SPDY Protocol

Definition - What does SPDY Protocol mean?

The SPDY (pronounced speedy) protocol is an open-source, Transmission Control Protocol (TCP)-based, application layer protocol that transports content over the Web. Developed as an experimental protocol by Google's Chromium group in 2009, SPDY is primarily geared toward reducing Web page latency.

Techopedia explains SPDY Protocol

The Chromium project was initiated to achieve higher transmission speeds by rendering a single connection per client to prioritize and multiplex the file transmission process. The SPDY protocol is made up of a session layer on top of a secure shell (SSL), which facilitates multiple concurrent and interleaved streams over a TCP connection. SPDY defines a new framing format for encoding and transmitting data over the wire.

SPDY protocol features include:

  • Server-initiated streams: SPDY facilitates content delivery to the client without a client request through an advanced server-initiated stream feature. Two different configuration options are available: Server push and server hint.
  • Multiplexed concurrent streams: SPDY facilitates unlimited concurrent streams across a single TCP connection.
  • Request prioritization: SPDY request priorities overcome clogging problems by assigning priority tags to each request, which allows unlimited client content requests.
  • Compression: SPDY compresses request and response HTTP headers, facilitating the transmission of fewer packets and bytes.

Google's Chrome browser uses SPDY while communicating with Google services, such as Gmail, Google Search, Chrome Sync and Google ads.

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