HPack

A pure Julia implementation for HPACK specification, header compression for HTTP/2. This library is intended to be used with a HTTP/2 implementation.

Note: JuliaWeb/HTTP.jl includes a work-in-progress HPack decoder for Julia 1.0: https://github.com/JuliaWeb/HTTP.jl/blob/so/lazyprep/src/HPack.jl

Quickstart

The main functionality of HPack are in the encode and decode function. HPack is stateful, and requires a dynamic table. The table can be created by new_dynamic_table.

First, install HPack:

julia> Pkg.add("HPack")
julia> using HPack

new_dynamic_table

The function takes no argument, and returns a dynamic table.

HPack.new_dynamic_table()
# => DynamicTable

encode

The encode function is defined as encode(table::DynamicTable, headers::Headers; huffman=false). The headers are a type imported from HttpCommon.jl library. The huffman key specifies whether it will use Huffman algorithm to compress header values. It can be used as follows:

headers = Headers("custom-key" => "custom-header")

HPack.encode(HPack.new_dynamic_table(), headers; huffman=false)
# => [0x00; 0x0a; 0x63; 0x75; 0x73; 0x74; 0x6f; 0x6d; 0x2d; 0x6b; 0x65; 0x79;
#     0x0d; 0x63; 0x75; 0x73; 0x74; 0x6f; 0x6d; 0x2d; 0x68; 0x65; 0x61; 0x64;
#     0x65; 0x72]

decode

The decode function is defined as decode(table::DynamicTable, buf::IOBuffer). Again, the headers are a type imported from HttpCommon.jl. buf needs to be an IOBuffer. It will handle any valid HPack messages.

headers_raw =
    [0x04; 0x0c; 0x2f; 0x73; 0x61; 0x6d; 0x70; 0x6c; 0x65; 0x2f; 0x70; 0x61;
     0x74; 0x68]

HPack.decode(HPack.new_dynamic_table(), IOBuffer(headers_raw))
# => Headers(":path" => "/sample/path")