadows a persistent variable with the same name. This means that when both a persistent and transient variable is set on a process instance and the getVariable "someVariable" is used, the transient variable value will be returned. Also, these config parameters are not important for historical audit purposes, so we pass them as transient variables:.
Note that the variables will be available until the user task is reached and persisted to the database. For example, in the Additional Work user task they are not available anymore. The Process Data would get the response transient variable, parse it and store the relevant data in real process variables as we need them later.
The condition on the sequence flow leaving the exclusive gateway are oblivious to whether persistent or transient variables are used in this case the status transient variable :. Activiti uses UEL for expression-resolving. Although there are 2 types of expressions, value-expression and method-expression, Activiti abstracts this so they can both be used where an expression is needed.
Value expression : resolves to a value. By default, all process variables are available to use. Also all spring-beans if using Spring are available to use in expressions. Some examples:. Method expression : invokes a method, with or without parameters. When invoking a method without parameters, be sure to add empty parentheses after the method-name as this distinguishes the expression from a value expression.
The passed parameters can be literal values or expressions that are resolved themselves. Note that these expressions support resolving primitives incl. On top of all process variables, there are a few default objects available to be used in expressions:. Note: Only works in expressions evaluated from task listeners. If no user is authenticated, the variable is not available. Business processes are an integral part of software projects and they should be tested in the same way normal application logic is tested: with unit tests.
Since Activiti is an embeddable Java engine, writing unit tests for business processes is as simple as writing regular unit tests. Activiti supports both JUnit versions 3 and 4 styles of unit testing.
In the JUnit 3 style, the org. ActivitiTestCase must be extended. This will make the ProcessEngine and the services available through protected member fields. In the setup of the test, the processEngine will be initialized by default with the activiti.
To specify a different configuration file, override the getConfigurationResource method. Process engines are cached statically over multiple unit tests when the configuration resource is the same. By extending ActivitiTestCase , you can annotate test methods with org. Before the test is run, a resource file of the form testClassName. At the end of the test, the deployment will be deleted, including all related process instances, tasks, etc.
The Deployment annotation also supports setting the resource location explicitly. See the class itself for more information. To get the same functionality when using the JUnit 4 style of writing unit tests, the org. ActivitiRule Rule must be used.
Through this rule, the process engine and services are available through getters. As with the ActivitiTestCase see above , including this Rule will enable the use of the org. Deployment annotation see above for an explanation of its use and configuration and it will look for the default configuration file on the classpath.
Process engines are statically cached over multiple unit tests when using the same configuration resource. The following code snippet shows an example of using the JUnit 4 style of testing and the usage of the ActivitiRule. When using the in-memory H2 database for unit tests, the following instructions allow to easily inspect the data in the Activiti database during a debugging session. The screenshots here are taken in Eclipse, but the mechanism should be similar for other IDEs.
Suppose we have put a breakpoint somewhere in our unit test. In Eclipse this is done by double-clicking in the left border next to the code:. If we now run the unit test in debug mode right-click in test class, select Run as and then JUnit test , the test execution halts at our breakpoint, where we can now inspect the variables of our test as shown in the right upper panel. Now select Display or execute the shortcut instead of right-clicking.
You can now see the Activiti data and use it to understand how and why your unit test is executing your process in a certain way. The ProcessEngine is a thread-safe class and can easily be shared among multiple threads. In a web application, this means it is possible to create the process engine once when the container boots and shut down the engine when the container goes down.
The following code snippet shows how you can write a simple ServletContextListener to initialize and destroy process engines in a plain Servlet environment:. The contextInitialized method will delegate to ProcessEngines. That will look for activiti. If you have multiple such resource files on the classpath, make sure they all have different names. When the process engine is needed, it can be fetched using. Of course, it is also possible to use any of the variants of creating a process engine, as described in the configuration section.
The contextDestroyed method of the context-listener delegates to ProcessEngines. That will properly close all initialized process engines. The ProcessEngine can be configured as a regular Spring bean.
The starting point of the integration is the class org. That bean takes a process engine configuration and creates the process engine. This means that the creation and configuration of properties for Spring is the same as documented in the configuration section. For Spring integration the configuration and engine beans will look like this:. Note that the processEngineConfiguration bean now uses the org.
