XHTML encoding and compression

Abstract

The wireless application environment uses the wireless markup language (WML) as the primary markup language. WML is based on XML and therefore is quite verbose. Mobile networks generally have low bandwidth and high latency, and verbose documents can therefore take a long time to transfer. Further, mobile devices, especially older ones, do not typically have the processing power or memory to process such verbosity. Since all WML documents have to go through a mobile gateway, WAP 1.x specifies that the WML files are encoded to make them smaller. This lowers the transfer times and simplifies processing on the mobile device. WAP 2.0 includes support for a restricted version of XHTML, called the XHTML mobile profile. This is to make content development and management easier. XHTML, though as verbose as WML, is never encoded by the gateway. This is mainly because WAP 2.0 does not require the use of a gateway. Besides, the advances in mobile processing power and mobile networks mitigate some of the issues arising from the verbosity of XML. This paper investigates what performance gains are possible if XHTML were encoded and compressed. The experiments show that while there is a substantial performance gain using compression, gains due to encoding are comparatively small. The empirical results justify that XHTML encoding is not generally useful.