##
##
+## $Log: SimpleServer.pm,v $
+## Revision 1.18 2003-09-09 20:12:38 mike
+## Return diagnostics on Init failure
+##
+## Revision 1.17 2003/09/09 11:40:10 mike
+## (Finally!) support implementation-ID
+##
+## Revision 1.16 2003/01/03 09:01:51 sondberg
+## Version 0.07.
+##
+## Revision 1.15 2002/09/16 14:00:16 sondberg
+## Updated Changes and added a few lines of documentation.
+##
+## Revision 1.14 2002/03/06 11:30:02 mike
+## Add RPN structure documentation to SimpleServer.pm's POD.
+## Add README to MANIFEST.
+##
+## Revision 1.13 2002/03/06 11:02:04 mike
+## Added simple README file, derived from POD comments in SimpleServer.pm
+## Fixed my (Mike Taylor's) email address
+##
+## Revision 1.12 2002/03/05 20:52:22 sondberg
+## Version 0.05 so that we can release the thing at CPAN.
+##
+## Revision 1.11 2002/03/05 20:49:56 sondberg
+## Added a couple of lines of documentation.
+##
+## Revision 1.10 2002/02/28 11:21:57 mike
+## Add RPN structure to search-handler argument hash.
+##
+## Revision 1.9 2001/08/29 11:48:36 sondberg
+## Added routines
+##
+## Net::Z3950::SimpleServer::ScanSuccess
+## Net::Z3950::SimpleServer::ScanPartial
+##
+## and a bit of documentation.
+##
+## Revision 1.8 2001/08/29 10:29:51 sondberg
+## Added some documentation of scan.
+##
+## Revision 1.7 2001/08/24 14:00:20 sondberg
+## Added support for scan.
+##
+## Revision 1.6 2001/03/13 14:17:15 sondberg
+## Added support for GRS-1.
+##
+
package Net::Z3950::SimpleServer;
use strict;
@EXPORT = qw(
);
-$VERSION = '0.02';
+$VERSION = '0.08';
bootstrap Net::Z3950::SimpleServer $VERSION;
sub new {
my $class = shift;
- my $args = shift || croak "SimpleServer::new: Usage new(argument hash)";
- my $self = {};
+ my %args = @_;
+ my $self = \%args;
if ($count) {
carp "SimpleServer.pm: WARNING: Multithreaded server unsupported";
}
$count = 1;
- $self->{INIT} = $args->{INIT};
- $self->{SEARCH} = $args->{SEARCH} || croak "SimpleServer.pm: ERROR: Unspecified search handler";
- $self->{FETCH} = $args->{FETCH} || croak "SimpleServer.pm: ERROR: Unspecified fetch handler";
- $self->{CLOSE} = $args->{CLOSE};
+ croak "SimpleServer.pm: ERROR: Unspecified search handler" unless defined($self->{SEARCH});
+ croak "SimpleServer.pm: ERROR: Unspecified fetch handler" unless defined($self->{FETCH});
bless $self, $class;
return $self;
if (defined($self->{CLOSE})) {
set_close_handler($self->{CLOSE});
}
+ if (defined($self->{PRESENT})) {
+ set_present_handler($self->{PRESENT});
+ }
+ if (defined($self->{SCAN})) {
+ set_scan_handler($self->{SCAN});
+ }
start_server(@args);
}
+# Register packages that we will use in translated RPNs
+package Net::Z3950::APDU::Query;
+package Net::Z3950::APDU::OID;
+package Net::Z3950::RPN::And;
+package Net::Z3950::RPN::Or;
+package Net::Z3950::RPN::AndNot;
+package Net::Z3950::RPN::Term;
+package Net::Z3950::RPN::Attributes;
+package Net::Z3950::RPN::Attribute;
+
+# Must revert to original package for Autoloader's benefit
+package Net::Z3950::SimpleServer;
+
+
# Autoload methods go after =cut, and are processed by the autosplit program.
1;
my $set_id = $args->{SETNAME};
- my $record = fetch_a_record($args->{OFFSET);
+ my $record = fetch_a_record($args->{OFFSET});
$args->{RECORD} = $record;
if (number_of_hits() == $args->{OFFSET}) { ## Last record in set?
## Register custom event handlers:
- my $handle = Net::Z3950::SimpleServer->new({
- INIT => \&my_init_handler,
+ my $z = new Net::Z3950::SimpleServer( INIT => \&my_init_handler,
CLOSE => \&my_close_handler,
SEARCH => \&my_search_handler,
- FETCH => \&my_fetch_handler
- });
+ FETCH => \&my_fetch_handler);
## Launch server:
- $handle->launch_server("ztest.pl", @ARGV);
+ $z->launch_server("ztest.pl", @ARGV);
=head1 DESCRIPTION
- Initialize request
- Search request
+ - Present request
- Fetching of records
+ - Scan request (browsing)
- Closing down connection
Note that only the Search and Fetch handler functions are required.