SpringProcessEngineConfiguration class. Below is the Spring configuration file that we use in this example you can find it in SpringTransactionIntegrationTest-context. The section shown below contains the dataSource, transactionManager, processEngine and the Activiti Engine services. This is done to make sure the SQL connections retrieved from the DataSource and the Spring transactions play well together.
In this case no additional wrapping will occur. First the application context is created with any of the Spring ways to do that. In this example you could use a classpath XML resource to configure our Spring application context:. Then we can get the service beans and invoke methods on them. The ProcessEngineFactoryBean will have added an extra interceptor to the services that applies Propagation. So, for example, we can use the repositoryService to deploy a process like this:.
The other way around also works. In this case, the Spring transaction will be around the userBean. The UserBean looks like this. Remember from above in the Spring bean configuration we injected the repositoryService into the userBean. The example below exposes a single bean printer , available to use under the key "printer". When no beans property is set, all Spring beans in the context will be available.
Now the exposed beans can be used in expressions: for example, the SpringTransactionIntegrationTest hello. Spring integration also has a special feature for deploying resources. In the process engine configuration, you can specify a set of resources. When the process engine is created, all those resources will be scanned and deployed.
There is filtering in place that prevents duplicate deployments. Only when the resources actually have changed, will new deployments be deployed to the Activiti DB. This makes sense in a lot of use case, where the Spring container is rebooted often e. By default, the configuration above will group all of the resources matching the filtering into a single deployment to the Activiti engine.
The duplicate filtering to prevent re-deployment of unchanged resources applies to the whole deployment. In some cases, this may not be what you want. For instance, if you deploy a set of process resources this way and only a single process definition in those resources has changed, the deployment as a whole will be considered new and all of the process definitions in that deployment will be re-deployed, resulting in new versions of each of the process definitions, even though only one was actually changed.
To be able to customize the way deployments are determined, you can specify an additional property in the SpringProcessEngineConfiguration , deploymentMode. This property defines the way deployments will be determined from the set of resources that match the filter. There are 3 values that are supported by default for this property:. This is the value you would use to have each process definition be deployed separately and only create a new process definition version if it has changed.
This value can be used to create separate deployments for most resources, but still be able to group some by placing them in a shared folder. In addition to using the values listed above for deploymentMode , you may require customized behavior towards determining deployments.
This method determines which deployment strategy is used for a certain value of the deploymentMode configuration. When integrating with Spring, business processes can be tested very easily using the standard Activiti testing facilities.
The following example shows how a business process is tested in a typical Spring-based unit test:. Note that for this to work, you need to define a org.
ActivitiRule bean in the Spring configuration which is injected by auto-wiring in the example above. When using Hibernate 4. This is not needed for Hibernate 4. The following dependency should be added:. Spring Boot is an application framework which, according to its website , makes it easy to create stand-alone, production-grade Spring based Applications that can you can "just run". It takes an opinionated view of the Spring platform and third-party libraries so you can get started with minimum fuss.
Most Spring Boot applications need very little Spring configuration. The Spring Boot - Activiti integration is currently experimental. It has been developer together with Spring committers, but it is still early days. We welcome all to try it out and provide feedback.
Spring Boot is all about convention over configuration. To get started, simply add the spring-boot-starters-basic dependency to your project.
For example for Maven:. This dependency will transitively add the correct Activiti and Spring dependencies to the classpath. You can now write the Spring Boot application:. Activiti needs a database to store its data. If you would run the code above, it would give you an informative exception message that you need to add a database driver dependency to the classpath.
For now, add the H2 database dependency:. So by just adding the dependency to the classpath and using the EnableAutoConfiguration annotation a lot has happened behind the scenes:. An in-memory datasource is created automatically since the H2 driver is on the classpath and passed to the Activiti process engine configuration.
Also, any BPMN 2. Create a folder processes and add a dummy process definition named one-task-process. Also add following code lines to test if the deployment actually worked. The CommandLineRunner is a special kind of Spring bean that is executed when the application boots:. As stated above, Spring Boot is about convention over configuration. By default, by having only H2 on the classpath, it created an in memory datasource and passed that to the Activiti process engine configuration.
