Jump to: navigation, search

JWT Monitoring

Introduction

We want to give to JWT the ability to monitor workflow engines (ie AgilPro, Bonita...) at thein runtime; to give the user the ability to check the state of a workflow from Eclipse.

Ideas

  • We think that "monitoring a workflow" is a synonymous for "getting full workflow state"
  • To define a workflow state, we need a generic API to define a workflow. This API must fit with most of workflow engines.
  • The monitoring tool must be able to support several workflow engines, and several ways to access them (WebService, RMI, ...)

Concretely

  • As this work has been done in the context of SCorWare SCA project, first implementation is done with the aim of monitoring a Workflow Engine (Bonita) through WebServices. SCorWare uses CXF webservice engine, with Aegis databinding. That is the only technologies that are currently supported.
  • However, we made some efforts to make the architecture extensible enough to handle other bindings; so that it might be easy to add a support for RMI, or an Eclipse internal Workflow Engine (eg MWE) or anything else. This is made by using extension points.

How do I monitor another workflow engine over another binding with this plugin?

  1. Implement an interface (WorkflowService) with your favorite workflow engine. (We use the "Adapter" design-pattern)
  2. Make this service accessible to the user who wants to monitor it in Eclipse (you can use webservices, rmi, or anything you are able to write a client programmaticaly)
  3. Implement an extension plug-in which defines the way to access the service (so called a service provider) from inside Eclipse.

Screenshot

These are a screenshot of what we currently have. Obviously, it can be improved...

Jwt monitor1.jpg

Jwt monitor2.jpg

Jwt monitor3.jpg

Jwt monitor4.jpg

Jwt monitor5.jpg

Implementation

General Schema

Jwt monitoring.jpg

Comments

  • The UI is implemented as an Eclipse View
  • The view uses the interface WorkflowService, and creates the tree wih the beans that WorkflowService methods provide. Those beans are then embedded in a composite pattern, to fit with TreeViewer requirements.
  • The interface WorkflowService is an adapter. Each workflow engine that is to be supported in JWT must implement this interface according to its own specifications.
  • When accessing a Workflow Service, the plug-in calls a method from a plug-in linked to the base plug-in through extension point. This extension provides an implementation for the interface WorkflowServiceProvider, and more specifically for its "processServiceAdd" method.
  • This way, we can consider that we have one plug-in per binding. (That's why SCA could be useful => One plug-in for several bindings)

Code

WorkflowService API:

package org.eclipse.jwt.runtime.workflow;
import org.eclipse.jwt.runtime.workflow.bean.Activity;
import org.eclipse.jwt.runtime.workflow.bean.Process;
import org.eclipse.jwt.runtime.workflow.bean.Processes;
import org.eclipse.jwt.runtime.workflow.bean.Project;
import org.eclipse.jwt.runtime.workflow.bean.Projects;
 
 
/**
 * @author gdecarnin
 * 
 * NB. These methods do not "officially" throw BonitaServerException because
 * it will rather result in an UndeclaredThrowableException in a ws client.
 */
public interface WorkflowService {
 
    public Projects listProjects(boolean returnProperties, boolean startableOnly, String login);
 
    public Project getProjectProperties(Project project, String login);
 
    public Process instanciateProject(Process process, String login);
 
    public Processes listUserActivities(boolean returnProperties, boolean returnTerminated, String login);
 
    public Process startActivity(Process process, String login);
 
    public Activity getActivityProperties(Process process, String login);
 
    public Activity setActivityProperties(Process process, String login);
 
    public Process terminateActivity(Process process, String login);
}

With SCA

  • SCA is aimed to make binding between several components (eg a Workflow Engine that promotes a service to monitor it, and a client to this service that monitor it in another application...) become more abstract. When possible, we could use SCA to manage theses bindings in JWT.
  • We could provide a composite generator binary (for SCA) in the base plugin. This is possible by adding a binary without problem of license (see java2wsdl binary in STP), so that it could be part of an official release.