1. What is the use of camunda's Java delegate
In Camunda, a Java delegate is a Java class used to execute custom logic during process execution. Using Java delegation, you can implement various complex business logic through Java code during process execution.
Here are some common uses for using Java delegates:
1. Calculated value: You can use Java delegates to calculate values. For example, in a service task, you can use Java delegates to compute results.
2. Access process variables: You can use Java delegates to access the values of process variables. For example, in a service task, you can use Java delegates to read or write the value of a process variable.
3. Judgment conditions: You can use Java delegates to judge conditions, for example, use Java delegates in the gateway to determine the execution path of the next process step.
4. Calling external systems: You can use Java delegates to call APIs of external systems, such as accessing databases, calling web services of other systems, and so on.
5. Execute custom logic: You can use Java delegates to execute custom business logic. For example, in a service task, you can use Java delegates to access a database or perform other custom logic.
Camunda provides a Java delegate interface that you can implement and use that class in your process definition. When using Java delegates, you can use the Camunda API to access process variables, execute business logic, and call external system APIs.
In summary, a Java delegate is a useful tool for manipulating data and computing results that can be used in a variety of scenarios. Using Java delegation can make your process definition more flexible and configurable, thereby improving the maintainability and scalability of business processes.
2. How to use camunda's Java delegate
To use Java delegates in Camunda, you need to perform the following steps:
1. Create a Java class: First, you need to create a Java class that implements the JavaDelegate interface provided by Camunda. In a Java class, you can implement the execute method, where you write your custom logic.
public class MyJavaDelegate implements JavaDelegate {
public void execute(DelegateExecution execution) throws Exception {
// your custom logic here
}
}2. Configure Java delegation in the process definition: Then, in the Camunda modeler or in the BPMN XML file, you can configure service tasks or other steps that use Java delegation. For example, here's how to configure a Java delegate for a service task in the Camunda modeler:
Right-click the service task, select "Configure Service Task";
under the "General" tab, select "Java Class";
enter the fully qualified name of the Java class, such as com.example.MyJavaDelegate.
In a BPMN XML file, you can configure a Java delegate using:
where the camunda:class attribute specifies the Java delegate class to use.
3. Use Camunda API in Java delegation: In Java delegation, you can use Camunda API to access process variables, execute business logic and call APIs of external systems. For example, the following is the code to read and write a process variable in a Java delegate:
// read process variable
String variableValue = (String) execution.getVariable("variableName");
// write process variable
execution.setVariable(" variableName", "variableValue");
In conclusion, using Java delegation can make your process definition more flexible and configurable, thereby improving the maintainability and scalability of business processes. When using Java delegates, you need to pay attention to writing high-quality Java code to ensure correct logic and good performance.
