The Goals of Architecture

Application architecture seeks to build a bridge between business requirements and technical requirements by understanding use cases, and then finding ways to implement those use cases in the software. The goal of architecture is to identify the requirements that affect the structure of the application. Good architecture reduces the business risks associated with building a technical solution. A good design is sufficiently flexible to be able to handle the natural drift that will occur over time in hardware and software technology, as well as in user scenarios and requirements. An architect must consider the overall effect of design decisions, the inherent tradeoffs between quality attributes (such as performance and security), and the tradeoffs required to address user, system, and business requirements.

Keep in mind that the architecture should:

• Expose the structure of the system but hide the implementation details.

• Realize all of the use cases and scenarios.

• Try to address the requirements of various stakeholders.

• Handle both functional and quality requirements.

The Architectural Landscape

It is important to understand the key forces that are shaping architectural decisions today, and which will change how architectural decisions are made in the future. These key forces are driven by user demand, as well as by business demand for faster results, better support for varying work styles and workflows, and improved adaptability of software design.

Consider the following key trends:

• User empowerment. A design that supports user empowerment is flexible, configurable, and focused on the user experience. Design your application with appropriate levels of user personalization and options in mind. Allow the user to define how they interact with your application instead of dictating to them, but do not overload them with unnecessary options and settings that can lead to confusion. Understand the key scenarios and make them as simple as possible; make it easy to find information and use the application.

• Market maturity. Take advantage of market maturity by taking advantage of existing platform and technology options. Build on higher level application frameworks where it makes sense, so that you can focus on what is uniquely valuable in your application rather than recreating something that already exists and can be reused. Use patterns that provide rich sources of proven solutions for common problems.

• Flexible design. Increasingly, flexible designs take advantage of loose coupling to allow reuse and to improve maintainability. Pluggable designs allow you to provide post-deployment extensibility. You can also take advantage of service orientation techniques such as SOA to provide interoperability with other systems.

• Future trends. When building your architecture, understand the future trends that might affect your design after deployment. For example, consider trends in rich UI and media, composition models such as mashups, increasing network bandwidth and availability, increasing use of mobile devices, continued improvement in hardware performance, interest in community and personal publishing models, the rise of cloud-based computing, and remote operation.