I have been spending a lot of time thinking about Application Architecture in the context of EA. More specifically, as an Enterprise Architect, what do I need to consider when looking at/defining/designing the Application Architecture Domain?

There are several definitions of Application Architecture. TOGAF says “The objective here [in Application Architecture] is to define the major kinds of application system necessary to process the data and support the business”. FEA says the Application Architecture “Defines the applications needed to manage the data and support the business functions”.

I agree with these definitions. They reflect what the Application Architecture domain does. However, they need to be decomposed to be practical.

I find it useful to define a set of views into the Application Architecture domain. These views reflect what an EA needs to consider when working with/in the Applications Architecture domain. These viewpoints are, at a high level:

Capability View: This view reflects how applications alignment with business capabilities. It is a super set of the following views when viewed in aggregate. By looking at the Application Architecture domain in terms of the business capabilities it supports, you get a good perspective on how those applications are directly supporting the business.

Technology View: The technology view reflects the underlying technology that makes up the applications. Based on the number of rationalization activities I have seen (more specifically application rationalization), the phrase “complexity equals cost” drives the importance of the technology view, especially when attempting to reduce that complexity through standardization type activities. Some of the technology components to be considered are:

• Software: The application itself as well as the software the application relies on to function (web servers, application servers).
• Infrastructure: The underlying hardware and network components required by the application and supporting application software.
• Development: How the application is created and maintained. This encompasses development components that are part of the application itself (i.e. customizable functions), as well as bolt on development through web services, API’s, etc. The maintenance process itself also falls under this view.
• Integration: The interfaces that the application provides for integration as well as the integrations to other applications and data sources the application requires to function.
• Type: Reflects the kind of application (mash-up, 3 tiered, etc). (Note: functional type [CRM, HCM, etc.] are reflected under the capability view).

Organization View: Organizations are comprised of people and those people use applications to do their jobs. Trying to define the application architecture domain without taking the organization that will use/fund/change it into consideration is like trying to design a car without thinking about who will drive it (i.e. you may end up building a formula 1 car for a family of 5 that is really looking for a minivan). This view reflects the people aspect of the application. It includes:

• Ownership: Who ‘owns’ the application? This will usually reflect primary funding and utilization but not always.
• Funding: Who funds both the acquisition/creation as well as the on-going maintenance (funding to create/change/operate)?
• Change: Who can/does request changes to the application and what process to the follow?
• Utilization: Who uses the application, how often do they use it, and how do they use it?
• Support: Which organization is responsible for the on-going support of the application?

Information View: Whether or not you subscribe to the view that “information drives the enterprise”, it is a fact that information is critical. The management, creation, and organization of that information are primary functions of enterprise applications. This view reflects how the applications are tied to information (or at a higher level – how the Application Architecture domain relates to the Information Architecture domain). It includes:

• Access: The application is the mechanism by which end users access information. This could be through a primary application (i.e. CRM application), or through an information access type application (a BI application as an example).
• Creation: Applications create data in order to provide information to end-users. (I.e. an application creates an order to be used by an end-user as part of the fulfillment process).
• Consumption: Describes the data required by applications to function (i.e. a product id is required by a purchasing application to create an order.

Application Service View: Organizations today are striving to be more agile. As an EA, I need to provide an architecture that supports this agility. One of the primary ways to achieve the required agility in the application architecture domain is through the use of ‘services’ (think SOA, web services, etc.). Whether it is through building applications from the ground up utilizing services, service enabling an existing application, or buying applications that are already ‘service enabled’, compartmentalizing application functions for re-use helps enable flexibility in the use of those applications in support of the required business agility. The applications service view consists of:

• Services: Here, I refer to the generic definition of a service “a set of related software functionalities that can be reused for different purposes, together with the policies that should control its usage”.
• Functions: The activities within an application that are not available / applicable for re-use. This view is helpful when identifying duplication functions between applications that are not service enabled.

Delivery Model View: It is hard to talk about EA today without hearing the terms ‘cloud’ or shared services.  Organizations are looking at the ways their applications are delivered for several reasons, to reduce cost (both CAPEX and OPEX), to improve agility (time to market as an example), etc.  From an EA perspective, where/how an application is deployed has impacts on the overall enterprise architecture. From integration concerns to SLA requirements to security and compliance issues, the Enterprise Architect needs to factor in how applications are delivered when designing the Enterprise Architecture. This view reflects how applications are delivered to end-users. The delivery model view consists of different types of delivery mechanisms/deployment options for applications:

• Traditional: Reflects non-cloud type delivery options. The most prevalent consists of an application running on dedicated hardware (usually specific to an environment) for a single consumer.
• Private Cloud: The application runs on infrastructure provisioned for exclusive use by a single organization comprising multiple consumers.
• Public Cloud: The application runs on infrastructure provisioned for open use by the general public.
• Hybrid: The application is deployed on two or more distinct cloud infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability.
  

While by no means comprehensive, I find that applying these views to the application domain gives a good understanding of what an EA needs to consider when effecting changes to the Application Architecture domain.

Finally, the application architecture domain is one of several architecture domains that an EA must consider when developing an overall Enterprise Architecture. The Oracle Enterprise Architecture Framework defines four Primary domains: Business Architecture, Application Architecture, Information Architecture, and Technology Architecture.

Each domain links to the others either directly or indirectly at some point. Oracle links them at a high level as follows:

Business Capabilities and/or Business Processes (Business Architecture), links to the Applications that enable the capability/process (Applications Architecture – COTS, Custom), links to the Information Assets managed/maintained by the Applications (Information Architecture), links to the technology infrastructure upon which all this runs (Technology Architecture - integration, security, BI/DW, DB infrastructure, deployment model).

There are however, times when the EA needs to narrow focus to a particular domain for some period of time. These views help me to do just that.