JSP 1.x Code Conventions - Open Discussion

Question

This morning, we posted a draft set of recommendations on Coding Conventions for the JavaServer PagesTM Version 1.x Language. The article can be found here:
http://developer.java.sun.com/developer/technicalArticles/javaserverpages/code_convention/
The article is intended to be a first draft of coding conventions, and we're getting some great, high-quality feedback on our comments alias, [email protected] Keep 'em coming!
This alias is one-way only (from you to us), and we'd love to see a more collaborative feedback forum as well. I've started this topic as a place so that users can discuss and share their experiences with JSP coding conventions, as used in their organizations.
Please continue to send feedback to [email protected] as well!
Mark Roth, Java Software
Specification Co-Lead of JSP 2.0
Sun Microsystems, Inc.

Answer 1

The JSP guidelines suggest that
"Indentations should be filled with space characters. Tab characters cause different interpretation in the spacing of characters in different editors and should not be used for indentation inside a JSP."
It is a simple observation that using spaces instead of tab characters increases the returned content length. While this may seem insignificant, in my opinion it is not. for example, checking the trivial table sample in the guideline:
<table>
<% if { tableHeaderRequired ) { %>
<tr>
<th>Last Name</th>
<th>First Name</th>
</tr>
<% } %>
<c:forEach var="customer" items="${customers}">
<tr>
<td><c:out value="${customer.lastName}"/></td>
<td><c:out value="${customer.firstName}"/></td>
</tr>
</c:forEach>
</table>
using tabs in indentation results in 329 bytes of data, while using spaces results in 443 bytes, or about 35% more data! Testing on several real-world pages gave similar results. While this this certainly varies with content and coding style, following the indentation guidelines, which are extremely important for readability, will result in several indentation levels in an avarage line of nontrivial code, and an increase in data size of similar proportions. In my opinion this increase in traffic and processing is quite significant in a production server. Or, as I like to think of it, imagine an internet where all web servers were jsp-based, and that all web transactions were 35% slower...
Finally, the stated reason that 'Tab characters cause different interpretation in the spacing of characters in different editors' doesn't seem like a very strong case. Developers who want to view JSP sources are most likely JSP developers, which should have their editors or IDEs set to 4-space tabs in the first place, as the guideline suggests. Perhaps some editors I'm not aware of don't allow these settings, which can cause the stated problem.
I wonder if these consequences were taken into account when deciding on the guidelines.
Other than that, I think the guidelines are great, and as with the other Java programming convention guidelines, I hope they reach widespread use and become standard developer practice, for the benefit of all.
-Amichai