October 25, 2022 • 139 Views
Have you ever questioned yourself what exactly software architecture is, or how various applications work? Actually, software architecture patterns may seem a complicated term, which is easy to confuse with other concepts. Thus, let’s sort it all out.
First things first, let’s consider the concept itself and compare it with the other terms, it may be confused with. Software architecture usage is the fundamental basis of any application. Just like any building, each app has its own structure, which is designed specifically to hold other superstructures, that are built on top of it. In other words, software architecture is the base of the app, which shapes its main working principles, and how the major components will interact within the application.
The term itself is an analogy to the building architecture itself. Clearly, such a complex but general concept has a wide variety of types. They are also known as patterns. Since the time this idea was formed, it was constantly improved and expanded. As a result, nowadays we have a number of approaches to building the fundament of the application. However, the development of the concept resulted in the improvement of another term - design patterns.
In fact, it is easy to confuse these two, because they have a lot in common. The main and most crucial difference lies in their scale: while software architecture patterns are related to the overall structure of the app, the design patterns are more about building components. To make it simple, design patterns are like decorating rooms inside the house.
Nonetheless, it is also true that software architecture, despite its assortment, is more of a concept rather than an actual “how to” tutorial. All of these patterns and approaches are plans or blueprints of the actual final product. The number of actual development possibilities is too hard to count. For instance, choosing the software architecture pattern is just the first step of the planning stage. Afterward, experienced developers are able to mix different toolsets and tech stacks even within a single pattern. So, even with a preset architecture, the product can be implemented in countless possible ways.
Hence, we can state that software architecture is an important step, that helps to plan the final version of the project, how will it work, what will it consist of, etc. Regardless, it doesn’t mean that choosing the architectural pattern significantly narrows down the diversity of implementation approaches. It only changes the type of possible instruments and components to use.
Finally, we can switch to the list of known and most common architecture patterns in the field of programming. Disclaimer: the number, as well as the name patterns, may vary, depending on the context. However, we tried our best to create the most complete and easy-to-understand list of known and regularly used architecture patterns.
Probably, it is the most widespread and standard pattern. Its main feature is the fact, that on the code level, the application is designed as a single unit of code, which ensures work and all related processes. It is so basic, that it also is known as traditional architecture.
The main significant characteristic of this pattern is that components within the structure are tightly connected and depend on each other. Therefore, the changes in one particular element can result in changes in other elements as well. To make it simple, a single change may result in a chain reaction. Most likely, developers will have to rewrite some related components. Nevertheless, it is hard to imagine a case, when the whole code must be adapted to the changes in a single part. Moreover, such design requires that all elements worked correctly. In other cases, it may affect the overall working of the app.
On the other hand, a monolithic architecture pattern is very easy to test and debug. Due to the fact, that all elements are built in the same code unit, developers can simply start the testing and fix issues or bugs one by one. In fact, a single codebase makes it much easier to track multiple operations at once, especially in the early stages of the software development process. We can also assume, that this software architecture type is a better solution for small and uncomplicated projects because the more scalable the app is - the more difficult it becomes to monitor and make changes. Not to mention the fact, that after each update, no matter how important or huge it is, all code must be compiled and redeployed.
It is almost opposite to the previous case. The main idea of this approach lies in dividing the app into individual components. In the microservices scenario, each service or feature is coded separately. As a result, on the code level, the application is rather a combination of various standalone functions, that are activated or connected if needed. To make it simple, each separate code unit is responsible for a single function, no more, no less.
It is worth admitting though, that comparing monolith vs microservices architecture patterns is a very common thing, yet some issues are the same for both. For instance, in each of these scenarios, the more complex application becomes - the harder it is to work with it. The only difference is that microservices are more agile and it is easier to distinguish one from another. Also, they are less dependent on each other. Thus, if a single component is updated or changed, there is no need to compile the whole code source, as well as redeploy it. Instead, developers can easily perform all these processes with only one component. As a great bonus, there is no need in rewriting either.
Talking about the major drawbacks of the microservices software architecture pattern, it is possible to name a few of them. First of all, they are more complex than monoliths, or some other development patterns. In addition to the overall complexity of the microservices structure, it is possible to add an unfriendly development environment: most of the common tools and instruments were developed and designed for the monolith architecture. Thus, even if they are compatible with microservices, it doesn’t guarantee that their combination will be easy to work with.
On the contrary, communication itself is a common problematic aspect of microservices architecture. Structure, which consists of numerous standalone components, highly relies on communication capabilities. For instance, a single user request may need a few independent structure elements to cooperate in order to process it.
This software architecture type is also known as an n-tier or tiered pattern. The main feature that is easy to notice lies in the way the application functions are sorted. As its name says, the app is divided into layers, each of which has its own specified process logic. The number of these layers may vary, depending on the scale and complexity of the final product, yet it usually fluctuates around 3-5 levels. Each layer is separated, meaning that they can be changed without affecting others. It is possible to suggest that layered software architecture is partly similar to the microservices one. The only difference is that these tiers are more general and complex than microservices, providing a combination of various features that have some common logic or solutions instead of separating them completely.
