Gridbus Workflow Enactment Engine - Grid Computing: Infrastructure, Service, and Applications - page 125

serviceKey

description

serviceAdministration +

nodeKey

accessAddress

node -

-

informationService

hostPublicKey

hostCA -

-

CAPublicKey

middlewareTypeKey

-

gridApplicationService -

value

middlewareType -

-

overviewURL

description

APIModelKey

value

-

APIModel -

overviewURL

description

hardware

-

Price -

software

FIGURE 5.8 Grid application service schema.

if users do not specify a particular service for a task in the workl ow
description, the scheduler uses the GAM name associated with the
execution of the task to query the GMD. The GMD will return a list of
services. These services are all able to execute the task.

5.5 Workflow Language
In order to allow users to describe tasks and their dependencies, an
XML-based workl ow language (xWFL) has been dei ned. The workl ow
language provides the means to build new applications by linking stand-
alone applications. Figure 5.9 shows the basic structure of the workl ow
language. It consists of two parts: task dei nitions dei ned in < tasks >, data
dependencies dei ned in < links >, and QoS constraints dei ned in
< QoSconstraints >.