--- loncom/auth/lonroles.pm 2000/06/12 18:25:03 1.3 +++ loncom/auth/lonroles.pm 2004/08/03 18:53:27 1.97 @@ -1,85 +1,819 @@ # The LearningOnline Network with CAPA # User Roles Screen -# (Directory Indexer -# (Login Screen -# 5/21/99,5/22,5/25,5/26,5/31,6/2,6/10,7/12,7/14 Gerd Kortemeyer) -# 11/23 Gerd Kortemeyer) -# 1/14,03/06,06/01 Gerd Kortemeyer # +# $Id: lonroles.pm,v 1.97 2004/08/03 18:53:27 albertel Exp $ +# +# Copyright Michigan State University Board of Trustees +# +# This file is part of the LearningOnline Network with CAPA (LON-CAPA). +# +# LON-CAPA is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# LON-CAPA is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with LON-CAPA; if not, write to the Free Software +# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA +# +# /home/httpd/html/adm/gpl.txt +# +# http://www.lon-capa.org/ +# +### + package Apache::lonroles; use strict; use Apache::lonnet(); +use Apache::lonuserstate(); use Apache::Constants qw(:common); use Apache::File(); +use Apache::lonmenu; +use Apache::loncommon; +use Apache::lonannounce; +use Apache::lonlocal; + +sub redirect_user { + my ($r,$title,$url,$msg,$launch_nav) = @_; + $msg = $title if (! defined($msg)); + &Apache::loncommon::content_type($r,'text/html'); + &Apache::loncommon::no_cache($r); + $r->send_http_header; + my $swinfo=&Apache::lonmenu::rawconfig(); + my $navwindow; + if ($launch_nav eq 'on') { + $navwindow.=&Apache::lonnavmaps::launch_win('now'); + } else { + $navwindow.=&Apache::lonnavmaps::close(); + } + my $bodytag=&Apache::loncommon::bodytag('Switching Role'); +# Note to style police: +# This must only replace the spaces, nothing else, or it bombs elsewhere. + $url=~s/ /\%20/g; + $r->print(<$title + + + +$bodytag + +$navwindow +

