NAME

DDC::Client - Client socket object and utilities for DDC::Concordance

SYNOPSIS

 use DDC::Client;

 ##---------------------------------------------------------------------
 ## Constructors, etc.

 $dc = DDC::Client->new( url=>"inet://localhost:50000" );

 ##---------------------------------------------------------------------
 ## Common Requests

 $rsp     = $dc->request($request);           ##-- generic request
 $rsp     = $dc->requestNC($request);         ##-- generic request, no close()
 $data    = $dc->requestJson($request);       ##-- generic JSON request

 $version = $dc->version();                   ##-- get server version string
 $status  = $dc->status();                    ##-- get server status HASH-ref
 $vstatus = $dc->vstatus();                   ##-- get verbose status HASH-ref
 $info    = $dc->info();                      ##-- get server info HASH-ref

 $rsp     = $dc->expand_terms(\@pipeline, \@terms);  ##-- raw term expansion
 @terms   = $dc->expand(\@pipeline, \@terms);        ##-- parsed term expansion

 $hits    = $dc->query($query_string);        ##-- fetch and parse hits
 $hits    = $dc->queryJson($query_string);    ##-- fetch and parse JSON-formatted hits
 $buf     = $dc->queryRaw($query_string);     ##-- fetch raw query result buffer
 $buf     = $dc->queryRawNC($query_string);   ##-- fetch raw query result, no close()
 @bufs    = $dc->queryMulti(@query_strings);  ##-- fetch multiple request results without intervening close()

 $rsp     = $dc->get_first_hits($query);      ##-- low-level request
 $rsp     = $dc->get_hit_strings();           ##-- low-level request
 $rsp     = $dc->run_query($corpus,$query);   ##-- low-level request

 ##---------------------------------------------------------------------
 ## Low-level Communications

 $connect = $dc->parseAddr();       ##-- parse connection parameters
 $urlstr  = $dc->addrStr();         ##-- get connection parameter string

 $io_socket = $dc->open();          ##-- open the connection
 undef      = $dc->close();         ##-- close the connection

 $dc->send(@command);               ##-- send a command (prepends size)
 $dc->sendfh($fh,@command);         ##-- ... to specified filehandle

 $size = $dc->readSize();           ##-- get size of return message from client socket
 $size = $dc->readSize($fh);        ##-- ... or from a given filehandle

 $buf  = $dc->readBytes($size);     ##-- read a sized return buffer from client socket
 $buf  = $dc->readBytes($size,$fh); ##-- ... or from a given filehandle

 $buf  = $dc->readData();           ##-- same as $dc->readBytes($dc->readSize())
 $buf  = $dc->readData($fh);        ##-- ... same as $dc->readBytes($dc->readSize($fh),$fh)

 $hits = $dc->parseData($buf);      ##-- parse a return buffer
 $hits = $dc->parseJsonData($buf);  ##-- parse a return buffer in 'json' mode
 $hits = $dc->parseTextData($buf);  ##-- parse a return buffer in 'text' mode
 $hits = $dc->parseTableData($buf); ##-- parse a return buffer in 'table' mode
 $hits = $dc->parseHtmlData($buf);  ##-- parse a return buffer in 'html' mode

 @terms = $dc->parseExpandTermsResponse($buf);  ##-- parse an expand_terms response buffer

DESCRIPTION

Globals

Variable: $ifmt

pack()-format to use for integer sizes passed to and from a DDC server. The default value ('V') should be right for ddc-2.x (always 32-bit unsigned little endian). For ddc-1.x, the machine word size and endian-ness should match the those native to the machine running the DDC server.

Variable: $ilen

Length of message size integer used for DDC protocol in bytes. If you change $ifmt, you should make sure to change $ilen appropriately, e.g. by setting:

 $ilen = length(pack($ifmt,0));
Variable: $JSON_BACKEND

Name of module to use for JSON response decoding via decodeJson(), defaults to JSON. Set this to JSON::PP or set the environment variable PERL_JSON_BACKEND=JSON::PP if you are using multiple DDC clients via the threads module.