The Perl programmer specifies the event handles for the server by
means of the the SimpleServer object constructor
- my $handle = Net::Z3950::SimpleServer->new({
- INIT => \&my_init_handler,
- CLOSE => \&my_close_handler,
- SEARCH => \&my_search_handler,
- FETCH => \&my_fetch_handler });
+ my $z = new Net::Z3950::SimpleServer(
+ INIT => \&my_init_handler,
+ CLOSE => \&my_close_handler,
+ SEARCH => \&my_search_handler,
+ PRESENT => \&my_present_handler,
+ SCAN => \&my_scan_handler,
+ FETCH => \&my_fetch_handler);
After the custom event handles are declared, the server is launched
by means of the method
- $handle->launch_server("MyServer.pl", @ARGV);
+ $z->launch_server("MyServer.pl", @ARGV);
Notice, the first argument should be the name of your server
script (for logging purposes), while the rest of the arguments
$args = {
## Response parameters:
- IMP_NAME => "" ## Z39.50 Implementation name
- IMP_VER => "" ## Z39.50 Implementation version
- ERR_CODE => 0 ## Error code, cnf. Z39.50 manual
+ IMP_ID => "", ## Z39.50 Implementation ID
+ IMP_NAME => "", ## Z39.50 Implementation name
+ IMP_VER => "", ## Z39.50 Implementation version
+ ERR_CODE => 0, ## Error code, cnf. Z39.50 manual
+ ERR_STR => "", ## Error string (additional info.)
+ USER => "xxx" ## If Z39.50 authentication is used,
+ ## this member contains user name
+ PASS => "yyy" ## Under same conditions, this member
+ ## contains the password in clear text
HANDLE => undef ## Handler of Perl data structure
};
it is always best to store them in a private session structure -
rather than leaving them in global variables in your script.
-The Implementation name and version are only really used by Z39.50
+The Implementation ID, name and version are only really used by Z39.50
client developers to see what kind of server they're dealing with.
Filling these in is optional.
The ERR_CODE should be left at 0 (the default value) if you wish to
accept the connection. Any other value is interpreted as a failure
-and the client will be shown the door.
+and the client will be shown the door, with the code and the
+associated additional information, ERR_STR returned.
=head2 Search handler
$args = {
## Request parameters:
- HANDLE => ref ## Your session reference.
- SETNAME => "id" ## ID of the result set
- REPL_SET => 0 ## Replace set if already existing?
- DATABASES => ["xxx"] ## Reference to a list of data-
+ HANDLE => ref, ## Your session reference.
+ SETNAME => "id", ## ID of the result set
+ REPL_SET => 0, ## Replace set if already existing?
+ DATABASES => ["xxx"], ## Reference to a list of data-
## bases to search
- QUERY => "query" ## The query expression
+ QUERY => "query", ## The query expression
+ RPN => $obj, ## Reference to a Net::Z3950::APDU::Query
## Response parameters:
- ERR_CODE => 0 ## Error code (0=Succesful search)
- ERR_STR => "" ## Error string
+ ERR_CODE => 0, ## Error code (0=Succesful search)
+ ERR_STR => "", ## Error string
HITS => 0 ## Number of matches
};
try to return good error codes if you run into something you can't or
won't support.
+A more convenient alternative to the QUERY member may be the RPN
+member, which is a reference to a Net::Z3950::APDU::Query object
+representing the RPN query tree. The structure of that object is
+supposed to be self-documenting, but here's a brief summary of what
+you get:
+
+=over 4
+
+=item *
+
+C<Net::Z3950::APDU::Query> is a hash with two fields:
+
+Z<>
+
+=over 4
+
+=item C<attributeSet>
+
+Optional. If present, it is a reference to a
+C<Net::Z3950::APDU::OID>. This is a string of dot-separated integers
+representing the OID of the query's top-level attribute set.
+
+=item C<query>
+
+Mandatory: a refererence to the RPN tree itself.
+
+=back
+
+=item *
+
+Each node of the tree is an object of one of the following types:
+
+Z<>
+
+=over 4
+
+=item C<Net::Z3950::RPN::And>
+
+=item C<Net::Z3950::RPN::Or>
+
+=item C<Net::Z3950::RPN::AndNot>
+
+These three classes are all arrays of two elements, each of which is a
+node of one of the above types.
+
+=item C<Net::Z3950::RPN::Term>
+
+See below for details.
+
+=back
+
+(I guess I should make a superclass C<Net::Z3950::RPN::Node> and make
+all of these subclasses of it. Not done that yet, but will do soon.)
+
+=back
+
+=over 4
+
+=item *
+
+C<Net::Z3950::RPN::Term> is a hash with two fields:
+
+Z<>
+
+=over 4
+
+=item C<term>
+
+A string containing the search term itself.
+
+=item C<attributes>
+
+A reference to a C<Net::Z3950::RPN::Attributes> object.
+
+=back
+
+=item *
+
+C<Net::Z3950::RPN::Attributes> is an array of references to
+C<Net::Z3950::RPN::Attribute> objects. (Note the plural/singular
+distinction.)
+
+=item *
+
+C<Net::Z3950::RPN::Attribute> is a hash with three elements:
+
+Z<>
+
+=over 4
+
+=item C<attributeSet>
+
+Optional. If present, it is dot-separated OID string, as above.
