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Web services, in Ben Forta's words, "allow remote execution—a host can make a request, have it executed remotely, and receive results." Request in, data out—with all calculations and look-ups done behind the scenes on the server hosting the web service. In our case, we'd like to specify a path to the SVG file and have the web service pass back a) an array of the contents of each path's d attribute, nicely formatted, or even b) an array of shape objects that contain only quadratic bezier data which could be used directly by the Macromedia Flash drawing API.

With ColdFusion MX, web services can be written in either CFML (good for developers familiar with ColdFusion or other similar server-side scripts), or in Server-Side ActionScript (SSAS) (good for Macromedia Flash developers familiar with ActionScript).

Web services based on ColdFusion MX components
Because I'm a believer in starting small and building up, I think the best way to develop a service with Cold Fusion is to start with a CFM file (a standard Cold Fusion page) which accepts whatever input you wish to pass to the service, does a little manipulation, and then does a <cfoutput> or <cfdump> of the results. When that appears to be working, you can add more code to the CFM page until it dumps out to the browser whatever content it is that you wish to have returned from the service (or some string equivalent thereof). Once you have a working input-in, data-out CFM page, you can turn all of the content into a function (or several functions, if your service will perform more than one function), and wrap that inside a <cfcomponent> tag. Here is the code I started with initially in my CFM file. It reads in a file, parses it to an XML object (svgObject), searches for all path tags in that object, and puts them all into an array (arPaths). Then it displays the number of paths it found, to confirm that it's working as I expect:

  <cfset 
                              svgFile = ExpandPath("candle.svg")>

                                <cffile action="READ" file="#svgFile#" 
                              variable="svgContents">

                                <cfset svgObject = XmlParse(svgContents)>

                              

                                <!-- Find all path tags in the SVG 
                              file, no matter what depth -->

                                <cfset arPaths = XmlSearch(svgObject, 
                              "//path")>

                              

                                <!-- Display number of paths; for 
                              debugging original .cfm -->

                                <cfoutput>Number of paths found: 
                              #ArrayLen(arPaths)#</cfoutput>

                              

                              (etc)

Once that part worked, I went on to add the code to loop through the array and do the operations I needed to do: scan for fill and stroke attributes and convert them to CF struct's (which Macromedia Flash MX can read as ActionScript objects), and convert the d attribute to a Macromedia Flash-readable array of drawCommands. All of that is displayed in the browser window with <cfoutput> and <cfdump> tags, as may be seen in the svgToArrayTest.cfm file included in the downloadable sample files from the first page of this tutorial.

Using the working CFM file, I removed the output tags (changing the final cfdump to a cfreturn instead), wrapped the content inside a function tag, and put that inside a cfcomponent tag, to define the function as part of a CFC (ColdFusion Component). The final CFC file is included in the sample file folder as svgToArray.cfc.

Once the function has been defined in a CFC it can be called as a web service with the steps outlined below. Because ColdFusion MX can parse XML, it did the parsing and array creation in half the time it took Macromedia Flash alone (using people.svg as a test file). The CFC file replaces the functions loadingDone, findPathNode, defineShape and drawSVG in the original Macromedia Flash-only drawsvg.as file.

To use this service from a Macromedia Flash movie, the following things need to be done in the FLA:

·	establish a connection to the Macromedia Flash Remoting gateway
·	create an object which holds parameters to be passed to the service
·	create an object with methods to deal with data (or errors) passed back from the service
·	define the WSDL for the service
·	tell the gateway connection object where the service is
·	call the service, specifying the function to execute

Following is the code that does this (from the file drawsvg_s1.as):

var gw = 

                              

                              NetServices.createGatewayConnection("http://localhost:8500/flashservices/gateway/");

                              // svgtoarray service needs filename (or path to 
                              file) passed as a string

                              // so set up params object to send it as a property

                              var params = new Object();

                              params.filename = "people.svg";

                              

                              //create an object to catch the response from the 
                              xml-parsing service

                              var drawInfo = new Object();

                              drawInfo.onResult = function(pathData) {

                                trace("number of shapes " 
                              + pathData.length);

                                findTime("xml parsed to array (service 
                              1)");

                                for (var i=0; i<pathData.length; 
                              i++) {

                                  shapes.push(createShapeDef(pathData[i].drawCommands, 
                              null, pathData[i].fill, pathData[i].stroke));

                                }

                                drawShapes();

                              }

                              

                              //this gets called if an error occurs.

                              drawInfo.onStatus = function(error)

                              {

                                  trace("drawInfo Error 
                              : " + error.description);

                              }

                              

                              //the path to the web service's WSDL file

                              var webServiceWSDL = "http://localhost:8500/com/ht/svgToArray.cfc?wsdl";

                              // returned object is drawInfo, defined above

                              var getDrawCommands = gw.getService(webServiceWSDL, 
                              drawInfo);

                              ...

                              getDrawCommands.svgtoarray(params);

Next, let's examine how to use web services that are based on Server-Side Actionscript.