Constructors etc

new
 $dc = $CLASS_OR_OBJ->new(%args);
accepted %args are keys of %$dc:
 (
  ##-- connection options
  connect  =>\%connectArgs,   ##-- passed to IO::Socket::(INET|UNIX)->new(), depending on $connectArgs{Domain}
                              ##   + you can also specify connect=>{url=>$url} or connect=>$url ; see parseAddr() method
  mode     =>$mode,           ##-- query mode; one of qw(json table text html raw); default='json'
  linger   =>\@linger,        ##-- SO_LINGER socket option (default=[1,0]: immediate termination)
 
  ##-- query options (formerly only in DDC::Client::Distributed)
  start    =>$start,          ##-- index of first hit to fetch (default=0)
  limit    =>$limit,          ##-- maximum number of hits to fetch (default=10)
  timeout  =>$secs,           ##-- query timeout in seconds (lower bound, default=60)
 
  ##-- hit parsing options (mostly obsolete)
  optFile  =>$filename,       ##-- parse meta names, separators from DDC *.opt file
  parseMeta=>$bool,           ##-- if true, hit metadata will be parsed to $hit->{_meta} (default=1)
  parseContext=>$bool,        ##-- if true, hit context data will be parsed to $hit->{_ctx} (default=1)
  keepRaw  =>$bool,           ##-- if false, raw context buffer $hit->{_raw} will be deleted after parsing context data (default=false)
  encoding =>$enc,            ##-- DDC server encoding (default='UTF-8')
  fieldSeparator => $str,     ##-- intra-token field separator (default="\x{1f}": ASCII unit separator); 'text' and 'table' modes only
  tokenSeparator => $str,     ##-- inter-token separator       (default="\x{1e}": ASCII record separator); 'text' and 'table' modes only
  metaNames      => \@names,  ##-- metadata names for 'text' and 'html' modes; default=none
 
  textHighlight => [$l0,$r0,$l1,$r1],  ##-- highlighting strings, text mode (default=[qw(&& && _& &_)])
  htmlHighlight => [$l0,$r0,$l1,$r1],  ##-- highlighting strings, html mode (default=[('<STRONG><FONT COLOR=red>','</FONT></STRONG>') x 2])
  tableHighlight => [$l0,$r0,$l1,$r1], ##-- highlighting strings, table mode (default=[qw(&& && _& &_)])
 )
default \%connectArgs:
 Domain=>'INET',              ##-- also accepts 'UNIX'
 PeerAddr=>'localhost',
 PeerPort=>50000,
 Proto=>'tcp',
 Type=>SOCK_STREAM,
 Blocking=>1,
Examples
  #-- connect to an INET socket on C<$HOST:$PORT>:
  $dc = DDC::Client->new(connect=>{Domain=>'INET',PeerAddr=>$HOST,PeerPort=>$Port});
  #
  # ... syntactic sugar:
  $dc = DDC::Client->new(connect=>{url=>"inet://$HOST:$PORT"})
  $dc = DDC::Client->new(connect=>"inet://$HOST:$PORT")
  $dc = DDC::Client->new(connect=>"$HOST:$PORT")

  #-- connect to an INET socket on localhost port C<$PORT>, setting socket timeout $TIMEOUT
  $dc = DDC::Client->new(connect=>{PeerPort=>$PORT,Timeout=>$TIMEOUT});
  $dc = DDC::Client->new(connect=>":$PORT?Timeout=$TIMEOUT")

  #-- connect to a UNIX socket at C<$SOCKPATH> on the local host:
  $dc = DDC::Client->new(connect=>{Domain=>'UNIX',Peer=>$SOCKPATH});
  #
  # ... syntactic sugar:
  $dc = DDC::Client->new(connect=>{url=>"unix://$SOCKPATH"})
  $dc = DDC::Client->new(connect=>"unix://$SOCKPATH")

Querying

queryRaw
 $buf = $dc->queryRaw($query_string);

