Hello dear reader. This is my last blog for my Software Construction and Design and as a very important part of development I choose to talk in this blog post for REST API.

REST API stands for Representational State Transferee and provides a lighter weight compared to SOAP. Instead of using XML to make a request, REST relies on a simple URL in many cases. In some situations, additional information needs to be provided. Most Web services using REST rely exclusively on obtaining the needed information using the URL approach. REST can use four different HTTP verbs (GET, POST, PUT, and DELETE) to perform tasks.
REST-based Web services output the data in Command Separated Value (CSV), JavaScript Object Notation (JSON) and Really Simple Syndication (RSS). The point is that you can keep the output you need in a form that’s easy to understand and use within the language you are using for your application. The information you receive when using REST is a JSON formatted document containing the information you asked for. You can use your browser to interact with the Web service, which makes it a lot easier to create the right URL and verify the output you need to parse with your application.
In most of the part REST is easier and more flexible to use. To use REST you do not need to purchase any tools, Postman or Insomnia can be downloaded for free. REST though, is efficient as it uses the small message formats and it has a fast process.
There are some very strong reasons that you should be using REST. First, REST is the most popular choice of programmers to build APIs.  Also REST API is great on making the data available as a resource as opposed to service.
To create a REST API, the following six architectural constraints are needed: 1. Uniform interface, which means that the same resource should not have more than one URL; 2. Client-server separating, which means that the client and the server should act independently. 3. Statelessness, which means that there should never be any server-side sessions; 4. Cacheable resources, means that the server responses should contain information even though the data sent might or not be cacheable; 5.Layered system, which means there might be different layers of servers between the client and the server that returns the purpose; 6. Code on demands, which means that the response can contain code that the user can execute.

If I also refer to the previous blog about SOAP API I would say that there are clearly good reasons why REST API is a better choice to use when requesting/ expecting data and when you want to build your own program. However the decision is yours. I hope I have helped your CS journey. Till next time…

https://en.wikipedia.org/wiki/Representational_state_transfer

From the blog CS@Worcester – Danja's Blog by danja9 and used with permission of the author. All other rights reserved by the author.

As I take my final step towards my journey in software C.D.A. this blog would be the last one regarding my journey with learning and researching topic related to my class Software Construction Design and Architecture. For this blog I will be talking about the blog “API management with Kong” by Alexander Melnyk. This blog is about the importance of API management and why does it matter. It also focuses on the Kong Architecture.

In the blog it explain why API management matter. The idea of API management is that it plays an important role when it comes to integration. Which can be done “by providing clear boundaries and abstractions between systems”. The blog also explains a few “ways to tackle the technical complexity and how Kong API gateway can help deal with it”. You may be wondering what is Kong it is an open source API gateway to manage RESTful APIs.” However the blog gives a better description of what and how it is use for. There are five components of Kong architecture:

1. nginx – “The core low-level component” also the most popular used web server.
2. OpenResty – “a web platform that glues nginx core, LuaJIT, Lua libraries and third-party nginx modules to provide a web server for scalable web applications and web services.”
3. Datastore – is a component that “uses Apache Cassandra or PostgreSQL to handle the storage of the configuration data, consumers, and plugins of all APIs.”
4. plugins – “are Lua modules that are executed during a request/response life-cycle. They enrich the API gateway with functionalities for different use cases.”
5. RESTful admin API – It is used to manage the API and provide an important tool to automate developers workflows.

The blog goes on and covers the Kong API gateway in action which “will show you how to create a minimal infrastructure for Kong API gateway. Then I will add an API and a security plugin to restrict the access to a specific user.” and then covers the consumers and plugins. If you have found this topic interesting or if your curiously left with question click on the title link above and read the blog the blogger does a much better job at explaining and getting the message across then I do.

Personally I really enjoyed reading the blog because it helped me realize that the Kong Architecture is in fact very useful and important. I also found the blog to be well written full of useful and important information that will benefit me as a software developer.

