ROME (Request Object Management Environment)

Abstract

Most current astronomical archive services are based on an HTML/ CGI architecture where users submit HTML forms via a browser and CGI programs operating under a web server process the requests. Most services return an HTML result page with URL links to the result files or, for longer jobs, return a message indicating that email will be sent when the job is done. This paradigm has a few serious shortcomings. First, it is all too common for something to go wrong and for the user to never hear about the job again. Second, for long and complicated jobs there is often important intermediate information that would allow the user to adjust the processing. Finally, unless some sort of custom queueing mechanism is used, background jobs are started immediately upon receiving the CGI request. When there are many such requests the server machine can easily be overloaded and either slow to a crawl or crash. Request Object Management Environment (ROME) is a collection of middleware components being developed under the National Virtual Observatory Project to provide mechanism for managing long jobs such as computationally intensive statistical analysis requests or the generation of large scale mosaic images. Written as EJB objects within the open-source JBoss applications server, ROME receives processing requests via a servelet interface, stores them in a DBMS using JDBC, distributes the processing (via queuing mechanisms) across multiple machines and environments (including Grid resources), manages realtime messages from the processing modules, and ensures proper user notification. The request processing modules are identical in structure to standard CGIprograms – though they can optionally implement status messaging – and can be written in any language. ROME will persist these jobs across failures of processing modules, network outages, and even downtime of ROME and the DBMS, restarting them as necessary.

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