In my Rest application, the resource url also support query parameters like pageSize, pageNum , name etc. So the request url looks like
/resource/{id}?pageNum=1&pageSize=25&desc="hello"
Now suppose a client adds an extra query parameter say 'lang' which my server is not supporting like
/resource/{id}?pageNum=1&pageSize=25&desc="hello"&lang="eng" , but my server doesnt support any lang parameter.
what should be the best design decision
Option 1 : Ignore the extra invalid queryparam and serve the request.
Option 2 : Throws bad request message to the client.
Thanks in Advance
Singla
No Doubt that clients must stick to the Api docs.
But what about certain changes in the APis ( just a small changes which does not involve migrating to a new API version )
Like say, an API resource : /dummy/api/Iid1 supports 3 query parameter, namely, a, b, c
so the complete URi : /dummy/api/Id1?a=1&b=20&c=45 is a valid request exposed by the API, and all the query params i.e a, b, c are optional params,
i.e if these params are not present in the request, then the server processes them to some default value like a = 0, b = 0, c= 0
Over sometime, a large number of clients build their application based in the above URL scheme.
Now the API provider, wants to scrap off the parameter 'b' and decides to throw off exception on extra/unknown parameters
This would , mean that all the clients application build around the last URL scheme that involved parameter 'b' would fail !
This simply suggests that, throwing exceptions for extra/unknown query parameters, invariably, leads to a tight coupling of client and server concerns, which I guess, completely goes against
the REST principles, which probably has a central theme to 'completely separte client and server concerns, so that both can evolve separately'
So I think only the missing/invalid 'mandatory' params should throw an exception, and not the options ones, never.
Just ignore it. Most other web servers would ignore request parameters it didn't understand.
Google ignore my two extra parameters here
https://www.google.com/#q=search+for+something&invalid=param&more=stuff
I guess ignoring bad parameters is standard practice, but it seems totally wrong to me in many cases.
Say I have a widget API with a widgets collection endpoint that finds widgets. Widgets have a foo attribute, so the following searches for widgets where foo = bar
GET https://example.com/widgets?foo=bar
Now an API client makes a typo.
GET https://example.com/widgets?foi=bar
Instead of returning only widgets where foo = bar, the typo is silently ignored and all widgets are returned (properly limited to some default size because I make well-designed API). My API client could spend hours trying to figure out why her call isn't working, or more likely light up my support site wondering why my API sucks.
Isn't it better to return a 400 status with an error message stating that "foi" is not a recognized parameter? This seems especially true because for the same kind of typo in a request body the best behavior is to return 400. (For example, see this answer: https://stackoverflow.com/a/20686925/2716301)
Ignoring it is common pattern, but query parameters are also part of URL (the resource id) and proper response code on this kind of request is 404 Not Found.
There is no general design pattern. You have to ask yourself what is best for your users. Is better to tell them that the resource they are asking is not available in the format they required or just give them another resource?
Note
HTTP contains great mechanism for dealing with languages; see Accept-Language and Content-Language headers (all browsers are using it)
Related
After having read a lot of material on REST versioning, I am thinking of versioning the calls instead of the API. For example:
http://api.mydomain.com/callfoo/v2.0/param1/param2/param3
http://api.mydomain.com/verifyfoo/v1.0/param1/param2
instead of first having
http://api.mydomain.com/v1.0/callfoo/param1/param2
http://api.mydomain.com/v1.0/verifyfoo/param1/param2
then going to
http://api.mydomain.com/v2.0/callfoo/param1/param2/param3
http://api.mydomain.com/v2.0/verifyfoo/param1/param2
The advantage I see are:
When the calls change, I do not have to rewrite my entire client - only the parts that are affected by the changed calls.
Those parts of the client that work can continue as is (we have a lot of testing hours invested to ensure both the client and the server sides are stable.)
I can use permanent or non-permanent redirects for calls that have changed.
Backward compatibility would be a breeze as I can leave older call versions as is.
Am I missing something? Please advise.
Require an HTTP header.
