Hi All, We are thinking of implementing an Airavata Orchestrator component to replace WorkflowInterpreter to avoid gateway developers to dealing with workflows when they simply have one single independent jobs to run in their gateways. This component is mainly focusing on how to invoke GFAC and accept requests from the client API.
I have following features in mind about this component. 1. It gives a web services or REST interface where we can implement a client to invoke it to submit jobs. 2. Accepts a job request and parse the input types and if input types are correct, this will create an Airavata experiment ID. 3. Orchestrtor then store the job information to registry against the generated experiment ID (All the other components identify the job using this experiment ID). 4. After that Orchestrator pull up all the descriptors related to this request and do some scheduling to decide where to run the job and submit the job to a GFAC node (Handling multiple GFAC nodes is going to be a future improvement in Orchestrator). If we are trying to do pull based job submission it might be a good idea to handle errors, if we store jobs to Registry and GFAC pull jobs and execute them Orchestrator component really doesn' t have to worry about the error handling. Because we can implement a logic to GFAC if a particular job is not updating its status fora g iven time it assume job is hanged or either GFAC node which handles that job is fauiled, so GFAC pull that job (we definitely need a locking mechanism here, to avoid two instances are not going to execute hanged job) and start execute it. (If GFAC is handling a long running job still it has to update the job stutus frequently with the same status to make sure GFAC node is running). 5. GFAC creates its execution chain and store it back to registry with experiment ID, and GFAC updates its states using check pointing. 6. If we are not doing pull based submission,during a GFAC failure Orchestrator have to identify it and submit the active jobs from failure gfac node to other nodes. This might cause job duplication in case Orchestrator falls alarm about GFAC failure (so have to handle carefully). We have lot more to discus about the GFAC but I limit our discussion to Orchestrator component for now. WDYT about this design ? Lahiru -- System Analyst Programmer PTI Lab Indiana University
