API Development Guide: REST, GraphQL, gRPC

Companies across different verticals use APIs to enable communication between the client and server side of their apps, to integrate with third-party software, and to allow external apps to access their system. Moreover, building and monetizing custom APIs can become an essential part of a business development strategy.

If APIs play a crucial role in your project, the requirements for their development may be rigorous. You need to know how to meet technical challenges, what protocol to choose, and what practices to apply for building top-notch API-focused products. The following guide aims at answering these questions.

API Protocols: Types & Development Specifics

Let’s first explore different kinds of APIs and their development features so that you can identify the most suitable protocol for your project. Regardless of which programming language you choose for API development, Node.js, Python, Ruby, or others, the type of protocol is more important. Currently, the top approaches in custom API development are REST, GraphQL, and gRPC.

REST API

REST, also known as Representational State Transfer, refers to APIs that are stateless, meaning each request holds all the details necessary to complete it. A vast majority of backend developers are familiar with REST API development. This is the most frequently used and versatile type of API, utilized in a large number of software projects. Being a simple protocol with a low barrier to entry, REST APIs are unlikely to face future support issues.

With REST, we clearly understand what and how we’re requesting, and we know what response to expect. The same applies to errors; we can pinpoint the error based on status codes at any given moment. We can also upgrade this protocol with custom elements to make errors more comprehensible on the client side.

Advantages of REST: simplicity, speed, and a clear relationship between the client and server, ease of caching responses, and built-in security features.

Downsides: a lack of flexibility due to the server’s standardized responses. For instance, let’s say we have a list of company managers, and on one page, we might want to have names with roles and contact details, and on another, just the names without any other data. In the REST scenario, we either have to use one request everywhere, responding with unnecessary data and using up bandwidth, or write a separate request for each page, leading to code duplication and complexity. Usually, the same request is used throughout.

GRAPHQL API

GraphQL is a query language for APIs developed by Facebook. More flexible than REST APIs, GraphQL lets developers obtain all needed data in a single request (client-driven query). Developers can also specify the data type they wish to receive from the API.

GraphQL resolves the issue of request-response interaction. We leverage a specific query language that instructs the server about the client’s specific data needs at any given moment. Revisiting the managers’ example, the client isn’t defaulted to receive standardized data but can choose the needed info (like name and phone number), and the server responds with this specific information.

This system is perfect for apps requiring greater flexibility and scalability, complex systems, and microservices.

Advantages of GraphQL: this approach saves bandwidth and boosts performance, providing more flexibility and scalability.

Downsides: the query language is more complex, and the entry barrier is fairly high, potentially complicating support if you lack specialists. The community is also smaller.

GRPC API

gRPC, an open-source RPC framework created by Google, is considered to be a high-performance API development technology. gRPC leverages Protocol Buffers, a language-agnostic, platform-neutral mechanism for serializing structured data.

Unlike REST and GraphQL, which are quite similar, gRPC offers a different client-server interaction and is only usable with the HTTP/2.0 protocol. This advanced protocol provides benefits in data compression, user connection, and more.

gRPC is perfect for projects with high-performance communication requirements.

Advantages: gRPC communicates with the server through streams and its query language, making the whole process appear as if it’s happening within a single system, regardless of whether you’re on the front end or back end. The front end can call methods written on the backend. However, in reality, you need to write server methods and build them first, and only then the front end understands that these methods exist and can be used. Setting up all this requires experience with this type of API.

Other advantages include more compact data, better performance, and quick responses.

Disadvantages include a small community (the protocol is still evolving) and a relatively high entry barrier. Understanding the data transmission protocol is also important; each newcomer is likely unfamiliar with this protocol and will need to be trained. Compared to other approaches to API development, this one is quite complex and takes more time, which is not always justified for the project.

Key Features for API Solutions

During the initiation and progress of the API development, software engineers should consider a few crucial points. This will ensure the security and efficiency of your APIs.

AUTHENTICATION AND AUTHORIZATION

Authentication verifies the correct identity, while authorization determines if a verified user can perform a specific action. Common specifications like JWT, OAuth, and OAuth2 handle these tasks.

