Legacy applications integration
The structure we propose is as depicted below (for a processing step named "align", provided as an example)
The application directory follows some best practices in its folders and files structure to ease the subsequent deployment of the application to the WPS-hadoop environment.
The application.xml file has two main blocks: the job template section and the workflow template section.
The first part is to define the job templates in the workflow XML application definition file. The second would not be used and it is just there to pave the road (if needed) to support workflows with oozie)
Our unique processing block of the workflow needs a job template.
A proposed example contains the XML lines below:
<jobTemplate id="align"> <streamingExecutable>/application/align/run</streamingExecutable> <defaultParameters> <parameter id="param1">2</parameter> <parameter id="param2">4</parameter> </defaultParameters> <defaultJobconf> <property id="ciop.job.max.tasks">1</property> </defaultJobconf> </jobTemplate>
We could provide tools to test a job on the local workstation.
Once done, this is packaged as a jar and stored in a repository accessible from the WPS-hadoop server. When a processing request is triggered, WPS-hadoop, via the hadoop streaming deploys that jar and the legacy application is invoked.
Hadoop clusters serving legacy applications only need to have R (and/or IDL, MatLab, Octave, etc.) installed (known procedure since SimpleTestNono has lead to that scenario)
