Job Control

and control. An interaction is initiated by a user submitting a request to start a job, including the job description, accompanied by the user’s Grid credentials, in the form of an X.509 certificate [5]. In the current case, this is just an identity certificate and asserts no other attributes about the user. This request is then evaluated by an Access Control Decision Function (ACDF) which may be called from several different Access Control Enforcement Functions (ACEF) located in the resource management modules. If the request is authorized, it is started under a local credential (namely User-ID). During the job execution, a VO user may submit management requests composed of a management action (e.g., request information, suspend or resume a job, cancel a job). The resource manager may decide to perform the action or to pass it on to the locally executing job. In order to perform these transactions, the Globus Resource Acquisition and Management (GRAM) [6] system is used, which has two major software components: the gatekeeper and the job manager. The gatekeeper is responsible for translating Grid credentials to local credentials (e.g. mapping the user to a local account based on their Grid credentials) and creating a job manager instance to handle the specific job invocation request. The job manager is a Grid service which instantiates and then provides for the ability to manage a job. Fig.1 shows the interaction of these elements