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Managing trade-offs

Managing trade-off decisions focuses on balancing the relationship among resources, the project schedule, and those features that need to be included in the application for the sake of quality.

When development teams try to complete this balancing, it is often at the expense of the management and operational requirements. One way to avoid that is to include management and operational requirements in the application-independent design guidelines – for example, in the form of an application framework. Operability and manageability effectively become standard components of all design processes – for example, in the form of an application framework – and get embedded into the working practices and culture of the development organization.

Typical design outputs

The following are examples of the outputs from an applications design forming part of the overall Service Design:

  • Input and output design, including forms and reports
  • A usable user interface (human computer interaction) design
  • A suitable data/object model
  • A process flow or workflow model
  • Detailed specifications for update and read-only processes
  • Mechanisms for achieving audit controls, security, confidentiality and privacy
  • A technology specific ‘physical’ design
  • Scripts for testing the systems design
  • Interfaces and dependencies on other applications.

There are guidelines and frameworks that can be adopted to determine and define design outputs within Applications Management, such as Capability Maturity Model Integration (CMMI).

Design patterns

A design pattern is a general, repeatable solution to a commonly occurring problem in software design. Object-oriented design patterns typically show relationships and interactions between classes or objects, without specifying the final application classes or objects that are involved. Design patterns describe both a problem and a solution for common issues encountered during application development.

An important design principle used as the basis for a large number of the design patterns found in recent literature is that of separation of concern. Separation of concerns will lead to applications divided into components, with a strong cohesion and minimal coupling between components. The advantage of such an application is that modification can be made to individual components with little or no impact on other components.

In typical application development projects, more than 70% of the effort is spent on designing and developing generic functions and on satisfying the management and operational requirements. That is because each individual application needs to provide a solution for such generic features as printing, error handling and security.

Among others, the Object Management Group (OMG, www.omg.com) defined a large number of services that are needed in every application. OMG’s Object Management Architecture (OMA) clearly distinguishes between functional and management and operational aspects of an application. It builds on the concept of providing a run-time environment that offers all sorts of facilities to an application.

In this concept, the application covers the functional aspects, and the environment covers all management and operational aspects. Application developers should, by definition, focus on the functional aspects of an application, while others can focus on the creation of the environment that provides the necessary management and operational services. This means that the application developers focus on the requirements of the business, while the architecture developers or application framework developers focus on the requirements of the application developers.

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