Service Registry Task
Introduction
The service registry is useful to interact with REST APIs, Expressions, and Scripts. It allows a central definition of the service model and a reference from a case. This task calls an operation from the service registry.
Properties
General
| Attribute | Type | Description | Category |
|---|---|---|---|
| Model Id | Text | Model Id identifies the element within the process model. | The model id, name and documentation properties can be found on any element. They are used respectively to uniquely identify the service registry task, to give it a user-friendly name and to add a free-form description. |
| Name | Text | The name of the element. This is the name displayed in the diagram. | |
| Documentation | Multiline Text | A free-form text that can be used to explain details about the particular element. | |
| Service model | ServiceModel | Service model | A service registry model is a reusable model that describes how an external service or a custom script can be invoked to produce data that can be used in a process or case instance. It's a good practice to encapsulate custom service invocations and scripts into a service registry model, which can be shared among multiple BPMN and CMMN models. Once a service registry model is selected, the operation needs to be selected and the input and output parameters can be mapped to process or case instance variables. |
| In same deployment | Boolean | Set it to true if the referenced definition should be referenced from within the same app deployment. Set it to false to always use the newest definition. | The Same deployment flag is used to indicate that the service registry model that is used is part of the same app deployment package as where the current model is in. If unchecked, the latest version is used which can come from an app that is deployed at a later point in time. |
| Output variable | Text | The variable name that stores the result of executing this service task. | The result of invoking a service registry task, after applying output parameter mappings, can be stored in a variable. This is an alternative to mapping the various output parameters one by one in the service model configuration. Mark the transient flag to store this variable in a non-persisted way. |
| Save output variables as transient variable | Boolean | Stores all variables created by invoking this service task as transient. |
Multi Instance
Multi instance
| Attribute | Type | Description | Category |
|---|---|---|---|
| Multi instance type | Selection:
| The type of multi-instance: default is 'None' meaning a single instance is created at runtime. Select either 'Parallel' or 'Sequential' if you want multiple instances to be created. | Multi-instance is used to define the repetition of this service registry task at runtime. This will call the external service and store the configured responses, either sequentially after each other or in parallel. For example, when referencing a collection a call to the external service can be made for each element of that collection. |
| Collection | Text | References a collection variable (for example a JSON array variable) by its name or using an expression that resolves to a collection. | |
| Element variable | Text | The name of the variable where the currently processed element from the multi-instance collection configured above will be stored (for example, 'invoicePosition'). The element can then be accessed through an expression, e.g., ${invoicePosition}. | |
| Element index variable | Text | The name of the variable where the index of the currently processed item from the multi-instance collection will be stored, for example, 'itemIndex'. The index is a number starting with 0 which is increased with every element that is being created. The index can then be accessed through an expression, e.g., ${itemIndex} further on in the process. | |
| Cardinality | Text | A fixed number or an expression that resolved to an integer that controls the number of instances that will be created. This is typically used when there is no collection available or needed. | |
| Completion condition | Text | An expression that should resolve to a boolean value. When evaluating to true, the remaining activity instances will be removed and the process instance will continue. |
Variable aggregation
| Attribute | Type | Description | Category |
|---|---|---|---|
| Variable Aggregations | List | Define an aggregation. Each element in this list will result in one aggregation variable. | When having multiple instances of this service registry task, there often is a need to create an aggregation of the responses of each call to the external service. With variable aggregation, a JSON variable can be merged that after all instances have been completed contains the summary of all the used variables. This is needed because typically variables are persisted locally, to avoid clashes on the process instance level. Alternatively, an 'overview' variable can be merged while the instances are still unfinished. Each aggregation consists of one or multiple definitions that map instance variables of one instance to the single aggregation variable. |
Advanced
| Attribute | Type | Description | Category |
|---|---|---|---|
| Optimize for only automatic steps | Boolean | (Advanced setting, only check it if you understand the implications) If checked, this instructs the Flowable engine that the multi-instance only contains automatic tasks and no wait states. In this situation, an asynchronous job is created when the multi-instance activity is entered that keeps checking if all instances are completed and completes the multi-instance. The benefit of this approach is that it is light on resources versus alternatives and doesn't lead to optimistic locking exceptions. |
Advanced
Execution
| Attribute | Type | Description | Category |
|---|---|---|---|
| Skip expression | Text | If the Skip expression evaluates to true, the flow is taken regardless of any condition. It is required to opt-in to this feature by setting a variable _FLOWABLE_SKIP_EXPRESSION_ENABLED with the Boolean value true on the process instance. | When the Skip expression resolves to true, this service registry task will not be executed at runtime. The Include in history flag can be used to store the historical entry of this service registry task when running with a history level that normally would not store the execution of the service registry task. Note that this flag has no effect when running with history level 'none'. |
| Include in history | Boolean | When the history level is set to "instance" or "task" level with this property it can be configured if this activity instance should be included in the historic activity data. | |
| Is for compensation | Boolean | Determines whether the activity can serve as a compensation for another activity. | A BPMN transaction is a set of activities that logically belongs together. Transactions can be cancelled through the Cancel End Event and handled through the Cancel Intermediate Boundary Event. The Is for compensation field can be used to indicate that the service registry task is meant as compensation steps for another activity. |
