Software Architecture and Design - Goals, Principles and Some Key Considerations

Philippe Kruchten, Grady Booch, Kurt Bittner, and Rich Reitman derived and refined a definition of architecture predicated on work by Mary Shaw and David Garlan (Shaw and Garlan 1996). Their definition is:

"Software architecture encompasses the group of significant decisions about the organization of a software system including the collection of the structural elements and their interfaces where the system is composed; behavior as specified in collaboration the type of elements; composition of the structural and behavioral elements into larger subsystems; and an architectural style that guides this organization. Software architecture also involves functionality, usability, resilience, performance, reuse, comprehensibility, economic and technology constraints, tradeoffs and aesthetic concerns."

In Patterns of Enterprise Application Architecture, Martin Fowler outlines some typically common recurring themes when explaining architecture. He identifies these themes as:

"The highest-level breakdown of a system into its parts; the decisions that are Hard to change; there are multiple architectures in a system; what is architecturally Significant can change over a system's lifetime; and, ultimately, architecture boils Down to regardless of the important stuff is."

Software application architecture may be the process of defining and creating a solution that's well structured and meets each of the technical and operational requirements. The architecture should be able to consider and improve upon the normal quality attributes such as for example performance, security, and manageability.

The main focus of the program architecture is how the major elements and components in a application are employed by, or connect to, other major elements and components within the application. The selection of data structures and algorithms or the implementation details of individual components are design concerns, they're no architectural concerns but sometimes Design and Architecture concerns overlap.

Prior to starting the architecting of any software, there are a few basic questions that people should make an effort to get answers for. They are as follows:

How the users of the system will be interacting with the machine?

How will the application be deployed into production and managed?

Do you know the various non-functional requirements for the application, such as security, performance, concurrency, internationalization, and configuration?

How can the application form be designed to be flexible and maintainable as time passes?

What are the architectural trends that might impact the application now or after it has been deployed?

Goals of Software Architecture

Building the bridge between business requirements and technical requirements is the main goal of any software architecture. The goal of architecture is to identify the requirements that affect the essential structure of the application form. Good architecture reduces the business enterprise risks associated with building a technical solution while an excellent design is flexible enough in order to handle the changes that may occur as time passes in hardware and software technology, in addition to in user scenarios and requirements. An architect must think about the overall aftereffect of design decisions, the inherent tradeoffs between quality attributes (such as for example performance and security), and the tradeoffs required to address user, system, and business requirements.

Principles of Software Architecture

The basic assumption of any architecture should be the belief that the design will evolve over time and that certain cannot know everything one need to know up front. The look will generally need to evolve through the implementation stages of the application form as one learn more, so when one tests the look against real world requirements.

Keeping the above statement in mind, let's make an effort to list down a few of the Architectural principles:

The system should be created to change instead of building to last.

Model the architecture to analyze and reduce risk.

Use models and visualizations as a communication and collaboration tool.

The key engineering decisions ought to be identified and acted upon upfront.

Architects should consider using an incremental and iterative method of refining their architecture. Focus on baseline architecture to obtain the big picture right, and evolve candidate architectures as one iteratively test and improve one's architecture. Do not try to get it all right the first time-design just as much as you can in order to start testing the design against requirements and assumptions. Iteratively add details to the look over multiple passes to make certain that you get the big decisions right first, and focus on the details. A standard pitfall is to dive in to the details too quickly and obtain the big decisions wrong by making incorrect assumptions, or by failing woefully to evaluate your architecture effectively.

When testing your architecture, think about the following questions:

What were the primary assumptions that were made while architecting the system?

What are the requirements both explicit and implicit this architecture is satisfying?

Do you know the key risks with this particular architectural approach?

What countermeasures are in spot to mitigate key risks?

In what ways is this architecture an improvement over the baseline or the final candidate architecture?

Design Principles

When getting started with Software design, one should take into account the proven principles and the principles that adheres to minimizes costs and maintenance requirements, and promotes usability and extensibility. The main element principles of any Software Design are:

Separation of concerns: The main element factor to be considered is minimization of interaction points between independent feature sets to attain high cohesion and low coupling.

Single Responsibility principle: Each component or module should be independent in itself and responsible for only a specific feature or functionality.

Principle of Least Knowledge: An element or object should not know about internal details of other components or objects.

Don't repeat yourself (DRY): The intent or implementation of any feature or functionality ought to be done at only one place. It will never be repeated in a few other component or module

Minimize upfront design: This principle can be sometimes referred to as YAGNI ("You ain't gonna need it"). Design only what is necessary. Specifically for agile development, you can avoid big design upfront (BDUF). If the application requirements are unclear, or if you have a possibility of the design evolving over time, one should avoid creating a large design effort prematurely.

Design Practices

Keep design patterns consistent within each layer.

Do not duplicate functionality within an application.

Prefer composition to inheritance. When possible, use composition over inheritance when reusing functionality because inheritance escalates the dependency between parent and child classes, thereby limiting the reuse of child classes. This reduces the inheritance hierarchies, that may become very difficult to cope with.

Set up a coding style and naming convention for development.

Maintain  empresa de reformas  using automated QA techniques during development. Use unit testing along with other automated Quality Analysis techniques, such as for example dependency analysis and static code analysis, during development

Not only development, also think about the operation of your application. Determine what metrics and operational data are needed by the IT infrastructure to guarantee the efficient deployment and operation of your application.

Application Layers: While architecting and designing the machine, one needs to carefully think about the various layers into that your application will be divided. There are a few key considerations that need to be considered while doing that:

Separate the regions of concern. Break your application into distinct features that overlap in functionality as little as possible. The advantage of this approach is that a feature or functionality can be optimized independently of other features or functionality

Be explicit about how exactly layers communicate with each other.

Abstraction ought to be used to implement loose coupling between layers.

Do not mix several types of components in exactly the same logical layer. For instance, the UI layer should not contain business processing components, but rather should contain components used to take care of user input and process user requests.

Keep carefully the data format consistent within a layer or component.