'\"
'\" Generated from file 'nns_protocol\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2007-2008 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>
'\"
.TH "nameserv::protocol" n 0\&.2 tcllib "Name service facility"
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.BS
.SH NAME
nameserv::protocol \- Name service facility, client/server protocol
.SH SYNOPSIS
\fBBind\fR \fIname\fR \fIdata\fR
.sp
\fBRelease\fR
.sp
\fBSearch\fR \fIpattern\fR
.sp
\fBProtocolVersion\fR
.sp
\fBProtocolFeatures\fR
.sp
\fBSearch/Continuous/Start\fR \fItag\fR \fIpattern\fR
.sp
\fBSearch/Continuous/Stop\fR \fItag\fR
.sp
\fBSearch/Continuous/Change\fR \fItag\fR \fBadd\fR|\fBremove\fR \fIresponse\fR
.sp
.BE
.SH DESCRIPTION
The packages \fBnameserv::server\fR, \fBnameserv\fR, and
\fBnameserv::common\fR provide a simple unprotected name service
facility for use in small trusted environments\&.
.PP
Please read \fIName service facility, introduction\fR first\&.
.PP
This document contains the specification of the network protocol which
is used by client and server to talk to each other, enabling
implementations of the same protocol in other languages\&.
.SH "NANO NAME SERVICE PROTOCOL VERSION 1"
This protocol defines the basic set of messages to be supported by a
name service, also called the \fICore\fR feature\&.
.SS "BASIC LAYER"
The basic communication between client and server is done using the
remote-execution protocol specified by the Tcl package \fBcomm\fR\&.
The relevant document specifying its on-the-wire protocol can be found
in \fIcomm_wire\fR\&.
.PP
All the scripts exchanged via this protocol are single commands in
list form and thus can be interpreted as plain messages instead of as
Tcl commands\&. The commands/messages specified in the next section are
the only commands understood by the server-side\&. Command and variable
substitutions are not allowed within the messages, i\&.e\&. arguments have
to be literal values\&.
.PP
The protocol is synchronous\&. I\&.e\&. for each message sent a response is
expected, and has to be generated\&. All messages are sent by the client\&.
The server does not sent messages, only responses to messages\&.
.SS "MESSAGE LAYER"
.TP
\fBBind\fR \fIname\fR \fIdata\fR
The client sends this message when it registers itself at the service
with a \fIname\fR and some associated \fIdata\fR\&. The server has to
send an error response if the \fIname\fR is already in use\&. Otherwise
the response has to be an empty string\&.
.sp
The server has to accept multiple names for the same client\&.
.TP
\fBRelease\fR
The client sends this message to unregister all names it is known
under at the service\&. The response has to be an empty string, always\&.
.TP
\fBSearch\fR \fIpattern\fR
The client sends this message to search the service for names matching
the glob-\fIpattern\fR\&. The response has to be a dictionary containing
the matching names as keys, and mapping them to the data associated
with it at \fBBind\fR-time\&.
.TP
\fBProtocolVersion\fR
The client sends this message to query the service for the highest
version of the name service protocol it supports\&. The response has to
be a positive integer number\&.
.sp
Servers supporting only \fINano Name Service Protocol Version 1\fR
have to return \fB1\fR\&.
.TP
\fBProtocolFeatures\fR
The client sends this message to query the service for the features of
the name service protocol it supports\&. The response has to be a
list containing feature names\&.
.sp
Servers supporting only \fINano Name Service Protocol Version 1\fR
have to return \fB{Core}\fR\&.
.PP
.SH "NANO NAME SERVICE PROTOCOL EXTENSION: CONTINUOUS SEARCH"
This protocol defines an extended set of messages to be supported by a
name service, also called the \fISearch/Continuous\fR feature\&. This
feature defines additional messages between client and server, and is
otherwise identical to version 1 of the protocol\&. See the last section
for the details of our foundation\&.
.PP
A service supporting this feature has to put the feature name
\fBSearch/Continuous\fR into the list of features returned by the
message \fIProtocolFeatures\fR\&.
.PP
For this extension the protocol is asynchronous\&. No direct response is
expected for any of the messages in the extension\&. Furthermore the
server will start sending messages on its own, instead of only
responses to messages, and the client has to be able to handle these
notifications\&.
.TP
\fBSearch/Continuous/Start\fR \fItag\fR \fIpattern\fR
The client sends this message to start searching the service for names
matching the glob-\fIpattern\fR\&.
In contrast to the regular \fISearch\fR request this one asks the
server to continuously monitor the database for the addition and
removal of matching entries and to notify the client of all such
changes\&. The particular search is identified by the \fItag\fR\&.
.sp
No direct response is expected, rather the clients expect to be
notified of changes via explicit \fISearch/Continuous/Result\fR
messages generated by the service\&.
.sp
It is further expected that the \fItag\fR information is passed
unchanged to the \fISearch/Continuous/Result\fR messages\&. This
tagging of the results enables clients to start multiple searches and
distinguish between the different results\&.
.TP
\fBSearch/Continuous/Stop\fR \fItag\fR
The client sends this message to stop the continuous search identified
by the \fItag\fR\&.
.TP
\fBSearch/Continuous/Change\fR \fItag\fR \fBadd\fR|\fBremove\fR \fIresponse\fR
This message is sent by the service to clients with active continuous
searches to transfer found changes\&. The first such message for a new
continuous search has to contains the current set of matching entries\&.
.sp
To ensure this a service has to generate an \fBadd\fR-message with
an empty \fIresponse\fR if there were no matching entries at the time\&.
.sp
The \fIresponse\fR has to be a dictionary containing the matching
names as keys, and mapping them to the data associated with it at
\fBBind\fR-time\&.
The argument coming before the response tells the client whether the
names in the response were added or removed from the service\&.
.PP
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fInameserv\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.PP
When proposing code changes, please provide \fIunified diffs\fR,
i\&.e the output of \fBdiff -u\fR\&.
.PP
Note further that \fIattachments\fR are strongly preferred over
inlined patches\&. Attachments can be made by going to the \fBEdit\fR
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar\&.
.SH "SEE ALSO"
comm_wire(n), nameserv(n), nameserv::server(n)
.SH KEYWORDS
comm, name service, protocol
.SH CATEGORY
Networking
.SH COPYRIGHT
.nf
Copyright (c) 2007-2008 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>

.fi
