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08.17.2008 at 05:54AM PDT, ID: 23654517
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9.2

How can I get a basic working AJAX Cross Site Proxy in C#?

Asked by Denisdh in Asynchronous Javascript and XML (AJAX), C# Programming Language, Programming for ASP.NET

Tags: ,

I'm looking for a working AJAX proxy to use to send and receive API requests/responses to http://ww1.caliber.ie/cram/api

I have the clientside code from Caliber (attached) that gives an example of how their API is used but can't get it working till I get a working proxy. I've read alot articles and ebooks. I've taken code from http://www.codeproject.com/KB/ajax/ajaxproxy.aspx (Example below) but can't get it to work. I get a missing assembly error for "using ProxyHelpers;" when I have it in a .ashx file.

I'm not sure how to go about writing my own are even altering this one. I don't know if it should be in a .aspx, .ashx or .asmx file.

Can anyone help me get this proxy attached working?
or
Can anyone point me to a working C# AJAX proxy?

I have a high level understanding of what's going on but keep getting lost when I get down into the coding of the process.Start Free Trial 
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Proxy.ashx:
 
<%@ WebHandler Language="C#" Class="proxy" %>
 
using System;
using System.Web;
using System.Web.Caching;
using System.Net;
using ProxyHelpers;
 
public class RegularProxy : IHttpHandler {
        
    public void ProcessRequest (HttpContext context) {
        string url = context.Request["url"];
        int cacheDuration = Convert.ToInt32(context.Request["cache"]?? "0");
        string contentType = context.Request["type"];
 
        // We don't want to buffer because we want to save memory
        context.Response.Buffer = false;
 
        // Serve from cache if available
        if (context.Cache[url] != null)
        {
            context.Response.BinaryWrite(context.Cache[url] as byte[]);
            context.Response.Flush();
            return;
        }
        using (WebClient client = new WebClient())
        {
            if (!string.IsNullOrEmpty(contentType))
                client.Headers["Content-Type"] = contentType;
            
            client.Headers["Accept-Encoding"] = "gzip";
            client.Headers["Accept"] = "*/*";
            client.Headers["Accept-Language"] = "en-US";
            client.Headers["User-Agent"] = 
                   "Mozilla/5.0 (Windows; U; Windows NT 6.0; " + 
                   "en-US; rv:1.8.1.6) Gecko/20070725 Firefox/2.0.0.6";
            
            byte[] data = client.DownloadData(url);
 
            context.Cache.Insert(url, data, null,
                        Cache.NoAbsoluteExpiration,
                        TimeSpan.FromMinutes(cacheDuration),
                        CacheItemPriority.Normal, null); 
            
            if (!context.Response.IsClientConnected) return;
 
            
            // Deliver content type, encoding and length
            // as it is received from the external URL
            context.Response.ContentType = 
                    client.ResponseHeaders["Content-Type"];
            string contentEncoding = 
                   client.ResponseHeaders["Content-Encoding"];
            string contentLength = 
                   client.ResponseHeaders["Content-Length"];
 
            if (!string.IsNullOrEmpty(contentEncoding))
                context.Response.AppendHeader("Content-Encoding", 
                                              contentEncoding);
            if (!string.IsNullOrEmpty(contentLength))
                context.Response.AppendHeader("Content-Length", 
                                              contentLength);
 
            if (cacheDuration > 0)
                HttpHelper.CacheResponse(context, cacheDuration);
            
            // Transmit the exact bytes downloaded
            context.Response.BinaryWrite(data);
        }
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }
 
}
 
End Proxy.ashx
 
Default2.aspx:
 
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>XML Test</title>
    <script type="text/javascript" runat="server">
        var isFirefox = false;
        if (typeof netscape != "undefined" &&
	        typeof netscape.security != "undefined" &&
	        typeof netscape.security.PrivilegeManager != "undefined" &&
	        typeof netscape.security.PrivilegeManager.enablePrivilege != "undefined") {
	        isFirefox = true;
        }
        function firefoxPermissionDeniedMessage(text) {
	        return "Permission denied to: " + text + "\n" +
	        "If you were not asked for permission and still want to perform this function,\n" +
	        "then type 'about:config' in the address bar, press Enter, find the property named\n" +
	        "'signed.applets.codebase_principal_support'\n" +
	        "and change its value to true.\n" +
	        "Then try this function again.";
        }
        var createXMLHttpRequest = function() {
	        // IE7 and Firefox 
	        if (typeof XMLHttpRequest != "undefined") { 
 
