The complaint is about how the compression is implemented- Header compression is a good feature with real world applications, and deflate with persistent

The complaint is about how the compression is implemented- Header compression is a good feature with real world applications, and deflate with persistent context is a good approach to achieve it. A fixed dictionary is probably not very effective as it complicates the implementation while only providing initial value to the compression. As an example, this is how the average requests sizes compares between HTTP and SPDY in different modes, using the set of captured headers used to train the current SPDY 3 dictionary. HTTP 821.1 HTTP zlib compressed 543.5 HTTP compressed with dictionary 497.0 SPDY 913.7 SPDY zlib compressed 606.5 SPDY compressed with dictionary 517.0 I.e. Just putting the HTTP request in a SPDY stream (after removing disallowed headers) only differs by 20 bytes to SPDY binary header format with dictionary based zlib compression. The benefit of using a dictionary basically goes away entirely on the subsequent request.