STEP APs contain two classes of information models. The first class represents the AP's information requirements from a user's point of view. The second class describes the information requirements from a system integrator's point of view and is represented as an EXPRESS schema. This EXPRESS schema is created by selecting applicable constructs from the IRs and specializing them as needed by creating additional attributes or adding new constraints[BARN]. Mapping the concepts from the user's view to the appropriate IR constructs is a challenging task for AP developers because it requires considerable study and understanding of the IRs. The APIB gateway's IR Query interface provides a way to quickly retrieve IR constructs by specifying name substrings, thereby helping AP developers meet this challenge.
Figure 7: Form for issuing an Integrated Resource query.
The form for issuing an Integrated Resource query, shown in Figure 7, contains a pull-down list of object types and a text entry field for specifying a search string. The object types available are schemas, entities, types, rules, and functions. Suppose the user is looking for an entity in the IRs to match a particular requirement, say a concept involving some kind of dimension. The user chooses entities from the pull-down list, enters dimension as the search string, and presses the Search button. The IR Query form's CGI script issues a query to the APIB for all entity definitions where the entity name begins with ``dimension''. It then uses the query result to build a web page containing a form from which the user can choose an entity definition to view from a pull-down list of all the entity names. This web page, shown in Figure 8 also contains a link back to the IR Query form in case the user is unsatisfied with the list of results and wants to make another query.
Figure 8: Generated web page providing form for choosing a query result to view.
If the user chooses an entity name from the pull-down list on the form in Figure 8 and presses the View ENTITY button, the same CGI script that created the entity definition web page in Figure 6 will create a web page for the entity chosen. At that point, the user will be in the APIB browser and can proceed in the same manner as if she had obtained the entity definition web page through pure browsing. Similarly, a user can use IR Query as a shortcut to a schema, type, function, or rule web page.