Jeremy H - March 4, 2024
API-first development prioritizes designing and building application programming interfaces (APIs) before any other components of the application. This approach ensures that APIs, which allow different software systems to communicate, are central to the development process. Essentially, the API-first approach recognizes that the consistency, reusability, and quality of your API ensures the following:
- Adoption: The widest range of users/clients can adopt and consume your API.
- Developer-friendly: Developers can easily use your API to integrate your app or service into their projects.
- Compatibility: Your app or service can integrate with a diverse array of apps and systems.
In this brief guide, we’ll help you understand the concept of “API-first development” and its tremendous advantages. We’ll also outline the most important steps for implementing an API-first development strategy in your next projects.
Here’s the key things to know about API first development:
- The API-first approach prioritizes APIs in development, focusing on consistency, reusability, and quality to enhance adoption, developer ease, and compatibility.
- API-first development uses languages like OpenAPI for clear planning and communication among developers.
- Increasingly popular, API-first supports the microservices style, enabling significant scalability and flexibility in applications.
- API-first offers benefits like scalable systems, flexibility for updates, fault tolerance, language/platform agnosticism, and quicker, more cost-effective development.
- Implementing API-first requires planning, collaboration, and tools for key functions identification, API contract creation, and automated API generation.
Table of Contents
History of API-First Development
Ever since Roy Thomas Fielding introduced the world to the concept of REST (representational state transfer) and RESTful systems in 2000, developers have been using REST APIs in their web development projects with an increasing level of frequency. That being said, it wasn’t until the last decade that programmers began to embrace the idea of “API-first” development.
The API-first approach to app development puts the focus on application programming interfaces (APIs) from the very beginning. This strategy emphasizes the importance of the API, knowing that its consistency, reusability, and quality will lead to:
- Adoption: By making it accessible and well-designed, a broad spectrum of users and clients can utilize your API.
- Developer-friendliness: The approach ensures that developers find it simple to incorporate your API into their own apps or services.
- Compatibility: With an API-first mindset, your application or service is crafted to work seamlessly with various other applications and systems, providing flexibility and adaptability.
What Is API-First App Development?
The API-first approach recognizes that the programming process should begin with planning the API. Then, each step of the API-first coding process will seek to preserve the initial API plan while ensuring the API’s consistency and reusability.
API-first development achieves consistency and reusability by using an API specification language that other developers can easily understand and navigate. The most widely-used API specification language is the OpenAPI Specification (originally called the Swagger Specification). While other API specification languages exist – like RAML and API Blueprint – OpenAPI has become the de facto “standard.”
Here’s how Swagger describes the OpenAPi Specification: “An API specification provides a broad understanding of how an API behaves and how the API links with other APIs. It explains how the API functions and the results to expect when using the API. A good example of an API specification is the OpenAPI Specification. You can view the latest version of this specification (3.0.1) on GitHub.”
To conclude this section, API-first means that you will plan how the API is going to behave before you start coding the application. It also means that you will commit to a consistent and reusable API specification before coding the application. This means that the form of your application – and the coding process – will reflect the API (and not the other way around).
From a workflow perspective, API-first requires you to invest more energy ahead of time into planning the API. Although this requires additional collaboration between developers, future API consumers, and key stakeholders, it helps ensure a more adoptable, developer-friendly, and compatible product.
How API-First Development Works
API-first development is a strategic approach that prioritizes the creation of APIs at the outset of a project, setting a foundation for all future development activities. This methodology is not just about the sequence of development but also about a mindset that considers APIs as the primary artifacts of the development process. Here’s a deeper dive into how API-first development unfolds, highlighting its technical intricacies and the rationale behind its practices.
1. Defining the API Contract
The first step in API-first development is to define the API contract. This involves specifying the endpoints, request-response structures, and the data models that the API will use. Tools like Swagger (OpenAPI) are often employed to create these API specifications in a standardized, language-agnostic format. This specification acts as a contract between the backend services and their consumers, ensuring consistency and understanding across all teams involved in the development process.
2. Mocking and Prototyping
With the API contract in place, developers can then proceed to mock or prototype the API. This involves creating a basic implementation of the API that returns predefined responses to requests. Tools like Postman, Swagger, or specialized mocking services can simulate the API behavior, allowing front-end developers and external teams to start integrating and testing against the API long before the actual logic is implemented. This parallel development streamlines the workflow, significantly reducing the time to market.