$msg

+Continue + + +ENDREDIR + return; +} sub handler { + my $r = shift; - $r->content_type('text/html'); - $r->send_http_header; - return OK if $r->header_only; -# --------------------------------------------------- Read Plain Text for Roles + my $now=time; + my $then=$ENV{'user.login.time'}; + my $envkey; - my $tabdir = $r->dir_config('lonTabDir'); - my @rolesplain; - my %plain; +# ================================================================== Roles Init - { - my $idf=Apache::File->new("$tabdir/rolesplain.tab"); - @rolesplain=<$idf>; + if ($ENV{'form.selectrole'}) { + if ($ENV{'request.course.id'}) { + my %temp=('logout_'.$ENV{'request.course.id'} => time); + &Apache::lonnet::put('email_status',\%temp); + } + &Apache::lonnet::appenv("request.course.id" => '', + "request.course.fn" => '', + "request.course.uri" => '', + "request.course.sec" => '', + "request.role" => 'cm', + "request.role.adv" => $ENV{'user.adv'}, + "request.role.domain" => $ENV{'user.domain'}); + foreach $envkey (keys %ENV) { + next if ($envkey!~/^user\.role\./); + my (undef,undef,$role,@pwhere)=split(/\./,$envkey); + my $where=join('.',@pwhere); + my $trolecode=$role.'.'.$where; + if ($ENV{'form.'.$trolecode}) { + my ($tstart,$tend)=split(/\./,$ENV{$envkey}); + my $tstatus='is'; + if ($tstart) { + if ($tstart>$then) { + $tstatus='future'; + } + } + if ($tend) { + if ($tend<$then) { $tstatus='expired'; } + if ($tend<$now) { $tstatus='will_not'; } + } + if ($tstatus eq 'is') { + $where=~s/^\///; + my ($cdom,$cnum,$csec)=split(/\//,$where); +# check for keyed access + if (($role eq 'st') && + ($ENV{'course.'.$cdom.'_'.$cnum.'.keyaccess'} eq 'yes')) { +# who is key authority? + my $authdom=$cdom; + my $authnum=$cnum; + if ($ENV{'course.'.$cdom.'_'.$cnum.'.keyauth'}) { + ($authnum,$authdom)= + split(/\W/,$ENV{'course.'.$cdom.'_'.$cnum.'.keyauth'}); + } +# check with key authority + unless (&Apache::lonnet::validate_access_key( + $ENV{'environment.key.'.$cdom.'_'.$cnum}, + $authdom,$authnum)) { +# there is no valid key + if ($ENV{'form.newkey'}) { +# student attempts to register a new key + &Apache::loncommon::content_type($r,'text/html'); + &Apache::loncommon::no_cache($r); + $r->send_http_header; + my $swinfo=&Apache::lonmenu::rawconfig(); + my $bodytag=&Apache::loncommon::bodytag + ('Verifying Access Key to Unlock this Course'); + my $buttontext=&mt('Enter Course'); + my $message=&mt('Successfully registered key'); + my $assignresult= + &Apache::lonnet::assign_access_key( + $ENV{'form.newkey'}, + $authdom,$authnum, + $cdom,$cnum, + $ENV{'user.domain'}, + $ENV{'user.name'}, + 'Assigned from '.$ENV{'REMOTE_ADDR'}.' at '.localtime().' for '. + $trolecode); + unless ($assignresult eq 'ok') { + $assignresult=~s/^error\:\s*//; + $message=&mt($assignresult). + '
'. + &mt('Logout').''; + $buttontext=&mt('Re-Enter Key'); + } + $r->print(<Verifying Course Access Key + + +$bodytag + +
+ + +$message
+ +
+ +ENDENTEREDKEY + return OK; + } else { +# print form to enter a new key + &Apache::loncommon::content_type($r,'text/html'); + &Apache::loncommon::no_cache($r); + $r->send_http_header; + my $swinfo=&Apache::lonmenu::rawconfig(); + my $bodytag=&Apache::loncommon::bodytag + ('Enter Access Key to Unlock this Course'); + $r->print(<Entering Course Access Key + + +$bodytag + +
+ + + + +
+ +ENDENTERKEY + return OK; + } + } + } + &Apache::lonnet::log($ENV{'user.domain'}, + $ENV{'user.name'}, + $ENV{'user.home'}, + "Role ".$trolecode); + my $tadv=0; + if (($trolecode!~/^st/) && + ($trolecode!~/^ta/) && + ($trolecode!~/^cm/)) { $tadv=1; } + &Apache::lonnet::appenv( + 'request.role' => $trolecode, + 'request.role.adv' => $tadv, + 'request.role.domain' => $cdom, + 'request.course.sec' => $csec); + my $msg=&mt('Entering course ...'); + + if (($cnum) && ($role ne 'ca')) { + my ($furl,$ferr)= + &Apache::lonuserstate::readmap($cdom.'/'.$cnum); + if (($ENV{'form.orgurl'}) && + ($ENV{'form.orgurl'}!~/^\/adm\/flip/)) { + my $dest=$ENV{'form.orgurl'}; + if ( &Apache::lonnet::mod_perl_version() == 2 ) { + &Apache::lonnet::cleanenv(); + } + $r->internal_redirect($dest); + return OK; + } else { + unless ($ENV{'request.course.id'}) { + &Apache::lonnet::appenv( + "request.course.id" => $cdom.'_'.$cnum); + $furl='/adm/roles?tryagain=1'; + $msg= + '

'. + &mt('Could not initialize course at this time.'). + '

'.&mt('Please try again.').'

