I need to make an AJAX request from a website to a REST web service hosted in another domain.
Although this is works just fine in Internet Explorer, other browsers such as Mozilla and Google Chrome impose far stricter security restrictions, which prohibit cross-site AJAX requests.
The problem is that I have no control over the domain nor the web server where the site is hosted. This means that my REST web service must run somewhere else, and I can't put in place any redirection mechanism.
Here is the JavaScript code that makes the asynchronous call:
var serviceUrl = "http://myservicedomain";
var payload = "<myRequest><content>Some content</content></myRequest>";
var request = new XMLHttpRequest();
request.open("POST", serviceUrl, true); // <-- This fails in Mozilla Firefox amongst other browsers
request.setRequestHeader("Content-type", "text/xml");
request.send(payload);
How can I have this work in other browsers beside Internet Explorer?
maybe JSONP can help.
NB youll have to change your messages to use json instead of xml
Edit
Major sites such as flickr and twitter support jsonp with callbacks etc
The post marked as the answer is erroneous: the iframes document is NOT able to access the parent. The same origin policy works both ways.
The fact is that it is not possible in any way to consume a rest based webservice using xmlhttprequest. The only way to load data from a different domain (without any framework) is to use JSONP. Any other solutions demand a serverside proxy located on your own domain, or a client side proxy located on the remote domain and som sort of cross-site communication (like easyXDM) to communicate between the documents.
The fact that this works in IE is a security issue with IE, not a feature.
Unfortunately cross-site scripting is prohibited, and the accepted work around is to proxy the requests through your own domain: do you really have no ability to add or modify server side code?
Furthermore, the secondary workaround - involving the aquisition of data through script tags - is only going to support GET requests, which you might be able to hack with a SOAP service, but not so much with the POST request to a RESTful service you describe.
I'm really not sure an AJAX solution exists, you might be back to a <form> solution.
The not very clear workaround (but works) is using iframe as container for requests to another sites. The problem is, the parent can not access iframe's content, can only navigate iframe's "src" attribut. But the iframe content can access parent's content.
So, if the iframe's content know, they can call some javascript content in parent page or directly access parent's DOM.
EDIT:
Sample:
function ajaxWorkaroung() {
var frm = gewtElementById("myIFrame")
frm.src = "http://some_other_domain"
}
function ajaxCallback(parameter){
// this function will be called from myIFrame's content
}
Make your service domain accept cross origin resource sharing (CORS).
Typical scenario: Most CORS compliant browsers will first send an OPTIONS header, to which, the server should return information about which headers are accepted. If the headers satisfy the service's requirements for the request provided (Allowed Methods being GET and POST, Allowed-Origin *, etc), the browser will then resend the request with the appropriate method (GET, POST, etc.).
Everything this point forward is the same as when you are using IE, or more simply, if you were posting to the same domain.
Caviots: Some service development SDK's (WCF in particular) will attempt to process the request, in which case you need to preprocess the OPTIONS Method to respond to the request and avoid the method being called twice on the server.
In short, the problem lies server-side.
Edit There is one issue with IE 9 and below with CORS, in that it is not fully implemented. Luckily, you can solve this problem by making your calls from server-side code to the service and have it come back through your server (e.g. mypage.aspx?service=blah&method=blahblah&p0=firstParam=something). From here, your server side code should implement a request/response stream model.
Just use a server side proxy on your origin domain. Here is an example: http://jquery-howto.blogspot.com/2009/04/cross-domain-ajax-querying-with-jquery.html
This can also be done using a webserver setup localy that calls curl with the correct arguments and returns the curl output.
app.rb
require 'sinatra'
require 'curb'
set :views,lambda {"views/"+self.name.to_s.downcase.sub("controller","")}
set :haml, :layout => :'../layout', :format => :html5, :escape_html=>true
disable :raise_errors
get '/data/:brand' do
data_link = "https://externalsite.com/#{params[:brand]}"
c = Curl::Easy.perform(data_link)
c.body_str
end
Sending an ajax request to localhost:4567/data/something will return the result from externalsite.com/something.
Another option would be to setup a CNAME record on your own domain to "Mask" the remote domain hostname.
Related
This question already has answers here:
What is JSONP, and why was it created?
(10 answers)
Closed 7 years ago.
As you know, the security of the web browser disallows making of cross domain requests. I read a book which says that you should use XMLHTTPRequest only if you can put the files on the server (means put the page you will load to the same requested domain). If you can't - you should search for an alternative.
My questions are:
What is the cross domain alternative to XMLHTTPRequest?
What about WebSockets? Does this technology allow cross domain request?
EDIT:
It still isn't clear to me...
