Design And Implementation On Asynchronous Callback Mechanism Based Lower-layer Of Embed Linux Browser

It is quiet often that the embed browser has limited performance because of the blocking network I/O operations. After carefully analyzing the network data of TCP connection in Http request, this paper found that the web browser faces five delay-sources while sending or retrieving data in: DNS querying, Initiating the TCP connection, Sending the query, Retrieving data, Closing the TCP connection. Then, put forward the design policy for the lower-layer of embed Linux browser.Considering running on embed system platform, each blocking I/O operation has been encapsulated to be independent module by using"request queue - asynchronous callback"mechanism implemented from Command Processor design pattern.The new architecture of embed browser lower-layer successfully decoupled the executing relationship between lower-layer modules, and improved the efficiency of network I/O operation. The new lower-layer adopted POSIX real-time signals as event-driven source, data cache to eliminate unnecessary network data transportation, and independent thread to do DNS domain name resolution job. This solution prevented the browser from blocking by network I/O operations and overlapping the waiting to process data in order to improve embed browser efficiency.