'.$ferr; + } + + # Check to see if the user is a CC entering a course + # for the first time + my (undef, undef, $role, $courseid) = split(/\./, $envkey); + if (substr($courseid, 0, 1) eq '/') { + $courseid = substr($courseid, 1); + } + $courseid =~ s/\//_/; + if ($role eq 'cc' && $ENV{'course.' . $courseid . + '.course.helper.not.run'}) { + $furl = "/adm/helper/course.initialization.helper"; + } + # + # Send the user to the course they selected + &redirect_user($r,&mt('Entering Course'), + $furl,$msg, + $ENV{'environment.remotenavmap'}); + return OK; + } + } + # + # Send the user to the construction space they selected + if ($role =~ /^(au|ca)$/) { + my $redirect_url = '/priv/'; + if ($role eq 'au') { + $redirect_url.=$ENV{'user.name'}; + } else { + $where =~ /\/(.*)$/; + $redirect_url .= $1; + } + $redirect_url .= '/'; + &redirect_user($r,&mt('Entering Construction Space'), + $redirect_url); + return OK; + } + } + } + } } - map { - my ($short,$long)=split(/:/,$_); - $plain{$short}=$long; - } @rolesplain; -# ---------------------------------------------------------------- Print Header + +# =============================================================== No Roles Init + + &Apache::loncommon::content_type($r,'text/html'); + &Apache::loncommon::no_cache($r); + $r->send_http_header; + return OK if $r->header_only; + + my $swinfo=&Apache::lonmenu::rawconfig(); + my $bodytag=&Apache::loncommon::bodytag('User Roles'); + my $helptag='
'.&Apache::loncommon::help_open_menu('','General Intro','General_Intro','User Roles',1,undef,undef,undef,undef,,&mt("Click here for help")).'
'; $r->print(< LON-CAPA User Roles - +$bodytag +$helptag
+ ENDHEADER # ------------------------------------------ Get Error Message from Environment my ($fn,$priv,$nochoose,$error,$msg)=split(/:/,$ENV{'user.error.msg'}); + if ($ENV{'user.error.msg'}) { + $r->log_reason( + "$msg for $ENV{'user.name'} domain $ENV{'user.domain'} access $priv",$fn); + } -# -------------------------------------------------------- Generate Page Output +# ------------------------------------------------- Can this user re-init, etc? + my $advanced=$ENV{'user.adv'}; + &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},['tryagain']); + my $tryagain=$ENV{'form.tryagain'}; + +# -------------------------------------------------------- Generate Page Output +# --------------------------------------------------------------- Error Header? if ($error) { $r->print("

LON-CAPA Access Control

"); - $r->print("
Access  : $plain{$priv}
");
-        $r->print("Resource: $fn
");
-        $r->print("Action  : $msg
"); - $r->log_reason( - "$msg for $ENV{'user.name'} domain $ENV{'user.domain'} access $priv",$fn); + $r->print("
Access  : ".
+                  Apache::lonnet::plaintext($priv)."\n");
+        $r->print("Resource: $fn\n");
+        $r->print("Action  : $msg\n
"); } else { - $r->print("

LON-CAPA User Roles

"); + if ($ENV{'user.error.msg'}) { + $r->print( + '

'. + &mt('You need to choose another user role or enter a specific course for this function').'

'); + } } - +# -------------------------------------------------------- Choice or no choice? if ($nochoose) { - $r->print("

Assigned User Roles

"); + if ($advanced) { + $r->print("

".&mt('Assigned User Roles')."

\n"); + } else { + $r->print("

".&mt('Sorry ...')."

\n". + &mt('This resource might be part of')); + if ($ENV{'request.course.id'}) { + $r->print(&mt(' another')); + } else { + $r->print(&mt(' a certain')); + } + $r->print(&mt(' course.').''); + return OK; + } } else { - $r->print("