Send a query string to the selected server and returns the raw result buffer. Implicitly close()s the connection.

queryRawNC
 $buf = $dc->queryRawNC($query_string);

Send a query string to the selected server and returns the raw result buffer. No implicit close().

queryMulti
 @bufs = $dc->queryMulti(@query_strings);

Sends a series of query strings or requests to the server, and returns a list of raw result buffers. Implicitly close()s the client after all requests have been sent, but not between individual requests.

query
 $hits = $dc->query($query_string);

Send a query string to the selected server and parses the result into a list of hits.

get_first_hits
 $buf = $dc->get_first_hits($query,$timeout?,$limit?,$hint?);

Requests IDs of the first $limit hit(s) for query $query, using optional navigation hint $hint, and returns the raw DDC response buffer. The optional parameters default to the %$dc keys of the same name.

get_hit_strings
 $buf = $dc->get_hit_strings($format?,$start?,$limit?)

Requests the full strings for up to $limit hits beginning at logical offset $start formatted as $format. $format defaults to $dc->{mode}, and the remaining optional parameters default to the %$dc keys of the same name.

run_query
 $buf = $dc->run_query($corpus,$query,$format?,$start?,$limit?,$timeout?,$hint?)

Requests a complete query evaluation of up to $limit hit(s) beginning at offset $start for query $query, formatted as $format with server-side timeout lower bound $timeout and optional navigation hint $hint. If $corpus is specified as undef, it defaults to the string "Distributed". Optional parameters default to the %$dc keys of the same name. Note that this method returns the raw DDC response; see the query() method for a more comfortable alternative.

Common Requests

request
 $rsp = $dc->request($request_string);

Send a raw DDC request and return the server's response as a raw byte-string.

requestJson
 $data = $dc->requestJson($request_string);

Send a raw DDC request and decode the server's response as JSON data.

version
 $server_version = $dc->version();

Request the current running version of the selected server, wraps $dc->request("version").

status
 $status = $dc->status();
 $status = $dc->status($timeout);

Get basic server status; wraps $dc->requestJson("status $timeout").

vstatus
 $vstatus = $dc->vstatus();
 $vstatus = $dc->vstatus($timeout);

Get verbose server status; wraps $dc->requestJson("vstatus $timeout").

info
 $info = $dc->info();
 $info = $dc->info($timeout);

Get verbose server information; wraps $dc->requestJson("info $timeout").

expand_terms
 $expandRaw = $dc->expand_terms($pipeline, $term);
 $expandRaw = $dc->expand_terms($pipeline, $term, $timeout);
 $expandRaw = $dc->expand_terms($pipeline, $term, $timeout, $subcorpus);

Perform server-side term-expansion for the term $term via pipeline $pipeline. Both $term and $pipeline may be specified as ARRAY-refs or bare strings. Returns the raw response data string.

expand
 @terms = $dc->expand($pipeline, $term);
 @terms = $dc->expand($pipeline, $term, $timeout);
 @terms = $dc->expand($pipeline, $term, $timeout, $subcorpus);

Perform server-side term-expansion for the term $term via pipeline $pipeline and parses the response with parseExpandTermsResponse. Returns an array @terms of server expansions in list-context; in scalar context returns the reference \@terms to such an array.

query
 $hits = $dc->query($query_string);

Send a query string to the selected server and parses the result into a DDC::HitList object.

queryRaw
 $buf = $dc->queryRaw($query_string);
 $buf = $dc->queryRaw(\@raw_strings);

Send a query string to the selected server and returns the raw result buffer. The second form is equivalent to

 $dc->queryRaw(join("\x01",@raw_strings));

Implicitly close()s the connection.

queryRawNC
 $buf = $dc->queryRawNC($query_string);

Send a query string to the selected server and returns the raw result buffer. No implicit close().

queryMulti
 @bufs = $dc->queryMulti(@query_strings);

Sends a series of query strings or requests to the server, and returns a list of raw result buffers. Implicitly close()s the client after all requests have been sent, but not between individual requests.

