Grid Services Orchestration with OMII-BPEL - Grid Computing: Infrastructure, Service, and Applications - page 201

FIGURE 8.2 The use of a tree in the properties view of an invoke activity.

Users will no longer need to i gure out WSDL and XSD dei nitions them-
selves to make matching declarations for new variables. The burden of XML
operation is greatly removed.
Similarly in the properties view of an assign activity, available variables
and their XML structures will be listed for both source and target specii -
cations. The user can select the XML element of a variable from the tree
and immediately obtain the corresponding XPath query that will locate the
select XML element in runtime (as shown in Figure 8.3). This is extremely
helpful for non-XML experts to get a grip on the XPath query quickly.
Advanced editing may be applied in addition whenever appropriate.
To deal with expressions in BPEL Designer, for example, to extract XML
data in an assign , or compose iteration conditions of a while , and so on, auto-
completion aid is available to suggest candidate elements on the go as the
user keys into the editor. Results are i ltered out instantly until the right one
is selected. XPath functions and XML elements are differentiated with dif-
ferent colors. Figure 8.4 is a dummy example for using input variable to
determine the i nal value of a for each counter.

FIGURE 8.3 XPath query editor of an assign activity.