Creating a Reload Event-Handler for Model-Glue

The Model-Glue framework has a number of configuration settings that modify its behavior. Perhaps the most important of these settings is the "reload" setting. When the reload setting is set to "true", the framework itself will be reload on each request, and any changes you made to the Model-Glue, ColdSpring, or ORM settings of your application since the last reload will be implemented. When reload is set to "false," those framework files will not be reloaded, and any changes you might have made to them are ignored.

So the idea is that you would have the reload setting set to "true" during development so that any changes you make are processed in the next request. The drawback to being in this constant-reload mode is that it takes time to reload the framework, an amount of time that increases as you add event handlers, message broadcasts, and such to the ModelGlue.xml file and add more bean definitions to your ColdSpring file. It's for this very reason that the Model-Glue team state that it is "imperative" that you set reload to "false" when you put your application into production.

As the development of your application progresses, you'll reach a point where you don't want to reload the framework for every single request because you're spending too much time waiting between requests. At that point, you would set reload to "false", and manually force a reload of the framework when necessary by adding the reloadKey and reloadPassword to the URL of one of your page requests, like so:

http://www.myModelGlueApp.org/index.cfm?init=true

...where "init" is the reloadKey and "true" is the reloadPassword.

Many Model-Glue developers open a separate tab in their web browsers pointing a URL for their application that contains the reloadKey and reloadPassword and simply reload that page whenever they need the framework reloaded, rather than navigating away from the current page they're working on. I decided to go a slightly different route and create a reload event-handler that I could trigger from any page in my Model-Glue application and execute the reload event in a new browser tab or window.

The page layouts of my applications always include some sort of header area at the top of the page. In the header area, I added a hyperlink labeled "Reload MG" with a URL pointing at my reload event-handler:

<cfif viewState.getValue("appEnvironment") EQ "local">
    <cfset reloadURL= viewState.getValue("myself") & "performReload&init=true">
    <p align="right"><a href="#reloadURL#" target="_blank">Reload MG</a></p>
</cfif>

In my last blog post, I explained how my applications determine whether they're running in my local development environment or my remote production environment. The <cfif> statement ensures that the reload link only appears in the header when I'm running the application on my local box. Having the "target" of the hyperlink set to "_blank" ensures that the reloader page opens in a new tab or window.

The performReload event-handler is defined in the ModelGlue.xml file like so:

<event-handler name="performReload">
    <broadcasts />
    <results />
    <views>
        <include name="body" template="util/dspReload.cfm" />
    </views>
</event-handler>

The reload action is initiated by the presence of the reloadKey and reloadPassword in the URL, so there isn't a need to execute any additional controller or model code. The event-handler simply loads the dspReload.cfm page in my "util" directory. This is what the dspReload.cfm page looks like:

<h2>Page Should Close Automatically</h2>

<script type="text/javascript">
    window.close();
</script>

The single Javascript statement is pretty self-explanatory: close the current window.

So when I click on the "Reload MG" link at the top of any of my Model-Glue application pages, a new browser tab opens and the focus of the browser is on that new tab. I can return to my previous tab (where I'm working) and simply wait for the reload event to complete over in the new tab. Once it does complete, the Javascript executes and the new tab is closed: I don't have to close it myself.

So instead of keeping an open browser tab that I'd have click on, click the reload button for, and the click back to my previous tab, I can just click a link in my current page to spawn a reload tab and simply navigate back to my original tab. While it's not a huge improvement, I prefer it over maintaining a reload tab.