Retrieving Collections on the COM+ Catalog
Data on the COM+ catalog is stored within a hierarchy of collections. In the Component Services administrative tool, many of these collections appear as folders in the console tree. Collections that don't appear as folders can be accessed only programmatically. Collections serve as containers for items. The items in a given collection are all of a consistent type; that is, they all represent the same kind of element, and there can be an arbitrary number of items in a collection. For example, the Applications collection contains an item for each COM+ application that is installed on the machine. This collection appears in the administrative tool as the COM+ Applications folder.
The collections occur in a hierarchical structure because the elements they contain follow an innate order of inclusion. For example, because components are installed into a COM+ application, the Components collection is logically subsumed under the Applications collection. More particularly, to hold the components installed into that particular application, there is a distinct Components collection for each item in the Applications collection.
You must get a collection on the catalog whenever you want to retrieve an item and set properties on it. In the general case, you need to step through several collections to get to the element you want. For the procedure for doing this, see Navigating the COM+ Collection Hierarchy.
After you have retrieved a collection and before you can work directly with the items it contains, you must populate the collection, which fetches data for the collection's contents from the COM+ catalog. For details, see Populating COM+ Collections.
Additionally, there is a facility you can use that enables you to dynamically query to see what related collections are available from a given collection you are holding. For details, see Querying for Available Related Collections.