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Mobile Data Services 76 MExE The Mobile Execution Environment (MExE) sounds like a reference to the possible health effects of mobile phones, but it's actually another proposed wireless standard from the European standards body ETSI. It aims to provide a thorough specification for running programs on a mobile phone, enabling sophisticated services to be provided by operators or downloaded by users. It requires a Java interpreter built in to the phone so that it is able to run applications written in Java in the same way as PC-based Web browsers do. The problem with MExE is that, so far, cellphones lack the processor power needed to interpret and compile programs. A typical PC is capable of calculating more than 1000 MIPS (millions of instruc- tions per second), while most phones can handle only 10 MIPS or less. This will change as tech- nology advances, so MExE specifies several different levels of support. Each allows more complex programs to run, but requires a more advanced device. To help phone companies fit Java into devices with limited computing power, Sun has produced a cut-down version of the language, called J2ME (Java 2 Platform, Micro Edition). Plenty of vendors and operators plan to support this, including Nokia, Sony, and NTT DoCoMo WAP In 1997, the U.S. operator Omnipoint decided to roll out a mobile Web service. It had no idea how to go about this or which technology to deploy, so opened the process to competitive tender. Anyone who could come up with a wireless data proposal was free to submit it to Omnipoint, and to explain how it would serve the company's customers and increase revenue. Four companies eventually took up this challenge. The cellphone vendors Nokia, Ericsson, and Motorola all suggested their own variants on messaging, while Unwired Planet submitted HDML. All had their advantages, but the big disadvantage of being proprietary: Omnipoint's customers would be locked into buying phones and software from a particular supplier, similar to the way that most PC users are locked into Microsoft. Omnipoint told the bidders that it would not accept a proprietary solution--they had to get together and thrash out a standard. The result was the formation of the WAP Forum, which originally con- sisted of these four companies, though not Omnipoint itself. A year later, they threw the Forum open to new members and announced the first version of the Wireless Application Protocol. WAP isn't the only nonproprietary solution. C-HTML is also open to all, and endorsed by the W3C. However, WAP differs from other wireless Web systems in that it isn't just a markup language--it's a complete new stack of protocols designed to overcome some of a wireless network's specific problems, such as high latency and jitter. This makes it more complicated than C-HTML, but also more reliable, if the WAP Forum is to be believed. If previous battles are anything to go by, the standards war between WAP and C-HTML will depend on which has the heaviest backers, not necessarily the best technology. Here WAP has a clear advantage: it was designed in part by the mobile phone manufacturers, who still call the shots in the wireless world. A compromise may be possible: the future version 2.0 of WAP will include C- HTML, while Microsoft already has a browser than can display both. Protocols In networking, a protocol is a set of rules for communication between similar devices. They can cover anything, but in general protocols regulate such conditions as whose turn it is to transmit, how errors are detected or fixed, and how to distinguish data from signals sent alongside it.