First Look: Flash Media Server 4

"The move from session encryption with RTMPE to persistent encryption with Flash Access 2.0 is key," said Florion Pestoni, Adobe's principal product manager of rich media solutions, when Flash Access launched. "Many content owners may choose to download content to AIR-based rich internet applications for offline viewing. Since Flash Access 2.0 content will play back on Flash Player 10.1 and AIR 2.0, persistent encryption is an important step toward making offline players adhere to licensing and DRM concerns."

UDP, on the other hand, doesn't play as well with other protocols. And its "take no prisoners" approach means that it gets the content delivered, no matter what other types of content are clogging up the pipe. Still, for wide-ranging or scalable implementations-especially those that require two-way communication-UDP is more effective that TCP.

"Reliable data transmission in TCP is achieved by re-transmission of lost data, which introduces latency," Adobe states in a FAQ on RTMFP. "Because minimizing end-to-end delay is one of the most important goals in real-time communications (a few hundred milliseconds' delay may render a conversation unusable), TCP is not well suited for this purpose."