This content is reprinted from Real-World AJAX: Secrets of the Masters published by SYS-CON Books. To order the entire book now along with companion DVDs for the special pre-order price, click here for more information. Aimed at everyone from enterprise developers to self-taught scripters, Real-World AJAX: Secrets of the Masters is the perfect book for anyone who wants to start developing AJAX applications.

Creating a ColdFusion Web Service
We'll duplicate our PHP Web service in ColdFusion now using XMLRPC.CFC to format our XML response and the CFJSON.cfm for our JSON response.

Listing 6.7 The Code

<CFSETTING showDebugOutput="no" enablecfoutputonly="yes">
<!--- Because of ColdFusion's poor whitespace handling it is necessary to
//--- use enablecfoutputonly="yes" and then wrap all of our output in CFOUTPUT tags.
--->

<!--- Only proceed if we were given numbers to sum --->
<CFIF IsDefined('URL.numbers')>
   <!--- Split our string into an array using REReplace on any non-digit character. --->
   <CFSET numbers = ListToArray(REReplace(URL.numbers, "[^\d]+", " ", "all"), ' ')>
   <CFSET sum = ArraySum(numbers)>

   <!--- Build our response object.
   //--- We include the original request only to make our response more complex.
   --->
   <CFSET response = StructNew()>
   <CFSET garbage = StructInsert(response, 'sum', sum)>
   <CFSET garbage = StructInsert(response, 'numbers', numbers)>

   <!--- Check to see if an output format was requested, and if it was JSON
   //--- Return XML output by default
   --->
   <CFIF IsDefined('URL.output') AND URL.output EQ 'json'>
     <CFINCLUDE template="jsencode.cfm">
     <CFOUTPUT>#jsonencode(response)#</CFOUTPUT>
   <CFELSE>
     <!--- Send our XML content-type header --->
     <CFHEADER name="Content-type" value="text/xml">
     <CFSET arr = ArrayNew(1)>
     <CFSET arr[1] = #response#>
       <!--- We're using the XMLRPC component to format our response --->
     <CFINVOKE component="xmlrpc"
       method="CFML2XMLRPC"
       returnvariable="rs"
       type="response"
       data="#arr#">

       <!--- Replace is only used to make our output more human-readable --->
       <CFOUTPUT><?xml version="1.0" encoding="iso-8859-1"?>
         #Replace(rs, "><", ">" & Chr(13) & Chr(10) & "<", "all")#
       </CFOUTPUT>
     </CFIF>
   </CFIF>

Dissecting the Code
This is the ColdFusion equivalent of the PHP Web service we just looked at. It can be accessed in a REST-like manner through the resources URI and expects two variables in the query string: numbers and output. The variable numbers will contain a delimited list of numbers that this Web service will sum and return. To make our return object more complex, we'll return the original request as well as the sum. You can specify your desired output format by setting output to JSON or XML.

A normal GET request to http://yourserver/add.cfm?numbers=1+2+3&output=json will print the following:

{"numbers":[1,2,3],"sum":6}

That same request with output set to XML (http://yourserver/add.cfm?numbers=1+2+3&output=xml) will return:

Listing 6.8

<?xml version="1.0" encoding="iso-8859-1"?>
<methodResponse>
  <params>
   <param>
    <value>
     <struct>
      <member>
       <name>numbers</name>
       <value>
        <array>
         <data>
          <value>
           <double>1</double>
          </value>
          <value>
           <double>2</double>
          </value>
          <value>
           <double>3</double>
          </value>
         </data>
        </array>
       </value>
      </member>
      <member>
       <name>sum</name>
        <value>
         <double>6</double>
        </value>
       </member>
      </struct>
     </value>
    </param>
   </params>
</methodResponse>

There are slight differences between the PHP and ColdFusion XML output, with the ColdFusion XML-RPC component choosing to define anything that passes isNumeric() as a double. You can force a type, but to keep the code simple we haven't done that here. We array_walk() to apply settype() to all the values of our array in PHP and set the type to integer.

Now that we've created some Web services, let's take a look at how to use AJAX to consume these and other Web services.

Server-Side Architectures
In this section we'll build several AJAX applications that will consume a Web service. We'll show examples that use a client-side framework and server-side frameworks.

This content is reprinted from Real-World AJAX: Secrets of the Masters published by SYS-CON Books. To order the entire book now along with companion DVDs, click here to order.