Heading:qjk40(635)\g
LookupFile Protocoly756qk40\g
Page Numbers: Yes  X: 527  Y: 10.5"qjk40\g
Inter-Office Memorandumz18592l4445y762\f5bg
To	Communication Protocols	Date	September 10, 1982
z18592l4445d2998e21(0,65535)(1,4445)(5,11684)(6,13300)\f1g2f0t2 1t0 23t6 1f1t0 4f0t7 1t0
From	Ed Taft	Location	PARC/CSL
z18592l4445d2998e25\f1g4f0t2 1t0 7t6 1f1t0 8f0t7 1t0
Subject	LookupFile Protocol	File	[Maxc]<Pup>LookupFile.bravo
z21167l4445d2998e25\f1g7f0t2 1t0 19t6 1f1t0 4t7 1t0 27f0
XEROX       z18592l508e14(2116)\f2g5f0
Attributes:	informal, technical, communication, filingz18697l4896d2999e10(0,4904)(1,65535)(5,65535)(6,65535)\f1g
Abstract:	The existence of a file, along with its create date and length hint, may be determined by a single exchange of packets with a LookupFile server.z18697l4896d2999e10j\f1g
z18697e10j(1270)\g
The existence of a file, along with its create date and length hint, may be determined by a single exchange of packets with the LookupFile server.  This is intended to provide a means of file validation much cheaper than either FTP or Leaf.  Its principal intended application is the CIFS file cache manager in Cedar.z18697e10jk40\g
The server resides on socket 61B of any file server that offers this service.  The client initiates the exchange with:z18697e10jk40\g31f1 1f0
LookupFileRequest:z18697l4269e10jk60\g
Pup type: 200Bz18697l5408d4833e4j\ig9I4f1 1f0
Pup ID: chosen by clientz18697l5408d4833e4j\ig7I
Pup contents: a text string identifying the filez18697l5408d4833e4j\ig13I
If the server is not offering this service, it responds with an Error Pup with sub-type 2, no such port''.  Otherwise, it responds with one of:z18697e10jk40\g
LookupFileReply:z18697l4269e10jk60\g
Pup type: 201Bz18697l5408d4833e4j\ig9I4f1 1f0
Pup ID: same as LookupFileRequest Pupz18697l5408d4833e4j\ig7I
Pup contents: 3 words, as follows:z18697l5408d4833e4j\ig13I
file version number (1 word)z18697l5397e4j\g
file create date, in standard Alto packed format (2 words, high-order word firstnote that this is the reverse of the word order for a Mesa LONG CARDINAL)z18697l5397e4j\g140f1 13f0
file length in 8-bit bytes (2 words, high-order word first)note that this is only a hint, and doesn't include the leader page.z18697l5397e4j\g
LookupFileError:z18697l4269e10jk60\g
Pup type: 202Bz18697l5408d4833e4j\ig9I4f1 1f0
Pup ID: same as LookupFileRequest Pupz18697l5408d4833e4j\ig7I
Pup contents: 1-word error code whose interpretation is server-dependentz18697l5408d4833e4j\ig13I
It is the client's responsibility to choose Pup IDs in such a way that it can correctly match responses with requests.z18697e10jk40\g
This protocol is currently implemented by IFS file servers running version 1.36.4 or newer of the IFS software.z18697e10jk40\g
The IFS implementation requires that the LookupFileRequest contain a complete IFS filename in the form <directory>subdirectories>..>name!version'', except that the version may be one of the special version designators (!H'' or !L''), or may be omitted altogether in which case "!H" is assumed.  Patterns containing *'' are not permitted.z18697e10jk40\g
The error codes returned by IFS LookupFile servers are IFS internal error codes, whose interpretation may be found in file <System>IFS.errors on that server.z18697e10jk40\g