An application chain is two or more applications linked together by dependencies. In its simplest form, an application chain consists of two levels, as shown in the following illustration.
Figure 37-3 A Two-Level Application Chain
However, when application dependencies are nested, an application chain can grow to include many levels. In the following example, Application A has a dependency on Application B. Application B, in turn, has dependencies on Application B1 and Application B2. As a result, all three applications (B, B1, B2), in addition to applications C and D, must be present in order for Application A to run.
Figure 37-4 A Three-Level Application Chain
In some cases, an application might belong to more than one application chain, as in the following example where Application D is a dependent application for both Application A and Application E.
Figure 37-5 An Application that Belongs to Two Different Application Chains