How to access results?

Now, it is time to consider how to make users easily and conveniently access the results of their workflows. There are several questions here:
(1) How to track output files in Karajan workflows?

The first option is to analyze content of the Karajan workflow to figure out output files. For example, for element execute, attribute stdout indicates the name of output file.
<execute executable="/bin/date" stdout="thedate" host="gf1.ucs.indiana.edu" provider="GT2" redirect="false"/>
However, if we use this method to track all output files, it is difficult and time-consuming because it is possible that many elements generate output files. As a result, we must capture possible output files from all these elements.
Another option I can think of is kind of tricky. The newly submitted workflow is executed in a newly created directory. After execution, the files (except workflow file) in the directory are output files. This is the method I am using in my implementation.

(2) How to organize output files?

For the same workflow, we can categorize it based on different criteria. For example, we can categorize a workflow based on the date on which it is submitted, or the date on which it is completed... I would like to make use of workflow id and user id to categorize the workflows. All workflows submitted by a user belong to the same group which can be accessed by this user. Within these workflows, workflow id is used by the user to access a specified workflow. The id of every workflow belonging to a user is unique.
So, the directory layout may look like this:
users/user1/workflow_122/output_file1

users/user1/workflow_122/output_file2
users/user2/workflow_1/output_file1
...

(3) How can users access output files?

After talking with Marlon, I would like to provide RESTful interface by which users can retrieve output files. In my implementation, URLs to access output files look like this:
http://domain:port/resources/user_name/workflow_id/ This retrieves list of all output files for the corresponding workflow.
http://domain:port/resources/user_name/workflow_id/output_file This will retrieve the specified output file directly.

RESTful web services in Java

Recently, I read some articles about RESTful web services and I am looking for some java libraries which have great support for REST. REST is supported by Axis2. However, the support is very limited. First, document(http://ws.apache.org/axis2/1_3/rest-ws.html) of REST support in the official web site is horrible. The content is very very brief so that I have more questions and confusions than what have been addressed by that document. Support for REST in Axis2 relies on a new feature in WSDL2 which enables HTTP binding. Here is a good article about it:http://www.ibm.com/developerworks/webservices/library/ws-rest1/. However, HTTP binding doesn't enable programmers to implement a full REST style system. I did not dig into WSDL2 to get more knowledge about its HTTP binding. Here(http://wso2.org/blog/footballsoccerpainting/949) is an article from someone else who complains Axis2.
Then, I found that JCP published a Java API specification about RESTful web services. It is JSR-311(http://jcp.org/en/jsr/detail?id=311). That looks pretty good because now we have a standard about how to use REST in Java. Jersey(https://jersey.dev.java.net/) is reference implementation of the specification. Besides Jersey, Restlet(http://www.restlet.org/) is another implementation which provides more features. Note that the specification itself is still in beta phase.

I decided to try Jersey. First download and unpack it.
Sample code:

@Path("/")
public class RESTTest{
    @HttpContext UriInfo uriInfo;	
    
    @GET
    @ProduceMime("text/plain")
    public String getUserAll(){
    	return "You want to retrieve information about all users.";
    }
    
    @Path("{user}")
    public UserResource getUserInfoAsText(@UriParam("user") String userid){
    	return new UserResource(userid);
    }
}

Most readers have noticed that Java annotation is used frequently. I think this method is handy and convenient.