rfc2229.txt

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       domain       =  msg-atom *("." msg-atom)

   Note that, in contrast to [RFC822], spaces and quoted pairs are not
   allowed in the msg-id.  This restriction makes the msg-id much easier
   for the client to locate and parse but does not significantly
   decrease any security benefits, since the msg-id may be arbitrarily
   long (as bounded by the response length limits set forth elsewhere in
   this document).

   Note also that the open and close brackets are part of the msg-id and
   should be included in the string that is used to compute the MD5
   checksum.

   This message id will be used by the client when formulating the
   authentication string used in the AUTH command.

   If the client's IP is not allowed to connect, then a code 530 is sent
   instead:

             530 Access denied

   Transient failure responses are also possible:

             420 Server temporarily unavailable
             421 Server shutting down at operator request



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   For example, response code 420 should be used if the server cannot
   currently fork a server process (or cannot currently obtain other
   resources required to proceed with a usable connection), but expects
   to be able to fork or obtain these resources in the near future.

   Response code 421 should be used when the server has been shut down
   at operator request, or when conditions indicate that the ability to
   service more requests in the near future will be impossible.  This
   may be used to allow a graceful operator-mediated temporary shutdown
   of a server, or to indicate that a well known server has been
   permanently removed from service (in which case, the text message
   might provide more information).

3.2.  The DEFINE Command

   DEFINE database word

3.2.1.  Description

   This command will look up the specified word in the specified
   database.  All DICT servers MUST implement this command.

   If the database name is specified with an exclamation point (decimal
   code 33, "!"), then all of the databases will be searched until a
   match is found, and all matches in that database will be displayed.
   If the database name is specified with a star (decimal code 42, "*"),
   then all of the matches in all available databases will be displayed.
   In both of these special cases, the databases will be searched in the
   same order as that printed by the "SHOW DB" command.

   If the word was not found, then status code 552 is sent.

   If the word was found, then status code 150 is sent, indicating that
   one or more definitions follow.

   For each definition, status code 151 is sent, followed by the textual
   body of the definition.  The first three space-delimited parameters
   following status code 151 give the word retrieved, the name of the
   database (which is the same as the first column of the SHOW DB
   command), and a short description for the database (which is the same
   as the second column of the SHOW DB command).  The short name is
   suitable for printing as:

             From name:

   before the definition is printed.  This provides source information
   for the user.




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   The textual body of each definition is terminated with a CRLF period
   CRLF sequence.

   After all of the definitions have been sent, status code 250 is sent.
   This command can provide optional timing information (which is server
   dependent and is not intended to be parsable by the client).  This
   additional information is useful when debugging and tuning the
   server.

3.2.2.  Responses

       550 Invalid database, use "SHOW DB" for list of databases
       552 No match
       150 n definitions retrieved - definitions follow
       151 word database name - text follows
       250 ok (optional timing information here)

   Response codes 150 and 151 require special parameters as part of
   their text.  The client can use these parameters to display
   information on the user's terminal.

   For code 150, parameters 1 indicates the number of definitions
   retrieved.

   For code 151, parameter 1 is the word retrieved, parameter 2 is the
   database name (the first name as shown by "SHOW DB") from which the
   definition has been retrieved, and parameter 3 is the the short
   database description (the second column of the "SHOW DB" command).

3.3.  The MATCH Command

   MATCH database strategy word

3.3.1.  Description

   This command searches an index for the dictionary, and reports words
   which were found using a particular strategy.  Not all strategies are
   useful for all dictionaries, and some dictionaries may support
   additional search strategies (e.g., reverse lookup).  All DICT
   servers MUST implement the MATCH command, and MUST support the
   "exact" and "prefix" strategies.  These are easy to implement and are
   generally the most useful.  Other strategies are server dependent.

   The "exact" strategy matches a word exactly, although different
   servers may treat non-alphanumeric data differently.  We have found
   that a case-insensitive comparison which ignores non-alphanumeric





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   characters and which folds whitespace is useful for English-language
   dictionaries.  Other comparisons may be more appropriate for other
   languages or when using extended character sets.

   The "prefix" strategy is similar to "exact", except that it only
   compares the first part of the word.

   Different servers may implement these algorithms differently.  The
   requirement is that strategies with the names "exact" and "prefix"
   exist so that a simple client can use them.

   Other strategies that might be considered by a server implementor are
   matches based on substring, suffix, regular expressions, soundex
   [KNUTH73], and Levenshtein [PZ85] algorithms.  These last two are
   especially useful for correcting spelling errors.  Other useful
   strategies perform some sort of "reverse" lookup (i.e., by searching
   definitions to find the word that the query suggests).

   If the database name is specified with an exclamation point (decimal
   code 33, "!"), then all of the databases will be searched until a
   match is found, and all matches in that database will be displayed.
   If the database name is specified with a star (decimal code 42, "*"),
   then all of the matches in all available databases will be displayed.
   In both of these special cases, the databases will be searched in the
   same order as that printed by the "SHOW DB" command.

   If the strategy is specified using a period (decimal code 46, "."),
   then the word will be matched using a server-dependent default
   strategy, which should be the best strategy available for interactive
   spell checking.  This is usually a derivative of the Levenshtein
   algorithm [PZ85].

   If no matches are found in any of the searched databases, then status
   code 552 will be returned.

   Otherwise, status code 152 will be returned followed by a list of
   matched words, one per line, in the form:

             database word

   This makes the responses directly useful in a DEFINE command.