The choice of authentication method depends on the balance between the required security level and ease of implementation and maintenance. OAuth provides scalability and excellent user experience but requires more effort for implementation and maintenance. OpenID can supplement OAuth by verifying a client’s identity and profile through the authorization server.

QUERY, FILTER, SORTING, AND PAGINATION

As your database grows, data retrieval may become slower. To mitigate this, implement caching, pagination, sorting, and filtering.

Sorting organizes data according to specific conditions, while pagination decides how much data to display and when. These features improve processing time, response time, and security.

Filtering in APIs narrows down result sets based on certain criteria, improving API performance and reducing network data transmission. You can implement sorting, filtering, and pagination in different ways depending on the API type (e.g., using path parameters in REST APIs).

CACHING FOR PERFORMANCE IMPROVEMENTS

Caching stores frequently requested data in a secondary store, reducing calls to the primary database. This strategy enhances data retrieval speed and reduces request costs. Tools like Memcached and Redis can assist in this process.

Depending on where you store the cache, you can use client caching or server caching. While client caching improves client and server efficiency by storing routine requests locally, server caching reduces server load by storing repeated calls in a cache.

REST provides simpler caching mechanisms. With the GraphQL API and the gRPC API, developers must spend more time on caching.

ERROR HANDLING

Effective error handling simplifies debugging by differentiating between client and server errors. Providing clear error codes, specifying the number of errors, explaining error causes, and distinguishing between general and domain errors are effective error-handling practices.

VALIDATION

Validation confirms data correctness. Client-side validation usually involves prompt feedback for correction, which is a plus for a product, while server-side validation is a must-have for ensuring security, data integrity, and vulnerability protection. It includes tasks like validating required properties or defining property types.

Best Practices for Custom API Development

There are some best practices for API development that will help you to avoid well-known mistakes and improve the performance, security, and scalability of your product. But it’s essential to note that each case is unique and might require tailored and innovative solutions.

RETURNING STANDARD ERROR CODES

It’s crucial to handle errors gracefully to avoid confusion for API users. When an error occurs, returning an appropriate HTTP response code that indicates the specific type of error provides valuable information for API maintenance. Leaving errors unhandled could potentially disrupt the system, so it’s best to handle them without delay.

Error codes must be accompanied by informative messages to aid maintainers in troubleshooting issues effectively. However, it’s crucial to ensure that these error messages do not expose sensitive information that attackers could exploit to carry out malicious activities, such as data theft or system disruption.

NAVIGATING API VERSIONING

To ensure smooth transitions and avoid disrupting clients, it’s essential to have different versions of the API whenever any changes are made. Versioning can be done using semantic versioning, such as 2.0.6 (indicating major version 2 and the sixth patch), which is a common practice in modern apps.

This approach allows us to gradually phase out older endpoints rather than requiring everyone to move to the new API simultaneously. For instance, the v1 endpoint can remain active for users who prefer not to change, while the v2, with its exciting new features, caters to those who are ready to upgrade. This becomes especially crucial when your API is public, as versioning ensures compatibility with third-party apps that rely on your APIs.

By implementing versioning, a web API can clearly indicate the features and resources it offers, and client applications can make requests directed at specific versions of these features or resources.

CRAFTING ACCURATE DOCUMENTATION FOR APIS

The API documentation educates developers on how to use your APIs and where to start. This is necessary both for developers who will integrate your APIs and for your team in case of software modernization.

If your APIs are documented in detail, it’s easier to increase awareness and adoption of the API and decrease the time and costs of onboarding both remote and in-house developers. At the same time, any internal team can tap into API documentation to understand applied methods, resources, requests, and responses, which will simplify maintenance and updates.

You need to provide concise tutorials to aid developers in a quick start, create a comprehensive glossary defining API terms, and ensure that resources and methods are explained in a user-friendly manner. List all project terms to unify understanding among end users (developers), allowing them to grasp concepts like URLs and URIs, even with limited technical knowledge.

Wrapping Up

Regardless of which type of protocol you choose to create an API, remember each approach has its specifics that require certain knowledge and skills. Also, you'll need API support in the future. This is the reason why REST, despite its imperfections, remains the most popular API development method. The experience of your development team is key to the success of API-focused products.

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