skk-server-protocol.md

SKK server-client protocol for dbskkd-cdb (unofficial)

By Kenji Rikitake, last updated 13-NOV-2016

Notes

• This document is for dbskkd-cdb only
• This document does not describe the sub-protocols for the server completion,which is unsupported on dbskkd-cdb

Notation

• 0 is an ASCII letter (0x30)
• LF is ASCII 0x0a
• space is ASCII 0x20
• abc is a string

Size limits

• Maximum request size: 1024 bytes
• Maximum result size: 4096 bytes

Request codes and actions

CLIENT_END

• Request to server: 0 + space + LF
• Server terminates and disconnects after receiving the request

CLIENT_REQUEST

• Request to server: 1 + dictionary_key + space + LF
• Answer if found: 1 + (/ + candidate) * (number of candidates) + / + LF
• Answer if not found: 4 + dictionary_key + space + LF
• The dictionary keys and candidates are all variable-length strings
• The dictionary keys and candidates have the same character encoding
• The primary encoding set of SKK is ASCII + euc-jp (note: UTF-8 can also be used in some implementations)

CLIENT_VERSION

• Request to server: 2 + space + LF
• Answer: string including server version + space, e.g., dbskkd-cdb-2.00
• Note: no known client parses this string
• Implementation on dbskkd-cdb: returns the version string

CLIENT_HOST

• Request to server: 3 + space + LF
• Answer: string including host information + space, e.g., localhost:127.0.0.1:
• Note: no known client parses this string
• Implementation on dbskkd-cdb: returns dummy string novalue:

Unexpected shutting down on errors

• Server disconnects the link and shuts down when received an unknown request
• Implementation on dbskkd-cdb: an internal error will cause shutdown such as that invoked by exit(1)