How do I get output to the webpage while still inside a cfscript?

Question

Sorry for the longer post, I'm trying to be specific. I'm a bit of a newb at cold fusion and lucee, so forgive me if I have missed something fundamental here. I'm just trying to do a quick POC, but can't get it working.

What I am trying to do is make a page call, write to a web page, sleep for a while. Kind of a heartbeat. What I can't get to happen is the write to the web page...until all sleep(s) have happened and the page cfm file completes processing. I've looked extensively for the past couple of days, and have tried numerous items, but to no avail.

From my index.cfm lucee page, I have a link to launch a new tab and call my cfm file.
<a href="./pinger2.cfm" target="_blank"><img class="ploverride" src="/assets/img/Ping.png" alt="Ping Test" width="125" height="75">
No problem here, a new tab opens and pinger2.cfm starts processing. What I'm hoping for is the table heading to almost immediately print to the page, then make the first call out, print the results to the page, sleep, make the next call out, print to the page...but it no workey. Anyone have a clue? The code in the pinger2.cfm file is:

<cfscript>
    public struct function pinger( required string url, required string verb, required numeric timeout, struct body )
    {
        var result = {
            success = false,
            errorMessage = ""
        };
        var httpService = new http();
        httpService.setMethod( arguments.verb );
        httpService.setUrl( arguments.url );
        httpService.setTimeout( arguments.timeout );
        if( arguments.verb == "post" || arguments.verb == "put" )
        {
            httpService.addParam(type="body", value=SerializeJSON(arguments.body));
        }
        try {
            callStart = getTickCount();
            var resultObject = httpService.send().getPrefix();
            callEnd = getTickCount();
            callLength = (callEnd-callStart)/1000;
            if( isDefined("resultObject.status_code") && resultObject.status_code == 200 )
            {
                result.success = true;
                logMessage = "Pinger took " & toString( callLength ) & " seconds.";
                outLine = "<tr><td>" & resultObject.charset &  "</td><td>" & resultObject.http_version  & "</td><td>" & resultObject.mimetype  & "</td><td>" & resultObject.status_code  & "</td><td>" & resultObject.status_text  & "</td><td>" & resultObject.statuscode  & "</td><td>" & logMessage & "</td></tr>";
                writeOutput( outLine );
                getPageContext().getOut().flush();
                return result;
            }
            else
            {
                throw("Status Code returned " & resultObject.status_code);
            }
        }
        catch(Any e) {
            // something went wrong with the request
            writeDump( e ); 
            abort;
        }
    }
    outLine = "<table><tr><th>charset</th>  <th>http_version</th>     <th>mimetype</th>      <th>status_code</th>      <th>status_text</th>      <th>statuscode</th>      <th>time</th> </tr>";
    writeOutput( outLine );
    getPageContext().getOut().flush();
    intCounter = 0;
    while(intCounter LT 2) 
    {
        theResponse = pinger(
            url = "https://www.google.com",
            verb = "GET",
            timeout = 5
        );
        intCounter = intCounter + 1;
        getPageContext().getOut().flush();
        sleep(2000);
    }
outLine = "</table>";
writeOutput( outLine );
</cfscript>

NOTE: I'm sure there are other "less than best" practices in there, but I'm just trying to do this quick and dirty.

I thought the getPageContext().getOut().flush(); would do the trick, but no bueno.

EDIT: If it matters, I'm using CF version 10,0,0,0 and Lucee version 4.5.2.018.

Answer 1

I do something similar to generate ETags by hand (using Lucee 4.5). I stick a simple

GetPageContext().getOut().getString()

in the onRequestEnd function in Application.cfc. This returns a string of HTML just like it's sent to the browser.

You could store that in the appropriate scope (APPLICATION, SESSION, etc) and use it later, or whatever you need. Obviously, all processing needs to be completed, but it shouldn't require any flushes. In fact, flushing may or may not alter its behavior.