3. Implementation of Business Logic
Once the API is mocked, backend developers begin the implementation of the underlying business logic. This phase involves setting up the server, database, and other backend components, and then coding the functionality that fulfills the API contract’s promises. During this phase, the emphasis is on adhering to the predefined API specification to ensure that any changes do not break the contract with the consumers
4. Continuous Testing and Iteration
API-first development emphasizes continuous testing to ensure the API meets its contract throughout the development process. This includes unit tests, integration tests, and contract tests. Contract testing, in particular, verifies that the API responses match the expectations set out in the API specification, ensuring compatibility between the server and client sides. Tools like Dredd or Pact can automate contract testing, facilitating a continuous integration/continuous deployment (CI/CD) pipeline that maintains API reliability and quality
5. Documentation and Versioning
Proper documentation is crucial in API-first development. The API specification document generated in the first step is a good starting point, but it should be supplemented with detailed documentation covering all aspects of the API, including authentication, error codes, and usage examples. This documentation must be kept up-to-date as the API evolves. Versioning strategies must be implemented to manage changes to the API without disrupting existing clients.
6. Feedback Loops and Evolution
An essential aspect of API-first development is the establishment of feedback loops with API consumers. Gathering and incorporating feedback from internal developers, external partners, and even third-party developers can drive the API’s evolution, ensuring it remains relevant and useful. This iterative process, coupled with robust versioning, allows the API to grow and adapt to new requirements without losing its core functionality.
Why Is API-First Growing in Popularity?
The API-first approach to application development is currently growing in popularity because it supports the trend toward “microservices application architectures.” Over the last decade, the microservices architectural style made it possible for enterprises – like Amazon, Netflix, Uber, and Etsy – to achieve unprecedented scalability, growth, and competitiveness – while absolutely dominating their industries. Considering the success these organizations have achieved through API-first and microservices-based application strategies, it’s not surprising that other businesses are following suit with microservices strategies of their own.
While the trend toward microservice is clear, not everyone knows what a microservices application architecture means. So let’s see how microservices thought-leaders James Lewis and Martin Fowler describe the concept: “The microservice architectural style is an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms, often an HTTP resource API [i.e., a REST API].” (Make note of the bolded text here; we’ll address it in a moment).
Ultimately, the microservices architectural style is a radical departure from traditional monolithic applications. A monolithic application consists of all services and features written into a single piece of code. Conversely, the microservices-based system breaks the monolith into its component services/features, and it runs each feature as an autonomous mini-application (or microservice). Ultimately, the individual microservices that comprise the architecture rely on REST APIs to interact with each other. Through loose REST API connections, the microservices connect to form the larger application.
As you can see, APIs are essential to microservices-based app development. Therefore, the growing popularity of microservices-based apps has led to a corresponding rise in API-first development strategies.
Now more than ever, modern developers need to consider first-and-foremost the APIs that their web services, apps, microapps, and microservices will expose. By planning the API first – and making sure it adheres to a consistent, reusable, and widely-understood API specification – developers ensure that their apps and services can easily integrate with virtually any microservices-based architecture.
The Advantages of API-First Development
The API-first approach (1) helps developers reap the benefits of microservices-based applications, and (2) helps developers ensure that their apps/services can be consumed by the widest range of clients/systems in the API economy.
Here are some of the most compelling advantages of API-first:
More Scalable Systems
The loose connections of APIs ensure that the services they expose are as stateless and RESTful as possible. REST APIs allow for “loose” connections while minimizing or eliminating dependencies. This supports scalability because it’s easier to deploy, replicate, and destroy instances of a specific microservices app component in response to fluctuating demands on the system.
Greater Flexibility to Upgrade and Update Systems
Well-designed APIs – and the fact that they promote app/client interactions without dependency – support pluggable, component-based architectures. This pluggability offers the flexibility to add, remove, or upgrade individual services/features while reducing the chance of impacting other parts of the system.
Highly-Available, Fault-Tolerant Systems
A microservices-based system that integrates through APIs allows you to build a highly-available and fault-tolerant system. This is because it’s easier to load-balance incoming requests, automate the deployment of microservices, achieve redundancy of key components, and carry out other orchestration strategies. Through the redundancy of systems and other fail-safes – like implementing circuit breaker patterns – if one microservice fails, there is less chance of it negatively impacting the rest of the system.
Language and Platform Flexibility
APIs offer a language and platform agnostic interface that different microservices can interact with. Because API-first development prompts the creation of consistent and reusable APIs, the API-first approach helps your systems integrate with a wide range of services – regardless of their languages and platforms.
Lowers Development Costs and Achieves Faster Time to Market
The pluggability that API-first achieves means that development teams can re-use different app components (or microservices) in other projects. Development teams can focus more time on building a minimum viable product, then complete the rest of the project by integrating with the APIs of other pre-built microservices components. An API management solution like DreamFactory is indispensable in this regard because it allows you to instantly integrate a wide range of features and services into the projects you’re developing.