Version: 1
The Version header is provisionally registered in RFC 4229 and there some legitimate reasons to avoid using an X- prefix or a usage-specific URI. A more typical header was proposed by yfeldblum at https://stackoverflow.com/a/2028664:
X-API-Version: 1
In either case, if the header is missing or doesn't match what the server can deliver, send a 412 Precondition Failed response code along with the reason for the failure. This requires clients to specify the version they support every single time but enforces consistent responses between client and server. (Optionally supporting a ?version= query parameter would give clients an extra bit of flexibility.)
This approach is simple, easy to implement and standards-compliant.
Alternatives
I'm aware that some very smart, well-intentioned people have suggested URL versioning and content negotiation. Both have significant problems in certain cases and in the form that they're usually proposed.
URL Versioning
Endpoint/service URL versioning works if you control all servers and clients. Otherwise, you'll need to handle newer clients falling back to older servers, which you'll end up doing with custom HTTP headers because system administrators of server software deployed on heterogeneous servers outside of your control can do all sorts of things to screw up the URLs you think will be easy to parse if you use something like 302 Moved Temporarily.
Content Negotiation
Content negotiation via the Accept header works if you are deeply concerned about following the HTTP standard but also want to ignore what the HTTP/1.1 standard documents actually say. The proposed MIME Type you tend to see is something of the form application/vnd.example.v1+json. There are a few problems:
There are cases where the vendor extensions are actually appropriate, of course, but slightly different communication behaviors between client and server doesn't really fit the definition of a new 'media type'. Also, RFC 2616 (HTTP/1.1) reads, "Media-type values are registered with the Internet Assigned Number Authority. The media type registration process is outlined in RFC 1590. Use of non-registered media types is discouraged." I don't want to see a separate media type for every version of every software product that has a REST API.
Any subtype ranges (e.g., application/*) don't make sense. For REST APIs that return structured data to clients for processing and formatting, what good is accepting */* ?
The Accept header takes some effort to parse correctly. There's both an implied and explicit precedence that should be followed to minimize the back-and-forth required to actually do content negotiation correctly. If you're concerned about implementing this standard correctly, this is important to get right.
RFC 2616 (HTTP/1.1) describes the behavior for any client that does not include an Accept header: "If no Accept header field is present, then it is assumed that the client accepts all media types." So, for clients you don't write yourself (where you have the least control), the most correct thing to do would be to respond to requests using the newest, most prone-to-breaking-old-versions version that the server knows about. In other words, you could have not implemented versioning at all and those clients would still be breaking in exactly the same way.
Edited, 2014:
I've read a lot of the other answers and everyone's thoughtful comments; I hope I can improve on this with the benefit of a couple of years of feedback:
Don't use an 'X-' prefix. I think Accept-Version is probably more meaningful in 2014, and there are some valid concerns about the semantics of re-using Version raised in the comments. There's overlap with defined headers like Content-Version and the relative opaqueness of the URI for sure, and I try to be careful about confusing the two with variations on content negotiation, which the Version header effectively is. The third 'version' of the URL https://example.com/api/212315c2-668d-11e4-80c7-20c9d048772b is wholly different than the 'second', regardless of whether it contains data or a document.
Regarding what I said above about URL versioning (endpoints like https://example.com/v1/users, for instance) the converse probably holds more truth: if you control all servers and clients, URL/URI versioning is probably what you want. For a large-scale service that could publish a single service URL, I would go with a different endpoint for every version, like most do. My particular take is heavily influenced by the fact that the implementation as described above is most commonly deployed on lots of different servers by lots of different organizations, and, perhaps most importantly, on servers I don't control. I always want a canonical service URL, and if a site is still running the v3 version of the API, I definitely don't want a request to https://example.com/v4/ to come back with their web server's 404 Not Found page (or even worse, 200 OK that returns their homepage as 500k of HTML over cellular data back to an iPhone app.)
