Saturday, December 4, 2010

Why I will Never Use Spring Tag Libraries in my HTML

The Facts - Web Design and Web Development Involve Completely Different Skills

I work with a team of developers and a team of designers. The designers I work with know Photoshop like they know the back of their hand. They are experts in writing clean, standards based, cross browser compatible HTML and CSS. They design and produce high-quality, beautiful, $15k websites for our clients. Their code validates with W3C validators. The results are amazing.

Our web developers know Java. They can pound away at any server-side problem and produce a solution. They use Struts, Spring, Restlets, JSP, JSTL, Velocity, they can configure Jetty and Tomcat, and they can look at log files and solve problems.

However, if you give them an HTML document, they'll give it such a severe beating that it becomes unrecognizable by it's original creators.

The beautiful HTML turns into a 3 headed monster with unclosed tags, numerous validation errors, and no IE support. The developers struggle for days with guesswork of adding a tag here, removing a tag there, editing a CSS rule here, and who knows what else there.

Of course, the designers are unable to help because of the code soup that results from mixing JavaScript, Java, and HTML into a JSP page.

The resulting web application looks great on the outside, but under the hood it's an absolute nightmare! Ask the designers to go back in and make a design update, and their faces go blank. A 4 hour change takes weeks! The developers can't make the changes because they barely got the HTML integrated with the backend system.

So developers and designers sit side by side trying to understand all of the complexity. The designers can't determine what the application is doing with the HTML, and the developer can't understand what modifications to make to the HTML. Logic mixed in with the HTML is of course overwhelming and makes the code completely unmaintainable.

In summary, designers and developers just plain have different skill sets, at least at my company, and it's foolish of us to think that designers and developers can use the same tools. People do better at what they specialize in, and to try to force that change is wasted energy.

How do I know this, you ask? Because I've fought this fight for years and have continued to lose miserably. "Eclipse is a software development tool, not a design tool", they tell me, "and we're not using it". End of discussion.

Of course, I have convinced a designer or two to try it out. In the end it just slowed both them and me down because Eclipse would inevitably break, and I would end up having to help fix it. Afterwards, we both silently agreed it was a bad idea. The designer stopped using it, and I stopped asking questions.

Light at the end of the tunnel - Keep Content and Behavior Separate

Recently, I took on the project of testing out a new Google App Engine feature and put together a prototype of Google's new ChannelAPI using Google App Engine SDK 1.4.0. Since we have chat designs, I used this as an opportunity to experiment with some new ideas regarding HTML integration with a J2EE application. Below are the details:

  • The HTML exists as a static HTML page. My rule for this experiment is no JSP pages!

  • I use JQuery to bind all my click event handlers dynamically, which leaves my HTML free of pockmarks and other markup that would bind it to the framework.

  • Chat applications involve inserting data in a message window. I used the concepts of manual templating to inject the messages dynamically, without mixing HTML and JavaScript. I'll describe more on this below.

  • My application sends messages to the server using AJAX. Calls to the server are made through the bound click event handlers. No tag libraries! Only client-side code!

I've observed designers over the years, and I've also observed developers. Our designers put placeholders in the HTML they create to mark where the dynamic content would go. The pages can be loaded as static files, and look just like the final result except the fake data. Below is an example of the body of an HTML file, with the placeholder in bold:

   <input type="text" name="alias" value="James" />
   <button id="join" value="Join Room!">Join room!</button>
   <button id="leave" value="Leave Room!">Leave room!</button>
   <button id="test" value="Test Message receive!">Receive Test Msg!</button>
   <div id="messages">
      <div class="message">
              <span class="name"></span>
              <span class="timestamp"></span>
          <div class="text"></div>

   <textarea id="messageBox"></textarea>
   <button id="sendBtn" value="Send">Send</button>

Now, my development team would normally be tempted to solve this problem by pulling out the bold HTML and placing it in the JavaScript callback method as follows:

// create the div for the message
var message = "<div class='message'><div><span class='name'>"+name+"</span><span class='timestamp'>"+timestamp+"</span></div><div class='text'>"+message+"</div></div>";

// inject the div onto the page
document.getElementById("messages").innerHTML += message;

When our designer needs to add a new feature to the chat application, he'll have to study the HTML that's inside the JavaScript to figure out where to make the changes. Instead of focusing on his area of expertise, the front-end, he'll have to become an expert on the actual application's inner workings. He'll need to understand Comet, JavaScript, and how the application works. As you can imagine, this is an extremely inefficient use of his time.

