APIs Are Forever, Wait No...They Can Go Away at Any Time
apievangelist.com
apievangelist.com
There is rarely a good reason to actively destroy old API - section it off, keep it out of new code, maybe even kill the documentation so new developers don't use it, but it's bad business and downright disrespectful to the third-party developers who enrich your platform.
If you don't pay for access and have some kind of contract (Twitter firehose, Bing API), yes your business goals are not aligned and you'd better prepare for the worse.
Once published, a specific version of an API should never change in a backward-incompatible way, only become superseded by newer versions. Likewise, you don't change or deprecate individual methods, you merely stop supporting older versions. That would make it much easier for developers to keep track of API changes.
It makes some good points, although I'm not sure I entirely agree with the conclusion drawn, since it places all of the responsibility on the authors of the client-side code:
https://secure.designinghypermediaapis.com/nodes/bujxbmhffep...
"This can be handled in the opposite way we dealt with new functionality: if you don't see something, don't display it."
In my experience that is just too simplistic idea to cover all cases hence the need for versioning.
It's possible to view different versions of an API as different representations of the same data. For example, an HTTP server is permitted to return different responses, or even return an error, depending on the contents of the client's "Accept:" header. If versioning was done with a header instead of the URL, it would achieve essentially the same results. The client would be saying "I want /user/123/posts/recent, and I want it in the APIv3 format."
If an API method changes so much that it is no longer recognizable as a different representation of the same data, the URL should probably change to reflect the new content. The old URL would then return data only when the old version is requested, and "406 Not Acceptable" when the new version is requested. So I don't see any reason why API versioning can't be RESTful. It's just slightly more difficult to do it RESTfully, compared to adding the version in the URL.
In any case, I'd rather take practicality over RESTful purity.
2. Who says it goes down? Might just have stale or incorrect data before the tweak is patched.
Plus, building a parser isn't always that much more work than trying to build a client for a convoluted API.
It's obviously case-by-case, but I think a lot of people dismiss scraping outright when there are a lot of useful applications.
Scraping data for offline processing, but certainly should not be for user-facing traffic. Cosmetic tweaks can blow up the scraper's parser, UI technologies are built on a taller stack and are prone to higher latencies and points of failure, yada yada.
The Yelp API doesn't expose a given user's public bookmarks, reviews, etc., but they can be easily scraped from the user-facing website.
> Google is also providing developers a reason to finally move their maps off of Google Maps V2. Overages for the old version of Google Maps costs $10 per 1,000 map views.
http://blog.programmableweb.com/2011/10/27/google-maps-usage...