IS-gLiteBridge

The IS-gLiteBridge is a gCube Service dedicated to interface with a gLite-based Grid infrastructure (e.g. EGEE), gather their resources and publish them in the gCore Based Information System to make them discoverable transparently like any other gCube resource. To implement such a functionality it must interface with the BDII Server, i.e. the gLite service playing the role of gCore Based Information System in the gLite system. Moreover, such a service must be capable to interface with multiple infrastructures relying on gLite. The internals of the IS-gLiteBridge are structures as depicted in Figure 1, i.e. it mainly follows a Factory pattern.

Figure 1. IS-gLiteBridge Architecture

Resources and Properties

This Service creates and manages a WS-Resource for each gLite resource that has to be considered part of the e-Infrastructure the IS-Registry is responsible for. Such WS-Resources implement the Resource Model described in the Resource Domain, in particular they instantiate the gLiteResource part. The following three types of WS-Resources are created and managed:

• gLiteService – to represent a gLite Service. It contains a unique ID, a status label and status information;
• gLiteCE – to represent a gLite Computing Element (CE). It contains a unique ID and information about the operational status of the resource including the number of running jobs, the number of waiting jobs, the number of total jobs, the estimated response time, the worst response time, the free jobs slot, the max wall clock time, the max CPU time, the max total jobs, the max running jobs, the assigned job slots and the priority;
• gLiteSE – to represent a gLite Storage Element (SE). It contains a unique ID and information about the operational status of the resource including the used storage space, the available storage space and the current IO load;

Such properties are also registered as Topics managed by the IS-Notifier thus making possible for interested clients to subscribe on events representing the changes of status of gLite-based Infrastructure constituents (e.g. the available storage space of a SE).

Functions

The main functions supported by the Service Factory (IS-gLiteBridgeFactory) are:

• createResource() – which takes as input parameter a message containing the profile of the resource to be created and returns the EPR of the created WS-Resource.
• queryForProfiles() – which start the harvesting phase to gather resources from the BDII Server; for each resource it creates a WS-Resource of the appropriate type and interacts with the IS-Registry to publish its profile;
• queryForProperties() – which starts the harvesting phase to gather resource properties from the BDII Service; for each gathered information it interacts with the relative WS-Resource and update the resource status;

The main functions supported by the IS-gLiteBridge Service (IS-gLiteBridgeService), i.e. the WSRF service managing the WS-Resource instances representing gLite resources, consist in the standard get and set operations.