I´m trying to design a REST API for my application and I read a lot about best practices and how REST is supposed to work. One of the most important topics about REST is, that the resources should be linked via references and the client should only know the root URL of the API.
But I cannot find any API documentation that really does this. Every REST API documentation I ever read on the web shows an exact description of the URLs of the possible endpoints.
Is there any API documentation out there that only shows the root URL and describes how to navigate through the resources?
One of the most important topics about REST is, that the resources should be linked via references and the client should only know the root URL of the API.
The root URL and the media types, yes. The client needs to know where to start, and also how to interpret the responses it gets.
Your primary example of a REST API would be the world wide web. You point your browser at www.google.com, and then you just follow links and submit forms until you get the result you want.
Another REST API that might be familiar is Atom Syndication / Atom Pub.
More academically, there is RESTBucks. That paper was somewhat popular, and you can find a number of sample implementations around.
Jon Moore (2011) presented a good demonstration of a hypermedia API.
Every REST API documentation I ever read on the web shows an exact description of the URLs of the possible endpoints.
Yes; bad examples are much more common than good examples.
So, I stepped once at this problem. I had offered a website that used the SoundCloud API. Everything worked properly. Content was extracted from the JSON and placed in the layout of the website. However, I received an email one day from the owner of the website, which indicated that the website did not work properly. I then came out to investigate and came to the conclusion that the "problem" was not on my side, but at SoundCloud's side. I studied on the API page of SoundCloud and came to the conclusion that the API had received a major update, making the link with SC and the site no longer worked.
Lately I'm trying many new APIs to, including those from Instagram and Dribbble. I was therefore wondering if it is at all possible to ensure that such problems can be reduced in the future or it might be appropriate API pages of this third-party APIs to monitor?
There's no "right" answer. After many years of using and maintaining many APIs here are some of the conclusions I've come to:
The best providers let you work with a specific version of their API whose interface and expected behavior never changes. They might release bug fixes and new endpoints, but you can be confident that as long as the API is supported it will not break your system.
A good provider will provide an end-of-life date for each version of their API. It's up to you to keep track of when you need to update.
Paid services will often be supported longer than free services. Plus the contract / SLA will guarantee it remains available for a specific amount of time.
The most popular APIs often have mailing lists and/or blogs. For those that offer it, sign up to be notified of updates. For those that don't you'll have to monitor their blogs or news posts. And I suggest not using any service that would drop support for an API version without warning.
I'm new to this game so I might be misunderstanding things. Actually, if someone tells me that I'm misunderstanding things, it will be a favor. Maybe this person will be considerate enough to show me the right path. But...
One of the "guidelines" or "best practices" of REST as it applies to Web Services (http://en.wikipedia.org/wiki/Representational_state_transfer#Applied_to_web_services) is that you should use the proper HTTP methods when making calls (did I misunderstand it?) to REST API's.
But looking at many API implementations on the web, what I see is that 100% of the calls made to them are actually GET calls that, depending on their URI, will be interpreted by the API as being of one of the HTTP verbs or methods.
So, for example, looking at the REST API documentation for Twitter (https://dev.twitter.com/rest/public) which, in principle, only defines two verbs/methods (GET and POST), actually have all calls sent as GET and, based on the URI in the GET call, are interpreted by the API and acted upon.
Example:
GET statuses/lookup: https://api.twitter.com/1.1/statuses/lookup.json
POST statuses/update (PUT?): https://api.twitter.com/1.1/statuses/update.json
In both cases, the call itself was made using GET and the last part of the URI defined it as a real GET or as a POST.
In summary, to be truly RESTful, shouldn't client side implementations of REST API's for web services use the proper HTTP verbs/methods?
What am I missing?
You're missing a lot, but don't worry about it, most people are.
The fact is that very few so-called REST APIs publicly available on the internet are really RESTful, mostly because they are not hypertext driven. REST became a buzzword to refer to any HTTP API that isn't SOAP, so don't expect for an API to really be RESTful just because it says it's a REST API. I recommend reading this answer.
From my experience, most API developers aren't aware what REST really is and believe any HTTP API that uses HTTP and avoids verbs in URIs is REST.
REST is defined by a set of constraints. Among them is the uniform interface, which in simple terms means that you should not change the expected behavior of the underlying protocol. REST isn't coupled to any particular protocol, but since it's common to be used with HTTP, they get convoluted sometimes.
HTTP has very well defined semantics for the GET, POST, PUT, DELETE, PATCH and HEAD methods, and the POST method has its semantics determined by the server. Ideally, a REST API should respond to the methods other than POST exactly as determined in the RFC 7231, but as you noticed, there are many APIs who call themselves REST but don't do that. This happens for many reasons. Sometimes there's a simple misunderstanding about the correct semantics, or it's done to keep consistency, or because of backwards compatibility with intermediaries that don't support all methods, and many other reasons.
So, there's a lot more that has to be done to be truly RESTful other than using the HTTP methods correctly. If an API doesn't get even that right, it needs to find another buzzword, because it's definitely not REST.
I can't exactly tell what your question is, but I believe there are some concepts that will help you. Allow me to elaborate...
You are correct that many APIs use a limited number of HTTP "verbs" in their API. GET/POST are the most common. PUT less so, and then all others (DELETE, HEAD, OPTIONS etc) are used with vanishing probabilities.
Dropbox Core API for file uploads allows optional PUT / POST and their stated reason is "For compatibility with browser environments, the POST HTTP method is also recognized."
Indeed the limitation is the browser. Popular web servers have no problem with all HTTP request methods and even made up ones. After all, the request method is just some string with regard to the web server.
