_Sereal_ is an efficient, compact-output, binary and feature-rich
serialization protocol. The Perl encoder is implemented as the
Sereal::Encoder module, the Perl decoder correspondingly as
Sereal::Decoder. They are distributed separately to allow for safe
upgrading without downtime. (Hint: Upgrade the decoder everywhere first,
then the encoder.)

This 'Sereal' module is a very thin wrapper around both 'Sereal::Encoder'
and 'Sereal::Decoder'. It depends on both and loads both. So if you have a
user of both encoder and decoder, it is enough to depend on a particular
version of 'Sereal' and you'll get the most recent released versions of
'Sereal::Encoder' and 'Sereal::Decoder' whose version is smaller than or
equal to the version of 'Sereal' you depend on.

The protocol specification and many other bits of documentation can be
found in the github repository. Right now, the specification is at
https://github.com/Sereal/Sereal/blob/master/sereal_spec.pod, there is a
discussion of the design objectives in
https://github.com/Sereal/Sereal/blob/master/README.pod, and the output of
our benchmarks can be seen at
https://github.com/Sereal/Sereal/wiki/Sereal-Comparison-Graphs.