Skip to content


The Athena::Negotiation component allows an application to support content negotiation. The component has no dependencies and is framework agnostic; supporting various negotiators.


First, install the component by adding the following to your shard.yml, then running shards install:

    github: athena-framework/negotiation
    version: ~> 0.1.0


The main type of Athena::Negotiation is ANG::AbstractNegotiator which is used to implement negotiators for each Accept* header. Athena::Negotiation exposes class level getters for each negotiator; that return a lazily initialized singleton instance. Each negotiator exposes two methods: ANG::AbstractNegotiator#best and ANG::AbstractNegotiator#ordered_elements.

Media Type#

negotiator = ANG.negotiator

accept_header = "text/html, application/xhtml+xml, application/xml;q=0.9"
priorities = ["text/html; charset=UTF-8", "application/json", "application/xml;q=0.5"]

accept =, priorities).not_nil!

accept.media_range # => "text/html"
accept.parameters  # => {"charset" => "UTF-8"}

The ANG::Negotiator type returns an ANG::Accept, or nil if negotiating the best media type has failed.

Character Set#

negotiator = ANG.charset_negotiator

accept_header = "ISO-8859-1, UTF-8; q=0.9"
priorities = ["iso-8859-1;q=0.3", "utf-8;q=0.9", "utf-16;q=1.0"]

accept =, priorities).not_nil!

accept.charset # => "utf-8"
accept.quality # => 0.9

The ANG::CharsetNegotiator type returns an ANG::AcceptCharset, or nil if negotiating the best character set has failed.


negotiator = ANG.encoding_negotiator

accept_header = "gzip;q=1.0, identity; q=0.5, *;q=0"
priorities = ["gzip", "foo"]

accept =, priorities).not_nil!

accept.coding # => "gzip"

The ANG::EncodingNegotiator type returns an ANG::AcceptEncoding, or nil if negotiating the best encoding has failed.


negotiator = ANG.language_negotiator

accept_header = "en; q=0.1, fr; q=0.4, zh-Hans-CN; q=0.9, de; q=0.2"
priorities = ["de", "zh-Hans-CN", "en"]

accept =, priorities).not_nil!

accept.language # => "zh"
accept.region   # => "cn"
accept.script   # => "hans"

The ANG::LanguageNegotiator type returns an ANG::AcceptLanguage, or nil if negotiating the best language has failed.