gwt; mixing html pages with java code

Question

I really like the approach in GWT where you can define "divs", "spans" etc in a regular html page, then in the GWT entry point simply push a button or some other component inside the div.

So small example, here is a snippet of a gwt html page:

<body class='page'>
    <iframe src="javascript:''" id="__gwt_historyFrame" tabIndex='-1' style="position: absolute; width: 0; height: 0; border: 0"></iframe>

    <div>
        Query Terms: <span id="txtQuery"></span>&nbsp;
        <span id="btnQuery"></span><br>
        ...
    </div>
</body>

And here is a small java snippet contained in the gwt entry point:

ClickHandler clickHandler = ...
TextBox txtQuery = new TextBox();
Button btnQuery = new Button("Query", clickHandler);

RootPanel.get("txtQuery").add(txtQuery);
RootPanel.get("btnQuery").add(btnQuery);

One of the reasons I like this approach is that it allows non java coders to design / write the html stuff, and I also like the separation between GWT / java code and the html code.

However... this may work well for a simple web page, but how do you scale this approach up into many webpages? From what I understand, the "GWT way" of doing things is to have one webpage and use history to hide and show various GWT components. I have built 2 projects in GWT using this standard technique, but recently discovered that you can do the sort of thing I showed above.

Is there any way of scaling the above 2 snippets into multiple html pages, where GWT injects its components into standard html pages?

jusio · Accepted Answer · 2012-01-04 21:06:21Z

here is no GWT way. At least not in GWT mission statement. If you want to pursue your aproach there are multiple ways how you can do it.

GWT app per page. (e.g. on each page a gwt app specific for this page is included). You simply compile a new GWT module for each page where you need some GWT functionality. You can use few of them together on one page, or none. This approach is good if you GWT apps are going to be really simple, and you don't need to use stuff like GXT Grid on every single page with different settings, otherwise you will waste user browser will have to download large chunks of JS code over and over, and this will be a big problem if you have a lot of pages.

One big GWT app for all pages. Just put everything into single GWT app, create some kind of switch (some js variable) so the app knows what it has to create. Some code splitting might be used, so on each page only things which are really required will be downloaded. Since the same JS will be used on each page, caching should solve the problem with downloading application code over and over (but you still have the problem with actually parsing/running the code very time user changes the page)

There is also a third approach, the most effective of all, but the hardest as well. As soon as the user loads one of the pages, there is no more navigation, gwt module simply takes template for page to which user wants to navigate, and replaces current html code with newly generated template. This is quite easy to achieve, if you will use TextResource from ClientBundle and HTMLPanel. The problem is with navigation in address field (GWT app will have to be responsible for changing the address, so the users can create bookmarks or send the link to their friends). You will use one single GWT script for this and some code splitting is recommended.

All three approaches are totally valid, depending on your requirements you can pick any of them. Also if all you want is to provide people ability to use HTML to layout GWT screens, you might want consider using combination of HtmlPanel and ClientBundle's TextResource.

Thanks for your detailed answer; I may look into some of this in more detail later on, but for now I think I'm going to try UiBinder as suggested by Thomas.

Thomas Broyer · Accepted Answer · 2012-01-05 03:48:28Z

1

If the goal is to have designers work on HTML rather than Java, then how about UiBinder? It'd give you what you want (separate HTML –or rather, XHTML-like– code from Java code) inside a GWT project.

answered Jan 5, 2012 at 3:48

Thomas Broyer

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