To change the datasource, simply override the default by providing a Datasource bean. For example, to switch to a MySQL database:. Spring Boot makes this really easy. Add following dependency to the classpath:. Create a new class, a Spring service, and create two methods: one to start our process and one to get a task list for a given assignee.
Here, we simply delegate to the service defined above. Both the Service and the RestController will be found by the automatic component scan ComponentScan we added to our application class.
Run the application class again. This will add in the Spring configuration and beans for using JPA. By default the JPA provider will be Hibernate. Create a file application. We add the method to find a Person by username. Spring will automagically implement this based on conventions i. The startProcess now gets an assignee username in, which is used to look up the Person, and put the Person JPA object as a process variable in the process instance. A method to create Dummy users is added. This is used in the CommandLineRunner to populate the database.
And there is a lot more to the Spring Boot integration:. To deploy processes, they have to be wrapped in a business archive. A business archive is the unit of deployment to an Activiti Engine. A business archive is equivalent to a zip file. It can contain BPMN 2. In general, a business archive contains a collection of named resources. When a business archive is deployed, it is scanned for BPMN files with a. Each of those will be parsed and may contain multiple process definitions.
Java classes present in the business archive will not be added to the classpath. All custom classes used in process definitions in the business archive for example Java service tasks or event listener implementations should be present on the Activiti Engine classpath in order to run the processes.
See the javadocs for more details. Process definitions live in the Activiti database. These process definitions can reference delegation classes when using Service Tasks or execution listeners or Spring beans from the Activiti configuration file. These classes and the Spring configuration file have to be available to all process engines that may execute the process definitions.
All custom classes that are used in your process e. When you are using the demo setup and you want to add your custom classes, you should add a jar containing your classes to the activiti-explorer or activiti-rest webapp lib.
When expressions or scripts use Spring beans, those beans have to be available to the engine when executing the process definition. If you are building your own webapp and you configure your process engine in your context as described in the spring integration section , that is straightforward.
But bear in mind that you also should update the Activiti rest webapp with that context if you use it. You can do that by replacing the activiti.
Instead of making sure that all process engines have all the delegation classes on their classpath and use the right Spring configuration, you may consider including the Activiti rest webapp inside your own webapp so that there is only a single ProcessEngine. That is actually good because the executable BPMN process file will probably live in a version control system repository e. Subversion, Git or Mercurial as part of your development project. Versions of process definitions are created during deployment.
For each process definition in a business archive the following steps are performed to initialize the properties key , version , name and id :. The process definition id attribute in the XML file is used as the process definition key property. The process definition name attribute in the XML file is used as the process definition name property.
If the name attribute is not specified, then id attribute is used as the name. The first time a process with a particular key is deployed, version 1 is assigned. For all subsequent deployments of process definitions with the same key, the version will be set 1 higher than the maximum currently deployed version.
The key property is used to distinguish process definitions. When deploying this process definition, the process definition in the database will look like this:. Suppose we now deploy an updated version of the same process e. The process definition table will now contain the following entries:. When the runtimeService. Should we create a second process, as defined below and deploy this to Activiti, a third row will be added to the table.
Note how the key for the new process is different from our first process. Even though the name is the same we should probably have changed that too , Activiti only considers the id attribute when distinguishing processes. The new process is therefore deployed with version 1. A process diagram image can be added to a deployment. This image will be stored in the Activiti repository and is accessible through the API. This image is also used to visualize the process in Activiti Explorer.
The following naming conventions for the process diagram image apply in this specific order :. If an image resource exists in the deployment that has a name of the BPMN 2. In case you have multiple images defined in one BPMN 2.
Each diagram image will then have the process key in its file name. If no such image exists, am image resource in the deployment matching the name of the BPMN 2. Note that this means that every process definition defined in the same BPMN 2. In case there is only one process definition in each BPMN 2. In case no image is provided in the deployment, as described in the previous section , the Activiti engine will generate a diagram image if the process definition contains the necessary diagram interchange information.
The resource can be retrieved in exactly the same way as when an image is provided in the deployment. If, for some reason, it is not necessary or wanted to generate a diagram during deployment the isCreateDiagramOnDeploy property can be set on the process engine configuration:. Both deployments and process definitions have user defined categories. This introduction is written under the assumption you are using the Eclipse IDE to create and edit files. Very little of this is specific to Eclipse, however.