| Asynchronous | Boolean | When enabled, the activity will be started as an asynchronous job. The process state is persisted before this element is executed. Then, the process execution will be resumed asynchroneously. This can be used when the execution an activity takes a long time to return the UI to the user quicker in case the user does not need to see the next step immediately. However, if an error occurs before the following wait state, there will be no direct user feedback. Please refer to the documentation for more details. | When making a service registry task asynchronous, the call to the external service is done in the background. This is useful for example to not block the UI of a user, as some external services might take long to respond. Choose exclusive to avoid other asynchronous steps of this process instance to run at the same time. |
| Exclusive | Boolean | Determines whether the activity or process is run as an exclusive job. An exclusive job makes sure that no other asynchronous exclusive activities within the same process are performed at the same time. This helps to prevent failing jobs in concurrent scenarios. | |
| Leave asynchronously | Boolean | When enabled, the activity will be left as an asynchronous job. This means that the activity is ended asynchronously, including end execution listeners. Please refer to the documentation for more details. | |
| Leave exclusive | Boolean | Determines whether the activity should leave as an exclusive job. An exclusive job makes sure that no other asynchronous exclusive activities within the same process are performed at the same time. This helps to prevent failing jobs in concurrent scenarios. | |
| Job Category | Text | When set, the underlying generated job will have a Job Category, which will be executed only by Application Servers, where the Process Engine has enabledJobCategories set to this category. |
Advanced options
| Attribute | Type | Description | Category |
|---|---|---|---|
| Exception Mappings | List | Define one or more exception mappings to map a technical Java exception to a BPMN error code. | Map technical java exceptions to BPMN error codes that can be caught with a boundary error event. |
| Failed job retry time cycle | ComplexTrigger | Service task logic defined with a failed job retry time cycle |
Listeners
| Attribute | Type | Description | Category |
|---|---|---|---|
| Execution listeners | List | Allows invoking custom after certain lifecycle events. Start: Executes after the activity has been started. End: Executes after the activity was completed. Transition: When defined on a sequence flow, executes once the flow is transition is taken. | Execution listeners are used to add logic on certain lifecycle events. Typically it is used to add extra technical logic which shouldn't be visible in the BPMN process model. |
Visual
| Attribute | Type | Description | Category |
|---|---|---|---|
| Background color | Color | The background color of the element in the diagram. | Visual properties that determine how the service registry task is shown in the diagram. This has no impact on the runtime execution. |
| Font size | Selection:
| Font size. | |
| Font weight | Selection:
| Select the style between bold and normal. | |
| Font style | Selection:
| Select the style between italic and normal. | |
| Font color | Color | Select a font color. | |
| Border color | Color | The border color of the element in the diagram. |
List Attribute Details
Variable Aggregations
| Attribute | Type | Description |
|---|---|---|
| Target (Variable / Expression) | Text | The name of the target variable or an expression that gives the variable name |
| Type | Selection:
| The type of aggregation. Use 'default' to use the standard behavior of creating an aggregation JSON variable. Use 'custom' to define a delegate expression that will handle the aggregation. Please see the documentation for more information. |
| Delegate Expression | Text | Define a delegateExpression that will resolve to an instance of VariableAggregator (for BPMN) or PlanItemVariableAggregator (for CMMN). This instance will then be responsible for aggregating the variables. |
| Class | String | A class that implements VariableAggregator (for BPMN) or PlanItemVariableAggregator (for CMMN). This instance will then be responsible for aggregating the variables. |
| Target variable creation | Selection:
| Configures the way the aggregation variable is created. The 'Default' option creates the aggregation variable when all instances of the multi-instance have been completed. Use 'Create overview variable' to create a variable at the start of the multi-instance and keep it up to date during multi-instance exeution. Once all the instances are completed it will create a JSON variable in the same way as for Default target variable creation. Use the 'Store as transient variable' option to have the default behavior, but store the resulting aggregation variable transiently. |
| Variable Definitions | BasicFormList | property.loopVariableAggregation.definitions.description |
Variable Definitions
| Attribute | Type | Description |
|---|---|---|
| Source (Variable / Expression) | Text | The name of the source variable or an expression that provides the value |
| Target (Variable / Expression) | Text | The name of the aggregation variable or an expression that resolves to a variable name. |
Exception Mappings
| Attribute | Type | Description |
|---|---|---|
| Error code | Text | The code of an error definition. |
| Exception class name | Text | |
| Root cause | Text | |
| Include child exceptions | Boolean |
Failed job retry time cycle
| Attribute | Type | Description |
|---|---|---|
| Time cycle | Text |
Execution listeners
| Attribute | Type | Description |
|---|---|---|
| Event | Selection:
| The lifecycle event. The 'Take' event is only available for sequence flow. |
| Class | Text | Fully qualified classname of a class to be invoked when executing the task. The class must implement either JavaDelegate or ActivityBehavior. |
| Expression | Text | JUEL Expression to be executed when the task is started. Expressions allow you to interact with the backend by calling services, making calculations etc. You can find more information about expressions in the documentation. |
| Delegate expression | Text | Delegate Expression to be executed when the task is started. A delegate expression must resolve to a Java object, for instance a Spring bean. The object's class must implement either JavaDelegate or ActivityBehavior. |
| Fields | List |
Fields
| Attribute | Type | Description |
|---|---|---|
| Name | Text | The name of the element. This is the name displayed in the diagram. |
| String value | Text | |
| Expression | Text | JUEL Expression to be executed when the task is started. Expressions allow you to interact with the backend by calling services, making calculations etc. You can find more information about expressions in the documentation. |
| String | Text |