I'm new to TOGAF and little bit confused on the Application Architecture concept. I own a Quote to Cash platform for my organization which consists of 30+ individual applications like quoting, ordering, payment, entitlement etc, so I'm wondering which level of Application Architecture concept from TOGAF actually means in my context. Does it mean the architecture for each of those apps or a higher level focusing on the interactions of those apps?
The answer to your question would be BOTH, but not limited to. That is, both "architecture for each of those apps" and "a higher level focusing on the interactions of those apps" are covered by TOGAF Application Architecture artifacts, yet there are other artifacts not in the scope of the two.
TOGAF's Business, Data, Application and Technology (usually referred as BDAT) Architecture are composed of architecture artifacts (catalogs, matrices and diagrams). A completed list of TOGAF's artifact recommendation is at Figure 3-4: Artifacts Associated with the Enterprise Metamodel.
From the "higher level" viewpoint you might create artifacts such as Application Portfolio Catalog (a list of your 30+ applications), Application/Function Matrix (to describe which application is assigned to which business function) or Application Interaction Diagram (to show the interaction among your 30+ applications).
On the other hand, to show the internal of an app you could use the Software Engineering Diagram artifact which breaks applications into packages, modules, services, and operations from a development perspective.
Other artifacts such as Application Migration Diagram (describe how an app is migrated from baseline to target) and Software Distribution Diagram (describe the physical deployment status of your 30+ applications) as you can see these are more from operational viewpoint.
Full list of TOGAF's recommended Application Architecture artifact is at 3.6.5 Phase C: Application Architecture. And, finally, you can extend with your own artifacts as long as these artifacts can help you in your Architecture Project.
