Adding a New Workflow Template

A workflow template defines a configurable flow. It is an abstract representation of a workflow. You can add a new template by creating a custom bundle as below and copying it to repository/components/dropins folder.

First, you need to create a SampleTemplate class which extends AbstractTemplate class. The following methods should be overridden:

getInputData() : Provides the parameter definition required by the template.
getTemplateId() : Should return the template Id which should be unique
getName() : Returns a user friendly name for the template. This will be the name shown at the admin UI
getDescription(): Returns a description about this template

Following is a sample class written for a multi step approval template.

Code Block

public class SampleTemplate extends AbstractTemplate {

    public SampleTemplate(String metaDataXML) throws WorkflowRuntimeException {
        super(metaDataXML);
    }

    @Override
    protected InputData getInputData(String parameterName) throws WorkflowException {
        return null;
    }

    @Override
    public String getTemplateId() {
        return TEMPLATE_ID;
    }

    @Override
    public String getName() {
        return APPROVAL_TEMPLATE_NAME;
    }

    @Override
    public String getDescription() {
        return DESCRIPTION;
    }
}

The configurable details of the template such as “Template ID”, “Template Name”, “Template Meta Data”, etc. should be separately defined in xml file like below.

Code Block

<met:MetaData xmlns:met="http://metadata.bean.mgt.workflow.identity.carbon.wso2.org">
    <met:Template>
        <met:TemplateId>SampleTemplate</met:TemplateId>
        <met:TemplateName>SampleTemplate</met:TemplateName>
        <met:TemplateDescription>Sample Template</met:TemplateDescription>
        <met:ParametersMetaData xmlns:met="http://metadata.bean.mgt.workflow.identity.carbon.wso2.org">
            <met:ParameterMetaData Name="UserAndRole" InputType="Multiple_Steps_User_Role" isRequired="true">
                <met:DisplayName>User and Role</met:DisplayName>
            </met:ParameterMetaData>
        </met:ParametersMetaData>
    </met:Template>
</met:MetaData>

The finally in the service component, we need to register this template at activation. We can do this as follows.

Code Block
bundleContext.registerService(AbstractTemplate.class, new SampleTemplate(readFileContent(Constants.TEMPLATE_PARAMETER_METADATA_FILE_NAME)), null);

Now we need to add a concrete implementation of this template.

Adding a Workflow Template Implementation

The template implementation defines how the template should be deployed and executed. Optionally you can write this as a separate bundle and copy into repository/components/dropins folder.

The implementations can be written by extending the AbstractWorkflow class. The following methods should be overridden:

getInputData() : Returns a parameter definition required by the template implementation

Following The following shows a sample class written for a sample template.

Code Block

public class SampleTemplateImplementation extends AbstractWorkflow {

    private static Log log = LogFactory.getLog(SampleTemplateImplementation.class);

    public SampleTemplateImplementation(Class<? extends TemplateInitializer> templateInitializerClass,
                                        Class<? extends WorkFlowExecutor> workFlowExecutorClass, String metaDataXML) {
        super(templateInitializerClass, workFlowExecutorClass, metaDataXML);
    }

    @Override
    protected InputData getInputData(ParameterMetaData parameterMetaData) throws WorkflowException {
        InputData inputData = null;
        if (parameterMetaData != null && parameterMetaData.getName() != null) {
            String parameterName = parameterMetaData.getName();
            if ("BPSProfile".equals(parameterName)) {
                inputData = new InputData();
                MapType mapType = new MapType();
                inputData.setMapType(mapType);
                Item item = new Item();
                item.setKey("embeded_bps");
                item.setValue("embeded_bps");
                mapType.setItem(new Item[]{item});
            } else if ("HTSubject".equals(parameterName)) {
                inputData = new InputData();
                MapType mapType = new MapType();
                inputData.setMapType(mapType);
                Item item1 = new Item();
                item1.setKey("subject1");
                item1.setValue("subject1");
                Item item2 = new Item();
                item2.setKey("subject2");
                item2.setValue("subject2");
                mapType.setItem(new Item[]{item1, item2});
            }
        }
        return inputData;
    }

    @Override
    public void deploy(List<Parameter> parameterList) throws WorkflowException {
        super.deploy(parameterList);
    }
}

The configurable details of the template implementation such as “Template ID”, “Template Implementation ID”, “Template Implementation Meta Data”, etc. should be separately defined in xml file like below.

Code Block

<met:MetaData xmlns:met="http://metadata.bean.mgt.workflow.identity.carbon.wso2.org">
    <met:WorkflowImpl>
        <met:WorkflowImplId>SampleWorkflow</met:WorkflowImplId>
        <met:WorkflowImplName>SampleWorkflow</met:WorkflowImplName>
        <met:WorkflowImplDescription>Sample Workflow</met:WorkflowImplDescription>
        <met:TemplateId>SampleTemplate</met:TemplateId>
        <met:ParametersMetaData>
            <met:ParameterMetaData Name="BPSProfile" InputType="Select" isRequired="true" isInputDataRequired="true">
                <met:DisplayName>BPS Profile(Server Profile Name)</met:DisplayName>
            </met:ParameterMetaData>
            <met:ParameterMetaData Name="HTSubject" InputType="Select" isRequired="true" isInputDataRequired="true">
                <met:DisplayName>Task Subject(Approval task subject to display)</met:DisplayName>
            </met:ParameterMetaData>
        </met:ParametersMetaData>
    </met:WorkflowImpl>
</met:MetaData>

Finally, in the service component, we need to register this template at activation as follows.

Code Block

bundleContext.registerService(AbstractWorkflow.class, new SampleTemplateImplementation(BPELDeployer.class, RequestExecutor.class, readFileContent(Constants.WORKFLOW_IMPL_PARAMETER_METADATA_FILE_NAME)), null);

Now when adding a new workflow, you will get a drop-down menu to select which template to follow in that workflow.

Source of the sample which used for this documentation can be found here.

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