Recently, WebRTC is a popular technology which makes point to point video transmission and data transmission realizable in Web applications. When combining with mobile
technologies and applied to collaborative design, designers in different areas could communicate through network in real time. The key point of WebRTC is to establish a peer
channel. However, when poor network or multiple communicating exists, the course may fail. Therefore, a delayed resend mode was introduced to solve the first problem.
Specifically, after supplicant sending SDP descriptors and waiting for a period of time, if the recipient could receive the corresponding message, the channel is been connected,
else the supplicant should resend the message. If this process failed five times, the trail would be terminated. Moreover, most endtoend file transfer relies on the
server, which means that high performance servers should be supplied as transferring large files. As for this problem, the solution is to split the file into pieces and to
transfer massage among terminals through WebRTC peer channel directly, which makes it no longer depends on the server, and takes full advantage of the upstream broadband of the
client. It shows that delay and resend mode can not only guarantee a successful connection of channels, but also be able to transfer files efficiently and quickly between
peers.
