Develop Reference

Which HTTP code should return as status?

I need to create REST API endpoint, and I am not sure which HTTP code to return as status.
Requirements are next:
- My API should accept URL as a parameter
- Make an API call to third-party service (use URL), and get a response
- Return response (content that fetched from third-party service)
In some cases, everything works fine. A call is made to external service, it returns content and status code 200.
But, sometimes there is no content and it returns 404. (Important, it is possible that content will be available in the future.)
From the perspective of my system, it is the regular situation.
Which HTTP code should I return?
202 - Accepted,
204 - No content,
206 - Partial content
or something else?

404 Not Found
The requested resource could not be found but may be available in the future. Subsequent requests by the client are permissible.
In REST-API request and response should only work with current "call". If the content is currently not available it should return 404 status. And It(404) is the exact status that should be returned.
However, if you want to bend the rules, 204 status code seems more appropriate. I'm not recommending you to do this.
204 No Content
The server successfully processed the request and is not returning any content Link.

Instead of creating the actual resources, create a temporary one. Instead of returning a 201 (Created) HTTP response, you can issue a 202 (Accepted) response code. This informs the client that the request has been accepted and understood by the server, but the resource is not (yet) created.
From: http://restcookbook.com/Resources/asynchroneous-operations/

You should return whatever the HTTP status code return by third party service unless your system is wrapping it up and processing it and changing the status.

Handle 302 status code upon HTML/JS request to server?

I'm using Require JS and Orace JET
How can we handle the 302 status code or any other status code returned by Server when the session is timeout.
Can it be configured to catch it and redirect the user to a login page upon such cases?

The status code 302 cannot be seen by RequireJS. That's just how browsers work: the browser will see 302 and automatically perform the next HTTP request. RequireJS won't know that there was a redirection.
Any HTTP status code that is an error (500, 400, etc.) will result in a module load failure and onError will be called.

Here is my solution (that works because of luck). Take it just as an inspiration. When session in my app expires, the request is being forwarded using 302 to login page as you would expect. There are 2 main types of requests where it can happen:
REST API call (via XMLHttpRequest)
navigation on page that user did
For #2, the 302 poses no problem. User is simply redirected to login page.
For #1, I can somehow detect it (with some probability) because login page is on different domain that does not support CORS. The XMLHttpRequest request will simply fail with readyState equal to 0 and statusText equal to "error" (because browser will block the XMLHttpRequest to different domain). I have a "listener" (interceptor) on all my REST API calls and whenever some fails with the 0 readyState and "error" statusText, it means that session probably expired.
This is not a solution of course and cannot be used everywhere. Just an idea to think about :)

Making post request from redirection in node.js

I am trying to redirect to another URL from node js by using response.writeHead method
response.writeHead(301, {Location : <redirecturl>})
I need to have this redirection is being executed by POST method, however it is always executed by GET. What is the way that the redirection can be made as a POST request.

A redirect by default sends a GET request. According to the HTTP spec, a 301 redirection means sending a GET request. If you want to redirect with the same method (POST), you can try doing a 307 redirect instead.

There is no difference between redirection in both GET and POST methods. Both method should work find. Better you can your expressjs framework in which it is
res.redirect('http://example.com');
Be careful, when using status code 301 which means Moved Perman­ently. Once browser gets 301 status code, it will directly try the redirected URL from the next time.

Without seeing more of your code, I believe this is what you are describing:
The client has made a request to your application using an HTTP method (get, post, etc.) You are responding to that request by sending back a 301 error and a new URL (redirecturl)
The client then decides to implement a get request for the redirecturl.
You can't change how a client responds to a 301. That is out of your control and it is normal for browsers to initiate a get for the redirecturl.
You could initiate a post request from your server to the redirecturl.
You could send back a webpage which would then submit a post request from the client.
What are you trying to achieve?

AJAX catch difference between «failed» and «canceled» sending request to another domain

I'm making ajax request to server on another domain but I don't actially need its response, just to know that it got my request.
When everything is ok, in Chrome Developer Tools (Header status) it says «canceled» and console writes «XMLHttpRequest cannot load» but server gets my requests.
When server is down then header status is not a number but just «failed».
Trying to catch this critical difference on JS I get XHR status 0 in both cases.

I'm making ajax request to server on another domain
You can't make an ajax request to a different domain, due to same-origin policy. You want to look at JSONP, which essentially writes out a <script> tag for a remote URL.
What is JSONP all about?
Detecting success/error with JSONP calls is tricky, it doesn't work like typical ajax calls at all. Ideally you want the remote server to call a callback function on your page, as the above link describes.
If you don't control the other domain, you can attempt to detect errors by using a timeout. Here is a post discussing the jQuery timeout argument for this, though you could certainly implement your own timeout with raw javascript as well.

Catching 302 FOUND in JavaScript

I use jQuery to make an AJAX POST request to my server, which can return HTTP response with status 302. Then JavaScript just sends GET request to this URL, while I'd like to redirect user to URL in this response. Is this possible?

The accepted answer does not work for the reasons given. I posted a comment with a link to a question that described a hack to get round the problem of the 302 being transparently handled by the browser:
How to manage a redirect request after a jQuery Ajax call
However, it is a bit of a dirty hack and after much digging around I found what I think is a better solution - use JSON. In this case, you can make all responses to ajax requests have the code 200 and, in the body of the response, you add some sort of JSON object which your ajax response handler can then use in the appropriate manner.

I don't think so. The W3C says that HTTP redirects with certain status codes, including 302, must be transparently followed. Quoted below:
If the response is an HTTP redirect (status code 301, 302, 303 or
307), then it MUST be transparently followed (unless it violates
security or infinite loop precautions). Any other error (including a
401) MUST cause the object to use that error page as the response.
As an experiment, I tried doing Ajax requests from various browsers (Firefox 3.5, Chrome, IE8, IE7, IE6) to a server giving a 302 status code, and showing the status in the browser's request object. In every case, it showed up as 200.

In my problem reason was:
i was using localhost/Home/Test addres for testing the page. But ajax request code using 127.0.0.1/Home/AjaxRequest for url parameter. When the urls are different this error occurs.
maybe it helps someone :)

Rather than asking the Javascript code to Handle 302, it would be better to return a 500 with custom error code+ message on event of 302

function doAjaxCall() {
$.ajaxSetup({complete: onRequestCompleted});
$.get(yourUrl,yourData,yourCallback);
}
function onRequestCompleted(xhr,textStatus) {
if (xhr.status == 302) {
location.href = xhr.getResponseHeader("Location");
}
}