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<html> <head> <meta name=Title content=" Session Three: Roles and lonnet/loncommon useful functions (Guy)"> <meta http-equiv=Content-Type content="text/html; charset=macintosh"> <link rel=Edit-Time-Data href="Session%20Three_files/editdata.mso"> <title> Session Three: Roles and lonnet/loncommon useful functions (Guy)</title> <style> </style> </head> <body bgcolor=#FFFFFF link=blue vlink=purple class="Normal" lang=EN-US> <div class=Section1><span style='font-size:12.0pt;font-family:Arial;'><b><i><br clear=ALL style='page-break-before:always'> </i></b></span> <h2><a name="_Toc421867053">Session Three: Roles and lonnet/loncommon useful functions (Guy)</a></h2> <h3><a name=name></a><a name="_Toc421867054">NAME</a></h3> <p>Apache::lonnet - Subroutines to ask questions about things in the network.</p> <div align=center style='text-align:center'> <hr size=2 width="100%" align=center> </div> <h3><a name=synopsis></a><a name="_Toc421867055">SYNOPSIS</a></h3> <p>Invoked by other LON-CAPA modules, when they need to talk to or about objects in the network.</p> <pre>  &Apache::lonnet::SUBROUTINENAME(ARGUMENTS);</pre> <p>Common parameters:</p> <ul type=disc> <li>$uname : an internal username (if $cname expecting a course Id specifically) </li> <li>$udom : a domain (if $cdom expecting a course's domain specifically) </li> <li>$symb : a resource instance identifier </li> <li>$namespace : the name of a .db file that contains the data needed or being set. </li> </ul> <div align=center style='text-align:center'> <hr size=2 width="100%" align=center> </div> <h3><a name=introduction></a><a name="_Toc421867056">INTRODUCTION</a></h3> <p>This module provides subroutines which interact with the lonc/lond (TCP) network layer of LON-CAPA. And Can be used to ask about - classes - users - resources</p> <p>For many of these objects you can also use this to store data about them or modify them in various ways.</p> <p>This is part of the LearningOnline Network with CAPA project described at <a href="http://www.lon-capa.org./">http://www.lon-capa.org.</a></p> <div align=center style='text-align:center'> <hr size=2 width="100%" align=center> </div> <h3><a name="return_messages"></a><a name="_Toc421867057">RETURN MESSAGES</a></h3> <ul type=disc> <li>con_lost : unable to contact remote host </li> <li>con_delayed : unable to contact remote host, message will be delivered when the connection is brought back up </li> <li>con_failed : unable to contact remote host and unable to save message for later delivery </li> <li>error: : an error a occured, a description of the error follows the : </li> <li>no_such_host : unable to fund a host associated with the user/domain that was requested </li> </ul> <div align=center style='text-align:center'> <hr size=2 width="100%" align=center> </div> <h3><a name="session_environment_functions"></a><a name="_Toc421867058">Session Environment Functions</a></h3> <ul type=disc> <li><code><span style='font-family: Courier'>appenv(%hash)</span></code> : the value of %hash is written to the user envirnoment file, and will be restored for each access this user makes during this session, also modifies the %ENV for the current process </li> <li><code><span style='font-family: Courier'>delenv($regexp)</span></code> : removes all items from the session environment file that matches the regular expression in $regexp. The values are also delted from the current processes %ENV. </li> </ul> <h3><a name="user_information"></a><a name="_Toc421867059">User Information</a></h3> <ul type=disc> <li><code><span style='font-family: Courier'>queryauthenticate($uname,$udom)</span></code> : try to determine user's current authentication scheme </li> <li><code><span style='font-family: Courier'>authenticate($uname,$upass,$udom)</span></code> : try to authenticate user from domain's lib servers (first use the current one), $upass should be the users password </li> <li><code><span style='font-family: Courier'>homeserver($uname,$udom)</span></code> : find the server which has the user's directory and files (there must be only one) . This caches the answer and also caches if there is an error.</li> <li><code><span style='font-family: Courier'>idget($udom,@ids)</span></code> : 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) </li> <li><code><span style='font-family: Courier'>idrget($udom,@unames)</span></code> : find the IDs behind a list of usernames (returns hash: name=>id,name=>id) </li> <li><code><span style='font-family: Courier'>idput($udom,%ids)</span></code> : store away a list of names and associated IDs </li> <li><code><span style='font-family: Courier'>rolesinit($udom,$username,$authhost)</span></code> : get user privileges </li> <li><code><span style='font-family: Courier'>usection($udom,$uname,$cname)</span></code> : finds the section of student in the course $cname, return section name/number or '' for ``not in course'' and '-1' for ``no section'' </li> <li><code><span style='font-family: Courier'>userenvironment($udom,$uname,@what)</span></code> : gets the values of the keys passed in @what from