--- loncom/lonnet/perl/lonnet.pm 2003/07/20 00:39:02 1.393 +++ loncom/lonnet/perl/lonnet.pm 2003/07/25 01:18:04 1.394 @@ -1,7 +1,7 @@ # The LearningOnline Network # TCP networking package # -# $Id: lonnet.pm,v 1.393 2003/07/20 00:39:02 www Exp $ +# $Id: lonnet.pm,v 1.394 2003/07/25 01:18:04 bowersj2 Exp $ # # Copyright Michigan State University Board of Trustees # @@ -4246,45 +4246,125 @@ being set. =back -=head1 INTRODUCTION +=head1 OVERVIEW -This module provides subroutines which interact with the -lonc/lond (TCP) network layer of LON-CAPA. And Can be used to ask about -- classes -- users -- resources +lonnet provides subroutines which interact with the +lonc/lond (TCP) network layer of LON-CAPA. They can be used to ask +about classes, users, and resources. For many of these objects you can also use this to store data about them or modify them in various ways. -This is part of the LearningOnline Network with CAPA project -described at http://www.lon-capa.org. +=head2 Symbs -=head1 RETURN MESSAGES +To identify a specific instance of a resource, LON-CAPA uses symbols +or "symbs"X. These identifiers are built from the URL of the +map, the resource number of the resource in the map, and the URL of +the resource itself. The latter is somewhat redundant, but might help +if maps change. -=over 4 +An example is -=item * + msu/korte/parts/part1.sequence___19___msu/korte/tests/part12.problem -con_lost : unable to contact remote host +The respective map entry is -=item * + + -con_delayed : unable to contact remote host, message will be delivered -when the connection is brought back up +Symbs are used by the random number generator, as well as to store and +restore data specific to a certain instance of for example a problem. -=item * +=head2 Storing And Retrieving Data -con_failed : unable to contact remote host and unable to save message -for later delivery +XXXThree of the most important functions +in C are C<&Apache::lonnet::cstore()>, +C<&Apache::lonnet:restore()>, and C<&Apache::lonnet::store()>, which +is is the non-critical message twin of cstore. These functions are for +handlers to store a perl hash to a user's permanent data space in an +easy manner, and to retrieve it again on another call. It is expected +that a handler would use this once at the beginning to retrieve data, +and then again once at the end to send only the new data back. -=item * +The data is stored in the user's data directory on the user's +homeserver under the ID of the course. -error: : an error a occured, a description of the error follows the : +The hash that is returned by restore will have all of the previous +value for all of the elements of the hash. -=item * +Example: + + #creating a hash + my %hash; + $hash{'foo'}='bar'; + + #storing it + &Apache::lonnet::cstore(\%hash); -no_such_host : unable to fund a host associated with the user/domain + #changing a value + $hash{'foo'}='notbar'; + + #adding a new value + $hash{'bar'}='foo'; + &Apache::lonnet::cstore(\%hash); + + #retrieving the hash + my %history=&Apache::lonnet::restore(); + + #print the hash + foreach my $key (sort(keys(%history))) { + print("\%history{$key} = $history{$key}"); + } + +Will print out: + + %history{1:foo} = bar + %history{1:keys} = foo:timestamp + %history{1:timestamp} = 990455579 + %history{2:bar} = foo + %history{2:foo} = notbar + %history{2:keys} = foo:bar:timestamp + %history{2:timestamp} = 990455580 + %history{bar} = foo + %history{foo} = notbar + %history{timestamp} = 990455580 + %history{version} = 2 + +Note that the special hash entries C, C and +C were added to the hash. C will be equal to the +total number of versions of the data that have been stored. The +C attribute will be the UNIX time the hash was +stored. C is available in every historical section to list which +keys were added or changed at a specific historical revision of a +hash. + +B: do not store the hash that restore returns directly. This +will cause a mess since it will restore the historical keys as if the +were new keys. I.E. 1:foo will become 1:1:foo etc. + +Calling convention: + + my %record=&Apache::lonnet::restore($symb,$courseid,$domain,$uname,$home); + &Apache::lonnet::cstore(\%newrecord,$symb,$courseid,$domain,$uname,$home); + +For more detailed information, see lonnet specific documentation. + +=head1 RETURN MESSAGES + +=over 4 + +=item * B: unable to contact remote host + +=item * B: unable to contact remote host, message will be delivered +when the connection is brought back up + +=item * B: unable to contact remote host and unable to save message +for later delivery + +=item * B: an error a occured, a description of the error follows the : + +=item * B: unable to fund a host associated with the user/domain that was requested =back @@ -4295,15 +4375,18 @@ that was requested =over 4 -=item * - -appenv(%hash) : the value of %hash is written to the user envirnoment -file, and will be restored for each access this user makes during this -session, also modifies the %ENV for the current process +=item * +X +B: the value of %hash is written to +the user envirnoment file, and will be restored for each access this +user makes during this session, also modifies the %ENV for the current +process =item * - -delenv($regexp) : removes all items from the session environment file that matches the regular expression in $regexp. The values are also delted from the current processes %ENV. +X +B: removes all items from the session +environment file that matches the regular expression in $regexp. The +values are also delted from the current processes %ENV. =back @@ -4312,50 +4395,51 @@ delenv($regexp) : removes all items from =over 4 =item * - -queryauthenticate($uname,$udom) : try to determine user's current +X +B: try to determine user's current authentication scheme =item * - -authenticate($uname,$upass,$udom) : try to authenticate user from domain's lib -servers (first use the current one), $upass should be the users password +X +B: try to +authenticate user from domain's lib servers (first use the current +one). C<$upass> should be the users password. =item * - -homeserver($uname,$udom) : find the server which has the user's -directory and files (there must be only one), this caches the answer, -and also caches if there is a borken connection. +X +B: find the server which has +the user's directory and files (there must be only one), this caches +the answer, and also caches if there is a borken connection. =item * - -idget($udom,@ids) : find the usernames behind a list of IDs (IDs are a -unique resource in a domain, there must be only 1 ID per username, and -only 1 username per ID in a specific domain) (returns hash: -id=>name,id=>name) +X +B: find the usernames behind a list of IDs +(IDs are a unique resource in a domain, there must be only 1 ID per +username, and only 1 username per ID in a specific domain) (returns +hash: id=>name,id=>name) =item * - -idrget($udom,@unames) : find the IDs behind a list of usernames (returns hash: -name=>id,name=>id) +X +B: find the IDs behind a list of +usernames (returns hash: name=>id,name=>id) =item * - -idput($udom,%ids) : store away a list of names and associated IDs +X +B: store away a list of names and associated IDs =item * - -rolesinit($udom,$username,$authhost) : get user privileges +X +B: get user privileges =item * - -usection($udom,$uname,$cname) : finds the section of student in the +X +B: finds the section of student in the course $cname, return section name/number or '' for "not in course" and '-1' for "no section" =item * - -userenvironment($udom,$uname,@what) : gets the values of the keys +X +B: gets the values of the keys passed in @what from the requested user's environment, returns a hash =back