Hamida Rebai is a Microsoft MVP in developer technologies. She is a member and speaker of the dotnet foundation. In this article, Hamida discusses modernizing your application with API patterns.
Application programming interface (API)
API is a set of abstract programming structures and protocols to enable communication between software applications. An API acts as an intermediary; it facilitates interaction between different software programs by defining how they can communicate and exchange information. APIs have become increasingly important in the modern software landscape, allowing developers to build complex systems that integrate with other software applications, systems, services, and platforms.
APIs allow software developers to leverage the functionality of existing software applications and services rather than having to build everything from scratch. You can save time and effort, allowing for more rapid development and innovation.
We have multiple key components in APIs; for example, the API itself acts as an interface between different applications. The API may contain several sub-components: authentication, authorization, mechanism, data models, and request-response formats.
Types of API Architectures
API architecture consists of the rules that guide what information an API can share with clients and how it shares the data, REST, SOAP, MVC, etc.
REST APIs – Representational State Transfer is a set of guidance of scalable, lightweight, and easy-to-use APIs. We have some guidelines to consider for REST.
- Client-server separation means that all client-server interactions must be in the form of a request from the client for load followed by a response from the server. Servers can request, and clients can respond.
- A uniform interface means that all requests and responses must be in HTTP protocol and be formatted in a specific way to ensure compatibility between any client and any server.
- Stateless – Each client-server interaction is independent of every other interaction. The server stores no data from frontline requesters and remembers nothing from past interactions.
- Layered systems – The request or response must always be formatted similarly, even when you pass it through intermediated servers between the client and API.
- Cacheable – Server responses should indicate whether the client can capture a resource and for how long.
If you follow these guidelines, REST APIs can be used for quick, easy, secure data transfer, making them a popular choice among developers.
SOAP – Simple Object Access Protocol. It’s a protocol for transmitting data across networks and can be used to build APIs. SOAP is strictly defined and makes SOAP API more secure than REST APIs. Rigid guidelines also make them more code heavy and hard to implement. For this reason, SOAP is often implemented for internal data transfers that require high security. An advantage of SOAP is that it works over any communication protocol, not only for HTTP.
GraphQL APL – Developed by Meta in 2012 and open-sourced in 2015. It is a query language for APIs.
API modernization approaches
- API Strategy
- API Management and governance
- API cost model
- Developer engagement
An API strategy should be in place to decide which data services can be exposed to API consumers. API strategy is a critical component of digital transformation. We start by defining an API strategy, which includes the types of APIs you will use, the security protocols you will employ, and the different processes for integrating and testing your APIs. Defining an API strategy will involve setting a clear direction for how your organization will design, build and manage APIs to meet business goals and customer needs. We need to have the right metrics in the digital value chain.
To build an API strategy, we start by identifying the target audience and the business outcome. We must then align the organization’s culture and have an API mindset. We must define the tools that help the organization design, develop, deploy, and manage APIs. We also have to evaluate and build supporting technology. Existing infrastructure needs to be evaluated and optimized for the new API strategy. Gaps, if any, need to be resolved. After this, we engage the current ecosystem.
We need to provide a good developer experience because it’s crucial for engaging the developer community around your APIs, which means documentation, sample code, tutorials, and any other resource that makes it easy for developers to get started with your APIs. You must actively contact the developer community and build a relationship with them. Engage partners and other stakeholders in your ecosystem.
API foundation deals with frontend integration, backend integration, and different types of APIs. Effective API design, security, documentation, data format, and error handling are all important considerations for fronted integration for backend integration.
API Gateway Pattern
API gateway pattern is an integration pattern for clients that communicates with a system device designed to provide a single abstraction layer between the underlying services and the customer’s needs. We need to consider a synchronized response. Features of the API Gateway pattern are notification authorization, service discovery, integration, response caching, retry policies, circuit breaker, rate limiting, and load balancing. A complex application may need multiple API gateways.
We use Azure API Management Service. The Azure API gateway is a hybrid, portable, multi-cloud management platform for APIs. It has developer engagement, business insight, analytics, security, and protection.