Thank you for your time. This has been YessyMer in the World Of Computer Science, until next time.

From the blog cs@Worcester – YessyMer In the world of Computer Science by yesmercedes and used with permission of the author. All other rights reserved by the author.

Hello dear reader. After explaining what API is, now I would like to talk about Architectural Styles for API. One of these styles is called SOAP.

SOAP stands for Simple Object Access Protocol. SOAP is a standard based Web services access protocol that enjoys the benefits of long-term use. SOAP is developed by Microsoft.
SOAP relies exclusively on XML to provide messaging services. Microsoft originally developed SOAP to take the place of older technologies that don’t work well on the Internet. These technologies are bad and fail because they rely on binary messaging; the XML messaging that SOAP employs works better over the Internet. SOAP is designed to support expansion, so it has all sorts of other acronyms and abbreviations associated with it, such as WS-Addressing, WS-ReliableMessaging, WS-Policy, WS-AtomicTransaction, WS-Federation, WS-Coordination, WS-Security, and WS-RemotePortlets. In SOAP you can only choose to use the pieces you need for a particular task.As we know, in some programming languages, you need to build requests manually, which becomes problematic because SOAP is intolerant of errors. However, SOAP provides shortcuts to help in this issue. The difficulty of using SOAP depends on the language you use.
One of the most important SOAP features is built-in error handling. If there’s a problem with your request, the response contains error information that you can use to fix the problem. An interesting SOAP feature is that you don’t necessarily have to use it with the HyperText Transfer Protocol (HTTP) transport. There’s an actual specification for using SOAP over Simple Mail Transfer Protocol (SMTP) and there isn’t any reason you can’t use it over other transports.
As SOAP is an ordinary XML file that consists of the following parts: 1. Envelope, which is the starting and the ending tags; 2. Header, which it allows you to extend the SOAP message in a modular way; 3. Body, which contains XML data that the server send to the receiver; 4. Fault, which carries the information about errors occurring during the process of sending the message.

SOAP is mostly used for enterprise-lever web service because that require high security. Some examples of SOAP that I found online were: financial services, payment gateways, identity management and telecommunication services. Also another feature of SOAP is that the API calls can not be cached. The biggest disadvantage is the poorer performance, more complexity and less flexibility.

I didn’t know SOAP existed until I searched for REST (the next blog). The reason why I choose to write about SOAP is that it is a wide used architectural style for API and it has its own place of use, places or situation where REST can not be used.

From the blog CS@Worcester – Danja's Blog by danja9 and used with permission of the author. All other rights reserved by the author.

Hello dear reader. As I was staring at my computer and was trying to find a good subject for today’s blogs a bell ringed in my mind: APIs.
I never came across the name API until I started my job. I remember when everyone used to say ‘The API is not working’, ‘We need to call the API to make this process happened’ etc. and I was super confused so I entered google and wrote what is API. Google told me ‘Application Programming Interface’ more fancy words. I started to watch videos about it and also, we started to use them at school. Now I am the one using the term API.

Application – think of an application like credit card. You expect the credit card to help you purchase items and goods.

Programming – API allow the credit card needs to contact your bank and make sure you haven’t extended the limit in your card and is okay to go on.

Interface – is the way we interact with an application.

Simple for you: API define rules that developers must follow to interact with a programming language, software library, web interface or any other software tool. Everyone uses an API every day in some way. A simple comparable example would be you accessing a webpage in your browser. You make a request by entering the webpage URL and the view you see after you press Enter is the response. The API has the same process of request/response but the difference is that API requests provide data in their response.

But why do we even use API? Many of the APIs are made with the intention to allow 3^rd party developers to build applications using company data, Since the APIs simply provide data, there are limits on how a company can then go on to use that data. APIs act just like a door and keys. Only the people having the key can open the door and enter the room.

https://www.youtube.com/watch?v=InoAIgBZIEA This video is a great example on how to use the API ( how to call and get the information you need).

