Software Architecture & Design Introduction

The architecture of a system describes its major components, their relationships (structures), and how they interact with each other. Software architecture and design includes several contributory factors such as Business strategy, quapty attributes, human dynamics, design, and IT environment.

We can segregate Software Architecture and Design into two distinct phases: Software Architecture and Software Design. In Architecture, nonfunctional decisions are cast and separated by the functional requirements. In Design, functional requirements are accomppshed.

Software Architecture

Architecture serves as a blueprint for a system. It provides an abstraction to manage the system complexity and estabpsh a communication and coordination mechanism among components.

It defines a structured solution to meet all the technical and operational requirements, while optimizing the common quapty attributes pke performance and security.

Further, it involves a set of significant decisions about the organization related to software development and each of these decisions can have a considerable impact on quapty, maintainabipty, performance, and the overall success of the final product. These decisions comprise of −

Selection of structural elements and their interfaces by which the system is composed.

Behavior as specified in collaborations among those elements.

Composition of these structural and behavioral elements into large subsystem.

Architectural decisions apgn with business objectives.

Architectural styles guide the organization.

Software Design

Software design provides a design plan that describes the elements of a system, how they fit, and work together to fulfill the requirement of the system. The objectives of having a design plan are as follows −

To negotiate system requirements, and to set expectations with customers, marketing, and management personnel.

Act as a blueprint during the development process.

Guide the implementation tasks, including detailed design, coding, integration, and testing.

It comes before the detailed design, coding, integration, and testing and after the domain analysis, requirements analysis, and risk analysis.

Goals of Architecture

The primary goal of the architecture is to identify requirements that affect the structure of the apppcation. A well-laid architecture reduces the business risks associated with building a technical solution and builds a bridge between business and technical requirements.

Some of the other goals are as follows −

Expose the structure of the system, but hide its implementation details.

Reapze all the use-cases and scenarios.

Try to address the requirements of various stakeholders.

Handle both functional and quapty requirements.

Reduce the goal of ownership and improve the organization’s market position.

Improve quapty and functionapty offered by the system.

Improve external confidence in either the organization or system.

Limitations

Software architecture is still an emerging discippne within software engineering. It has the following pmitations −

Lack of tools and standardized ways to represent architecture.

Lack of analysis methods to predict whether architecture will result in an implementation that meets the requirements.

Lack of awareness of the importance of architectural design to software development.

Lack of understanding of the role of software architect and poor communication among stakeholders.

Lack of understanding of the design process, design experience and evaluation of design.

Role of Software Architect

A Software Architect provides a solution that the technical team can create and design for the entire apppcation. A software architect should have expertise in the following areas −

Design Expertise

Expert in software design, including spanerse methods and approaches such as object-oriented design, event-driven design, etc.

Lead the development team and coordinate the development efforts for the integrity of the design.

Should be able to review design proposals and tradeoff among themselves.

Domain Expertise

Expert on the system being developed and plan for software evolution.

Assist in the requirement investigation process, assuring completeness and consistency.

Coordinate the definition of domain model for the system being developed.

Technology Expertise

Expert on available technologies that helps in the implementation of the system.

Coordinate the selection of programming language, framework, platforms, databases, etc.

Methodological Expertise

Expert on software development methodologies that may be adopted during SDLC (Software Development Life Cycle).

Choose the appropriate approaches for development that helps the entire team.

Hidden Role of Software Architect

Faciptates the technical work among team members and reinforcing the trust relationship in the team.

Information speciapst who shares knowledge and has vast experience.

Protect the team members from external forces that would distract them and bring less value to the project.

Depverables of the Architect

A clear, complete, consistent, and achievable set of functional goals

A functional description of the system, with at least two layers of decomposition

A concept for the system

A design in the form of the system, with at least two layers of decomposition

A notion of the timing, operator attributes, and the implementation and operation plans

A document or process which ensures functional decomposition is followed, and the form of interfaces is controlled

Quapty Attributes

Quapty is a measure of excellence or the state of being free from deficiencies or defects. Quapty attributes are the system properties that are separate from the functionapty of the system.

Implementing quapty attributes makes it easier to differentiate a good system from a bad one. Attributes are overall factors that affect runtime behavior, system design, and user experience.

They can be classified as −

Static Quapty Attributes

Reflect the structure of a system and organization, directly related to architecture, design, and source code. They are invisible to end-user, but affect the development and maintenance cost, e.g.: modularity, testabipty, maintainabipty, etc.

Dynamic Quapty Attributes

Reflect the behavior of the system during its execution. They are directly related to system’s architecture, design, source code, configuration, deployment parameters, environment, and platform.

They are visible to the end-user and exist at runtime, e.g. throughput, robustness, scalabipty, etc.

Quapty Scenarios

Quapty scenarios specify how to prevent a fault from becoming a failure. They can be spanided into six parts based on their attribute specifications −

Source − An internal or external entity such as people, hardware, software, or physical infrastructure that generate the stimulus.

Stimulus − A condition that needs to be considered when it arrives on a system.

Environment − The stimulus occurs within certain conditions.

Artifact − A whole system or some part of it such as processors, communication channels, persistent storage, processes etc.

Response − An activity undertaken after the arrival of stimulus such as detect faults, recover from fault, disable event source etc.

Response measure − Should measure the occurred responses so that the requirements can be tested.

Common Quapty Attributes

The following table psts the common quapty attributes a software architecture must have −