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[Comments] (6) "API": Next Friday is my last day at Canonical. I've taken a 90-day contract at a startup, on which more later, and after that I'm not sure. I may join the startup as an employee, I may take a few months to revise RESTful Web Services, or... something else.

Apropos revising RESTful Web Services, I have a question for you. When I started talking with people as part of my job search, I noticed that nobody uses the term "web services" anymore. Everyone talks about "APIs".

I don't want to overstate the magnitude of the change here; people have been referring to web services as APIs for years. I did this myself until around the time RWS came out, and even today the Launchpad web service is officially called the "API". The change I noticed is just that the terms used to be used interchangeably, and now "web service" has pretty much died out. When I say "web service" people know what I'm talking about, but I feel like I'm speaking out of a phrasebook, or doggedly saying "free software" in an "open source" world.

This is one of those little nagging things that may or may not be important. I have an inkling that it's fairly important: that there's a reason people might have stopped saying "web service" around 2007, but that using "API" as a generic term leads to products that are worse than they could be, and that it's something I'd need to address in any second edition of RWS. But I would like to get a broader spectrum of opinion on this.

Has the term "web service" really died out in the past few years (or, as I suspect, changed its meaning)? When do you think this happened, and why?

Update: This post spawned an InfoQ article, so I should probably stop playing coy and say what I think.

I agree with commentor Foone. I think that WS-* successfully claimed the term "web service" in the mid-2000s, and that when people soured on WS-* they also stopped using the term "web service". While looking for work, the only companies I saw talking about their "web services" were big companies that were using SOAP/WSDL. Everyone who wanted to go above level 0 on the maturity heuristic was talking about "APIs".

The problem is, this terminology is backwards! SOAP/WSDL services are at level 0 just because they're not "web services". They don't use any of the web technologies. Their goal is to abstract away the network boundary in order to appear like a native client library. An API, if you will. As you adopt more of the web technologies, your product becomes less like a native client library ("API") and more like the web ("web service").

Thinking of all web services as APIs buys into the assumption that a web service is like a native client library. You can do a lot with that assumption, you can even get to level 3 of the maturity heuristic, but I don't think you can use that assumption to build complex hypermedia-driven applications of the kind seen in REST in Practice. Saying "API" is saying that SOAP/WSDL had the right idea, but the technologies were too heavyweight.


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