Make sure that the file ends with. The root element of the BPMN 2. Within this element, multiple process definitions can be defined although we advise to have only one process definition in each file, since this simplifies maintenance later in the development process.
An empty process definition looks as listed below. Note that the minimal definitions element only needs the xmlns and targetNamespace declaration. The targetNamespace can be anything, and is useful for categorizing process definitions. Optionally you can also add the online schema location of the BPMN 2.
This id can then be used to start a new process instance of the process definition, through the startProcessInstanceByKey method on the RuntimeService. This method will always take the latest deployed version of the process definition. Important to note here is that this is not the same as calling the startProcessInstanceById method. This method expects the String id that was generated at deploy time by the Activiti engine, and can be retrieved by calling the processDefinition.
The format of the generated id is key:version , and the length is constrained to 64 characters. If you get an ActivitiException stating that the generated id is too long, limit the text in the key field of the process. In this section we will cover a very simple business process that we will use to introduce some basic Activiti concepts and the Activiti API. This tutorial assumes that you have the Activiti demo setup running , and that you are using a standalone H2 server.
Edit db. The end result will be a simple Java SE program that deploys a process definition, and interacts with this process through the Activiti engine API. In BPMCorp, a financial report needs to be written every month for the company shareholders.
This is the responsibility of the accountancy department. When the report is finished, one of the members of the upper management needs to approve the document before it is sent to all the shareholders. The business process as described above can be graphically visualized using the Activiti Designer. The graphical BPMN 2. What we see is a none Start Event circle on the left , followed by two User Tasks : 'Write monthly financial report' and 'Verify monthly financial report' , ending in a none end event circle with thick border on the right.
The none start event tells us what the entry point to the process is. The User Tasks declarations are the representation of the human tasks of our process. Note that the first task is assigned to the accountancy group, while the second task is assigned to the management group.
See the section on user task assignment for more information on how users and groups can be assigned to user tasks. The elements are connected with each other through sequence flows. These sequence flows have a source and target , defining the direction of the sequence flow. We have now created the process definition of our business process. From such a process definition, we can create process instances.
In this case, one process instance would match with the creation and verification of a single financial report for a particular month. All the process instances share the same process definition. To be able to create process instances from a given process definition, we must first deploy this process definition. Deploying a process definition means two things:.
The process definition will be stored in the persistent datastore that is configured for your Activiti engine. So by deploying our business process, we make sure that the engine will find the process definition after an engine reboot.
The BPMN 2. More information on deployment can be found in the dedicated section on deployment. As described in that section, deployment can happen in several ways. One way is through the API as follows. Note that all interaction with the Activiti engine happens through its services. Now we can start a new process instance using the id we defined in the process definition see process element in the XML file.
Note that this id in Activiti terminology is called the key. This will create a process instance that will first go through the start event. After the start event, it follows all the outgoing sequence flows only one in this case and the first task write monthly financial report is reached.
The Activiti engine will now store a task in the persistent database. At this point, the user or group assignments attached to the task are resolved and also stored in the database. At such a wait state, the current state of the process instance is stored in the database. It remains in that state until a user decides to complete their task. At that point, the engine will continue until it reaches a new wait state or the end of the process.
When the engine reboots or crashes in the meantime, the state of the process is safe and well in the database. After the task is created, the startProcessInstanceByKey method will return since the user task activity is a wait state. In this case, the task is assigned to a group, which means that every member of the group is a candidate to perform the task. We can now throw this all together and create a simple Java program.
Create a new Eclipse project and add the Activiti JARs and dependencies to its classpath these can be found in the libs folder of the Activiti distribution. Before we can call the Activiti services, we must first construct a ProcessEngine that gives us access to the services. Here we use the 'standalone' configuration, which constructs a ProcessEngine that uses the database also used in the demo setup. You can download the process definition XML here.
This file contains the XML as shown above, but also contains the necessary BPMN diagram interchange information to visualize the process in the Activiti tools.
We can now retrieve this task through the TaskService by adding the following logic:. Note that the user we pass to this operation needs to be a member of the accountancy group, since that was declared in the process definition:.
We could also use the task query API to get the same results using the name of the group. We can now add the following logic to our code:. By default, no user is in the accountancy group.
