1nameserv::protocol(n) Name service facility nameserv::protocol(n)
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8 nameserv::protocol - Name service facility, client/server protocol
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11 Bind name data
12 Release
14 Search pattern
16 ProtocolVersion
18 ProtocolFeatures
20 Search/Continuous/Start tag pattern
22 Search/Continuous/Stop tag
24 Search/Continuous/Change tag add|remove response
26_________________________________________________________________
28
30 The packages nameserv::server, nameserv, and nameserv::common provide a
31 simple unprotected name service facility for use in small trusted envi‐
32 ronments.
33 Please read Name service facility, introduction first.
35 This document contains the specification of the network protocol which
37 is used by client and server to talk to each other, enabling implemen‐
38 tations of the same protocol in other languages.
39
41 This protocol defines the basic set of messages to be supported by a
42 name service, also called the Core feature.
43 BASIC LAYER
45 The basic communication between client and server is done using the
46 remote-execution protocol specified by the Tcl package comm. The rele‐
47 vant document specifying its on-the-wire protocol can be found in
48 comm_wire.
49 All the scripts exchanged via this protocol are single commands in list
51 form and thus can be interpreted as plain messages instead of as Tcl
52 commands. The commands/messages specified in the next section are the
53 only commands understood by the server-side. Command and variable sub‐
54 stitutions are not allowed within the messages, i.e. arguments have to
55 be literal values.
56 The protocol is synchronous. I.e. for each message sent a response is
58 expected, and has to be generated. All messages are sent by the client.
59 The server does not sent messages, only responses to messages.
60 MESSAGE LAYER
62 Bind name data
63 The client sends this message when it registers itself at the
64 service with a name and some associated data. The server has to
65 send an error response if the name is already in use. Otherwise
66 the response has to be an empty string.
67 The server has to accept multiple names for the same client.
69 Release
71 The client sends this message to unregister all names it is
72 known under at the service. The response has to be an empty
73 string, always.
74 Search pattern
76 The client sends this message to search the service for names
77 matching the glob-pattern. The response has to be a dictionary
78 containing the matching names as keys, and mapping them to the
79 data associated with it at Bind-time.
80 ProtocolVersion
82 The client sends this message to query the service for the high‐
83 est version of the name service protocol it supports. The
84 response has to be a positive integer number.
85 Servers supporting only Nano Name Service Protocol Version 1
87 have to return 1.
88 ProtocolFeatures
90 The client sends this message to query the service for the fea‐
91 tures of the name service protocol it supports. The response has
92 to be a list containing feature names.
93 Servers supporting only Nano Name Service Protocol Version 1
95 have to return {Core}.
96
98 This protocol defines an extended set of messages to be supported by a
99 name service, also called the Search/Continuous feature. This feature
100 defines additional messages between client and server, and is otherwise
101 identical to version 1 of the protocol. See the last section for the
102 details of our foundation.
103 A service supporting this feature has to put the feature name
105 Search/Continuous into the list of features returned by the message
106 ProtocolFeatures.
107 For this extension the protocol is asynchronous. No direct response is
109 expected for any of the messages in the extension. Furthermore the
110 server will start sending messages on its own, instead of only
111 responses to messages, and the client has to be able to handle these
112 notifications.
113 Search/Continuous/Start tag pattern
115 The client sends this message to start searching the service for
116 names matching the glob-pattern. In contrast to the regular
117 Search request this one asks the server to continuously monitor
118 the database for the addition and removal of matching entries
119 and to notify the client of all such changes. The particular
120 search is identified by the tag.
121 No direct response is expected, rather the clients expect to be
123 notified of changes via explicit Search/Continuous/Result mes‐
124 sages generated by the service.
125 It is further expected that the tag information is passed
127 unchanged to the Search/Continuous/Result messages. This tagging
128 of the results enables clients to start multiple searches and
129 distinguish between the different results.
130 Search/Continuous/Stop tag
132 The client sends this message to stop the continuous search
133 identified by the tag.
134 Search/Continuous/Change tag add|remove response
136 This message is sent by the service to clients with active con‐
137 tinuous searches to transfer found changes. The first such mes‐
138 sage for a new continuous search has to contains the current set
139 of matching entries.
140 To ensure this a service has to generate an add-message with an
142 empty response if there were no matching entries at the time.
143 The response has to be a dictionary containing the matching
145 names as keys, and mapping them to the data associated with it
146 at Bind-time. The argument coming before the response tells the
147 client whether the names in the response were added or removed
148 from the service.
149
151 This document, and the package it describes, will undoubtedly contain
152 bugs and other problems. Please report such in the category nameserv
153 of the Tcllib SF Trackers [http://source‐
154 forge.net/tracker/?group_id=12883]. Please also report any ideas for
155 enhancements you may have for either package and/or documentation.
156
158 comm_wire(n), nameserv(n), nameserv::server(n)
159
161 comm, name service, protocol
162
164 Copyright (c) 2007-2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>
165nns 0.1 nameserv::protocol(n)