 
		        return function() { 
			        return new XMLHttpRequest();
		        }
	        }
	        // old IE
	        if (typeof ActiveXObject != "undefined") { 
		        return function() { 
			        return new ActiveXObject("Msxml2.XMLHTTP");
		        }
	        }
	        alert("XMLHttpRequest not supported");
	        return function() { 
		        return null;
	        }
        }();
        function encodeHTML(str) {
           return str.toString().replace(/&/g,"&amp;").replace(/"/g,"&quot;").replace(/</g,"&lt;").replace(/>/g,"&gt;");
        }
        function decodeXML(str) {
           return str.toString().replace(/&amp;/g,"&").replace(/&lt;/g,"<");
        }
        function encodeXML(str) {
           return str.toString().replace(/&/g,"&amp;").replace(/</g,"&lt;");
        }
 
        // all requests must be UTF-8 encoded
        // root node is <request>
        // must contain a <header> which must contain a valid <userId> and <password>
        // must contain a <body> which must contain a valid <command>
        // <body> can also contain a <parms> element which in turn contains one or more <parm> elements
        // sequence is important so the parameter must exist even if optional
        // each API determines the number of <parm> elements that must be defined, if any
 
        // all responses are UTF-8 encoded
        // root node is <response>
        // will contain a <header> which in turn will contain a <success> element with value 1 for yes or 0 for no
        // if <success> is no ("0") then the next element in <header> will be <error> containing an error message
        // if <success> is yes ("1") then <response> will contain a <body> which will contain one or more <record> elements
        // the format of the <record> elements is determined by the API
        // uncomment the alert(xmlStr) statement below to see the XML response
 
        // The following string shows the format of the searchJobs API
        	
        var xmlString = 
        '<?xml version="1.0" encoding="UTF-8"?>' +
        '<request>' +
        '<header>' +
	        '<userId>*GUEST</userId>' +
	        '<password>guest</password>' +
        '</header>' +
        '<body>' +
	        '<command>searchJobs</command>' +
	        '<parms>' +
		        // maxHits: for top five jobs put 5 here (integer)(optional)
		        '<parm>100</parm>' +
		        // space delimited list of vacancy statuses (required)
		        '<parm>Open</parm>' +
		        // space delimited list of vacancy categories (optional)
		        '<parm></parm>' +
		        // space delimited list of vacancy categories 2 (optional)
		        '<parm></parm>' +
		        // space delimited list of vacancy categories 3 (optional)
		        '<parm></parm>' +
		        // preferred location (optional)
		        '<parm></parm>' +
		        // preferred salary (integer)(optional)
		        '<parm></parm>' +
		        // list of keywords and/or double-quoted phrases (optional)
		        '<parm></parm>' +
	        '</parms>' +
        '</body>' +
        '</request>';
 
        // The following string shows the format of the getVacancy API (get a specific job by vacancy ID)
        	
        var xmlString2 = 
        '<?xml version="1.0" encoding="UTF-8"?>' +
        '<request>' +
        '<header>' +
	        '<userId>*GUEST</userId>' +
	        '<password>guest</password>' +
        '</header>' +
        '<body>' +
	        '<command>getVacancy</command>' +
	        '<parms>' +
		        // vacancyId (required)
		        '<parm>*vacancyId</parm>' +
	        '</parms>' +
        '</body>' +
        '</request>';
 
        // The following string shows the format of the getVacancyDescriptions API (get detailed descriptions by vacancy ID)
        	
        var xmlString3 = 
        '<?xml version="1.0" encoding="UTF-8"?>' +
        '<request>' +
        '<header>' +
	        '<userId>*GUEST</userId>' +
	        '<password>guest</password>' +
        '</header>' +
        '<body>' +
	        '<command>getVacancyDescriptions</command>' +
	        '<parms>' +
		        // vacancyId (required)
		        '<parm>*vacancyId</parm>' +
	        '</parms>' +
        '</body>' +
        '</request>';
 