If you want very simple /client/ implementations (and wider adoption), it's very hard to argue that requiring a custom header in the HTTP request is as simple for client authors as GET-ting a vanilla URL. (Although authentication often requires your token or credentials to be passed in the headers, anyway. Using Version or Accept-Version as a secret handshake along with an actual secret handshake fits pretty well.)
Content negotiation using the Accept header is good for getting different MIME types for the same content (e.g., XML vs. JSON vs. Adobe PDF), but not defined for versions of those things (Dublin Core 1.1 vs. JSONP vs. PDF/A). If you want to support the Accept header because it's important to respect industry standards, then you won't want a made-up MIME Type interfering with the media type negotiation you might need to use in your requests. A bespoke API version header is guaranteed not to interfere with the heavily-used, oft-cited Accept, whereas conflating them into the same usage will just be confusing for both server and client. That said, namespacing what you expect into a named profile per 2013's RFC6906 is preferable to a separate header for lots of reasons. This is pretty clever, and I think people should seriously consider this approach.
Adding a header for every request is one particular downside to working within a stateless protocol.
Malicious proxy servers can do almost anything to destroy HTTP requests and responses. They shouldn't, and while I don't talk about the Cache-Control or Vary headers in this context, all service creators should carefully consider how their content is consumed in lots of different environments.
This is a matter of opinion; here's mine, along with the motivation behind the opinion.
include the version in the URL.
For those who say, it belongs in the HTTP header, I say: maybe. But putting in the URL is the accepted way to do it according to the early leaders in the field. (Google, yahoo, twitter, and more). This is what developers expect and doing what developers expect, in other words acting in accordance with the principle of least astonishment, is probably a good idea. It absolutely does not make it "harder for clients to upgrade". If the change in URL somehow represents an obstacle to the developer of a consuming application, as suggested in a different answer here, that developer needs to be fired.
Skip the minor version
There are plenty of integers. You're not gonna run out. You don't need the decimal in there. Any change from 1.0 to 1.1 of your API shouldn't break existing clients anyway. So just use the natural numbers. If you like to use separation to imply larger changes, you can start at v100 and do v200 and so on, but even there I think YAGNI and it's overkill.
Put the version leftmost in the URI
Presumably there are going to be multiple resources in your model. They all need to be versioned in synchrony. You can't have people using v1 of resource X, and v2 of resource Y. It's going to break something. If you try to support that it will create a maintenance nightmare as you add versions, and there's no value add for the developer anyway. So, http://api.mydomain.com/v1/Resource/12345 , where Resource is the type of resource, and 12345 gets replaced by the resource id.
You didn't ask, but...
Omit verbs from your URL path
REST is resource oriented. You have things like "CallFoo" in your URL path, which looks suspiciously like a verb, and unlike a noun. This is wrong. Use the Force, Luke. Use the verbs that are part of REST: GET PUT POST DELETE and so on. If you want to get the verification on a resource, then do GET http://domain/v1/Foo/12345/verification. If you want to update it, do POST /v1/Foo/12345.
Put optional params as a query param or payload
The optional params should not be in the URL path (before the first question mark) unless you are suggesting that those optional params constitute a self-standing resource. So, POST /v1/Foo/12345?action=partialUpdate¶m1=123¶m2=abc.
Don't do either of those things, because they push the version into the URI structure, and that's going to have downsides for your client applications. It will make it harder for them to upgrade to take advantage of new features in your application.
Instead, you should version your media types, not your URIs. This will give you maximum flexibility and evolutionary ability. For more information, see this answer I gave to another question.
I like using the profile media type parameter:
application/json; profile="http://www.myapp.com/schema/entity/v1"
More Info:
https://www.rfc-editor.org/rfc/rfc6906
http://buzzword.org.uk/2009/draft-inkster-profile-parameter-00.html
It depends on what you call versions in your API, if you call versions to different representations (xml, json, etc) of the entities then you should use the accept headers or a custom header. That is the way http is designed for working with representations. It is RESTful because if I call the same resource at the same time but requesting different representations, the returned entities will have exactly the same information and property structure but with different format, this kind of versioning is cosmetic.
