Is there a standard syntax for encoding structure objects as parameters for an HTTP GET request?

I understand that you are very good at understanding. I have loved and used XML and XML Schema for many years. For half a year I've been using JavaScript and jQuery along with RESTfull WFC services, ASP.NET MVC technologies with JSON encoded data for transmission. So I should have asked me the same question a while ago. Here is my answer with a short explanation.

The XML structure that you define can represent one input parameter to our web service. If you prefer to split your XML structure into different props (such as Locale, Layout and Query), everything I write here can be easily changed in this case of parameter coding.

The most natural way, in my opinion, is the way we implement using off-the-shelf tools . So let's have our web service with a type method MyMethod

and an input parameter of param

1 with a type MyData

(something like public int MyMethod (MyData param1)

). The class MyData

represents our data from an XML structure. Then the corresponding HTTP GET request should look like

http: // server / Service / MyMethod? param1 = JsonEncodedData

where JsonEncodedData strong>:

% 7B% 22locale% 22% 3A% 22en% 22% 2C% 22layout% 22% 3A% 5B% 7B% 22id% 22% 3A% 22header% 22% 2C% 22value% 22% 3A% 22hide% 22% 7D% 2C % 7B% 22id% 22% 3A% 22footer% 22% 2C% 22value% 22% 3A% 22hide% 22% 7D% 2C% 7B% 22id% 22% 3A% 22navigation% 22% 2C% 22value%

or without HTML encoding:

{"locale": "an", "location": [{"ID": "title", "value": "skin"}, {"ID": "footer", "value": "hide"}, {"ID": "navigation", "value": "minimize"}], "query": {"what": "water", "when": {"Start": {"Year": 2010, "month ": 1," Day ": 1}}}

This data is JSON encoded JavaScript objects.

var myInput = {
  locale: "en",
  layout:[
    {id: "header", value: "hide"},
    {id: "footer", value: "hide"},
    {id: "navigation", value: "minimize"}
  ],
  query:{
    what: "water",
    when: {
      Start:{Year:2010,Month:1,Day:1}
    }
  }
};

      

        
        
        
      

    

NOTE . Since the JavaScript class Date

can be serialized in a number of ways, I slightly changed the start date representation. In the "Microsoft world" we can use Sys.Serialization.JavaScriptSerializer.serialize

to serialize a DateTime

.NET type that will encode 2010-01-01, for example "/ Date (1262300400000) /".

We can write in C # a simple web method Web Service Service1.asmx like

[WebMethod]
[ScriptMethod (UseHttpGet = true, ResponseFormat = ResponseFormat.Json)]
public int MyMethod (MyData param1) {
    return param1.query.when.Start.Year;
}

      

        
        
        
      

    

Where

public enum BlockType {
    hide,
    minimize
}
public class Block {
    public string id { get; set; }
    //public BlockType value { get; set; }
    public string value { get; set; }
}
public class MyDate {
    public int Year { get; set; }
    public int Month { get; set; }
    public int Day { get; set; }
}
public class When {
    public MyDate Start { get; set; }
}
public class Query {
    public string what { get; set; }
    public When when { get; set; }
}
public class MyData {
    public string locale;
    public List<Block> layout;
    public Query query;
}

      

        
        
        
      

    

And the corresponding client code would look like this

var myInput = {
  locale: "en",
  layout:[
    {id: "header", value: "hide"},
    {id: "footer", value: "hide"},
    {id: "navigation", value: "minimize"}
  ],
  query:{
    what: "water",
    when: {
      Start:{Year:2010,Month:1,Day:1}
    }
  }
};

$.ajax({
    type: "GET",
    url: "/Service1.asmx/Method2",
    data: {param1: JSON.stringify(myInput)},
    contentType: "application/json; charset=utf-8",
    success: function(data, textStatus, XMLHttpRequest) {
        alert(XMLHttpRequest.responseText);
    },
    error: function(res, status) {
        if (status ==="error") {
            // errorMessage can be an object with 3 string properties:
            //      ExceptionType, Message and StackTrace
            var errorMessage = $.parseJSON(res.responseText);
            alert(errorMessage.Message);
        }
    }
});

      

        
        
        
      

    

For JSON encoding, I am using json2.js in the example (see https://github.com/douglascrockford/JSON-js/blob/master/json2.js and http://www.json.org/js.html ) ... JSON jQuery (from http://code.google.com/p/jquery-json/ ) can be used instead , then JSON.stringify

should be replaced with $.toJSON

.

The data initialization of the type MyData

might look like

new MyData {
        locale = "en",
        layout = new List<Block> {
            new Block() { id="header", value=BlockType.hide.ToString()},
            new Block() { id="footer", value=BlockType.hide.ToString()},
            new Block() { id="navigation", value=BlockType.minimize.ToString()}
        },
        query = new Query {
            what = "water",
            //when = new When() {Start = new DateTime(2010,1,1)}
            when = new When () {
                Start = new MyDate () {
                    Year = 2010,
                    Month = 1,
                    Day = 1
                }
            }
        }
    };
}

      

        
        
        
      

    

If you are using WCF with webHttpBinding (RESTfull endpoints) instead of asmx based web services, you can get a more flexible solution.

If the use is using JSON with HTTP GET, you should take into account the existence of a JSON Hijacking problem (see http://weblogs.asp.net/scottgu/archive/2007/04/04/json-hijacking-and-how-asp- net-ajax-1-0-mitigates-these-attacks.aspx , http://haacked.com/archive/2009/06/25/json-hijacking.aspx ). This problem can be solved (or drastically reduced) in different ways, and that doesn't stop me from using JSON in HTTP requests, which can be ideally cached.

For more information on the same subject, you can view my answer to related questions: How do I create a JSON object to send to an AJAX WebService? Is it possible to return JSON from .asmx webservice if ContentType is not JSON? JQuery ajax call httpget webmethod (C #) not working