Then click Users and add the group to fozzie. As explained, the process will execute up to the first user task. Select the Tasks page to view this new task. Note that even if the process was started by someone else, the task would still be visible as a candidate task to everyone in the accountancy group. An accountant now needs to claim the task. By claiming the task, the specific user will become the assignee of the task and the task will disappear from every task list of the other members of the accountancy group.
Claiming a task is programmatically done as follows:. In the Activiti UI App, clicking the claim button will call the same operation. The task will now move to the personal task list of the logged on user. You also see that the assignee of the task changed to the current logged in user. The accountant can now start working on the financial report. Once the report is finished, he can complete the task , which means that all work for that task is done.
For the Activiti engine, this is an external signal that the process instance execution must be continued. The task itself is removed from the runtime data. The single outgoing transition out of the task is followed, moving the execution to the second task 'verification of the report'.
The same mechanism as described for the first task will now be used to assign the second task, with the small difference that the task will be assigned to the management group. In the demo setup, completing the task is done by clicking the complete button in the task list. The second task is now visible in the unassigned task lists.
The verification task can be retrieved and claimed in exactly the same way as before. Completing this second task will move process execution to the end event, which finishes the process instance.
The process instance and all related runtime execution data are removed from the datastore. When you log into Activiti Explorer you can verify this, since no records will be found in the table where the process executions are stored. Programmatically, you can also verify that the process is ended using the historyService. Combine all the snippets from previous sections, and you should have something like this this code takes in account that you probably will have started a few process instances through the Activiti Explorer UI.
As such, it always retrieves a list of tasks instead of one task, so it always works :. However, as you are going through the BPMN 2. This way, a manager could reject the financial report which would recreate the task for the accountant.
Frameworks, and particularly open-source frameworks such as Activiti, can implement a solution that has the same and often better implemented ;- features as those of a big vendor. Due to the BPMN 2. The downside of a standard however, is the fact that it is always the result of many discussions and compromises between different companies and often visions.
As a developer reading the BPMN 2. Since Activiti puts ease of development as a top-priority, we introduced something called the Activiti BPMN extensions. These extensions are new constructs or ways to simplify certain constructs that are not in the BPMN 2. Although the BPMN 2. The prerequisite of such a custom extension is that there always must be a simple transformation to the standard way of doing things. When using a custom extension, this is always clearly indicated by giving the new XML element, attribute, etc.
So whether you want to use a custom extension or not, is completely up to you. Several factors will influence this decision graphical editor usage, company policy, etc. We only provide them since we believe that some points in the standard can be done simpler or more efficient. Who knows, some day your idea might pop up in the specification! Events are used to model something that happens during the lifetime process. Events are always visualized as a circle. In BPMN 2.
Catching: when process execution arrives in the event, it will wait for a trigger to happen. The type of trigger is defined by the inner icon or the type declaration in the XML. Catching events are visually differentiated from a throwing event by the inner icon that is not filled i.
Throwing: when process execution arrives in the event, a trigger is fired. Throwing events are visually differentiated from a catching event by the inner icon that is filled with black. Event definitions define the semantics of an event. Without an event definition, an event "does nothing special". For instance a start event without and event definition does not specify what exactly starts the process.
If we add an event definition to the start event like for instance a timer event definition we declare what "type" of event starts the process in the case of a timer event definition the fact that a certain point in time is reached. Timer events are events which are triggered by defined timer.
They can be used as start event , intermediate event or boundary event. The behavior of the time event depends on the business calendar used. Every timer event has a default business calendar, but the business calendar can also be defined on the timer event definition. Where businessCalendarName points to business calendar in process engine configuration. When business calendar is omitted default business calendars are used. This format specifies fixed date in ISO format, when trigger will be fired.
To specify how long the timer should run before it is fired, a timeDuration can be specified as sub-element of timerEventDefinition. Example interval lasting 10 days :. Specifies repeating interval, which can be useful for starting process periodically, or for sending multiple reminders for overdue user task. Time cycle element can be in two formats. First is the format of recurring time duration, as specified by ISO standard. Example 3 repeating intervals, each lasting 10 hours :.