+
+=item C<attributeType>
+
+An integer indicating the type of the attribute - for example, under
+the BIB-1 attribute set, type 1 indicates a ``use'' attribute, type 2
+a ``relation'' attribute, etc.
+
+=item C<attributeValue>
+
+An integer indicating the value of the attribute - for example, under
+BIB-1, if the attribute type is 1, then value 4 indictates a title
+search and 7 indictates an ISBN search; but if the attribute type is
+2, then value 4 indicates a ``greater than or equal'' search, and 102
+indicates a relevance match.
+
+=back
+
+=back
+
+Note that, at the moment, none of these classes have any methods at
+all: the blessing into classes is largely just a documentation thing
+so that, for example, if you do
+
+ { use Data::Dumper; print Dumper($args->{RPN}) }
+
+you get something fairly human-readable. But of course, the type
+distinction between the three different kinds of boolean node is
+important.
+
+By adding your own methods to these classes (building what I call
+``augmented classes''), you can easily build code that walks the tree
+of the incoming RPN. Take a look at C<samples/render-search.pl> for a
+sample implementation of such an augmented classes technique.
+
+
+=head2 Present handler
+
+The presence of a present handler in a SimpleServer front-end is optional.
+Each time a client wishes to retrieve records, the present service is
+called. The present service allows the origin to request a certain number
+of records retrieved from a given result set.
+When the present handler is called, the front-end server should prepare a
+result set for fetching. In practice, this means to get access to the
+data from the backend database and store the data in a temporary fashion
+for fast and efficient fetching. The present handler does *not* fetch
+anything. This task is taken care of by the fetch handler, which will be
+called the correct number of times by the YAZ library. More about this
+below.
+If no present handler is implemented in the front-end, the YAZ toolkit
+will take care of a minimum of preparations itself. This default present
+handler is sufficient in many situations, where only a small amount of
+records are expected to be retrieved. If on the other hand, large result
+sets are likely to occur, the implementation of a reasonable present
+handler can gain performance significantly.
+
+The informations exchanged between client and present handle are:
+
+ $args = {
+ ## Client/server request:
+
+ HANDLE => ref, ## Reference to datastructure
+ SETNAME => "id", ## Result set ID
+ START => xxx, ## Start position
+ COMP => "", ## Desired record composition
+ NUMBER => yyy, ## Number of requested records
+
+
+ ## Respons parameters:
+
+ HITS => zzz, ## Number of returned records
+ ERR_CODE => 0, ## Error code
+ ERR_STR => "" ## Error message
+ };
+
+
=head2 Fetch handler
The fetch handler is asked to retrieve a SINGLE record from a given
NOTE: The record offset is 1-indexed - 1 is the offset of the first
record in the set.
+=head2 Scan handler
+
+A full featured Z39.50 server should support scan (or in some literature
+browse). The client specifies a starting term of the scan, and the server
+should return an ordered list of specified length consisting of terms
+actually occurring in the data base. Each of these terms should be close
+to or equal to the term originally specified. The quality of scan compared
+to simple search is a guarantee of hits. It is simply like browsing through
+an index of a book, you always find something! The parameters exchanged are
+
+ $args = {
+ ## Client request
+
+ HANDLE => $ref ## Reference to data structure
+ TERM => 'start', ## The start term
+ NUMBER => xx, ## Number of requested terms
+ POS => yy, ## Position of starting point
+ ## within returned list
+ STEP => 0, ## Step size
+
+ ## Server response
+
+ ERR_CODE => 0, ## Error code
+ ERR_STR => '', ## Diagnostic message
+ NUMBER => zz, ## Number of returned terms
+ STATUS => $status, ## ScanSuccess/ScanFailure
+ ENTRIES => $entries ## Referenced list of terms
+ };
+
+where the term list is returned by reference in the scalar $entries, which
+should point at a data structure of this kind,
+
+ my $entries = [
+ { TERM => 'energy',
+ OCCURRENCE => 5 },
+
+ { TERM => 'energy density',
+ OCCURRENCE => 6, },
+
+ { TERM => 'energy flow',
+ OCCURRENCE => 3 },
+
+ ...
+
+ ...
+ ];
+
+The $status flag should be assigned one of two values:
+
+ Net::Z3950::SimpleServer::ScanSuccess On success (default)
+ Net::Z3950::SimpleServer::ScanPartial Less terms returned than requested
+
+The STEP member contains the requested number of entries in the term-list
+between two adjacent entries in the response.
+
=head2 Close handler
The argument hash recieved by the close handler has one element only:
=head1 AUTHORS
Anders Sønderberg (sondberg@indexdata.dk) and Sebastian Hammer
-(quinn@indexdata.dk).
+(quinn@indexdata.dk). Substantial contributions made by Mike Taylor
+(mike@miketaylor.org.uk).
=head1 SEE ALSO
-perl(1).
-
Any Perl module which is useful for accessing the database of your
choice.
=cut
-
-
projects / simpleserver-moved-to-github.git / blobdiff