It is straightforward to put resource id into url if it is a int or long type. e.g.
GET files/123
But my problem is that my resource identifier is a path. e.g. /folder_1/folder_2/a.sh because the underlying implementation is a filesystem. So I can not put it as part of rest api url because it is conflict with url path.
Here's approaches what I can think of:
Put the path id as the request param. e.g.
GET files?path=/folder_1/folder_2/a.sh
Encode/decode the path to make it qualifier as part of url.
Introduce another int/long id for this resource in backend. And map it to the path. The int/long type resource id is stored in database. And I need to maintain the mapping for each CURD operation.
I am not sure whether approach 1 is restful, approach 2 needs extra encoding/decoding, and approach 3 needs extra work to maintain the mapping.
I wonder what is the best practice to design the rest api url for this kind of case.
Simple:
#GET
#Path("/files/{path:.+}")
#Produces({MediaType.TEXT_PLAIN})
public String files(
#PathParam("path") String path
) {
return path;
}
When you query files/test1/tes2 via url output is:
test1/tes2
Just put the path after a prefix, for example:
GET /files/folder_1/folder_2/a.sh
There isn't a conflict, since when the request path starts with your known prefix (/files/, in the above example), you know that the rest should be parsed as the path to the file, including any slashes.
Well, my experience designing "restful" APIs shows that you have to take into consideration future extensions of your API.
So, the guidelines work best when followed closely when it makes sense.
In your specific example, the path of the file is more of an attribute of the file, that can also serve as its unique ID.
From your API client's perspective, /files/123 would make perfect sense, but /files/dir1/file2.txt is debatable.
A query parameter here would probably help more, much like what you would do if you wanted to retrieve a filtered list of files, rather than the whole collection.
On the other hand, using a query parameter would also help for future extensions, since supporting /files/{path} would also mean conflicts when attempting to add sub-resources to your files endpoint.
For example, let's assume that you might need in the future another endpoint /files/attributes. But, having such an endpoint, would exclude any possibility for your clients to match a file named attributes.
I would like to modify an url parameter /resource/{VaRiAbLe} in an API gateway to S3 mapping so that it actually points to /my-bucket/{variable}. That is, it accepts mixed-case input, and maps it to a lower-case name. Mapping path variables is relatively simple enough to S3 integrations, but I can't seem to get a lower-case mapping working.
Reading through the documentation for mapping parameters, it looks like the path parameters are simple string values (and not templated values), and so defining a mapping as method.request.path.variable.toLowerCase() won't work.
Does anyone have any ideas how to implement this mapping?
Map path variables to a JSON body, and then call another API method that actually does the S3 call?
Bite the bullet, and implement a Lambda function to do the S3 get for me?
Find another api method for S3 that accepts a JSON body that I can use to get the data?
Update using Orchestrated calls
Following the info from Jack, I figured I should try doing the orchestrated call, since the traffic volume is low enough that I am sure that I won't be able to keep the lambda hot.
As a proof of concept, I added two methods to my resource (sitting at /resource/{variable} - GET and POST. The GET method chains to the POST, which does the actual retrieving of the data.
POST method configuration
This is a vanilla S3 proxying method, where you set the URL Path parameter for {variable} to be method.request.body.variable.
GET method configuration
This is a HTTPS proxying method. You'll need an URL for the POST method, so you'll need to deploy the API to get the URL. The only other configuration needed here is a body mapping template with content like:
{
"variable" : "$input.params('variable').toLowerCase()",
"something" : "$input.params('something')"
}
This should be enough to get this working.
The downside to this looks to be that I'm adding an extra method (POST) to my API for that resource that could confuse consumers of the API. I think it should be possible to make the POST on the /resource resource, which would at least make a bit more sense from an API design standpoint.
Depending on how frequently this API will be called, I'd either go with the Lambda proxy or chaining two API Gateway methods together. If the API is called frequently enough to keep a Lambda function warm (say once a minute), then go with Lambda. If not, go with the orchestrated API call.
The orchestrated API call would be interesting, I'd be happy to help with that if you have questions.
As far as I know the only S3 API for getting object data is the GET that is documented in their API reference.
I have a design question on REST. I need to expose a validate method as a rest resource. Let us say it looks like this
public ValidatedResult validate(ObjectToBeValidated object)
ObjectToBeValidated is a class that contains the actual Object and also some parameters concerning the validation.
