Re: How do I send program generated Images to my users?

The remote service servlets used by RPC have code in them to prevent GET requests from doing anything.

As was said before, if your images are small (or you don't care about IE) you can return the image as a data URI (google is your friend here) and when you get the response simply do: new Image(myImageDataURI); 

Another option would be to save your image (either to the filesystem, or datastore) using some sort of identifier (hash maybe) 

Then use a separate HTTPServlet to return this image something like: /GetImage?ID=someid

But your original idea should have worked as well ... GWT.getModuleBaseURL()+imageName 

module base url is the location of the Module.js file used in the host page.

There is also GWT.getHostPageBaseURL() which is the location of the Host HTML page (which may be different than the module's location) 

-jason

On Oct 26, 2010, at 3:18 PM, Greg Dougherty wrote:

Thank you Thomas.

Given what I'm trying to do, I need to have the Image created via a
GWT RPC call.  However, nothing keeps me from implementing doGet ()
within my servlet, so I did that, and now I can serve up the images
cleanly, and I can even cache them! :-)

Greg

On Oct 26, 11:26 am, Thomas Broyer <t.bro...@gmail.com> wrote:

On 26 oct, 16:18, Greg Dougherty <dougherty.greg...@mayo.edu> wrote:

- Generate the image with a servlet on the fly (return the appropriate mime

type and the image) or (if the images are small)

Great idea.  HOW DO I DO THAT?

Sorry for the shouting, but I'm already generating the things on the

fly.  If I knew how to return them other than as a file, I'd already

be doing that.

I've got a GWT client and a GWT Servlet.  The GWT Servlet has an image

sitting in its memory.  I want to get that image to the client.  If

you can give me sample code, point me to sample code, or point me to a

well documented Java function, that would be great, and you would have

my full appreciation.

Telling me to "do X' is pointless, if you don't give me some way of

figuring out how to DO that X.  Because if I knew how to do it, I

would have already done it, and not wasted everyone's time with these

questions.

The thing is: instead of calling your servlet through GWT-RPC or

whatever (anything implemented above XMLHttpRequest) to generate the

image; "generate" the call through a new Image(), passing the

"arguments" in the URL.

Your servlet will then be a bare HttpServlet (no GWT involved, just

implement de doGet method) and you'd send the image back using the

HttpServletResponse's OutputStream (after setting the

HttpServletResponse's content-type to the appropriate value, for

instance "image/png").

To get the arguments on the server-side, if you passed them in the

query string, then HttpServletRequest#getParameter will work

seamlessly.

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