Why GWT & App Engine?

I said last post that we didn't have any code written yet, and that's technically true.

We haven't written any code yet, but by creating a Web Application Project using GWT and App Engine, we do have a skeleton project that shows communication between a GWT client and an App Engine server. And it'll all run right on our machine from within Eclipse.

Start Eclipse and click on the project name for your project in the upper left pane. Then click on the toolbar icon that looks like a red suitcase with a G on it. On the next screen click Compile. That will take the GWT code and compile it down into Javascript.

Now if you right click on the project name and choose Run As->Web Application, a local web server will start with Java App Engine running, and the web page defined by our GWT application will open. Type in your name and click Send to see a full round trip to the server and back.

It's important to understand that all this is running on your local machine. We haven't signed up for App Engine space yet (and won't until we figure out what the project is!), and we haven't had to transfer anything to a web server. It's all local, and we can keep it local until we're ready for it to go online.

Okay, so on to the question, Why GWT? There are many reasons, but here are the important ones for this course.

1) My students already know Java, so they don't need to learn Javascript.

2) GWT takes care of browser compatibility

3) GWT limits the security concerns of web apps (to at least a manageable level)

4) It all works in Eclipse, which my students are already used to using

Why App Engine? We could write GWT apps that communicate with any server language, including PHP, Python, etc, hosted on any shared hosting account. We're using App Engine because:

1) With Java App Engine and Eclipse, it all integrates beautifully for testing locally

2) There's no cost for App Engine hosting at the basic level

3) If a student's project takes off, App Engine can scale with their success

Sure, I could have used a Javascript library on the client and PHP on the server, but I'd have lost at least some of the advantages of GWT and App Engine in doing so. This way, I'll know that students who complete the course will have a leg up on their colleagues who don't have this sort of experience.