Low-level Communications

parseAddr
 \%connect = $dc->parseAddr()
 \%connect = $CLASS_OR_OBJECT->parseAddr(\%connect,    $PEER_OR_LOCAL, %options)
 \%connect = $CLASS_OR_OBJECT->parserAddr({url=>$url}, $PEER_OR_LOCAL, %options)
 \%connect = $CLASS_OR_OBJECT->parserAddr($url,        $PEER_OR_LOCAL, %options)

Parses connect options into a form suitable for use as parameters to IO::Socket::INET::new() rsp. IO::Socket::UNIX::new(). Sets $connect{Domain} to either INET or UNIX. If called as an object method, operates directly on (and updates) $dc->{connect}.

Honors bare URL-style strings $url of the form:

 inet://ADDR:PORT?OPT=VAL...   # canonical INET socket URL format
 unix://UNIX_PATH?OPT=VAL...   # canonical UNIX socket URL format
 unix:UNIX_PATH?OPT=VAL...     # = unix://UNIX_PATH?OPT=val
 ADDR?OPT=VAL...               # = inet://ADDR:5000?OPT=VAL...
 :PORT?OPT=VAL...              # = inet://localhost:PORT?OPT=VAL...
 ADDR:PORT?OPT=VAL...          # = inet://ADDR:PORT?OPT=VAL...
 /UNIX_PATH?OPT=VAL...         # = unix:///UNIX_PATH?POT=VAL...
addrStr
 $urlstr = $dc->addrStr();
 $urlstr = $CLASS_OR_OBJECT->addrStr(\%connect, $PEER_OR_LOCAL);
 $urlstr = $CLASS_OR_OBJECT->addrStr($url,  $PEER_OR_LOCAL);
 $urlstr = $CLASS_OR_OBJECT->addrStr($sock, $PEER_OR_LOCAL);

Formats specified socket connection parameters (by default those of the calling object if called as an object method) as a URL-style string.

open
 $io_socket = $dc->open();

Open the underlying INET- or UNIX-domain socket; returns undef on failure. Most users will never need to call this method, since it will be called implicitly by higher-level methods such as requiest(), query(), status() if required.

close
 undef = $dc->close();

Closes the underlying socket if currently open. Most users will never need to call this method, since it will be called implicitly by higher-level methods such as requiest(), query(), status() if required.

send
 undef = $dc->send(@message_strings);
  • Sends @message_strings to the underlying socket as a single message.

sendfh
 undef = $dc->sendfh($fh,@message_strings);
  • Sends @message_strings to filehandle $fh, prepending total length.

readSize
 $size = $dc->readSize();
 $size = $dc->readSize($fh)

Reads message size from $fh (default=underlying socket).

readBytes
 $data = $dc->readBytes($nbytes);
 $data = $dc->readBytes($nbytes,$fh)

Reads fixed number of bytes from $fh (default=underlying socket).

readData
 $data = $dc->readData();
 $data = $dc->readData($fh)

Reads pending data from $fh (default=underlying socket); calls readSize() and readBytes().

Hit Parsing

parseTableData
parseTextData
parseJsonData
 \@hits = $dc->parseTableData($buf);
 \@hits = $dc->parseTextData($buf);
 \@hits = $dc->parseJsonData($buf);

Parses raw DDC data buffer in $buf. Returns an array-ref of DDC::Hit objects representing the individual hits.

JSON parsing requires the JSON module.

parseExpandTermsResponse
 \@terms = $dc->parseExpandTermsResponse($buf);
  @terms = $dc->parseExpandTermsResponse($buf);

Parses a DDC server expand_terms response buffer. Returns an array @terms of server expansions in list-context; in scalar context returns the reference \@terms to such an array.

AUTHOR

Bryan Jurish <moocow@cpan.org>

COPYRIGHT AND LICENSE

Copyright (C) 2006-2020 by Bryan Jurish

This package is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.24.1 or, at your option, any later version of Perl 5 you may have available.