it may be convenient to define some different levels of a FASEnvironment so it's more clear what it is expected to do. A first proposal of this would be:

• Level 0 environment/framework:
  • command line execution of tasks. The command lines would be given in some kind of shell e.g. Unix-shell or Python.
  • transfer parameters into a standard format (e.g. XML).
  • execute tasks specified using the standard container-component interface.
  • add logging information to file.
  • transfer result parameters back to command line shell (e.g. bash, Python).

This level would not require the implementation of a software bus structure or a service which can handle multiple containers. Thus, the Framework could be a collection of (class) libraries.

• Level 1 environment/framework adds:
  • interface to Application layer (e.g. Python).
  • execution of several containers on single CPU.
  • support of a logging system.
  • feedback of results and status information to Application layer.
  • support of events
  • VO compatible Web service Presentation layer
  • access to VO services through container

At this level one would need some kind of software bus and management service to handle multiple containers but it could be relative simple as all happens on the same CPU.

• Level 2 environment/framework adds:
  • support of execution of containers on multiple CPU's on local domain
  • support of asynchronous execution of tasks

Since multiple CPU are used a full scale software bus and servers are required.

• Level 3 environment/framework adds:
  • security features to restrict or permit shared access to data and resources
  • access to GRID services

-- PrebenGrosbol - 19 Jul 2005
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