API needed for running background/asynchronous TASKS

[jamoore]

The Task API should be responsible for all asynchronous/background/timed actions within the server.

Things to consider:

• Abstract Task && Task Inheritance
  • Task becomes a model object which can be persisted to the DB.
  • Specific tasks can then inherit and share the DB table. E.g. Task->Importer (can be viewed generically with SEAM)

• Profiles for Defining Tasks
  • sets some variables (allowCreateOMEISDirectory=false e.g.)

• AntTask?
  • reuse AntLauncher? for things like creating OMEIS directory
  • buildException -> Task Exception
  • if it happens to be a Startup Task, server doesn't startup.

• use spring.AppListener? to listen for events to do things (essentially our Startup)

What exactly are the requirements? Initial/future tasks?

Originally ​http://bugs.openmicroscopy.org.uk/show_bug.cgi?id=658

[jmoore]

Rescheduling as milestone:3.0-M4 story (for #407)

[jmoore]

r1054 adds an initial Task API. Specifically the ome.util.tasks.Task abstract class.

[jmoore]

Note the use of "fork=yes" in the usage from ant. Until #464 (AntAdapter) is fixed, running tasks from ant requires a <java/> task, and fork must be set, or you'll have weird problems a la:

ClassCastException: [Ljava.lang.StackTraceElement...

etc.

[jmoore]

Tasks work fine for running from the command-line. See #667 for the more asynchronous side of things.