a. It is possible to communication routing done based on EPR on service side.

b. ARC clients do not use EPRs for adressing A-REX.

2. Client sends CreateActivity request to service. Upon reception of request service permorms basic processing of job description - checks for supported and required elements of JSLD, allocates place for collecting input files, creates internal records necessary for processing job.

3. After request is processed response is sent containing Job Identifier - EPR. EPR contains following elements:

a. Address - URL of A-REX service. This URL is then used by client to access execution service for managing activity.

b. Reference - xsd:string element (own namespace) representing internal identifier of job. This is just a big number which is unique for activity at that particular service at that moment. It is also with high probability unique for that service for quite long time in the past.

c. Reference - XML element (own namespace) with URL of HTTP service providing access to virtual space - actually local filesystem directory - representing location for files accessible for activity locally on service side.

Example of Job Identifier:

      <bes-factory:ActivityIdentifier>
        <wsa:Address>https://slackware-aleksandr.review.knowarc:60001/arex</wsa:Address>
        <wsa:ReferenceParameters>
          <a-rex:JobID>243511266477858814568533</a-rex:JobID>
          <a-rex:JobSessionDir>https://slackware-aleksandr.review.knowarc:60001/arex/243511266477858814568533</a-rex:JobSessionDir>
        </wsa:ReferenceParameters>
      </bes-factory:ActivityIdentifier>

4. For requesting activity management operation client contacts A-REX service using URL contained inside Job Identifier (EPR) also providing that whole EPR as part of request.