Select a User Role

\n"); - $r->print('
'); -$r->print('
'); + if ($advanced) { + $r->print(&mt("Your home server is "). + $Apache::lonnet::hostname{&Apache::lonnet::homeserver + ($ENV{'user.name'},$ENV{'user.domain'})}. + "
\n"); + $r->print(&mt( + "Author and Co-Author roles may not be available on servers other than your home server.")); + } + if (($ENV{'REDIRECT_QUERY_STRING'}) && ($fn)) { + $fn.='?'.$ENV{'REDIRECT_QUERY_STRING'}; + } + $r->print('
'); + $r->print(''); + $r->print(''); } - my $envkey; + if ($ENV{'user.adv'}) { + $r->print( + '
'.&mt('Show all roles').': print(' checked'); } + $r->print('>'); + } + + my (%roletext,%sortrole,%roleclass); + my $countactive=0; + my $inrole=0; + my $possiblerole=''; foreach $envkey (sort keys %ENV) { - $r->print("$envkey ---- $ENV{$envkey}
"); + my $button = 1; + my $switchserver=''; + my $roletext; + my $sortkey; if ($envkey=~/^user\.role\./) { - my ($dum1,$dum2,$role,$where)=split(/\./,$envkey); - $r->print("$plain{$role} for $where
"); + my (undef,undef,$role,@pwhere)=split(/\./,$envkey); + next if (!defined($role) || $role eq ''); + my $where=join('.',@pwhere); + my $trolecode=$role.'.'.$where; + my ($tstart,$tend)=split(/\./,$ENV{$envkey}); + my $tremark=''; + my $tstatus='is'; + my $tpstart=' '; + my $tpend=' '; + my $tfont='#000000'; + if ($tstart) { + if ($tstart>$then) { + $tstatus='future'; + if ($tstart<$now) { $tstatus='will'; } + } + $tpstart=&Apache::lonlocal::locallocaltime($tstart); + } + if ($tend) { + if ($tend<$then) { + $tstatus='expired'; + } elsif ($tend<$now) { + $tstatus='will_not'; + } + $tpend=&Apache::lonlocal::locallocaltime($tend); + } + if ($ENV{'request.role'} eq $trolecode) { + $tstatus='selected'; + } + my $tbg; + if (($tstatus eq 'is') || ($tstatus eq 'selected') || + ($ENV{'form.showall'})) { + if ($tstatus eq 'is') { + $tbg='#77FF77'; + $tfont='#003300'; + $possiblerole=$trolecode; + $countactive++; + } elsif ($tstatus eq 'future') { + $tbg='#FFFF77'; + $button=0; + } elsif ($tstatus eq 'will') { + $tbg='#FFAA77'; + $tremark.=&mt('Active at next login. '); + } elsif ($tstatus eq 'expired') { + $tbg='#FF7777'; + $tfont='#330000'; + $button=0; + } elsif ($tstatus eq 'will_not') { + $tbg='#AAFF77'; + $tremark.=&mt('Expired after logout. '); + } elsif ($tstatus eq 'selected') { + $tbg='#11CC55'; + $tfont='#002200'; + $inrole=1; + $countactive++; + $tremark.=&mt('Currently selected. '); + } + my $trole; + if ($role =~ /^cr\//) { + my ($rdummy,$rdomain,$rauthor,$rrole)=split(/\//,$role); + $tremark.='
'.&mt('Defined by ').$rauthor. + &mt(' at ').$rdomain.'.'; + $trole=$rrole; + } else { + $trole=Apache::lonnet::plaintext($role); + } + my $ttype; + my $twhere; + my ($tdom,$trest,$tsection)= + split(/\//,Apache::lonnet::declutter($where)); + # First, Co-Authorship roles + if ($role eq 'ca') { + my $home = &Apache::lonnet::homeserver($trest,$tdom); + my $allowed=0; + my @ids=&Apache::lonnet::current_machine_ids(); + foreach my $id (@ids) { if ($id eq $home) { $allowed=1; } } + if (!$allowed) { + $button=0; + $switchserver=&Apache::lonnet::escape('http://'. + $Apache::lonnet::hostname{$home}. + '/adm/login?domain='.$ENV{'user.domain'}. + '&username='.$ENV{'user.name'}. + '&firsturl=/priv/'.$trest.'/'); + } + #next if ($home eq 'no_host'); + $home = $Apache::lonnet::hostname{$home}; + $ttype='Construction Space'; + $twhere=&mt('User').': '.$trest.'
'.&mt('Domain'). + ': '.$tdom.'
'. + ' '.&mt('Server').': '.$home; + $ENV{'course.'.$tdom.'_'.$trest.'.description'}='ca'; + $tremark.=&Apache::lonhtmlcommon::authorbombs('/res/'.$tdom.'/'.$trest.'/'); + $sortkey=$role."$trest:$tdom"; + } elsif ($role eq 'au') { + # Authors + my $home = &Apache::lonnet::homeserver + ($ENV{'user.name'},$ENV{'user.domain'}); + my $allowed=0; + my @ids=&Apache::lonnet::current_machine_ids(); + foreach my $id (@ids) { if ($id eq $home) { $allowed=1; } } + if (!$allowed) { + $button=0; + $switchserver=&Apache::lonnet::escape('http://'. + $Apache::lonnet::hostname{$home}. + '/adm/login?domain='.$ENV{'user.domain'}. + '&username='.$ENV{'user.name'}. + '&firsturl=/priv/'.$ENV{'user.name'}.'/'); + } + #next if ($home eq 'no_host'); + $home = $Apache::lonnet::hostname{$home}; + $ttype='Construction Space'; + $twhere=&mt('Domain').': '.$tdom.'
'.&mt('Server'). + ': '.$home; + $ENV{'course.'.$tdom.'_'.$trest.'.description'}='ca'; + $tremark.=&Apache::lonhtmlcommon::authorbombs('/res/'.$tdom.'/'.$ENV{'user.name'}.'/'); + $sortkey=$role; + } elsif ($trest) { + $ttype='Course'; + if ($tsection) { + $ttype.='
'.&mt('Section/Group').': '.$tsection; + } + my $tcourseid=$tdom.'_'.$trest; + if ($ENV{'course.'.$tcourseid.'.description'}) { + $twhere=$ENV{'course.'.$tcourseid.'.description'}; + $sortkey=$role."\0".$tdom."\0".$twhere."\0".$envkey; + unless ($twhere eq &mt('Currently not available')) { + $twhere.=' '. + &Apache::loncommon::syllabuswrapper(&mt('Syllabus'),$trest,$tdom,$tfont). + ''; + } + } else { + my %newhash=Apache::lonnet::coursedescription + ($tcourseid); + if (%newhash) { + $sortkey=$role."\0".$tdom."\0".$newhash{'description'}. + "\0".$envkey; + $twhere=$newhash{'description'}. + ' '. + &Apache::loncommon::syllabuswrapper(&mt('Syllabus'),$trest,$tdom,$tfont). + ''; + } else { + $twhere=&mt('Currently not available'); + $ENV{'course.'.$tcourseid.'.description'}=$twhere; + $sortkey=$role."\0".$tdom."\0".$twhere."\0".$envkey; + } + } + if ($role ne 'st') { $twhere.="
".&mt('Domain').":".$tdom; } + } elsif ($tdom) { + $ttype='Domain'; + $twhere=$tdom; + $sortkey=$role.$twhere; + } else { + $ttype='System'; + $twhere=&mt('system wide'); + $sortkey=$role.$twhere; + } + + $roletext.=''; + unless ($nochoose) { + if (!$button) { + if ($switchserver) { + $roletext.=''.&mt('Switch Server').''; + } else { + $roletext.=(' '); + } + } elsif ($tstatus eq 'is') { + $roletext.=(''); + } elsif ($tryagain) { + $roletext.= + ''; + } elsif ($advanced) { + $roletext.= + ''; + } else { + $roletext.=' '; + } + } + $tremark.=&Apache::lonannounce::showday(time,1, + &Apache::lonannounce::readcalendar($tdom.'_'.$trest)); + + $roletext.=''.$trole. + ''.$ttype. + ''.$twhere. + ''.$tpstart. + ''.$tpend. + ''.$tremark. + ' '."\n"; + $roletext{$envkey}=$roletext; + if (!$sortkey) {$sortkey=$twhere."\0".$envkey;} + $sortrole{$sortkey}=$envkey; + $roleclass{$envkey}=$ttype; + } } } - +# No active roles + if ($countactive==0) { + if ($inrole) { + $r->print('