For example, I pull my page from www.domain1.com and I need to request javascript from www.domain2.com. So the pulled page should include something like:
<script src="www.domain2.com/script.js"></script>
to avoid cross domain restrictions.
And I can use JSONP, and request will look like:
http://ww.domain1.com/?callback=someFunction.js
But: isn't it the same? I just pull js from another domain! Does it avoid cross domain restrictions?
You can make cross domain requests using the XMLHttpRequest object. This is done using something called "Cross Origin Resource Sharing". See:
http://en.wikipedia.org/wiki/Cross-origin_resource_sharing
Very simply put, when the request is made to the server the server can respond with a Access-Control-Allow-Origin header which will either allow or deny the request. The browser needs to check this header and if it is allowed then it will continue with the request process. If not the browser will cancel the request.
You can find some more information and a working example here:
http://www.leggetter.co.uk/2010/03/12/making-cross-domain-javascript-requests-using-xmlhttprequest-or-xdomainrequest.html
JSONP is an alternative solution, but you could argue it's a bit of a hack.
Do a cross-domain AJAX call
Your web-service must support method injection in order to do JSONP.
Your code seems fine and it should work if your web services and your web application hosted in the same domain.
When you do a $.ajax with dataType: 'jsonp' meaning that jQuery is actually adding a new parameter to the query URL.
For instance, if your URL is http://10.211.2.219:8080/SampleWebService/sample.do then jQuery will add ?callback={some_random_dynamically_generated_method}.
This method is more kind of a proxy actually attached in window object. This is nothing specific but does look something like this:
window.some_random_dynamically_generated_method = function(actualJsonpData) {
//here actually has reference to the success function mentioned with $.ajax
//so it just calls the success method like this:
successCallback(actualJsonData);
}
Check the following for more information
Make cross-domain ajax JSONP request with jQuery
If you're willing to transmit some data and that you don't need to be secured (any public infos) you can use a CORS proxy, it's very easy, you'll not have to change anything in your code or in server side (especially of it's not your server like the Yahoo API or OpenWeather).
I've used it to fetch JSON files with an XMLHttpRequest and it worked fine.
This question already has answers here:
What is JSONP, and why was it created?
(10 answers)
Closed 7 years ago.
As you know, the security of the web browser disallows making of cross domain requests. I read a book which says that you should use XMLHTTPRequest only if you can put the files on the server (means put the page you will load to the same requested domain). If you can't - you should search for an alternative.
My questions are:
What is the cross domain alternative to XMLHTTPRequest?
What about WebSockets? Does this technology allow cross domain request?
EDIT:
It still isn't clear to me...
For example, I pull my page from www.domain1.com and I need to request javascript from www.domain2.com. So the pulled page should include something like:
<script src="www.domain2.com/script.js"></script>
to avoid cross domain restrictions.
And I can use JSONP, and request will look like:
http://ww.domain1.com/?callback=someFunction.js
But: isn't it the same? I just pull js from another domain! Does it avoid cross domain restrictions?
You can make cross domain requests using the XMLHttpRequest object. This is done using something called "Cross Origin Resource Sharing". See:
http://en.wikipedia.org/wiki/Cross-origin_resource_sharing
Very simply put, when the request is made to the server the server can respond with a Access-Control-Allow-Origin header which will either allow or deny the request. The browser needs to check this header and if it is allowed then it will continue with the request process. If not the browser will cancel the request.
You can find some more information and a working example here:
http://www.leggetter.co.uk/2010/03/12/making-cross-domain-javascript-requests-using-xmlhttprequest-or-xdomainrequest.html
JSONP is an alternative solution, but you could argue it's a bit of a hack.
Do a cross-domain AJAX call
Your web-service must support method injection in order to do JSONP.
Your code seems fine and it should work if your web services and your web application hosted in the same domain.
When you do a $.ajax with dataType: 'jsonp' meaning that jQuery is actually adding a new parameter to the query URL.
For instance, if your URL is http://10.211.2.219:8080/SampleWebService/sample.do then jQuery will add ?callback={some_random_dynamically_generated_method}.
This method is more kind of a proxy actually attached in window object. This is nothing specific but does look something like this:
window.some_random_dynamically_generated_method = function(actualJsonpData) {
//here actually has reference to the success function mentioned with $.ajax
//so it just calls the success method like this:
successCallback(actualJsonData);
}
Check the following for more information
Make cross-domain ajax JSONP request with jQuery
If you're willing to transmit some data and that you don't need to be secured (any public infos) you can use a CORS proxy, it's very easy, you'll not have to change anything in your code or in server side (especially of it's not your server like the Yahoo API or OpenWeather).
