In: Categories » Computers and technology » AJAX » Creating HTTP Resources with Ajax
It would seem that the original idea of retrieving the unique URL in the body of the action URL response is the only solution, but never fear. Another solution does exist, and it’s compliant with the HTTP protocol. The HTTP status code 201 corresponds to a response where the server has created another URL that can be found in the Location HTTP header. This logic corresponds closely to what the role of the action URL is with respect to the unique URL. When the server responds with an HTTP status 201, the browser or XMLHttpRequest instance doesn’t perform a redirect automatically. It’s up to the code or browser to take action on the response. You can use the following JavaScript class to retrieve the unique URL from the action URL.
Source: /client/scripts/jaxson/communications.js
function UniqueURL( url) {
this.asynchronous = null;
this.baseURL = url;
this.uniqueURL = null;
this.haveIt = function() { }
}
UniqueURL.prototype.getIt = function() {
var instance = this;
this.asynchronous = FactoryHttp.getAsynchronous();
this.asynchronous.settings = {
onComplete : function(xmlhttp) {
if( xmlhttp.status == 201) {
instance.uniqueURL = xmlhttp.getResponseHeader( "Location");
instance.haveIt();
}
}
}
this.asynchronous.get(this.baseURL);
}
UniqueURL.prototype.postIt = function( inpData) {
var instance = this;
this.asynchronous = FactoryHttp.getAsynchronous();
this.asynchronous.settings = {
onComplete : function(xmlhttp) {
if( xmlhttp.status == 201) {
instance.uniqueURL = xmlhttp.getResponseHeader( "Location");
instance.haveIt();
}
}
}
this.asynchronous.post(this.baseURL, inpData);
}
The class UniqueURL is a single-purpose class, only in that you use it to retrieve the unique URL based on what is defined as the action URL. UniqueURL is instantiated, and the constructor requires you to define the action URL that is then assigned to the data member baseURL. You could call two methods to retrieve the unique URL: getIt and postIt. Both methods serve the same purpose, except getIt uses the HTTP GET verb, and postIt uses the HTTP POST verb. Internally, the Asynchronous methods are used to make the GET or POST requests. The methods would execute the action URL using either get or post methods and then await a response in the onComplete method. Because UniqueURL is only interested in a redirection, the onComplete method only processes HTTP status code 201. Every other status code is ignored. When the 201 status code is received, the method getResponseHeader retrieves the HTTP header location, as it contains the unique URL. Once the unique URL has been retrieved, the user-implemented method haveIt is called, indicating that a unique URL has been generated.
The implementation of UniqueURL is simple and only does one thing, which is convert an action URL into a unique URL. How the server generates the unique URL depends on how the consumer of UniqueURL called the server. In the case of the shopping cart example, all that is required is calling the method getIt. In the case of the bank account, the postIt method with appropriate data is called.
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