In the other hand if you understand 'versions' as changes in entity structure, for example adding a field 'age' to the 'user' entity. Then you should approach this from a resource perspective which is in my opinion the RESTful approach. As described by Roy Fielding in his disseration ...a REST resource is a mapping from an identifier to a set of entities... Therefore makes sense that when changing the structure of an entity you need to have a proper resource that points to that version. This kind of versioning is structural.
I made a similar comment in: http://codebetter.com/howarddierking/2012/11/09/versioning-restful-services/
When working with url versioning the version should come later and not earlier in the url:
GET/DELETE/PUT onlinemall.com/grocery-store/customer/v1/{id}
POST onlinemall.com/grocery-store/customer/v1
Another way of doing that in a cleaner way but which could be problematic when implementing:
GET/DELETE/PUT onlinemall.com/grocery-store/customer.v1/{id}
POST onlinemall.com/grocery-store/customer.v1
Doing it this way allows the client to request specifically the resource they want which maps to the entity they need. Without having to mess with headers and custom media types which is really problematic when implementing in a production environment.
Also having the url late in the url allows the clients to have more granularity when choosing specifically the resources they want, even at method level.
But the most important thing from a developer perspective, you don't need to maintain the whole mappings (paths) for every version to all the resources and methods. Which is very valuable when you have lot of sub-resources (embedded resources).
From an implementation perspective having it at the level of resource is really easy to implement, for example if using Jersey/JAX-RS:
#Path("/customer")
public class CustomerResource {
...
#GET
#Path("/v{version}/{id}")
public IDto getCustomer(#PathParam("version") String version, #PathParam("id") String id) {
return locateVersion(version, customerService.findCustomer(id));
}
...
#POST
#Path("/v1")
#Consumes(MediaType.APPLICATION_JSON)
public IDto insertCustomerV1(CustomerV1Dto customer) {
return customerService.createCustomer(customer);
}
#POST
#Path("/v2")
#Consumes(MediaType.APPLICATION_JSON)
public IDto insertCustomerV2(CustomerV2Dto customer) {
return customerService.createCustomer(customer);
}
...
}
IDto is just an interface for returning a polymorphic object, CustomerV1 and CustomerV2 implement that interface.
Facebook does verisoning in the url. I feel url versioning is cleaner and easier to maintain as well in the real world.
.Net makes it super easy to do versioning this way:
[HttpPost]
[Route("{version}/someCall/{id}")]
public HttpResponseMessage someCall(string version, int id))
I am creating an API and I wonder why it is common to have a id parameter in URI for PUT?
Such as PUT /cars/5
Why don't have PUT /cars? The request entity contains an id field isn't that enough? I can get the id from that entity, or is it some downsides to this, and is it considered bad to do it?
Because if you were to send a PUT request to /cars, semantically that would imply you are trying to modify attributes about the set of cars, rather than modifying attributes of an individual car. The URI in a RESTful API should indicate the exact resource the action is acting upon, so if you are modifying a resource, your URI should exactly indicate that resource.
Also, from RFC 2616:
The URI in a PUT request identifies the entity enclosed with the request -- the user agent knows what URI is intended and the server MUST NOT attempt to apply the request to some other resource.
So the spec indicates that if the client knows the resource's unique ID, it should be included in the URI.
this comes from rest "ideology".
the idea is that a url uniquely represents an entity - so you must PUT the entity youre creating/editing to the url of that entity.
to quote from the wikipedia page:
Identification of resources
Individual resources are identified in requests, for example using URIs in web-based REST systems. The resources themselves are conceptually separate from the representations that are returned to the client.
PUT aims to udpate ONE precised entity.
With merely using /cars, you aren't focus on a specific entity.
And on the contrary of what you wrote, your full entity isn't passed in a basic String (URI).
Excepted if your targeted method focus on a hard-coded car id ... but I don't think so..
It comes down to the API interface. There are several approaches to API design. And, like you suggested, you can leave the id out of the request. However, since many API designs are structured in a fashion you described, like PUT /cars/5, it`s considered good practise.