How to Implement an API-First Approach
Implementing an API-first development approach in your organization requires planning, cooperation, and enforcement. Here are some key tasks and concepts to build into your API-first strategy to make sure it’s a success:
1. Collaborate with API Consumers and Stakeholders
Determine who the API stakeholders are inside your organization, and determine who the consumers of the API will be. Before and during the API planning stage, collaborate closely with these individuals to ensure that (1) stakeholders/consumers will have the easiest time using the API, and (2) the API is designed to satisfy their unique use-cases.
2. Identify API Functions and Endpoints Before Coding
Brainstorm the key functions and services that the API needs to expose before starting to code. Based on collaboration with stakeholders and API consumers, what key features/capabilities are needed? Make sure to understand the different use-cases for the API, confirm these with stakeholders, and determine the API end-points required to service those needs.
3. Create an API Contract for Each Project
The API contract codifies the standards and best practices that you will adhere to when building the API. At this stage, you should design and document the API in a way that ensures compatibility with APIs and adherence to consistent and reusable standards. We recommend that your REST APIs adhere to the OpenAPI standard since it is the most widely used.
4. Develop a Company-Wide API Style Guide
An API style guide ensures that the different teams in your organization use the same consistency and reusability standards for all APIs. For example, the API style guide should codify the API status codes, error handling, versioning strategies, and other aspects of your APIs.
5. Enforce Style Guide Best Practices with API Governance
Use API governance to enforce the API standards that you establish in the style guide. Enforcing your established standards may involve peer reviews of both the APIs themselves and the application code.
6. Automate Your API Generation Process
Automate your API generation processes with DreamFactory. The DreamFactory API management platform includes tools that help you automatically generate REST APIs for nearly any service or database – in just a matter of minutes. Best of all, DreamFactory generates APIs with full Swagger documentation, and they adhere to the OpenAPI standard. Swagger documentation is also interactive, so developers can explore and test the API endpoints before integrating your API into their systems.
DreamFactory: Advanced Support for Your API-First Strategy
After reading this guide, you should have a clear understanding of what API-first development is, and why it’s essential to modern, microservices-based application development. You might even want to try adopting an API-first development strategy of your own.
Whether you’re already an API-first developer – or planning to adopt this strategy in the future – the DreamFactory API manager can facilitate your API-led development journey while reducing your labor costs and dramatically speeding up your time to market. Not unlike an “API Swiss army knife,” DreamFactory’s API portfolio allows you to instantly integrate useful tools, features, and services into your applications and IT infrastructure projects. Moreover, DreamFactory’s automatic API generation features empower you to generate fully-documented REST APIs for virtually any database or system in minutes.
If you’d like to learn more about DreamFactory and how it can speed up your time to market while supporting your API-first development goals, contact the DreamFactory team now!
Frequently Asked Questions: API First Development
What Is API-First Development?
API-First Development is an approach that emphasizes the creation of APIs at the beginning of the development process. It focuses on consistency, reusability, and quality to ensure broad adoption, ease of integration, and compatibility with diverse systems.
Why Is API-First Development Important?
API-First Development offers several benefits, including scalability, flexibility, and cost-effectiveness. It also supports the growing trend toward microservices architecture, making it vital in modern software development.
What Are the Key Advantages of an API-First Approach?
Some key advantages include scalable systems, greater flexibility to update, fault tolerance, language/platform flexibility, and lowered development costs.
What Is OpenAPI Specification, and Why Is It Used?
OpenAPI Specification is the most widely-used language for API specification. It helps developers understand how an API behaves, ensuring consistency and reusability in API-first development.
How Does API-First Relate to Microservices?
API-First is closely aligned with microservices architecture, where applications are built as a collection of loosely connected services. APIs enable these connections, so planning them first ensures seamless integration and scalability.
How Can I Implement an API-First Approach in My Organization?
Implementing API-first requires careful planning, collaboration with stakeholders, and the use of tools to identify functions, create API contracts, and possibly automate API generation. Following a well-documented strategy, like using OpenAPI standards, is recommended.
What Are Microservices, and Why Are They Important?
Microservices are a way of developing applications as a suite of small, autonomous services. They offer greater scalability and flexibility and are essential in modern applications, often supported by API-first development.
Are There Any Tools to Automate API Generation?
Yes, platforms like DreamFactory can automatically generate REST APIs, adhering to OpenAPI standards, and provide interactive documentation to ease integration.
Fascinated by emerging technologies, Jeremy Hillpot uses his backgrounds in legal writing and technology to provide a unique perspective on a vast array of topics including enterprise technology, SQL, data science, SaaS applications, investment fraud, and the law. Contact Jeremy at [email protected].