The API-first approach
The API-first approach is a design strategy for enterprise application development. As a Pega Lead System Architect (LSA), when you begin designing an application, consider taking the API-first approach alongside standard factors such as performance, scalability, security, maintenance, cost, time, and effort. By adopting the API-first approach, you design interfaces for your application that facilitate integration with other applications, thereby avoiding the duplication of code that already exists in other applications. Additionally, this approach promotes sharing your code so that others can reuse your services without having to build them from scratch.
What is the API-first approach?
The API-first approach involves designing interfaces in your application so that other applications have access to your services. It is called API first because, from the beginning of the application development process, you need to clearly define which services you provide to external applications. In this way, you incorporate interface design and development efforts from the start. For example, the Pega Infinity team identifies which aspects of their product they expose as services, which is why Constellation DX APIs are included in the product.
Need for the API First Approach
Pega LSAs design applications using SOLID principles. The goal is to create Single Responsibility applications in Pega Infinity that align with Microservice architecture.
When each application is responsible for only one functionality, it becomes crucial to integrate and consume functionalities from other applications to achieve end-to-end automation of enterprise business processes. Defining interfaces is essential for the development of Single Responsibility applications (microservices). Without these interfaces, the implementation of business requirements is incomplete.
Standards in the API First Approach
Creating interfaces for applications has long been a part of software development, but recently, global standards and specifications have been established. Some of these standards include RESTful API Modeling Language (RAML), API Blueprint, and OpenAPI.
Pega Constellation APIs adhere to these best practices and standards. As a Lead System Architect, start by designing and defining the API. After stakeholders review and approve the design, instruct your team to proceed with the development of the API
The process of designing and defining an API involves several key stages:
- Defining the API Contract
- Designing the API Structure
- Describing API Prototyping
- Documenting API Usage
Defining the API Contract
The first step in API-first development is to define the API contract. This involves specifying the functions that the API performs and the business goals it supports. Proper segregation of interfaces is essential during this phase.
Designing the API Structure
This stage includes detailing the endpoints, request-response formats, and data models that the API uses.
Describing API Prototyping
With the API contract established, developers can create a prototype or mock version of the API. This prototype provides predefined responses to requests, facilitating initial testing and validation.
Documenting API Usage
Comprehensive documentation is crucial in API-first development. While the initial API specification document serves as a good starting point, you should enhance it with detailed documentation. This should cover all aspects of the API, including authentication, error codes, versioning, terms of service, and usage examples.
Once API specifications are designed and defined, then actual development of the API starts, which has the following stages in its lifecycle:
- API logic implementation
- API functionality testing
- API usage feedback
- API versioning
API Logic Implementation
After prototyping the API in the design phase, the development team starts implementing the API business logic that meets the API contract's requirements. Throughout this phase, the Lead System Architect conducts a code review to ensure that the code is written according to the predefined API specifications. Any changes disrupt the contract with the API consumer.
API Functionality Testing
API-first development prioritizes continuous testing to ensure that the API consistently fulfills its contract throughout the development process. Unit tests and functionality tests are important, but contract tests hold particular significance. Contract testing involves integrating server and client sides. Contract testing verifies that API responses align with the expectations outlined in the API specification, ensuring seamless compatibility between the producer and consumer.
API Usage Feedback
A critical phase of API-first development involves collecting and integrating feedback from API users. By gathering insights from both the internal quality assurance team and external consumers, you can drive continuous improvement of the API, ensuring its relevance and value.
API Versioning
In API-first development, the final phase before starting the next iteration involves refining the API based on user feedback. Enhancing the API, along with effective versioning, enables it to evolve and adapt to new requirements while preserving its core functionality. Implement versioning strategies to manage changes without disrupting existing clients. Additionally, update documentation consistently to reflect the API's evolution.
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This Topic is available in the following Modules:
- Interface design v1
- API design v1
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