Since all data requested from a content server must pass through the WAP gateway, it is very important that the contents reaches the browser in a proper state. WAP gateways convert or compile the textual WML code into a binary format, and this conversion process is different in virtually every gateway. Some do it faster than others, some do it better than others. One piece of code does not necessarily produce the same binary content. It's not uncommon to find that one deck works fine via one gateway, while crashing via another.

The intention is to give you as an application developer an overview of what to expect from each gateway, and maybe even to help gateway developers get their products on the right track.

With the help of the brilliant people of the WML and WMLscript Programmers mailing list, a detailed list of gateway inconsistencies will be compiled.

For now, the following aspects of the WAP gateway will be examined: (The list is guaranteed to change frequently)

• Does the gateway identify itself to the web server?
• Does the gateway support some form of unique ID for the device it's provisioning?
• Does the gateway support cookies according to the HTTP specifications?
• Does the gateway support some form of cookie?
• Does the gateway pass through any unrecognized element/attribute to the browser as unencoded text?
• Does the gateway scramble HTTP headers?
• Does the gateway convert content and images in some way?
• Does the gateway handle and convert charsets to and from what the device requested?
• What is the best, average and worst average compilation ratio?
• Is the gateway normally deployed by network operators?
• How does the gateway handle already compiled WMLC?
• How does the gateway handle WMLscript compilations?
• How does the gateway handle caching?
• How does the gateway support additional data types such as GIF, BMP, HTML etc etc?
• How does the gateway handle different character sets?
• How well does the gateway comply with interoperability specifications?
• Is the gateway mostly used in vertical or horizontal applications?
• Which platforms does the gateway run on?
• Does the gateway support subscriber number forwarding?
• Does the gateway support WTLS and SSL?
• Is the gateway also capable of serving content?
• How much does the gateway cost?

Chapter 1 in "Professional WAP" from Wrox