When the endDate is reached the application will stop creating other jobs for this task. Additionally, you can specify time cycle using cron expressions, example below shows trigger firing every 5 minutes, starting at full hour:. Please see this tutorial for using cron expressions.
The recurring time duration is better suited for handling relative timers, which are calculated with respect to some particular point in time e. You can use expressions for the timer event definitions, by doing so you can influence the timer definition based on process variables. The process variables must contain the ISO or cron for cycle type string for appropriate timer type. Note: timers are only fired when the job or async executor is enabled i.
In fact, the two have nothing in common. BPMN error events are a way of modeling business exceptions. Java exceptions are handled in their own specific way.
Signal events are events which reference a named signal. A signal event definition is declared using the signalEventDefinition element. The attribute signalRef references a signal element declared as a child element of the definitions root element. The following is an excerpt of a process where a signal event is thrown and caught by intermediate events. The following methods on the org. RuntimeService can be used to throw a signal programmatically:.
The difference between signalEventReceived String signalName ; and signalEventReceived String signalName, String executionId ; is that the first method throws the signal globally to all subscribed handlers broadcast semantics and the second method delivers the signal to a specific execution only. We could then use the signalEventReceived String signalName, String executionId method to deliver the signal to these executions. By default, signals are broadcast process engine wide.
This means that you can throw a signal event in a process instance, and other process instances with different process definitions can react on the occurrence of this event. However, sometimes it is wanted to react to a signal event only within the same process instance.
A use case for example is a synchronization mechanism in the process instance, if two or more activities are mutually exclusive. To restrict the scope of the signal event, add the non-BPMN 2. The following is an example of two separate processes communicating using signals. The first process is started if an insurance policy is updated or changed.
After the changes have been reviewed by a human participant, a signal event is thrown, signaling that a policy has changed:. This event can now be caught by all process instances which are interested. The following is an example of a process subscribing to the event. Note: it is important to understand that a signal event is broadcast to all active handlers.
This means in the case of the example given above, that all instances of the process catching the signal would receive the event. In this case this is what we want.
However, there are also situations where the broadcast behavior is unintended. Consider the following process:. The pattern described in the process above is not supported by BPMN. The idea is that the error thrown while performing the "do something" task is caught by the boundary error event and would be propagated to the parallel path of execution using the signal throw event and then interrupt the "do something in parallel" task.
So far Activiti would perform as expected. The signal would be propagated to the catching boundary event and interrupt the task. However, due to the broadcast semantics of the signal, it would also be propagated to all other process instances which have subscribed to the signal event.
In this case, this might not be what we want. Note: the signal event does not perform any kind of correlation to a specific process instance. On the contrary, it is broadcast to all process instances. If you need to deliver a signal to a specific process instance only, perform correlation manually and use signalEventReceived String signalName, String executionId and the appropriate query mechanisms.
Activiti does have a way to fix this, by adding the scope attribute to the signal event and set it to processInstance. Message events are events which reference a named message.
A message has a name and a payload. Unlike a signal, a message event is always directed at a single receiver. A message event definition is declared using the messageEventDefinition element. The attribute messageRef references a message element declared as a child element of the definitions root element.
The following is an excerpt of a process where two message events is declared and referenced by a start event and an intermediate catching message event.
As an embeddable process engine, Activiti is not concerned with actually receiving a message. The reception of messages is therefore something you have to implement as part of the application or infrastructure into which the process engine is embedded. After you have received a message inside your application, you must decide what to do with it. If the message should trigger the start of a new process instance, choose between the following methods offered by the runtime service:.
If the message needs to be received by an existing process instance, you first have to correlate the message to a specific process instance see next section and then trigger the continuation of the waiting execution. The runtime service offers the following methods for triggering an execution based on a message event subscription:.
In the case of a message start event, the message event subscription is associated with a particular process definition. Such message subscriptions can be queried using a ProcessDefinitionQuery :. Since there can only be one process definition for a specific message subscription, the query always returns zero or one results.
If a process definition is updated, only the newest version of the process definition has a subscription to the message event. In the case of an intermediate catch message event, the message event subscription is associated with a particular execution. Such message event subscriptions can be queried using a ExecutionQuery :. Such queries are called correlation queries and usually require knowledge about the processes in this case that there will be at most one process instance for a given orderId.