the requested user's environment, returns a hash </li> </ul> <h3><a name="user_roles"></a><a name="_Toc421867060">User Roles</a></h3> <ul type=disc> <li><code><span style='font-family: Courier'>allowed($priv,$uri)</span></code> : check for a user privilege; returns codes for allowed actions F: full access U,I,K: authentication modes (cxx only) '': forbidden 1: user needs to choose course 2: browse allowed </li> <li><code><span style='font-family: Courier'>definerole($rolename,$sysrole,$domrole,$courole)</span></code> : define role; define a custom role rolename set privileges in format of lonTabs/roles.tab for system, domain, and course level </li> <li><code><span style='font-family: Courier'>plaintext($short)</span></code> : return value in %prp hash (rolesplain.tab); plain text explanation of a user role term </li> </ul> <h3><a name="user_modification"></a><a name="_Toc421867061">User Modification</a></h3> <ul type=disc> <li><code><span style='font-family:Courier'>assignrole($udom,$uname,$url,$role,$end,$start)</span></code> : assign role; give a role to a user for the level given by URL. Optional start and end dates (leave empty string or zero for ``no date'') </li> <li><span style='font-family: "Courier New"'>changepass($uname,$udom,$currentpass,$newpass,$server):</span> attempts to change a users, password, possible return values are: <span style='font-family:"Courier New"'>ok, pwchange_failure, non_authorized, auth_mode_error, unknown_user, refused</span></li> <li><code><span style='font-family:Courier'>modifyuserauth($udom,$uname,$umode,$upass)</span></code> : modify user authentication </li> <li><code><span style='font-family:Courier'>modifyuser($udom,$uname,$uid,$umode,$upass,$first,$middle,$last,$gene)</span></code> : modify user </li> <li>modifystudent($udom,$uname,$uid,$umode,$upass,$first,$middle,$last,$gene,$usec, $end,$start) : modify student </li> <li><code><span style='font-family:Courier'>assigncustomrole($udom,$uname,$url,$rdom,$rnam,$rolename,$end,$start)</span></code> : assign custom role; give a custom role to a user for the level given by URL. Specify name and domain of role author, and role name </li> <li><code><span style='font-family:Courier'>revokerole($udom,$uname,$url,$role)</span></code> : revoke a role for url </li> <li><code><span style='font-family:Courier'>revokecustomrole($udom,$uname,$url,$role)</span></code> : revoke a custom role </li> </ul> <h3><a name="course_infomation"></a><a name="_Toc421867062">Course Infomation</a></h3> <ul type=disc> <li><code><span style='font-family: Courier'>coursedescription($courseid)</span></code> : course description </li> <li><span style='font-family: "Courier New"'>courseresdata($coursenum,$coursedomain,@which) :</span> request for current parameter setting for a specific course, @what should be a list of parameters to ask about. This routine caches answers for 5 minutes.</li> </ul> <h3><a name="course_modification"></a><a name="_Toc421867063">Course Modification</a></h3> <ul type=disc> <li><code><span style='font-family:Courier'>writecoursepref($courseid,%prefs)</span></code> : write preferences (environment database) for a course </li> <li><code><span style='font-family:Courier'>createcourse($udom,$description,$url)</span></code> : make/modify course </li> </ul> <h3><a name="resource_subroutines"></a><a name="_Toc421867064">Resource Subroutines</a></h3> <ul type=disc> <li><code><span style='font-family: Courier'>subscribe($fname)</span></code> : subscribe to a resource, returns URL if possible (probably should use repcopy instead) </li> <li><code><span style='font-family: Courier'>repcopy($filename)</span></code> : subscribes to the requested file, and attempts to replicate from the owning library server, Might return HTTP_SERVICE_UNAVAILABLE, HTTP_NOT_FOUND, FORBIDDEN, OK, or HTTP_BAD_REQUEST, also attempts to grab the metadata for the resource. Expects the local filesystem pathname (/home/httpd/html/res/....) </li> </ul> <h3><a name="resource_information"></a><a name="_Toc421867065">Resource Information</a></h3> <ul type=disc> <li>EXT($varname,$symb,$udom, $uname) : evaluates and returns the value of a vairety of different possible values, $varname should be a request string, and the other parameters can be used to specify who and what one is asking about. </li> </ul> <p><span style='font-size:10.0pt'>Possible values for $varname are environment.lastname (or other item from the environment hash), user.name (or someother aspect about the user), resource.0.maxtries (or some other part and parameter of a resource)</span></p> <ul type=disc> <li><code><span style='font-family:Courier'>directcondval($number)</span></code> : get current value of a condition; reads from a state string </li> <li><code><span style='font-family:Courier'>condval($condidx)</span></code> : value of condition index based on state </li> <li><code><span style='font-family:Courier'>metadata($uri,$what,$liburi,$prefix,$depthcount)</span></code> : request a resource's metadata, $what should be either a specific key, or either 'keys' (to get a list of possible keys) or 'packages' to get a list