Yesterday evening (Tuesday February 27th) I gave my first live presentation! The Kansas City Coldfusion User's group (www.kcdevcore.org) invited me to come and speak about Model-Glue since I've been using it on my day job for the past six months or so and have learned it and OO coming from a strictly procedural background. I wasn't nervous until Jim Pickering (the UG manager) and I drove up to the building where they meet. The nervousness finally subsided about five minutes after I got into the presentation and then I felt like it flowed pretty smoothly.

My approach to this presentation was a little different than what most probably expected. I opted NOT to do a demo app at all since there's already a plethora of sample apps and tutorials out there already that are really great. Instead, I decided to take the time to share all of the things needed in order to know how to "think about" OO and model-glue...all of the things that I spent the most time researching and trying to comprehend so that I COULD take advantage of Model-Glue's simplicity.

So, for what it's worth, here is a link to my first presentation!

https://admin.adobe.acrobat.com/_a200985228/p45002941/

Actual PPT and accompanying Word doc for my presentation (caution: the PPT is nearly 5mb, so only click it if you really want it): MMG.PPT   MGPreso.DOC

Disclaimer: Everything I shared in this presentation is as I understand it to be, and was not painstakingly researched to validate it's accuracy. Whether it's accurate or not, complete or not, the understandings I share in the presentation work for me in my real-world scenarios and should be considered as "this guy's view"  and not as gospel fact.

I've been hearing the term 'Service Layer' everywhere for at least the past year and a half, as I'm sure most of my peers have as well. Whether it's seen in blog posts, heard during casual conversation at conferences, found in articles, or woven throughout almost any discussion at all concerning OO and Coldfusion...the term is quite prevalent and common these days. But I had a problem: the term held absolutely ZERO connotation in my mind. No picture was ever conjured up when I came across it, no corresponding 'Doug Boude' translation was found in my internal lexicon; I felt quite out of the loop. Ah, but recently that has all changed, as the phrase itself has not only come to life for me, but found an absolute and permanent place in all that I do, technically speaking; an epiphany, if you will.  I just figured there were others out there who, like myself, may still be kinda grasping for a way to think about the term, so what follows is my personal definition/explanation of what a Service Layer really is. Please feel free to append, addend, flip, and twist it to your heart's content until it's as whole as it ever can be.

SERVICE LAYER

This is not NEARLY as gray and ambiguous a term as you might think. Picture if you will, a man sitting comfortably on his sofa. In one hand is the remote for his very large plasma TV; in the other hand is a remote for his home theater system. The two remotes and the man are all objects, and all three come pre-built with things they can do. In the kitchen is the man’s wife; let’s think of her as the calling application. She barks out the order to the husband object, “START THE MOVIE, YOU IMBECILE!”. The husband object just happens to have a startTheMovie method, and begins to execute it. First, he manipulates the objTVRemote object, calling its “tvOn” method. Then, he manipulates the objDVDRemote object, calling it’s “dvdOn” and “dvdPlay” methods. Now he manipulates the objTVRemote again, calling the “inputSRC” method and switching the tv to receive the dvd input. Tada! Movie is playing now!

Pretty clear scenario, eh? Well, in this illustration, the MAN is acting as the SERVICE LAYER. Although he has a “startTheMovie” method, all he’s really doing is coordinating efforts between other lower level objects that actually do the work. His wife doesn’t care about the remotes or how they work, and her life is then simplified because she need only make her one call to her SERVICE LAYER OBJECT and he handles the nitty gritty details. Service Layer…not such a deep, complicated mystery after all, is it?

Doug out.