Searching for Header Names using conversion to canonical form including integer value

摘要

Headers in some protocols (eg. SIP, HTTP) can include header names/header field names/methods that are case insensitive strings (Fig. 7 - 711,712,714-716) and which may also have abbreviated forms (713). Searching for all possible strings can be laborious. The invention proposes converting the strings into a canonical format (720,722) which reduces the string searching required. Mappings from received strings to canonical forms are built up by converting strings to lower case 305, searching with the lower case version 306 and then adding a map from the received string to a new 309/existing 308 canonical form. Once strings are in the map they can be used for direct look up of canonical forms 302-304. The canonical form includes an integer (eg. memory location or other index value) that may be used for further searching (Fig. 4 404).