API Versioning Strategies

Developing an API involves a lot of work, from planning to implementation. It's crucial to have a clear and easy-to-understand versioning strategy to avoid confusing developers.

Let's begin by examining the reasons for versioning APIs and when it's necessary to release a new version. We'll also investigate different strategies on how to label API versions, and how to retire outdated API versions.

Why Version APIs?

Adding new features to our API, fixing existing issues, or even changing the way the API works - all of these need to be delivered to the user without disrupting our users.

Consider an API for weather forcasts. Thousands of websites use it to build dashboards and other applications.

If we want to change the data contract of our response object. This could involve renaming a field, adding a new one, or changing the entire data contract. If we change an existing field name, our users' applications might stop working or start throwing errors.

We gotta ask all our users to update their applications to work with our newest changes if we need to fix this. Most user will not like the sound of this. Versioning solves this problem. When we want to release a breaking change, we upgrade the version of our API. We release it in a way that lets users choose when to accept the changes.

Reliability is a very important factor when designing APIs. Making changes or releasing new versions without considering our client's needs could cause problems.

When to Version APIs?

Versioning your API is necessary whenever you implement changes that require consumers to update their code to maintain compatibility. Such changes, known as "breaking changes," can affect the API's input and output structures, success and error responses, and security protocols. Common examples of breaking changes include:

• Renaming a property or endpoint: Occasionally, renaming a property or method can enhance clarity. However, once an API is live, changing property or method names can break consumers' code, making such modifications challenging.
• Turning an optional parameter into a required parameter: As your API matures, you might find that certain parameters should be mandatory, even if they were initially optional. While this change can standardize inputs and make the API more predictable, it will cause errors for clients that don’t supply the required parameters.
• Modifying a data format or type: You might realize that properties like firstName and lastName should be encapsulated within a user object rather than existing as separate string properties. Although this enhances the API’s design, it is a breaking change that can lead to parsing errors.
• Changing a property’s characteristics: You may want to adjust the rules for certain properties. For example, the description property of type string might have a maxLength constraint that needs revision. Depending on how this change is implemented, it can result in various issues, including database or UI errors.

By carefully managing these types of changes and versioning your API appropriately, you can minimize disruptions for your consumers while continuing to improve your API’s functionality and design.

Types of API Versioning

• URL Versioning: In this method, the version number is embedded in the API endpoint's URL. For example, to retrieve all products from a database, consumers would send a request to https://example-api.com/v1/products. This is the most widely used API versioning method.
• Query Parameter Versioning: This technique involves appending the version number as a query parameter in the API request. For instance, consumers might send a request to https://example-api.com/products?version=v1.
• Header Versioning: With this approach, consumers include the version number in the request header, which separates the versioning information from the URL structure.
• Consumer-Based Versioning: This strategy allows consumers to select the appropriate version based on their requirements. The version in use at the time of the consumer's initial request is stored with their information, and all subsequent requests are processed using this version unless the consumer updates their configuration.