A better approach would be to use a templating engine, such as Velocity or Freemarker:

      <div class="message">
              <span class="name">${NAME}</span>
              <span class="timestamp">${TIMESTAMP}</span>
          <div class="text">${MESSAGE}</div>

This is better, but it's still based on old ideas that still suffer from the same problems. I can't give a JSP file to a designer who knows nothing about Spring, Tomcat, Jetty, Eclipse, JavaBeans, and other technologies that bind the document to the framework. In addition, even if he did understand these technologies, he doesn't have 4 hours to spare to setup his development environment for just a 2 hour change. Even with templating, the files can't really be loaded outside of the JVM and outside the context of the framework.

Velocity and Freemarker are marketing ideas that in practice are failures. Anything that involves a developer mixing non-HTML markup with HTML will create more problems than it solves.

Instead, I took the approach of leaving the fake, empty HTML-valid message in the HTML and using it as the actual template:

var template;
$(document).ready( function() {
chat_template_read_only = $('.message'); // store the original template from the HTML (in bold) for later use.

Now, in my callback method, I do the following:

// make a copy from the template I saved earlier
var message = chat_template_read_only.clone();

// now use JQuery DOM methods to inject the content in the appropriate places in the copy.

// dynamically inject the new message into the HTML.

Here you can see I'm accomplishing the same goal. I'm placing the dynamic content in an HTML block and injecting it into the DOM. Now, if in 6 months the design team needs to add a department header and maybe a response time to each chat, we can give them the current, live, HTML file and they can load it outside the context of the web framework, code their changes, and then send it back to the development team.

We can integrate new changes simply by making changes to the Jquery CSS selectors in the JavaScript files! There is no need for the web designers to understand anything about Eclipse, Java, Jetty, Tomcat, how to configure the application, or any of the applications inner workings.

Let me repeat that one more time: The HTML document is not bound to the framework and can be loaded outside the framework. It can be loaded from an Apache server, it can be loaded from the desktop by clicking on the file. It can be modified by the designers without needing to look at any Java, JSP, or JavaScript.

Spring Taglibraries

I was looking at Spring's JSTL tag, which is used to bind server-side data to an HTML form element so the form can be rendered with a session ID and any preloaded data from the server. The server-side tag generates an HTML form tag.

The benefit here is that web designers are supposed to be able to work with these tags, or at least that's what they say. In practice, in all my years of software development and programming, I have yet to ever see this magical unicorn walk out of the shadows and into the sunlight.

Where are these mystical organizations that operate in this manner? I'd like to meet one of these developers. Are they human? Do they eat and breathe like I do or are they just mere fiction?

This tag is useful in cases where a developer needs to pre-load the form with data from a persistent object. Although I'd love to just ask the developers not to use it anymore, but that's just as difficult as trying to set the web designers up with Eclipse! It just ain't gonna happen!

The problem with these templating languages and tag libraries is that they completely alienate the web designers while simultaneously encouraging the developers to trash the HTML. These frameworks make it impossible for designers to use their own tools. Although these templating engines claim their goal is to allow everyone to work together, they fall way short of the mark. These frameworks were obviously developed by programmers who have absolutely no clue about design.

JQuery Manual Templating

While looking at a <form:form> tag, I thought to myself: "Now wouldn't it be nice if I could use some tool on the server-side to bind my data to that form dynamically, without having to actually make any changes whatsoever to the actual HTML document, just like I did on the client side with JQuery?

Then it hit me! Java doesn't have anything like this that I know of, but since JQuery can run in server-side JavaScript, perhaps Rhino or Claypool is the answer! Imagine using JQuery to manipulate HTML documents on the server side without ever having to modify or template the code.

What I picture is a form of binding server-side tags dynamically. If we can use CSS selectors on the client side, why not create a method of doing so on the server side. I picture a solution such as this:

Import server-side JQuery into our JSP page:

<script type="extjs" src="server-side.js"><script>

// server-side.js

Now, instead of editing the HTML directly, we can bind our server side tags dynamically. When the designer needs to update the page, he can load it completely independent of the Spring environment, make modifications to it, and give the file back to the developer.

There is currently no solution out there for this, but I would greatly appreciate any advice from anyone who has ideas/suggestions for how to get this concept started!


Anonymous said...

Nice article. Having clean html files in a web application is a very good idea. I also agree that Spring / Struts server frameworks and other tag based technologies are a major headache for software development and don't lend themselves to component based enterprise web applications.

J2EE web developer

James Mortensen said...

I really believe an unobtrusive approach to taglibraries where tags could be dynamically inserted into JSP documents would help make everyone happy. The developers would be able to use their taglibraries, and the designers would still be able to easily maintain and update the user interface.

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