HTML4 and HTML5 only allow GET and POST requests for form requests. If you want your API to be used through a browser at all - and hey why not, it sounds like a useful thing - then you're limited to GET/POST. For a useful discussion on this see: https://softwareengineering.stackexchange.com/questions/114156/why-are-there-are-no-put-and-delete-methods-on-html-forms
Further complicating things is the fact that REST is not an industry standard. There exists no RFC, ISO or other document detailing what a "compliant" implementation must and must not do. While many folks have been playing concepts related to REST for some time, the REST concept was "invented" in the PhD disseration of Roy Fielding. A fantastic read if you're interested in such things.
Yes, according to REST, APIs should be using the correct verbs. However, as long as the documentation is clear and all GET requests are idempotent, then life should continue smoothly.
(Source: I wrote PipeThru.com which integrates 40+ APIs, Dropbox and Twitter included)
I think that this link could give you some hints about the design of RESTful services / Web API: https://templth.wordpress.com/2014/12/15/designing-a-web-api/.
It's clear that not all Web services that claim to be RESTful are really RESTful ;-)
To be short, RESTful services should leverage HTTP methods for what they are designed for:
method GET: return the state of a resource
method POST: execute an action (creation of an element in a resource list, ...)
method PUT: update the complete state of a resource
method PATCH: update partially the state of a resource
method DELETE: delete a resource
You need to be also to be aware that they can apply at different levels, so methods won't do the same things:
a list resource (for example, path /elements)
an element resource (for example, path /elements/{elementid})
a field of an element resource (for example, path elements/{elementid}/fieldname). This is convenient to manage field values with multiple cardinality. You don't have to send the complete value of the fields (whole list) but add / remove elements from it.
Another important thing is to leverage HTTP headers. For example, the header Accept for content negotiation...
I find the Web API of Github well designed and its documentation is also great. You could browse it to make you an idea. See its documentation here: https://developer.github.com/v3/.
Hope it helps you,
Thierry
You are correct. If they want to be "RESTful", their API should respect the semantics of each HTTP method.
Roughly, REST is about method Information (what the server should do), scoping information (where the server should do it) and, I almost forgot to mention, hypermedia driven (make sure you check #PedroWerneck's great answer to this question as it talks about it a little more and referecences a blog post from Fielding on the matter).
What the API you mentioned does is have both method and scoping information in the URL. That would not fit the RESTful architecture very well, as it, in general terms, tells us to:
1) use the HTTP methods the proper way (respecting their properties, such as idempotency and others), and
2) use unique URIs to identify unique resources.
Point 1 says "use HTTP methods to convey method information" and point 2 says "use URIs to convey scoping information".
Again, if an API uses GET with a specific parameter in the URI to do something (and not get something), then it is using URI to convey method information.
Now, don't be alarmed. Most APIs out there are just RESTful-ish (like twitter's of flickr's), meaning they are an animal between REST and something else. That is not bad per se, it just means they will not fully benefit from what RESTful architectures (and HTTP) have to offer.
Remember that being RESTful isn't just a matter of fashion, it does have its benefits, such as statelesness, adressability, and so on. And those can only be fully achieved by using the HTTP verbs like they were supposed to be used.
About using POST instead of PUT, considering they have different properties (PUT is idempotent, POST is not), it is not bad to use POST, as long as it is uniformly designed, that is, a programmer should not wonder what POST will do for each and every URI in the API: they all should behave the same. (PUT does not suffer from that because it already is uniform.) I talked a little more about this - and quoted Roy Fielding's say on it - in another question (check out the "Wrapping Up" part).
Consider looking at REST Richardson Maturity Model topic.
This specification is about how much RESTful particular API is:
Level 0:
Simple GET and POST request to descriptive url
/getUserByName?name=Greg
Level 1:
Divide all content in resources and define actions in resource group
/user/getByName?name=Greg
Level 2:
Proper use of HTTP verbs.
GET /user/Greg
Level 3:
Use hypermedia controls
Different APIs in interent implement different maturity level of REST. That's why some APIs don't support all HTTP features.
I'm working on a cloud project and I have to use Contrail it provides a RESTful API to use, but it is documentation is too small. I would like to know how to perform rest requests, especially post requests on "project" resource.
Each Contrail config node provides supported API details(searchable) at http://:8082/documentation/index.html
You could also check here which is a bit old but should serve your project API needs.
Your question is old, but as there are no other answers I thought I would contribute one. Were you interested in an answer or just wanted to share the documentation you'd written? I agree with you that Contrail documentation is very scarce, and every attempt to contribute to it should be appreciated. I had to integrate with Contrail API a while ago, and found out that in some cases I had to call OpenStack APIs to get the job done (Contrail is built on top of OpenStack). Project and user management were some of them.
I wrote a documentation about Contrail api, For each resource I mention the allowed methods and which parameters to integrate on the request body and I test it until I get it to work finally I put an example. I haven't finished the documentation, I stopped working on Open Contrail. The documentation is my personal try maybe it would be useful and maybe it contains some mistakes, Thus, I would like to share it. You can find it here.
Will there be an "activity" endpoint for us 3rd Party developers to use so we may build apps that have the same information as the "official" apps?
Even piecing together data from other endpoints we cannot build such a feature since there's no way for us to get checkin history for users other than "self". We can only get other users last checkin.
Thought I'd read some time ago that the website and official apps were just going to use the api so there must be some hidden/not public endpoints.
Just curious.
The official app does use the same endpoints exposed through the API, but the public API is only a subset of what the official app uses :) (e.g., we don't allow account creation)
Having said that, there's currently no "activity" endpoint we expose, nor will we likely expose one in the future. Sorry bout that!