I've used it to fetch JSON files with an XMLHttpRequest and it worked fine.
I know it's possible to load any kind of document from any domain from JavaScript (without necessarily being able to peek at its content), but it usually concerns regular GET requests. What about POST?
Is it possible to make an HTTP POST request from JavaScript to any domain name? (I'm specifically interested in form submissions.)
If so, how?
As per some answers on a nearby question, «HTTP GET request in JavaScript?», you might use XMLHttpRequest, since, according to the docs, the POST method is supported, too.
http://www.w3.org/TR/XMLHttpRequest/
https://developer.mozilla.org/en-US/docs/DOM/XMLHttpRequest
A sample code from the above w3.org document:
function log(message) {
var client = new XMLHttpRequest();
client.open("POST", "/log");
client.setRequestHeader("Content-Type", "text/plain;charset=UTF-8");
client.send(message);
}
However, it would seem like in order for it to work with POST requests to domains unrelated to yours (where instead of "/log", a complete http or https URL is specified), the Cross-Origin Resource Sharing may have to be supported and enabled on the target server, as per https://developer.mozilla.org/en-US/docs/HTTP/Access_control_CORS#Simple_requests.
So, it seems like, at least through XMLHttpRequest, you cannot make form submissions through POST requests (in fact, looks like even GET requests won't fly, either).
I've posted before on this subject, but after a year of getting on with other things, I've managed to get into a pickle once again. I'll try and give a brief overview of the scenario and the current attempts to make things work:
IIS web server hosting HTML, JS etc. on host: iis.mycompany.com (referred to as foo)
WCF RESTful web services hosted via a Windows Service on host: wcf.mycompany.com (referred to as bar)
The Javascript served from foo works by making RESTful ajax calls (GET or POST depending on the action) to the WCF services on bar, obviously these are cross domain calls as they aren't on the same host.
The Javascript uses the jQuery (1.7.2) framework to manipulate the DOM and perform ajax calls to bar, the expected content type for POSTS is JSON, and the response from GETS is expected to be JSON too (application/json).
Bar has it's WCF services configured using TransportCredentialOnly as the security mode and the transport client credentail type is NTLM, so only authed users to contact the services.
CORS Support has been added to bar's WCF services using an extension to WCF:
http://blogs.msdn.com/b/carlosfigueira/archive/2012/05/15/implementing-cors-support-in-wcf.aspx
We have added additional headers and modfied some that the post already contained based on numerous internet articles:
property.Headers.Add("Access-Control-Allow-Headers", "Accept, Content-Type");
property.Headers.Add("Access-Control-Allow-Methods", "POST, GET, OPTIONS");
property.Headers.Add("Access-Control-Max-Age", "172800");
property.Headers.Add("Access-Control-Allow-Origin", "http://iis.mycompany.com");
property.Headers.Add("Access-Control-Allow-Credentials", "true");
property.Headers.Add("Content-type", "application/json");
Sites giving information on enabling CORS suggest that the Access-Control-Allow-Origin response header should be set to "*" however, this is not possible in our case as we make jQuery ajax calls using the following setup:
$.ajaxSetup({
cache: "false",
crossDomain: true,
xhrFields: {
withCredentials: true
}
});
As it turns out you cannot use "*" for the accepted origin when you are using "withCredentials" in the ajax call:
https://developer.mozilla.org/en/http_access_control
"Important note: when responding to a credentialed request, server
must specify a domain, and cannot use wild carding."
Currently in our development lab, this doesn't matter as we can hard code the requests to the IIS (foo) server URL.
The main problem now appears to be attempting POST requests (GET is working using the above configuration). When the browser attempts the POST process, it first sends an OPTIONS header to the server requesting allowed OPTIONS for the subsequent post. This is where we would like to see the headers we've configured in the CORS Support WCF extension being passed back, however we aren't getting that far; before the response comes back as "401 Unauthorized", I believe this is to do with the transport security binding configuration requesting NTLM, but I'm not sure.
Also, I'm not very experienced with this, but I haven't seen much information about POST using application/json content type as opposed to text/plain when performing cross domain requests.
I know that people will probably suggest JSONP as the one true solution, I'm not against different approaches, indeed I encourage anyone to suggest best practices as it would help others reading this question later. However, please attempt to answer the question before suggestion alternatives to it.
Many thanks in advance for anyone who contributes.
peteski
:)
UPDATE:
It appears that Chrome (20.x.x) doesn't suffer the problem of not negotiating NTLM to retrieve the OPTIONS header response from the server, but Firefox (13.0.1) does.