   The textual body of the match list is terminated with a CRLF period
   CRLF sequence.

   Following the list, status code 250 is sent, which may include
   server-specific timing and statistical information, as discussed in
   the section on the DEFINE command.



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3.3.2.  Responses

        550 Invalid database, use "SHOW DB" for list of databases
        551 Invalid strategy, use "SHOW STRAT" for a list of strategies
        552 No match
        152 n matches found - text follows
        250 ok (optional timing information here)

   Response code 152 requires a special parameter as part of its text.
   Parameter 1 must be the number of matches retrieved.

3.4.  A Note on Virtual Databases

   The ability to search all of the provided databases using a single
   command is given using the special "*" and "!" databases.

   However, sometimes, a client may want to search over some but not all
   of the databases that a particular server provides.  One alternative
   is for the client to use the SHOW DB command to obtain a list of
   databases and descriptions, and then (perhaps with the help of a
   human), select a subset of these databases for an interactive search.
   Once this selection has been done once, the results can be saved, for
   example, in a client configuration file.

   Another alternative is for the server to provide "virtual" databases
   which merge several of the regular databases into one.  For example,
   a virtual database may be provided which includes all of the
   translating dictionaries, but which does not include regular
   dictionaries or thesauri.  The special "*" and "!" databases can be
   considered as names of virtual databases which provide access to all
   of the databases.  If a server implements virtual databases, then the
   special "*" and "!" databases should probably exclude other virtual
   databases (since they merely provide information duplicated in other
   databases).  If virtual databases are supported, they should be
   listed as a regular database with the SHOW DB command (although,
   since "*" and "!" are required, they need not be listed).

   Virtual databases are an implementation-specific detail which has
   absolutely no impact on the DICT protocol.  The DICT protocol views
   virtual and non-virtual databases the same way.

   We mention virtual databases here, however, because they solve a
   problem of database selection which could also have been solved by
   changes in the protocol.  For example, each dictionary could be
   assigned attributes, and the protocol could be extended to specify
   searches over databases with certain attributes.  However, this
   needlessly complicates the parsing and analysis that must be
   performed by the implementation.  Further, unless the classification



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   system is extremely general, there is a risk that it would restrict
   the types of databases that can be used with the DICT protocol
   (although the protocol has been designed with human-language
   databases in mind, it is applicable to any read-only database
   application, especially those with a single semi-unique alphanumeric
   key and textual data).

3.5.  The SHOW Command

3.5.1.  SHOW DB

   SHOW DB
   SHOW DATABASES

3.5.1.1.  Description

   Displays the list of currently accessible databases, one per line, in
   the form:

             database description

   The textual body of the database list is terminated with a CRLF
   period CRLF sequence.  All DICT servers MUST implement this command.

   Note that some databases may be restricted due to client domain or
   lack of user authentication (see the AUTH and SASLAUTH commands in
   sections 3.11 and 3.12).  Information about these databases is not
   available until authentication is performed.  Until that time, the
   client will interact with the server as if the additional databases
   did not exist.

3.5.1.2.  Responses

             110 n databases present - text follows
             554 No databases present

        Response code 110 requires a special parameter.  Parameter 1
        must be the number of databases available to the user.

3.5.2.  SHOW STRAT

   SHOW STRAT
   SHOW STRATEGIES








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3.5.2.1.  Description

   Displays the list of currently supported search strategies, one per
   line, in the form:

             strategy description

   The textual body of the strategy list is terminated with a CRLF
   period CRLF sequence.  All DICT servers MUST implement this command.

3.5.2.2.  Responses

             111 n strategies available - text follows
             555 No strategies available

   Response code 111 requires a special parameter.  Parameter 1 must be
   the number of strategies available.

3.5.3.  SHOW INFO

   SHOW INFO database

3.5.3.1.  Description

   Displays the source, copyright, and licensing information about the
   specified database.  The information is free-form text and is
   suitable for display to the user in the same manner as a definition.
   The textual body of the information is terminated with a CRLF period
   CRLF sequence.  All DICT servers MUST implement this command.

3.5.3.2.  Responses

             550 Invalid database, use "SHOW DB" for list of databases
             112 database information follows

   These response codes require no special parameters.

3.5.4.  SHOW SERVER

   SHOW SERVER

3.5.4.1.  Description

   Displays local server information written by the local administrator.
   This could include information about local databases or strategies,
   or administrative information such as who to contact for access to
   databases requiring authentication.  All DICT servers MUST implement
   this command.



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3.5.4.2.  Responses

             114 server information follows

   This response code requires no special parameters.

3.6.  The CLIENT Command

   CLIENT text

3.6.1.  Description

   This command allows the client to provide information about itself
   for possible logging and statistical purposes.  All clients SHOULD
   send this command after connecting to the server.  All DICT servers
   MUST implement this command (note, though, that the server doesn't
   have to do anything with the information provided by the client).

3.6.2.  Responses

             250 ok (optional timing information here)

   This response code requires no special parameters.

3.7.  The STATUS Command

   STATUS

3.7.1.  Description

   Display some server-specific timing or debugging information.  This
   information may be useful in debugging or tuning a DICT server.  All
   DICT servers MUST implement this command (note, though, that the text
   part of the response is not specified and may be omitted).

3.7.2.  Responses

             210 (optional timing and statistical information here)

   This response code requires no special parameters.

3.8.  The HELP Command

   HELP







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