[glue-wg] Entity descriptions

[Burke, S (Stephen)]

Hi,

I have an action to provide general descriptions for half of the
computing entities, and this is my attempt. I think we also need better
descriptions for many of the attributes, but I'd rather do that by
editing the file. I'm not sure if we should say anything about how GLUE
1 concepts map to GLUE 2, but it may be helpful.

ExecutionEnvironment

The ExecutionEnvironment class describes the hardware and operating
system environment in which a job will run. It represents a set of
homogeneous Worker Nodes, so if a computing system contains nodes with
significantly different properties there may be several
ExecutionEnvironment instances. (This is similar to the GlueSubCluster
object in GLUE 1.) This implies that it should be possible to request a
specific environment when a job is submitted. The ExecutionEnvironment
may refer to virtual rather than physical machines.

  As well as attributes describing a typical node, the class gives
summary information about the size and usage of the set of nodes which
posess those properties. However, there is no way to relate these to the
information in other entities, e.g. it is not possible to know which
jobs in a given ComputingShare are running on which
ExecutionEnvironment.

ApplicationEnvironment

The ApplicationEnvironment class describes the software environment in
which a job will run, i.e. what pre-installed software will be available
to it. Each Application is identified by a name (the AppName attribute);
these names are not defined within the schema, but SHOULD be assigned in
a way which allows applications to be uniquely identifed. The properties
of installed software may vary substantially, but the attributes of the
class cover the most common cases, in particular for licensed software.
If necessary, additional information can be added using the OtherInfo
attribute and the Extension class.

ApplicationHandle

The ApplicationHandle class is an extension to ApplicationEnvironment
for applications which need to be set up in some way before they can be
used. For each supported setup method a string can be specified, the
interpretation of which is specific to the method - in the simplest case
this could just be a setup script to execute.

ComputingActivity

The ComputingActivity class represents a single (but possibly
multi-processor) job. The attributes give the job properties and state
as seen by the local batch system, together with some Grid-level
information.

ToStorageService

The ToStorageService class represents the case where a filesystem from a
Storage Service is available to jobs running on a Computing Service via
posix access, e.g. as an NFS mount. Each ToTorageService instance
represents a single mount point. It is assumed that such mounts are
available on all nodes (i.e. all Execution Environments) in the
Computing Service.

Stephen
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