Versioning REST

Freshness Warning
This blog post is over 15 years old. It's possible that the information you read below isn't current and the links no longer work.

One thing I dislike about URL schemes for versioning a web services resource is it feels decidedly un-RESTful. The URL of a resource shouldn’t change simply because the format of that resource’s representation does.

By placing version information in the URL and simply adding that to the documentation, clients are not able to find old versions or even be updated when there is a new version. Version information should be located in the document, and clients should be able to tell which version they are using and if it is the latest version.

A nagging concern I had for versioned URLs is that small, backward-compatible changes or new features won’t be available to the client because they’re using /v2/yourapi but the new features are only in /v3/yourapi. If I add new data or enrich the existing data, I want all clients to have access to it immediately.

To avoid client synchronization problems the server always allows clients to access old representations of a resource and gives these clients an easy way to locate both the old and new representations.

In Tagyu, I’ve going to accomplish this by placing a <versions/> element in the XML file. This element will provide access to the previous, next, and latest resource representations as well as a reference for which one is being used currently. Instead of referring to versions with version numbers, I’m using the date that the version was released, simply because this date has more meaning than an arbitrarily-chosen version number.

<versions>
	<version rel="this" date="2006-01-12" href="http://tagyu.com/api/2006/01/12/"/>
	<version rel="previous" date="2005-11-02" href="http://tagyu.com/api/2005/11/02/"/>
	<version rel="next" date="2006-02-14" href="http://tagyu.com/api/2006/02/14/"/>	
	<version rel="latest" date="2006-02-15" href="http://tagyu.com/api/2006/02/15/"/>
</versions>

The latest version of the REST data will always live at tagyu.com/api/ without a date modifier as well as a URL with the date modifier. In the example above, the latest version is both at http://tagyu.com/api/ and http://tagyu.com/api/2006/02/15/. Clients that need a particular version should ensure they request the correct representation by using the date format.

The REST documentation will also list all alternate versions of the representations, and the documentation for each version will be available as well.

Sre
March 30, 2010 10:25 AM

What is approach to rolling out updates that are not backwards compatible? If you always have latest on the default/standard URL and have a change that is not backwards compatible how are going to deal with the endpoints that are going to break? Thanks, Sre

Adam Kalsey
March 30, 2010 10:36 AM

What I suggest is that apps keep track of the LATEST tag and ensure they always use a consistent version of the API until they have a chance to test. In fact, many apps would use a specific version instead of the standard URL. When LATEST changed, use that as a signal to look into the new API changes.

This discussion has been closed.

Recently Written

The Trap of The Sales-Led Product (Dec 10)
It’s not a winning way to build a product company.
The Hidden Cost of Custom Customer Features (Dec 7)
One-off features will cost you more than you think and make your customers unhappy.
Domain expertise in Product Management (Nov 16)
When you're hiring software product managers, hire for product management skills. Looking for domain experts will reduce the pool of people you can hire and might just be worse for your product.
Strategy Means Saying No (Oct 27)
An oft-overlooked aspect of strategy is to define what you are not doing. There are lots of adjacent problems you can attack. Strategy means defining which ones you will ignore.
Understanding vision, strategy, and execution (Oct 24)
Vision is what you're trying to do. Strategy is broad strokes on how you'll get there. Execution is the tasks you complete to complete the strategy.
How to advance your Product Market Fit KPI (Oct 21)
Finding the gaps in your product that will unlock the next round of growth.
Developer Relations as Developer Success (Oct 19)
Outreach, marketing, and developer evangelism are a part of Developer Relations. But the companies that are most successful with developers spend most of their time on something else.
Developer Experience Principle 6: Easy to Maintain (Oct 17)
Keeping your product Easy to Maintain will improve the lives of your team and your customers. It will help keep your docs up to date. Your SDKs and APIs will be released in sync. Your tooling and overall experience will shine.

Older...

What I'm Reading

Contact

Adam Kalsey

+1 916 600 2497

Resume

Public Key

© 1999-2021 Adam Kalsey.