We've also noticed that someone has already posted a bug up on the Firefox forum, which we've added information to:
http://bugzilla.mozilla.org/show_bug.cgi?id=751552
Please vote for this bug to be fixed on the bugzilla site!
Using the following code, we can watch the network trace to see Firefox failing and Chrome working fine:
var url = "http://myWebServiceServer/InstantMessagingService/chat/message/send";
var data = '{ "remoteUserUri" : "sip:foo.bar#mydomain.com", "message" : "This is my message" }';
var request = new XMLHttpRequest();
request.open("POST", url, true);
request.withCredentials = true;
request.setRequestHeader("Content-Type", "application/json");
request.send(data);
console.log(request);
On a separate note, IE8 doesn't support the XMLHttpRequest for cross domain calls, favouring it's own magical XDomainRequest object, so we've got some work to do in changing the client side code to handle IE8 vs the world cases. (Thanks IE8).
/me crosses fingers that Mozilla fix the Firefox bug.
UPDATE 2:
After some digging it appears that IE8's XDomainRequest cannot be used to make cross domain requests where NTLM must be negotiated, this basically means that the security on our WCF binding can't be used thanks to limitations in a web browser.
http://blogs.msdn.com/b/ieinternals/archive/2010/05/13/xdomainrequest-restrictions-limitations-and-workarounds.aspx
"No authentication or cookies will be sent with the request"
So, I guess we've taken this as far as it is going to go for now.. It looks like we're going to have to create our own custom token authentication and pass it across to the WCF service in a cookie, or in IE8's case, POST it with the JSON. The WCF service will then have to handle decrypting the data and using that instead of the ServiceSecurityContext.Current.WindowsIdentity we previously had access to with NTLM auth.
I know you said you would rather have the problem itself addressed, but you may consider using a "reverse proxy."
I don't know what technologies you are using, but we use Apache web server and have a Java RESTful API running on a different server that required authentication. For a while, we messed with JSONP and CORS, but were not satisfied.
In the end, we setup an Apache Reverse Proxy and it worked miracles. The web browser believes it is communicating with its own domain and acts appropriately. The RESTful API doesn't know it is being used via a proxy. Therefore, everything just works. And Apache does all the magic.
Hopefully, all web servers have a feature like Apache's reverse proxy.
Here is some documentation on the feature: http://httpd.apache.org/docs/2.2/mod/mod_proxy.html
All we had to do is ensure the mod_proxy module was installed, then add the following lines to our Apache config file:
ProxyPass /restapi http://restfulserver.com/restapi
ProxyPassReverse /restapi http://restfulserver.com/restapi
Then restart the web server and voila!
I need to send data to a remote server using javascript. How do I do this?
Background info:
There's a webpage from which I extract some information using JS, and I need to send it back to another server for processing. Response is not neccesary. The data is XML, Which I've URLencode'd.
How would one do this?
EDIT
The server I'm requesting the data from is not the same that receives the data. Just to clarify.
One of the most common ways to do this is AJAX. Here's how you perform an AJAX post request using jQuery:
<script type="text/javascript">
$.post('/remote-url', {xml: yourXMLString });
</script>
On the server side you process it like any other POST request. If you're using PHP it's $xml = $_POST['xml'];
The biggest limitation of AJAX is that you're only allowed to make requests to the same domain the document has been loaded from (aka cross-domain policy). There are various ways to overcome this limitation, one of the easiest one is JSONP.
UPD. For cross-domain requests an extremely simple (though not universal) solution would be:
(new Image).src = 'http://example.com/save-xml?xml=' + escape(yourXMLString)
This will issue a GET request (which cannot exceed 2KB in Internet Explorer). If you absolutely need a POST request or support for larger request bodies you can either use an intermediate server-side script on your domain or you can post a dynamically created html form to iframe.
submit a form using POST. That is working on all browsers cross domains. Have the server process the post. the form can be submitted to a hidden frame if you want to simulate AJAX
Use Cross Domain Resource Sharing (MDC) (IE XDR)
use a web bug (create an image, set the source to the url you want - smallish GET requests only)
var img = new Image();
img.src="http://www.otherserver.com/getxml?xml="+encodeURIComponent(yourXML);
(Oops, I see Lebedev did more or less the same in his update)
use a proxy, i.e. have your server talk to the other server for you
Look into Javascript's XMLHTTPRequest method -- or start with a Google search for AJAX. There's lots of ways to do this -- including some very easy ways through JS libraries like jQuery -- but a more specific answer would require some more specifics on the specific technologies you're using.
EDIT: You can set up the AJAX request to post to a server-side script (acting as a proxy) on your own domain, and have that script turn around and post the data to your remote server.