When I design this as a Restful resource, which action do I use? From my understanding GET is the action that best suits this case. If that is so, how I can pass my ObjectTobeValidated as an object but not as URL parameters? I shy away from URL parameters because ObjectToBeValidated may contain a lot of properties, ending up with an URL like below which is feel is too long
http://localhost/rest/validate?prop1=somevalu&prop2=somevalue&prop3=something&prop11=somevalu&prop22=somevalue&prop33=something
Any help would be appreciated
Thanks
Kay
The HTTP standard allows you to use the POST method. It does not necessary need to have a side effect.
The action performed by the POST method might not result in a resource
that can be identified by a URI. In this case, either 200 (OK) or 204
(No Content) is the appropriate response status, depending on whether
or not the response includes an entity that describes the result.
HTTP 1.1 / method definitions / POST
In your case you can do something like this if you want to follow the noun-verb approach Tim suggested:
POST /api/my/object/validator
Be aware that by REST the messages must be self-descriptive, so either you need a vendor MIME type or you need to add meta-data e.g. RDF to describe what this link does and what params are allowed. Otherwise we are not talking about REST, just a regular webapp.
I'm having two rest methods as follows
/objects/(int:type)/(id:objectID)/(ver:version)
/objects/(int:type)/(id:objectID)/(str:version)
if i send the request as like the following URI
http://localhost/REST/objects/0/123/latest which of the above method gets called.
whether the 2 methods are same or different.
need to know what are all the parameter types available and what is the actual usage of each type.
And how the URI identifies the exact method
That question is all about the server framework you are using and nothing about REST. REST says nothing about URI structure, and certainly nothing about how URIs are mapped to handlers.
What is the best way to version REST URIs? Currently we have a version # in the URI itself, ie.
http://example.com/users/v4/1234/
for version 4 of this representation.
Does the version belong in the queryString? ie.
http://example.com/users/1234?version=4
Or is versioning best accomplished another way?
Do not version URLs, because ...
you break permalinks
The url changes will spread like a disease through your interface. What do you do with representations that have not changed but point to the representation that has? If you change the url, you break old clients. If you leave the url, your new clients may not work.
Versioning media types is a much more flexible solution.
Assuming that your resource is returning some variant of application/vnd.yourcompany.user+xml all you need to do is create support for a new application/vnd.yourcompany.userV2+xml media type and through the magic of content negotiation your v1 and v2 clients can co-exist peacefully.
In a RESTful interface, the closest thing you have to a contract is the definition of the media-types that are exchanged between the client and the server.
The URLs that the client uses to interact with the server should be provided by the server embedded in previously retrieved representations. The only URL that needs to be known by the client is the root URL of the interface. Adding version numbers to urls only has value if you construct urls on the client, which you are not suppose to do with a RESTful interface.
If you need to make a change to your media-types that will break your existing clients then create a new one and leave your urls alone!
And for those readers currently saying that this makes no sense if I am using application/xml and application/json as media-types. How are we supposed to version those? You're not. Those media-types are pretty much useless to a RESTful interface unless you parse them using code-download, at which point versioning is a moot point.
I would say making it part of the URI itself (option 1) is best because v4 identifies a different resource than v3. Query parameters like in your second option can be best used to pass-in additional (query) info related to the request, rather than the resource.
Ah, I'm putting my old grumpy hat on again.
From a ReST perspective, it doesn't matter at all. Not a sausage.
The client receives a URI it wants to follow, and treats it as an opaque string. Put whatever you want in it, the client has no knowledge of such a thing as a version identifier on it.
What the client knows is that it can process the media type, and I'll advise to follow Darrel's advice. Also I personally feel that needing to change the format used in a restful architecture 4 times should bring huge massive warning signs that you're doing something seriously wrong, and completely bypassing the need to design your media type for change resiliance.
But either way, the client can only process a document with a format it can understand, and follow links in it. It should know about the link relationships (the transitions). So what's in the URI is completely irrelevant.
I personally would vote for http://localhost/3f3405d5-5984-4683-bf26-aca186d21c04
A perfectly valid identifier that will prevent any further client developer or person touching the system to question if one should put v4 at the beginning or at the end of a URI (and I suggest that, from the server perspective, you shouldn't have 4 versions, but 4 media types).