From the blog CS@Worcester – Danja's Blog by danja9 and used with permission of the author. All other rights reserved by the author.

Hello dear reader. Another concept that I came across this semester in my Software Design and Construction class was UML diagrams and I wanted to write about UML diagrams in one of my posts.

For all of you that are new to UML, UML is not a programing language. UML stands for Unified Modeling Language. UML is a standard model language of an integrated set of diagrams. UML was developed to help system and software developers for specifying, constructing, visualizing, and documenting the code of software systems. It is a very important part of developing object-oriented software and the software development process. UML uses mostly graphical notations to express the design a software. Using UML helps teams communicate and validate the architectural design of the software. We use it to portray the behavior and the structure of a system/project.

A question that I asked myself when I started to learn about UML was: Do we really need UML? The more I learned about it the more I understood how important UML is. This for different reasons like: – there are a lot complex applications and systems that need planning from a lot of different teams, and clear explanation need to go to each and every team working on the same project; most of our users might not ever know what code is, but there are a very important part of our project and that’s where UML kicks in by translating this ‘foreign language’ called code.

UML can be classified in two types: Structural and Behavior Diagrams. Structural Diagrams get the static aspect or structure of a system. It includes Object Diagrams, Deployment Diagrams, Class Diagrams and Component Diagrams. Behavior Diagrams on the other hand get the dynamic aspect or behavior of the system and it includes Interaction Diagrams, State Diagrams, Use Case Diagrams and Activity Diagrams.

Except school I have come across UML Diagrams at my job too. The diagram I have seen and that we use a lot if the Deployment Diagram as each of us should be aware of the architecture of the system as deployment.

I like the way Noel explains UML diagrams and where/how to use them. He provides great graphic examples of the diagrams.
https://tallyfy.com/uml-diagram/

From the blog CS@Worcester – Danja's Blog by danja9 and used with permission of the author. All other rights reserved by the author.

Hello dear readers. In this blog post I would like to write about Refactoring, documentation and software framework. While explaining what they are I will try define why are they needed.

Refactoring is very used term in software development and has played a major role in the maintenance of software. Refactoring is one of the most self-evident processes, but it is surprisingly difficult to perform properly. In most cases, we deviate from strict refactoring and execute an approximation of the process; sometimes, things work out and we are left with cleaner code, but other times, we get snared, wondering where we went wrong. In either case, it is important to fully understand the importance and simplicity of barebones refactoring. Refactoring is a controlled technique for improving the design of an existing code base. Its essence is applying a series of small behavior-preserving transformations. The cumulative effect of each of these transformations is quite significant. By doing them in small steps you reduce the risk of introducing errors. You also avoid having the system broken while you are carrying out the restructuring — which allows you to gradually refactor a system over an extended period of time.

I also want to talk about documentation in this blog post. For a programmer reliable documentation is always needed. The presence of documentation helps keep track of all aspects of an application and it improves on the quality of a software product. Its main focuses are maintenance, development, and knowledge transfer to other programmers. Successful documentation will make information easily accessible, simplify the product, help new users learn quickly, provide a limited number of user entry points and help cut support costs. Documentation is usually focused on the following components that make up an application: business rules, troubleshooting, server environments, application installation, database/files and code deployment.

A software framework is a concrete platform where common code with general functionality can be specialized or overridden by developers or users. Frameworks take the form of libraries, where a well-defined API is reusable anywhere within the software under development. There exist some features that make a framework different form other library form. These features are: default behavior, inversion of control, extensibility, non-modifiable framework code.

I am attaching the following links that will help you have a better understanding of these concepts as these blog posts also provide examples.
https://refactoring.com/
https://medium.freecodecamp.org/why-documentation-matters-and-why-you-should-include-it-in-your-code-41ef62dd5c2f
https://www.quora.com/What-is-a-framework-in-programming

From the blog CS@Worcester – Danja's Blog by danja9 and used with permission of the author. All other rights reserved by the author.

