JGo web application examples or documentation

While reading the description of the JGo product on the GoDiagram website, my eyes caught this line:

“makes it easy to
to provide such functionality in Web applications with very thin
clients by putting the graph image generation and editing on the
server as servlets.”

Can a JGo servlet provide this functionality (image generation and editing) in a web app without the use of applets? If so, are there any examples or writeups of how one might get started building on of these web apps?

Thanks for any input!

Yes, you can use the JGoWebApp.war file to run a simple sample application. The sources are in the examples\imager subdirectory.

I can’t find a file named JGoWebApp.war, or an examples/imager subdirectory.

Here’s my setup, in case that helps: I’m using the JGo for SWT evaluation version for Windows.


It’s only in the JGo for Swing kit. I don’t know that it couldn’t work using SWT, but I don’t think any of us have tried it, so I can’t be sure.

Thanks for your quick responses, Walter!

I grabbed JGo for swing and deployed the webapp war file to Tomcat. I’m looking at a 2-pane web page, with instructions and controls on the left and an empty space on the right which I assume is where the diagram should appear. I can’t seem to get anything to happen.

Several times, I get a message in the status bar such as “Waiting for localhost” or “Downloading picture…”, but nothing seems to resolve. I’ve clicked “Change Document” and entered a document name, etc., but still nothing. Also, I restarted Tomcat and restarted JGoWebApp within Tomcat, but still no luck.

Any suggestions?

Thanks again.

PS - Using both Internet Explorer and Firefox.

Actually the pane on the right shows information and controls for modifying whatever was selected in the diagram image on the left side. When nothing is selected, the right pane will be empty.

What versions of Tomcat/Java are you using?

I’m using Tomcat 5.5 and Java 1.5.

When I browse the web app URL, I get a page divided vertically in half.

The left half has a header that reads: “This is a demonstration of JGo Image Servlet”. Below the header are a bunch of controls: change the view’s position […], change the size of the view, adjust view, layout graph, etc.

The right half is empty.

I don’t see any diagram image.

I’d be happy to email a screenshot of the page.

Whenever I click “Adjust View” or “Layout Graph”, my browser’s status field reads “Downloading picture […]”, but it never seems to resolve.

I think the problem might be related to the message boxes that are supposed to pop up on the server because I’m using the evaluation version of JGo:

This web application may be using an evaluation version of JGo.jar and/or JGoLayout.jar.
<i>You may need to dismiss some message boxes before you can see any images,
   or before you can see the results of an automatic layout.</i>

The message boxes will display on the server.</span>

These message boxes are not appearing (as far as I can tell), so I have no way of dismissing them.

The image should appear on the left side of the left pane. You can see where the element is in the ImageServer.html page. As you can see in the web.xml file, the ImageServlet class should be in the classes/com/nwoods/jgo/examples/imager subdirectory, along with the other example classes; JGo*.jar should be in the lib subdirectory.

(Crossed posts)

Are you running Tomcat on your development machine? If so, perhaps you didn't see the message box because it's underneath some other window.
They do appear when I run the sample.

I’ve been running Tomcat both on my dev machine and a remote machine - that was part of the problem (inconsistency).

The other part of the problem was that, just as you suggested, the message box was popping up at the very bottom of all my windows and I wasn’t clever enough to think of that possibility.

Finally, I made sure I was using the dev machine’s Tomcat, then minimized my windows one by one and voila, there it was.

Thanks a bunch for your help, Walter.

me too!