Basically, you have 8 ways to interact with your API. GET, POST, PUT, DELETE and an optional HEAD. ( if you count head, the total would be 9 or 10, depending on the interactions).
So, to clear it up, you have 2 ways of GET. GET /cars would retrieve all cars, GET /cars/5 would retrieve any car with an ID of 5.So, you have 2 ways of using GET. The same goes for POST, PUT and DELETE. 4*2 = 8 right?
Now, there are people who would say that PUT /cars would be ambigious, however you are completely valid in doing it without the extra ID field, because, as you mentioned, you are already passing in the ID field in the request.
The guys at Apigee have been researching API designs for a while now. I recommend watching some of their video`s to understand better what API design means and why some arguments are valid, and others are not.
Apigee Best practises
This must have been answered previously, but my Google powers are off today and I have been struggling with this for a bit. We are migrating from an old PHP base to a Jersey-based JVM stack, which will ultimately provide a JSON-based RESTful API that can be consumed from many applications. Things have been really good so far and we love the easy POJO-to-JSON conversion. However, we are dealing with difficulties in Cross-Domain JSON requests. We essentially have all of our responses returning JSON (using #Produces("application/json") and the com.sun.jersey.api.json.POJOMappingFeature set to true) but for JSONP support we need to change our methods to return an instance of JSONWithPadding. This of course also requires us to add a #QueryParam("callback") parameter to each method, which will essentially duplicate our efforts, causing two methods to be needed to respond with the same data depending on whether or not there is a callback parameter in the request. Obviously, this is not what we want.
So we essentially have tried a couple different options. Being relatively new to Jersey, I am sure this problem has been solved. I read from a few places that I could write a request filter or I could extend the JSON Provider. My ideal solution is to have no impact on our data or logic layers and instead have some code that says "if there is a call back parameter, surround the JSON with the callback, otherwise just return the JSON". A solution was found here:
http://jersey.576304.n2.nabble.com/JsonP-without-using-JSONWithPadding-td7015082.html
However, that solution extends the Jackson JSON object, not the default JSON provider.
What are the best practices? If I am on the right track, what is class for the default JSON filter that I can extend? Is there any additional configuration needed? Am I completely off track?
If all your resource methods return JSONWithPadding object, then Jersey automatically figures out if it should return JSON (i.e. just the object wrapped by it) or the callback as well based on the requested media type - i.e. if the media type requested by the client is any of application/javascript, application/x-javascript, text/ecmascript, application/ecmascript or text/jscript, then Jersey returns the object wrapped by the callback. If the requested media type is application/json, Jersey returns the JSON object (i.e. does not wrap it with the callback). So, one way to make this work is to make your resource method produce all the above media types (including application/json), always return JSONWithPadding and let Jersey figure out what to do.
If this does not work for you, let us know why it does not cover your use case (at users at jersey.java.net). Anyway, in that case you can use ContainerRequest/ResponseFilters. In the request filter you can modify the request headers any way you want (e.g. adjust the accept header) to ensure it matches the right resource method. Then in the response filter you can wrap the response entity using the JSONWithPadding depending on whether the callback query param is available and adjust the content type header.
So what I ultimately ended up doing (before Martin's great response came in) was creating a Filter and a ResponseWrapper that intercepted the output. The basis for the code is at http://docs.oracle.com/cd/B31017_01/web.1013/b28959/filters.htm
Essentially, the filter checks to see if the callback parameter exists. If it does, it prepends the callback to the outputted JSON and appends the ) at the end. This works great for us in our testing, although it has not been hardened yet. While I would have loved for Jersey to be able to handle it automatically, I could not get it to work with jQuery correctly (probably something on my side, not a problem with Jersey). We have pre-existing jQuery calls and we are changing the URLs to look at the new Jersey Server and we really didn't want to go into each $.ajax call to change any headers or content types in the calls if we didn't have to.
Aside from the small issue, Jersey has been great to work with!
I'm constructing a restful service which needs to accept any number of parameters instead of the one from the sample below.
