DCI Bridge: Executing WS-PGRADE Workflows in Distributed Computing Infrastructures - Science Gateways for Distributed Computing Infrastructures - page 58

activity by the DCI-speci c plugin thread. Meanwhile, as the job is executed in the

target DCI, the thread handling the DCI status queue periodically polls the status of
the job execution and places the status information into the queue. Whenever the
status is changed in the DCI status queue it is written back to the job status queue
and then passed back to the gUSE workflow interpreter. Once the status is success
or failed, the output file management step is initiated, where the output files of the

job execution are collected into the DCI output queue.

4.3.4 Output File Management

Output file management can also be done at two places. The generic solution is to

do it inside the DCI Bridge, but for optimization purposes this activity can be
executed by special wrappers in the target resources. In the latter case, the DCI
Bridge administrator should set the same optimization parameter that was men-
tioned in the case of the input le

management activities in the DCI Bridge. This is also the case when the user
speci

file management. In this case there is no need for

file access for the output of the job.
In the generic case JSDL describes the place of the output

es remote

files, and the job
output queue service inside the plugin manager uploads the output files to the
storage service of gUSE or to an HTTP server.

4.4 Configuration of the DCI Bridge

In order to control the operation of the DCI Bridge and to con gure the connected

resources the DCI Bridge administration interface has been introduced. The
administration interface has two main parts (Fig. 4.4 ):

1. The base part, where the con guration affects the generic settings of DCI

Bridge, and
2. The middleware-speci

c part, where the settings are unique for each individual

middleware.
1. The Base menus ( Manager , Settings , Log entries ) — from the DCI Bridge tab —

are responsible for

a. Managing DCI Bridge generic operation by enabling or disabling the flow of
jobs between the workflow interpreter and DCI Bridge (in Manager menu).
In case of troubleshooting, it is useful to disable the DCI Bridge to accept
jobs from the workflow interpreter. In this case the DCI Bridge is still able to
accept the status and outputs of the jobs already sent to the connected DCIs.
As a result, the gateway administrator can check how the previously allo-
cated jobs are executed in their target DCIs. In fact, these status information
and result

files are transferred back to the gUSE storage.