        function post(xmlString) {
	        var xmlhttp = createXMLHttpRequest();
	        var url = encodeURIComponent('http://ww1.caliber.ie/cram/api');
	        if (isFirefox) {
		        try {
			        netscape.security.PrivilegeManager.enablePrivilege("UniversalBrowserRead");
		        } catch (e) {
			        alert(firefoxPermissionDeniedMessage("UniversalBrowserRead"));
		        }
	        }
            xmlhttp.open('POST','proxy.ashx?url=' + url, true);
	        xmlhttp.setRequestHeader("Content-Type", "text/xml; charset=UTF-8");
	        try {
		        xmlhttp.send(xmlString);
		        if (xmlhttp.status != 200) {
			        return {"ok": false, "msg": "API failed with HTTP status code: " + xmlhttp.status};
		        }
		        //var xmlStr = xmlhttp.responseXML.xml;
		        var xmlStr = xmlhttp.responseText;
		        if (xmlStr == "") {
			        return {"ok": false, "msg": "No response from Caliber"};
		        }
		        //alert(xmlStr);
		        if (window.ActiveXObject) {
			        var doc = new ActiveXObject("Microsoft.XMLDOM");
			        doc.async = "false";
			        doc.loadXML(xmlStr);
		        }
		        else { // code for Mozilla, Firefox, Opera, etc.
			        var parser = new DOMParser();
			        var doc = parser.parseFromString(xmlStr, "text/xml");
		        }
		        var x = doc.getElementsByTagName("success")[0];
		        var success = x.firstChild.nodeValue;
		        if (success != "1") {
			        var err = x.nextSibling.firstChild.nodeValue;
			        return {"ok": false, "msg": err};
		        }
	        }
	        catch (e) {
		        return {"ok": false, "msg": "Caliber is not ready, please try again later (" + e.message + ")"};
	        }
	        return {"ok": true, "doc": doc};
        }
        function listJobs() {
	        var result = post(xmlString);
	        if (!result.ok) return alert(result.msg);
	        var doc = result.doc;
	        var descs = doc.getElementsByTagName("description");
	        var ids = doc.getElementsByTagName("vacancyId");
	        var listElem = document.getElementById("list");
	        var list2Elem = document.getElementById("list2");
	        if (list2Elem) listElem.removeChild(list2);
	        list2Elem = document.createElement("div");
	        listElem.appendChild(list2Elem);
	        for (var i = 0, n = descs.length; i < n; i++) {
		        var divElem = document.createElement("div");
		        var aElem = document.createElement("a");
		        aElem.href = "javascript: showJob(" + ids[i].firstChild.nodeValue + ")";
		        var txtNode = document.createTextNode(descs[i].firstChild.nodeValue);
		        aElem.appendChild(txtNode);
		        divElem.appendChild(aElem);
		        list2Elem.appendChild(divElem);
	        }
        }
        function showJob(vacancyId) {
	        var result = post(xmlString2.replace(/\*vacancyId/,vacancyId));
	        if (!result.ok) return alert(result.msg);
	        var doc = result.doc;
	        var salaryRange = "";
	        var node = doc.getElementsByTagName("salaryRange")[0].firstChild;
	        if (node) salaryRange = node.nodeValue;
	        //alert(salaryRange);
	        var details= document.getElementById("details");
	        details.innerHTML = "Salary range: " + salaryRange;
 
	        var result = post(xmlString3.replace(/\*vacancyId/,vacancyId));
	        if (!result.ok) return alert(result.msg);
	        var doc = result.doc;
	        var desc = "";
	        var node = doc.getElementsByTagName("externalDesc")[0].firstChild;
	        if (node) desc = node.nodeValue;
	        //alert(desc);
	        var iframe = document.getElementById("desc").contentWindow;
	        iframe.document.open();
	        iframe.document.write(decodeXML(desc));
	        iframe.document.close();
        }
    </script>
</head>
 
<body>
    <form id="form1" runat="server">
        <div id="content" style="margin-top:10px;">
        <button id="okButton" onclick="listJobs();">List</button></div>		
        <div id="list" style="margin-top:10px;height:80px;width:350px;overflow:auto;border:1px solid #ccc;">
        </div>
        <div id="details"></div>		
        <iframe id="desc" style="margin-top:10px;height:280px;width:350px;overflow:auto;">
        </iframe>
    </form>
</body>
</html>
 
End Default2.aspx
 
Keywords: How can I get a basic working AJAX C…
Title
1 AJAX Proxy 101
2 AJAX Security
3 AJAX Auto Complete Control
4 Google AJAX Search API
5 Accessing Web Service through proxy
6 AJAX CalendarExtender Error
 
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[+][-]08.17.2008 at 06:55PM PDT, ID: 22249036

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About this solution

Zones: Asynchronous Javascript and XML (AJAX), C# Programming Language, Programming for ASP.NET
Tags: AJAX / ASP.Net / C#, All commonly used browsers
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Solution Provided By: philipjonathan
Participating Experts: 1
Solution Grade: A
 
 
[+][-]08.20.2008 at 09:02AM PDT, ID: 22271124

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