The BBC Betsie program is probably the nearest comparison to mod_accessibility. We believe mod_accessibility has very substantially more to offer than betsie, and have prepared a brief comparison.
| Subject | Betsie | mod_accessibility |
|---|---|---|
| Installation | Runs as CGI and requires some site-specific configuration. It is well-commented, but requires some basic familiarity with CGI. | Requires only a simple configuration directive. Site-specific configuration is available but not necessary. |
| Performance: Initial Overhead | A Perl script running as CGI incurs a basic performance penalty with every hit, in addition to the processing it performs. | An Apache module incurs no overhead other than the processing it performs. |
| Performance: Parser Overhead | Performs Perl pattern-manipulation and text substitutions on the entire document, requiring it to hold the whole document in memory, parse and rewrite it several times, and slowing substantially for larger documents. | Runs a lean and efficient SAX parser (written in C), requiring just a single pass through the document. No performance penalty even for the largest documents. |
| Performance: Cacheability | As far as I can tell, Betsie output is not cacheable. | Output from mod_accessibility mostly preserves the cacheability of the original contents. |
| Parser | Ad-hoc Perl text manipulation (commonly known as "tag soup" parsing). | A markup-aware SAX parser based on the htmlParser module of libxml2. |
| Compatibility: Webservers | Runs on any server that supports CGI and has Perl available. | Runs only on Apache 2.0. Can be used with other servers by deploying Apache as a proxy. |
| Compatibility: Dynamic or non-local contents | Runs as CGI, so using it with another content-generator (such as another CGI script, PHP, mod_xml, or in a proxy server) requires a significant hack, such as an entire new HTTP request. | Works out-of-the-box with any content generator. No hacks required. |
| User Choices | Appears to offer superficial configuration options (such as fonts and colours) that rely on deprecated markup to work, and are in any case generally available as browser options. | Offers different views on page structure, complementing rather than duplicating normal browser functions. Available views include Betsie emulation. |