Workflows in AEM 05 - Trigger Workflow Programmatically

It is often needed to trigger a workflow programmatically. Hence, in this small post, we will see how we can easily do that.

package org.redquark.demo.core.servlets;

import java.io.IOException;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.Servlet;

import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.SlingHttpServletResponse;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.servlets.HttpConstants;
import org.apache.sling.api.servlets.SlingSafeMethodsServlet;
import org.osgi.framework.Constants;
import org.osgi.service.component.annotations.Component;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.adobe.granite.workflow.WorkflowException;
import com.adobe.granite.workflow.WorkflowSession;
import com.adobe.granite.workflow.exec.WorkflowData;
import com.adobe.granite.workflow.model.WorkflowModel;

/**
 * @author Anirudh Sharma
 */
@Component(
  service = Servlet.class, 
  property = { 
    Constants.SERVICE_DESCRIPTION + "=Trigger Worklow Servlet",
    "sling.servlet.methods=" + HttpConstants.METHOD_GET, 
    "sling.servlet.paths=" + "/bin/triggerWorkflow" 
    }
  )
public class TriggerWorkflowServlet extends SlingSafeMethodsServlet {

 private static final long serialVersionUID = 4235730140092282985L;

 private final Logger log = LoggerFactory.getLogger(this.getClass());

 @Override
 protected void doGet(SlingHttpServletRequest request, SlingHttpServletResponse response) {

  try {
   final String payloadPath = "/content/we-retail/language-masters/en/equipment";

   // Getting the resource resolver
   final ResourceResolver resolver = request.getResourceResolver();

   // Get the workflow session from the resource resolver
   final WorkflowSession workflowSession = resolver.adaptTo(WorkflowSession.class);

   // Workflow model path - This is the already created workflow
   final String model = "/var/workflow/models/metadata_map_example";

   // Get the workflow model object
   final WorkflowModel workflowModel = workflowSession.getModel(model);

   // Create a workflow Data (or Payload) object pointing to a resource via JCR
   // Path (alternatively, a JCR_UUID can be used)
   final WorkflowData workflowData = workflowSession.newWorkflowData("JCR_PATH", payloadPath);

   // Optionally pass in workflow metadata via a Map
   final Map<String, Object> workflowMetadata = new HashMap<>();
   workflowMetadata.put("anyData", "You Want");
   workflowMetadata.put("evenThingsLike", new Date());

   // Start the workflow!
   workflowSession.startWorkflow(workflowModel, workflowData, workflowMetadata);

   log.info("Workflow: {} started", model);
   
   response.getWriter().println("Workflow Exxecuted");

  } catch (WorkflowException | IOException e) {
   log.error(e.getMessage(), e);
  }
 }

}

Following things are needed for this -

• Payload path - the payload on which we wish to run the workflow
• Workflow session - this is taken from the Resource Resolver.
• Workflow model - the path of the workflow model that is going to be run on the payload.
• Workflow data - the data (if any) that we are needed to pass in the workflow.
• In the end, we start the workflow.

Conclusion

So, we saw that it is pretty easy to trigger a workflow programmatically. This post shows how to run a workflow from a servlet but we can easily use this code in a service/component/slingmodel etc.

You can find the code to this in my GitHub repository.

I hope you enjoyed this post. Your suggestions and feedback are always welcome. Feel free to befriend me on Facebook, Twitter or Linked In or say Hi by email.