You should NOT put the version in the URL, you should put the version in the Accept Header of the request - see my post on this thread:
Best practices for API versioning?
If you start sticking versions in the URL you end up with silly URLs like this:
http://company.com/api/v3.0/customer/123/v2.0/orders/4321/
And there are a bunch of other problems that creep in as well - see my blog:
http://thereisnorightway.blogspot.com/2011/02/versioning-and-types-in-resthttp-api.html
These (less-specific) SO questions about REST API versioning may be helpful:
Versioning RESTful services?
Best practices for web service REST API versioning
There are 4 different approaches to versioning the API:
Adding version to the URI path:
http://example.com/api/v1/foo
http://example.com/api/v2/foo
When you have breaking change, you must increment the version like: v1, v2, v3...
You can implement a controller in you code like this:
#RestController
public class FooVersioningController {
#GetMapping("v1/foo")
public FooV1 fooV1() {
return new FooV1("firstname lastname");
}
#GetMapping("v2/foo")
public FooV2 fooV2() {
return new FooV2(new Name("firstname", "lastname"));
}
Request parameter versioning:
http://example.com/api/v2/foo/param?version=1
http://example.com/api/v2/foo/param?version=2
The version parameter can be optional or required depending on how you want the API to be used.
The implementation can be similar to this:
#GetMapping(value = "/foo/param", params = "version=1")
public FooV1 paramV1() {
return new FooV1("firstname lastname");
}
#GetMapping(value = "/foo/param", params = "version=2")
public FooV2 paramV2() {
return new FooV2(new Name("firstname", "lastname"));
}
Passing a custom header:
http://localhost:8080/foo/produces
With header:
headers[Accept=application/vnd.company.app-v1+json]
or:
headers[Accept=application/vnd.company.app-v2+json]
Largest advantage of this scheme is mostly semantics: You aren’t cluttering the URI with anything to do with the versioning.
Possible implementation:
#GetMapping(value = "/foo/produces", produces = "application/vnd.company.app-v1+json")
public FooV1 producesV1() {
return new FooV1("firstname lastname");
}
#GetMapping(value = "/foo/produces", produces = "application/vnd.company.app-v2+json")
public FooV2 producesV2() {
return new FooV2(new Name("firstname", "lastname"));
}
Changing Hostnames or using API Gateways:
Essentially, you’re moving the API from one hostname to another. You might even just call this building a new API to the same resources.
Also,you can do this using API Gateways.
I wanted to create versioned APIs and I found this article very useful:
http://blog.steveklabnik.com/posts/2011-07-03-nobody-understands-rest-or-http
There is a small section on "I want my API to be versioned". I found it simple and easy to understand. The crux is to use Accept field in the header to pass version information.
If the REST services require authentication before use, you could easily associate the API key/token with an API version and do the routing internally. To use a new version of the API, a new API key could be required, linked to that version.
Unfortunately, this solution only works for auth-based APIs. However, it does keep versions out of the URIs.
If you use URIs for versioning, then the version number should be in the URI of the API root, so every resource identifier can include it.
Technically a REST API does not break by URL changes (the result of the uniform interface constraint). It breaks only when the related semantics (for example an API specific RDF vocab) changes in a non backward compatible way (rare). Currently a lot of ppl do not use links for navigation (HATEOAS constraint) and vocabs to annotate their REST responses (self-descriptive message constraint) that's why their clients break.
Custom MIME types and MIME type versioning does not help, because putting the related metadata and the structure of the representation into a short string does not work. Ofc. the metadata and the structure will frequently change, and so the version number too...
So to answer your question the best way to annotate your requests and responses with vocabs (Hydra, linked data) and forget versioning or use it only by non backward compatible vocab changes (for example if you want to replace a vocab with another one).
I'd include the version as an optional value at the end of the URI. This could be a suffix like /V4 or a query parameter like you've described. You might even redirect the /V4 to the query parameter so you support both variations.
I vote up for doing this in mime type but not in URL.
But the reason is not the same as other guys.
I think the URL should be unique (excepting those redirects) for locating the unique resource.
So, if you accept /v2.0 in URLs, why it is not /ver2.0 or /v2/ or /v2.0.0? Or even -alpha and -beta? (then it totally becomes the concept of semver)
So, the version in mime type is more acceptable than the URL.