| <!-- $Id$ --> |
| <html> |
| <head> |
| <title>Xerces 2 | Crimson</title> |
| <link rel='stylesheet' type='text/css' href='css/site.css'> |
| </head> |
| <body> |
| <span class='netscape'> |
| <a name='TOP'></a> |
| <h1>Evaluation of Crimson Code</h1> |
| <a name='Overview'></a> |
| <h2>Overview</h2> |
| <p> |
| The Crimson code donated to the <a href='http://xml.apache.org/'>XML |
| Apache Project</a> by <a href='http://www.sun.com/'>Sun Microsystems</a> |
| is a relatively clean and straightforward implementation of a |
| conforming <a href='http://www.w3.org/XML/'>XML</a> parser. However, |
| there are some serious drawbacks to its design that hamper its use |
| in the Xerces2 effort. This page will highlight some of the problems |
| that I see with the Crimson code. This doesn't mean, however, that |
| there aren't good ideas in Crimson! I'll highlight some of the things |
| that I like about Crimson as well. |
| </p> |
| <a name='TheGood'></a> |
| <h2>The Good</h2> |
| <p> |
| <table border='0'> |
| <tr> |
| <th>Size:</th> |
| <td>Crimson has a small code footprint.</td> |
| </tr> |
| <tr> |
| <th>Simplicity:</th> |
| <td> |
| The code is very straightforward and easy to grok. I especially |
| like the simple approach to reading the input streams. The advanced |
| reader code in Xerces has been a continual source of bugs and |
| developer confusion. See my <a href='xerces.html'>evaluation of |
| Xerces</a> for more detail. |
| </td> |
| </tr> |
| </table> |
| </p> |
| <a name='TheBad'></a> |
| <h2>The Bad</h2> |
| <p> |
| <table border='0'> |
| <tr> |
| <th>Standards:</th> |
| <td> |
| Crimson is lacking implementation of important standards. Some |
| examples are DOM Level 2 and XML Schema. |
| </td> |
| </tr> |
| <tr> |
| <th>Modularity:</th> |
| <td> |
| The design of Crimson is not modular enough to be of general |
| use in a wide variety of applications. For example, the document |
| and DTD scanning code is hard-coded into the parser. Also, a lot |
| of the classes used by the parser rely on package visibility of |
| members. (Yuck!) |
| </td> |
| </tr> |
| <tr> |
| <th>Validation:</th> |
| <td> |
| The validation engine is rather simplistic and not very fast. |
| Plus, it doesn't seem to be able to handle the advanced |
| validation requirements of XML Schema. |
| </td> |
| </tr> |
| <tr> |
| <th>Performance:</th> |
| <td> |
| The general performance of the Crimson code is good but there |
| are some areas where it can (and should) be tuned for performance. |
| First, validation is not as fast as it could be but there are |
| comments in the code that suggest "compiling" the model into a |
| DFA for faster validation. Also, the DOM implementation wastes a |
| lot memory when traversing the document. |
| </td> |
| </tr> |
| </table> |
| </p> |
| </span> |
| <a name='BOTTOM'></a> |
| <hr> |
| <span class='netscape'> |
| Author: Andy Clark <br> |
| Last modified: $Date$ |
| </span> |
| </body> |
| </html> |
