Transcoding Middleware

Trans coding Middle ware is used to trans code one format of data to another format to suit the need of the client. For example, if we want to access a web site through a mobile phone supporting WAP, we need to trans code the HTML page to WML page so that the mobile phone can access it. Another example could be accessing a map from a PDA. The same map, which can be shown in a computer, needs to be reduced in size to fit the PDA screen. Technically trans coding is used for content adaptation to fit the need of the device. Content adaptation is also required to meet the network bandwidth needs. For example, some frames in a video clip need to be dropped for a low bandwidth network. Content adaptation used to be done through proprietary protocols. To allow interloper-ability, IETF has accepted the Internet Content Adaptation Protocol (ICAP). ICAP is now standardized and described in RFC3507. Internet Content Adaptation Protocol (ICAP) Popular web servers are required to deliver content to millions of users connected at ever-increasing bandwidths. Progressively, contents is being accessed through different devices and agents. A majority of these services have been designed keeping the desk-top user in mind. Some of them are also available for other types of protocols. For exam-ole, there are a few sites that offer contents in HTML and WML to service desktop and WA? phones. However, the model of centralized services that are responsible for all aspects of every client's request seems to be reaching the end of its useful life. ICAP, the Internet Content Adaptation Protocol, is a protocol aimed at providing simple object-based content vectoring for HTTP services. ICAP is a lightweight protocol to do transcoding on HTTP messages. This is similar to executing a 'remote procedure call' on a HTIP request. The protocol allows ICAP clients to pass HTIP messages 10 ICAP