In Camunda, support for multiple versions of processes is achieved through Process Definition. The process definition is the deployment entity of the process model, which contains all the information of the process model, such as flow charts, nodes, connection lines, events, etc. Every time a process model is deployed, a new process definition is created and assigned a unique version number. Each process definition can have multiple versions, but only one version can be active. The active version of the process definition can be used to start new process instances.
Camunda supports a variety of process definition deployment methods, including manual deployment, automatic deployment, dynamic deployment, etc. Manual deployment refers to uploading process definition XML files or BPMN 2.0 files to the Camunda system for deployment, which can be implemented through the Camunda Modeler tool or REST API. Automatic deployment refers to placing the process definition XML file or BPMN 2.0 file in the specified directory, and the Camunda system will automatically scan the directory and deploy it. Dynamic deployment refers to the deployment of process definition by calling Camunda API through Java code or REST API when Camunda is running, which can realize dynamic deployment and update process definition.
For the already deployed process definition, if you need to modify or update, you can do the following:
1. Suspend the old version: Before deploying the new version, the process definition of the old version can be suspended so that it can no longer be used to start a new process instance.
2. Deploy the new version: deploy the modified process definition to the Camunda system, generate a new version number, and set it to the active state.
3. Start a new process instance: use the new version of the process definition to start a new process instance. Older versions of process instances can still be running, but newer process instances will use the newer version of the process definition.
With the support of multiple versions of the process, Camunda can easily manage and track different versions of the process model, improving the maintainability and scalability of the process model.