This is useful if the process needs alternative ways to react to different start events but eventually continues in a uniform way. A start event indicates where a process starts. The type of start event process starts on arrival of message, on specific time intervals, etc. In the XML representation, the type is given by the declaration of a sub-element.
Start events are always catching : conceptually the event is at any time waiting until a certain trigger happens. The authenticated user must be set with the method IdentityService.
This code is baked into the Activiti Explorer application. So it works in combination with Forms. A none start event technically means that the trigger for starting the process instance is unspecified. This means that the engine cannot anticipate when the process instance must be started. The XML representation of a none start event is the normal start event declaration, without any sub-element other start event types all have a sub-element declaring the type.
More information can be found in the forms section Example:. A timer start event is used to create process instance at given time. It can be used both for processes which should start only once and for processes that should start in specific time intervals. Note: a start timer event is scheduled as soon as process is deployed. Note: when a new version of a process with a start timer event is deployed, the job corresponding with the previous timer will be removed.
The reasoning is that normally it is not wanted to keep automatically starting new process instances of this old version of the process. The XML representation of a timer start event is the normal start event declaration, with timer definition sub-element.
Please refer to timer definitions for configuration details. A message start event can be used to start a process instance using a named message. This effectively allows us to select the right start event from a set of alternative start events using the message name. When deploying a process definition with one or more message start events, the following considerations apply:. The name of the message start event must be unique across a given process definition.
A process definition must not have multiple message start events with the same name. Activiti throws an exception upon deployment of a process definition such that two or more message start events reference the same message of if two or more message start events reference messages with the same message name. The name of the message start event must be unique across all deployed process definitions. Activiti throws an exception upon deployment of a process definition such that one or more message start events reference a message with the same name as a message start event already deployed by a different process definition.
Process versioning: Upon deployment of a new version of a process definition, the message subscriptions of the previous version are cancelled. This is also true for message events that are not present in the new version. When starting a process instance, a message start event can be triggered using the following methods on the RuntimeService :. The messageName is the name given in the name attribute of the message element referenced by the messageRef attribute of the messageEventDefinition.
The following considerations apply when starting a process instance:. Message start events are only supported on top-level processes. Message start events are not supported on embedded sub processes. If a process definition has multiple message start events, runtimeService. If a process definition has multiple message start events and a single none start event, runtimeService. If a process definition has multiple message start events and no none start event, runtimeService.
If a process definition has a single message start event, runtimeService. A message start event is visualized as a circle with a message event symbol. The symbol is unfilled, to visualize the catching receiving behavior. The XML representation of a message start event is the normal start event declaration with a messageEventDefinition child-element:.
A signal start event can be used to start a process instance using a named signal. The signal can be fired from within a process instance using the intermediary signal throw event or through the API runtimeService. In both cases, all process definitions that have a signal start event with the same name will be started.
Note that in both cases, it is also possible to choose between a synchronous and asynchronous starting of the process instances.
The signalName that must be passed in the API is the name given in the name attribute of the signal element referenced by the signalRef attribute of the signalEventDefinition. A signal start event is visualized as a circle with a signal event symbol. The XML representation of a signal start event is the normal start event declaration with a signalEventDefinition child-element:. An error start event can be used to trigger an Event Sub-Process. An error start event cannot be used for starting a process instance.
An error start event is visualized as a circle with an error event symbol. The XML representation of an error start event is the normal start event declaration with an errorEventDefinition child-element:. An end event signifies the end of a path of a sub process. An end event is always throwing. This means that when process execution arrives in the end event, a result is thrown. The type of result is depicted by the inner black icon of the event.
A none end event means that the result thrown when the event is reached is unspecified. As such, the engine will not do anything extra besides ending the current path of execution. A none end event is visualized as a circle with a thick border with no inner icon no result type.
The XML representation of a none end event is the normal end event declaration, without any sub-element other end event types all have a sub-element declaring the type. When process execution arrives in an error end event , the current path of execution is ended and an error is thrown.
This error can caught by a matching intermediate boundary error event. In case no matching boundary error event is found, an exception will be thrown.
An error end event is visualized as a typical end event circle with thick border , with the error icon inside. The error icon is completely black, to indicate the throwing semantics. And error end event is represented as an end event, with an errorEventDefinition child element.