'.&mt('Currently no additional roles or courses').'

'); + } else { + $r->print('

'.&mt('Currently no active roles or courses').'

'); + } + $r->print('
'); + return OK; +# Is there only one choice? + } elsif (($countactive==1) && ($ENV{'request.role'} eq 'cm')) { + $r->print('

'.&mt('Please stand by.').'

'. + ''); + $r->print("\n"); + $r->rflush(); + $r->print(''); + $r->print(''); + return OK; + } +# More than one possible role +# ----------------------------------------------------------------------- Table + unless (($advanced) || ($nochoose)) { + $r->print("

".&mt('Select a Course to Enter')."

\n"); + } + $r->print('
'); + unless ($nochoose) { $r->print(''); } + $r->print(''."\n"); + my $doheaders=-1; + foreach my $type ('Construction Space','Course','Domain','System') { + my $haverole=0; + foreach my $which (sort {uc($a) cmp uc($b)} (keys(%sortrole))) { + if ($roleclass{$sortrole{$which}} =~ /^\Q$type\E/) { + $haverole=1; + } + } + if ($haverole) { $doheaders++; } + } + foreach my $type ('Construction Space','Course','Domain','System') { + my $output; + foreach my $which (sort {uc($a) cmp uc($b)} (keys(%sortrole))) { + if ($roleclass{$sortrole{$which}} =~ /^\Q$type\E/) { + $output.=&mt($roletext{$sortrole{$which}}); + } + } + if ($output) { + if ($doheaders > 0) { + $r->print("". + ""); + } + $r->print($output); + } + } + my $tremark=''; + my $tfont='#003300'; + if ($ENV{'request.role'} eq 'cm') { + $r->print(''); + $tremark=&mt('Currently selected. '); + $tfont='#002200'; + } else { + $r->print(''); + } + unless ($nochoose) { + if ($ENV{'request.role'} ne 'cm') { + $r->print(''); + } else { + $r->print(''); + } + } + $r->print(''."\n"); + + $r->print('
 '.&mt('User Role').''.&mt('Extent'). + ''.&mt('Start').''.&mt('End').''. + &mt('Remark').'
".&mt($type)."
 '.&mt('No role specified'). + ''.$tremark. + ' 
'); + unless ($nochoose) { + $r->print("\n"); + } +# ------------------------------------------------------------ Privileges Info + if (($advanced) && (($ENV{'user.error.msg'}) || ($error))) { + $r->print('