You may have also heard of the Presentational layer. It is the first in the chain, and, obviously, is responsible for the final client-side view of the application. At this level, all UI elements and interaction options are designed and embodied. It deals with all user requests, shaping them and sending them down the chain.
It is the next stage, where the business logic operates. It is the set of rules and guidelines, which defines the exact procedures and behavior of the application. In simple words, it consists of step-by-step tutorials for each process, so that the app “knows” what to do with each request. After it is processed and “instructed”, the user request is sent further.
Or persistence level, if you may. This step is designed specifically for security measures. On the one hand, it has the ability to give the request access to the databases if it has passed the preliminary stages. Additionally, it is flexible and may be used for database management or adjustment.
Eventually, no matter how many levels the application can have. In any case, the DB stage will be always present and the final one. Clearly, at this tier, the data is being operated. All the operations, related to the database processes, whether it is simply storing, updating, deleting, or any other procedure with data.
Summing up, a Layered architecture pattern is a great out-of-box solution, that does not require any specific skills or rich background knowledge. It can become a great decision both for skilled and inexperienced developers. Such an approach helps to simplify and speed up the agile software development process by dividing the whole code structure into separate units with a single and very specific use purpose. Thus, it will be easier to navigate the code and distribute responsibilities in the development team.
On the flip side, this architectural pattern requires strict subordination to its logic. So, if the source code will be unorganized, or the overall operating process will try to skip some steps it may result in additional working issues up to critical errors.
If we continue talking about the work with databases, the Master-slave architecture pattern is a great alternative. This approach means that databases are divided by roles: master for writing requests and slave for reading them. This split helps to improve and optimize the input/output traffic. As a result, we will have a single master component, which writes requests and delegates the read request to its slaves. Additionally, the master is able to determine and prioritize processes, delegated to the slaves.
Therefore, in case of numerous user requests, the application will stay reliable and won’t be as impacted and overloaded as it might be in other cases. This approach is a nice decision for large projects, that have to deal with numerous users. Talking about the drawbacks of such an architectural pattern, it must be said that one of the most vulnerable aspects is the master component. Its crash may result not only in working issues but cause losing data and backups.
It is another example of a binary pattern, where there are only 2 main components: client and server. However, it is the only thing that is common between this and previously mentioned software architecture designs.
The client-server pattern is built on top of communication between these two components. The client sends a request to the server, where it is processed. After the server clarifies it, it sends a response with the requested resources. Such an approach may easily support numerous users or servers. They may be defined by the resources they can work with. Therefore, a single client can be served by multiple servers. The single server can proceed with requests from numerous users at a time. This pattern is very fast and flexible, able to support different types of content and files. For instance, it is a very popular architecture design for email or file-sharing applications.
It is possible to highlight two main disadvantages of such a pattern: they are extremely vulnerable to various harmful content like viruses due to the linked nature of the structure and it may be expensive to implement such architecture from scratch. Nonetheless, it will be cheaper to support it in the long-term perspective. It is worth admitting that if the critical server goes down, most likely, other servers will struggle with working issues as well.
The P2P pattern’s main specific lies in operating two elements as well. Thus, it is regularly opposed to the client-server architecture. The main difference is that a peer-to-peer network is able to share not only demands as a C/S pattern but also distribute resources. This feature is possible thanks to the fact that peers in this approach can switch their roles: they can work as clients and send requests, or become a server, sharing content.
Furthermore, this flexibility of components allows for avoiding centralized server options. In other words, within such a network, each participant can take an equal part in the process. Thus, we can assume that it is a very horizontal architecture, that treats each element respectfully, no matter what role it is performing at the particular moment.
Contrary to other software architecture types, P2P is becoming easier and more productive to work with growing the scale. To make it simple, the more participants or nodes are connected - the more effective it is.
However, applications, built with the use of this architecture, probably will require additional tools to work with various formats of resources and data, in order to be able to read it. Additionally, this chaotic hierarchy makes it difficult to embody effective security measures, that will prevent harmful content or processes.
As a matter of fact, it is only a limited number of software architecture models. There is a wide variety of alternative types like event-driven, microkernel, space-based, pipe-filter types, and many others. It is impossible to describe all of them in detail, yet we are able to assume that each type has something in common with its competitors. For instance, client-server, P2P, and master-slave architecture patterns have used some similar principles, yet in a different ways. Why is it important to understand and be able to distinguish software architecture? As was mentioned before, it is the first thing to choose. It defines the overall structure, capabilities, and functions. Therefore, it can help to design quality attributes and improve the performance of the application. Clearly, architecture does not work as a one-time solution, when a single pattern can be used for a single and very specific case. On the contrary, they can regularly replace each other. Nevertheless, each software architecture usage has at least one perfect usage case, it was originally designed for.
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