Assuming the following service routine
#RequestMapping("/start/id/{id}", RequestMethod.GET)
public void startService(#PathVariable String id) {...}
there's a client implementation based on RestTemplate
restTemplate.getForObject("/start/id/{id}", null, id);
Question: But given that it might be thousands of ids, what restful approaches do I have to sending all parameters in one request using RestTemplate? I've seen the suggestions
Add request body to GET request - Doesn't seem possible with RestTemplate?
Use a separator in id, (e.g., id1|id2|....|idn) - Seems like a hack
PUT the parameters first, then issue a GET to reference the ids - Double requests, seems non-intuitive
Adding multiple URL parameters (?id=foo&id=bar&.....&id=foobar)
I know similar questions (calling-a-restful-service-with-many-parameters, how-to-create-rest-urls-without-verbs, can-you-build-a-truly-restful-service-that-takes-many-parameters) has been asked before but I found it hard to spot a satisfactory answer, or at least an answer based on RestTemplate.
I don't think any part of RESTful design states that your url structure should be able to resolve entire collections. Your first (request parameter) and third (url parameter) suggestions are likely the best.
I would recommend the first. I'm sure its allowed in resttemplate. Looking at the documentation you provided, just implement one of the post methods. Each of them takes the request as a parameter. Inside there, I'm sure there is some kind of implementation of a getRequestParameters() method you can use to parse json/xml from the request body containing your ids.
Or, even better, how are all of these id's related? Do they all have a common parent resource? If so, then you could (and probably should) do something like...
/commonparent/{parentId}
And then inside your request handler, query for all of the ids, and procede like normal.
You could use a query parameter for all the ids:
/search?ids=1,2,3,4,5,6,7
Then tokenize by the comma and do your search. Remember that you will be capped by the maximum URL length if you issue this as a GET query string parameter.
I am creating a web application that incorporates REST-style services and I wanted some clarification as to the preferred (standard) method of how the POST requests should be accepted by my Java server side:
Method 1:
http://localhost:8080/services/processser/uid/{uidvalue}/eid/{eidvalue}
Method 2:
http://localhost:8080/services/processuser
{uid:"",eid:""} - this would be sent as JSON in the post body
Both methods would use the "application/json" content-type, but are there advantages, disadvantages to each method. One disadvantage to method 2, I can immediately think of is that the JSON data, would need to be mapped to a Java Object, thus creating a Java object any time any user access the "processuser" servlet api. Your input is much appreciated.
In this particular instance, the data would be used to query the database, to return a json response back to the client.
I think we need to go back a little from your question. Your path segment starts with:
/services/processuser
This is a mistake. The URI should identify a resource, not an operation. This may not be always possible, but it's something you should strive for.
In this case, you seem to identify your user with a uid and an eid (whatever those are). You could build paths such as a user is referred to by /user/<uid>/<eid>, /user/<uid>-<eid> (if you must /user/uid/<uid>/eid/<eid>); if eid is a specialization, and not on equal footing with uid, then /user/<uid>;eid=<eid> would be more appropriate.
You would create new users by posting to /user/ or /user/<uid>/<eid> if you knew the identifiers in advance, deleting users by using DELETE on /user/<uid>/<eid> and change state by using PUT on /user/<uid>/<eid>.
So to answer your question, you should use PUT on /user/<uid>/<eid> if "processuser" aims to change the state of the user with data you provide. Otherwise, the mapping to the REST model is not so clean, possibly the best option would be to define a resource /user/process/<uid>/<eid> and POST there with all the data, but a POST to /user/process with all the data would be more or less the same, since we're already in RPC-like camp.
For POST requests, Method 2 is usually preferred, although often the resource name will be pluralized, so that you actually post to:
http://localhost:8080/services/processusers
This is for creating new records, however.
It looks like you're really using what most RESTful services would use a GET request for (retrieving a record), in which case, Method 1 is preferred.
Edit:
I realize I didn't source my answer, so consider the standards set by Rails. You may or may not agree that it is a valid standard.