Current Privileges

'); + + foreach $envkey (sort keys %ENV) { + if ($envkey=~/^user\.priv\.$ENV{'request.role'}\./) { + my $where=$envkey; + $where=~s/^user\.priv\.$ENV{'request.role'}\.//; + my $ttype; + my $twhere; + my ($tdom,$trest,$tsec)= + split(/\//,Apache::lonnet::declutter($where)); + if ($trest) { + if ($ENV{'course.'.$tdom.'_'.$trest.'.description'} eq 'ca') { + $ttype='Construction Space'; + $twhere='User: '.$trest.', Domain: '.$tdom; + } else { + $ttype='Course'; + $twhere=$ENV{'course.'.$tdom.'_'.$trest.'.description'}; + if ($tsec) { + $twhere.=' (Section/Group: '.$tsec.')'; + } + } + } elsif ($tdom) { + $ttype='Domain'; + $twhere=$tdom; + } else { + $ttype='System'; + $twhere='/'; + } + $r->print("\n

".$ttype.': '.$twhere.'

    '); + foreach (sort split(/:/,$ENV{$envkey})) { + if ($_) { + my ($prv,$restr)=split(/\&/,$_); + my $trestr=''; + if ($restr ne 'F') { + my $i; + $trestr.=' ('; + for ($i=0;$iprint('
  • '. + Apache::lonnet::plaintext($prv).$trestr. + '
    • '); + } + } + $r->print('
'); + } + } + } + $r->print(&Apache::lonnet::getannounce()); + if ($advanced) { + $r->print('

This is LON-CAPA '. + $r->dir_config('lonVersion').'
'. + ''.&mt('Logout').'

'); + } $r->print("\n"); return OK; } 1; __END__ + +=head1 NAME + +Apache::lonroles - User Roles Screen + +=head1 SYNOPSIS + +Invoked by /etc/httpd/conf/srm.conf: + + + PerlAccessHandler Apache::lonacc + SetHandler perl-script + PerlHandler Apache::lonroles + ErrorDocument 403 /adm/login + ErrorDocument 500 /adm/errorhandler + + +=head1 OVERVIEW + +=head2 Choosing Roles + +C is a handler that allows a user to switch roles in +mid-session. LON-CAPA attempts to work with "No Role Specified", the +default role that a user has before selecting a role, as widely as +possible, but certain handlers for example need specification which +course they should act on, etc. Both in this scenario, and when the +handler determines via C's C<&allowed> function that a certain +action is not allowed, C is used as error handler. This +allows the user to select another role which may have permission to do +what they were trying to do. C can also be accessed via the +B button in the Remote Control. + +=begin latex + +\begin{figure} +\begin{center} +\includegraphics[width=0.45\paperwidth,keepaspectratio]{Sample_Roles_Screen} + \caption{\label{Sample_Roles_Screen}Sample Roles Screen} +\end{center} +\end{figure} + +=end latex + +=head2 Role Initialization + +The privileges for a user are established at login time and stored in the session environment. As a consequence, a new role does not become active till the next login. Handlers are able to query for privileges using C's C<&allowed> function. When a user first logs in, their role is the "common" role, which means that they have the sum of all of their privileges. During a session it might become necessary to choose a particular role, which as a consequence also limits the user to only the privileges in that particular role. + +=head1 INTRODUCTION + +This module enables a user to select what role he wishes to +operate under (instructor, student, teaching assistant, course +coordinator, etc). These roles are pre-established by the actions +of upper-level users. + +This is part of the LearningOnline Network with CAPA project +described at http://www.lon-capa.org. + +=head1 HANDLER SUBROUTINE + +This routine is called by Apache and mod_perl. + +=over 4 + +=item * + +Roles Initialization (yes/no) + +=item * + +Get Error Message from Environment + +=item * + +Who is this? + +=item * + +Generate Page Output + +=item * + +Choice or no choice + +=item * + +Table + +=item * + +Privileges + +=back + +=cut