Software patterns

As we all know, patterns are a kind of simplified and smarter solution for a repetitive concern and recurring challenge in any field of importance. In the field of software engineering, there are primarily many designs, integration, and architecture patterns. These patterns come in handy in speedily surmounting some of the routine and fresh issues being encountered by software architects, developers, and integrators in their everyday assignments and engagements. Design patterns are very popular and are used for expertly designing enterprise-class software systems whereas architectural patterns are used for skilfully deciding the optimized and organized architecture for a system under development. The changes and complexities are substantially taken care of through the deft leverage of various architectural patterns. The architectural patterns enable taking a series of decisions regarding the choice of technologies and tools. The various system components, their distinct capabilities, and how they connect and collaborate with one another are the key ingredients in architecting and designing next-generation software systems. The architectural patterns render their yeoman services here. With system architectures increasingly becoming complicated, the role and responsibility of architectural patterns are consistently on the increase. Similarly, as we tend towards the distributed and decentralized era, the integration patterns are very significant as they bring a lot of praiseworthy simplifications and delegations.

With the flourishing of the DevOps concept, there are additional patterns emerging in IT agility. Patterns also assiduously accelerate the process of building newer and powerful software packages. Besides the development-centric patterns, there are deployment and delivery-specific patterns also. In the ensuing DevOps and NoOps days, the deployment patterns are going to be highly beneficial in automating the time-consuming and tedious tasks. Similarly, there are delivery-enablement patterns. Patterns are fast-evolving and stabilizing tellingly with more usage and continuous refinements. Patterns are capable of overcoming the initial hiccups for newer technologies, too. Patterns will be a key ingredient for IT to survive and shine in the market-driven, knowledge-driven and cut-throat competitive environment. Precisely speaking, patterns are a crucial enabler in building sophisticated software by minimizing the workload of software developers. The risks being associated with constructing enterprise-scale, high-quality, and microservices-based applications are being substantially moderated by meticulously using the proven software patterns.

Why software patterns?

There is a bevy of noteworthy transformations happening in the IT space, especially in software engineering. The complexity of recent software solutions is continuously going up due to the continued evolution of the business expectations. With complex software, not only does the software development activity become very difficult, but also the software maintenance and enhancement tasks become tedious and time-consuming. Software patterns come as a soothing factor for software architects, developers, and operators.

Software systems are becoming extremely complicated and sophisticated in order to meet up the newer demands of the business. The field of software architecture helps to smoothen and straighten the path towards producing well-defined and designed software suites. Software architecture is primarily tuned for moderating the rising software complexities and changes. Hence, there are purported efforts to bring forth software architecture patterns to arrive at easy-to-implement and sustainable software architectures. This section begins with some basics about architecture and goes on to elaborate on some of the widely used software architectural patterns.

Architecture is essential for systems that are increasingly becoming complex due to the continuous addition of fresh modules. Architectures generally are decided by three crucial aspects: the participating components, the distinct capabilities of each of those components, and, finally, the connectivity between those components. Establishing software architectures is not an easy job. A variety of factors need to be taken into consideration while deciding the architecture. A number of architectural decisions need to be meticulously considered in order to strengthen the final architecture. Not only functional requirements but also non-functional requirements too need to be inscribed in the architecture. Typically, the architecture pattern is for designing a generic architecture for a system, such as a software solution.

The prime ingredients of a software pattern

Several different formats are used in the literature for describing patterns, and no single format has achieved widespread acceptance. The following elements described will be found in most patterns, even if different headings are used to describe them. In the Opengroup.org site, the following terminologies are used:

• Name: A meaningful and memorable way to refer to the pattern, typically a single word or short phrase.
• Problem: This is a concise description of the problem at hand. It has to throw some light on the intended goals and objectives to be reached within the context.
• Context: The context typically illustrates the preconditions under which the pattern can be applied. That is, it is a description of the initial state before the pattern is applied.
• Forces: This is for describing the relevant forces and constraints and how they interact/conflict with each other. It inscribes the intended goals and objectives. The description should clarify the intricacies of the problem and make explicit the kinds of trade-offs that must be considered. The notion of forces more or less equates to the QoS attributes (availability, scalability, security, sustainability, composability, maneuverability, resiliency, reliability, reusability, and so on) that architects seek to obtain and optimize besides the concerns they seek to address in designing architectures.
• Solution: This is all about clearly explaining how to achieve the intended goals and objectives. The description should identify both the solution's static structure and its dynamic behavior.
• Resulting context: This indicates the post-conditions after the pattern is applied. Implementing the solution normally requires trade-offs among competing forces. This element describes which forces have been resolved and how, and which remain unresolved. It may also indicate other patterns that may be applicable in the new context.
• Examples: This is about incorporating a few sample applications of the pattern for illustrating each of the elements (a specific problem, the context, the set of forces, how the pattern gets applied, and the resulting context).
• Rationale: It is necessary to give a convincing explanation/justification of the pattern as a whole or of the individual components within it. The rationale has to indicate how the pattern actually works and how it resolves the forces to achieve the desired goals and objectives.
• Related patterns: There are other similar patterns and hence the relationships between this pattern and others have to be clearly articulated. These may be predecessor patterns, whose resulting contexts correspond to the initial context of this one. Or, these may be successor patterns, whose initial contexts correspond to the resulting context of this one. There may also be alternative patterns, which describe a different solution to the same problem, but under different forces. Finally these may be co-dependent patterns, which may/must be applied along with this pattern.
• Known uses: This has to detail the known applications of the pattern within existing systems. This is for verifying that the pattern does indeed describe a proven solution to a recurring problem. The known uses can also serve as value-added examples.

Patterns may also begin with an abstract providing an overview of the pattern and indicating the types of problems it addresses. The abstract may also identify the target audience and what assumptions are made of the reader.

The types of software patterns

Several newer types of patterns are emerging in order to cater to different demands. This section throws some light on these.

An architecture pattern expresses a fundamental structural organization or schema for complex systems. It provides a set of predefined subsystems, specifies their unique responsibilities, and includes the decision-enabling rules and guidelines for organizing the relationships between them. The architecture pattern for a software system illustrates the macro-level structure for the whole software solution. An architectural pattern is a set of principles and a coarse-grained pattern that provides an abstract framework for a family of systems. An architectural pattern improves partitioning and promotes design reuse by providing solutions to frequently recurring problems. Precisely speaking, an architectural pattern comprises a set of principles that shape an application.

A design pattern provides a scheme for refining the subsystems or components of a system, or the relationships between them. It describes a commonly recurring structure of communicating components that solves a general design problem within a particular context. The design pattern for a software system prescribes the ways and means of building the software components. The design pattern articulates how the various components within the system collaborate with one another in order to fulfil the desired functionality.

There are other patterns, too. The dawn of the big data era mandates for distributed computing. The monolithic and massive nature of enterprise-scale applications demands microservices-centric applications. Here, application services need to be found and integrated in order to give an integrated result and view. Thus, there are integration-enabled patterns. Similarly, there are patterns for simplifying software deployment and delivery. Other complex actions are being addressed through the smart leverage of simple as well as composite patterns. In the next section, we will discuss the various dimensions of IT with the intention of conveying the tremendous impacts of software patterns for next-generation IT.