Hello dear readers. Welcome back to my blog. As we know by now most programming language support and encourage object-oriented programming and in this blog post we are going to talk about the principles of the Object-Oriented Programming. The key design principles of Object-Oriented Programming are:

Abstraction – is the idea of simplifying a concept to its bare essentials in some context. It allows you to better understand the concept by stripping it down to a simplified version. Your abstraction should be intuitive.

Encapsulation – can be thought of as putting something inside a capsule. In software, restricting access to inner objects and properties helps with data integrity. Encapsulation makes your classes easier to manage, because you know what part is used by other systems and what isn’t. This means that you can easily rework the inner logic while retaining the public parts and be sure that you have not broken anything. A disadvantage of it is that working with the encapsulated functionality from the outside becomes simpler as you have less things to think about.

Decomposition – is the action of splitting an object into multiple separate smaller parts. Spitted parts are easier to understand, maintain and program. There exist three types of decomposition relationships: 1. Association, which defines a loose relationship between two components. They don’t depend on each other but work together. 2. Aggregation, which defines a weak ‘has-a’ relationship between a whole and its parts. The parts though can exist without the whole. 3. Composition, which defines a strong ‘has-a’ relationship where the whole and the part can’t exist without each other.

Polymorphism – is the ability for data to be processed in more than one form. It allows the performance of the same task in various ways. It also consists of method overloading and method overriding.

Inheritance – is the ability of one class to inherit properties of another class, called the parent class. We can inherit properties from other classes s well.  So, when we create a class, we do not need to write all the properties and functions again and again, as these can be inherited from another class which possesses it. Inheritance allows the user to reuse the code whenever needed.

Design principles are rules in software design that have proven themselves valuable over the years. Just like any other ‘game’ even when we code we need to know and follow the rules. This is the main reason why I choose to write about the principles of Object-Oriented Programming.

From the blog CS@Worcester – Danja's Blog by danja9 and used with permission of the author. All other rights reserved by the author.

Hello dear readers. Today we are going to talk about SOLID, the first five principles of the object oriented design.

S.O.L.I.D is an acronym for the first five object-oriented design principle. When these principles are combined together, it makes it easy for a programmer to develop software that are easy to maintain and extend. They also make it easy for developers to avoid easily refactor code and are also a part of the agile or adaptive software development. SOLID stands for:
S – Single responsibility principle
O – Open/Closed principle
L – Liskov substitution principle
I – Interface segregation principle
D – Dependency Inversion principle

Single Responsibility Principle states that a class should only have one job, only one reason to change. The reason why we should use SRP is because it makes your software easier to implement and prevents unexpected side-effects of future changes. Another benefit of this principle is that classes and software components that have only one responsibility are much easier to understand, explain and implement than the ones that provide solution for everything.

Open/Closed Principle states that objects or entities should be open for extension but closed for modifications. Using this principle prevents situations in which a change to one of your classes also requires you to adapt all depending classes.

Liskov substitution principle states that every subclass/derived class should be substitute for their base/parent class. To achieve that, your subclasses need to follow the following rules: 1. Don’t implement any stricter validation rules on input parameters than implemented by the parent class. 2. Apply at the least the same rules to all output parameters as applied by the parent class.

Interface segregation principle states that a client should not be forces to implement an interface that it doesn’t use, or clients shouldn’t be forced to depend on methods they do not use. By following this principle, you will be able to prevent bloated interfaces that define methods for multiple responsibilities. You should avoid classes and interfaces with multiple responsibilities because they change often and make your software hard to maintain.

Dependency Inversion principle states that entities must depend on abstractions not on concretions. High-lever and low-lever modules also depend on the abstraction. This design principle does not just change the direction of the dependency, it also splits the dependency between the two levels by introducing an abstraction between them.

From the blog CS@Worcester – Danja's Blog by danja9 and used with permission of the author. All other rights reserved by the author.