of packages that this resource currently uses, the last 3 arguments are only used internally for recursive metadata. This function automatically caches all requests</li> <li><code><span style='font-family:Courier'>metadata_query($query,$custom,$customshow)</span></code> : make a metadata query against the network of library servers; returns file handle of where SQL and regex results will be stored for query</li> <li><code><span style='font-family:Courier'>symbread($filename)</span></code> : return symbolic list entry (filename argument optional); returns the data handle </li> <li><span style='font-family: "Courier New"'>symbverify($symb,$thisfn):</span> verifies that $symb actually exists and is a possible symb for the URL in $thisfn, returns a 1 on success, 0 on failure, user must be in a course, as it assumes the existance of the course init hash, and uses $ENV('request.course.id'}</li> <li><span style='font-family: "Courier New"'>symbclean($symb):</span> removes versions numbers from a symb, returns the cleaned symb</li> <li><span style='font-family: "Courier New"'>is_on_map($uri) :</span> checks if the $uri is somewhere on the current course map, user must be in a course for it to work</li> <li><code><span style='font-family:Courier'>numval($salt)</span></code> : return random seed value (addend for rndseed) </li> <li><code><span style='font-family:Courier'>rndseed($symb,$courseid,$udom,$username)</span></code> : create a random sum; returns a random seed, all arguments are optional, if they aren't sent it uses the environment to derive them. Note: if symb isn't sent and it can't get one from &symbread it will use the current time as its return value </li> <li><code><span style='font-family:Courier'>ireceipt($funame,$fudom,$fucourseid,$fusymb)</span></code> : return unique, unfakeable, receipt </li> <li><code><span style='font-family:Courier'>receipt()</span></code> : API to ireceipt working off of ENV values; given out to users </li> <li><code><span style='font-family:Courier'>countacc($url)</span></code> : count the number of accesses to a given URL </li> <li><code><span style='font-family:Courier'>checkout($symb,$tuname,$tudom,$tcrsid)</span></code> : creates a record of a user having looked at an item, most likely printed out or otherwise using a resource </li> <li><code><span style='font-family:Courier'>checkin($token)</span></code> : updates that a resource has beeen returned (a hard copy version for instance) and returns the data that $token was Checkout with ($symb, $tuname, $tudom, and $tcrsid) </li> <li><code><span style='font-family:Courier'>expirespread($uname,$udom,$stype,$usymb)</span></code> : set expire date for spreadsheet </li> <li><code><span style='font-family:Courier'>devalidate($symb)</span></code> : devalidate temporary spreadsheet calculations, forcing spreadsheet to reevaluate the resource scores next time. </li> </ul> <h3><a name="storing/retreiving_data"></a><a name="_Toc421867066"><span style='"storing\/retreiving_data"'>Storing/Retrieving Data</span></a></h3> <ul type=disc> <li><code><span style='font-family:Courier'>store($storehash,$symb,$namespace,$udom,$uname)</span></code> : stores hash permanently for this url; hashref needs to be given and should be a \%hashname; the remaining args aren't required and if they aren't passed or are '' they will be derived from the ENV </li> <li><code><span style='font-family:Courier'>cstore($storehash,$symb,$namespace,$udom,$uname)</span></code> : same as store but uses critical subroutine </li> <li><code><span style='font-family:Courier'>restore($symb,$namespace,$udom,$uname)</span></code> : returns hash for this symb; all args are optional </li> <li><code><span style='font-family:Courier'>tmpstore($storehash,$symb,$namespace,$udom,$uname)</span></code> : storage that works very similar to store/cstore, but all data is stored in a temporary location and can be reset using tmpreset, $storehash should be a hash reference, returns nothing on success </li> <li><code><span style='font-family:Courier'>tmprestore($symb,$namespace,$udom,$uname)</span></code> : storage that works very similar to restore, but all data is stored in a temporary location and can be reset using tmpreset. Returns a hash of values on success, error string otherwise. </li> <li><code><span style='font-family:Courier'>tmpreset($symb,$namespace,$udom,$uname)</span></code> : temporary storage reset, deltes all keys for $symb form the temporary storage hash. </li> <li><code><span style='font-family:Courier'>get($namespace,$storearr,$udom,$uname)</span></code> : returns hash with keys from array reference filled in from namesp ($udomain and $uname are optional) </li> <li><code><span style='font-family:Courier'>del($namespace,$storearr,$udom,$uname)</span></code> : deletes keys out of array from namesp ($udomain and $uname are optional) </li> <li><code><span style='font-family:Courier'>dump($namespace,$udom,$uname,$regexp)</span></code> : dumps the complete (or key matching regexp) namespace into a hash ($udomain, $uname and $regexp are optional) </li> <li><code><span style='font-family:Courier'>put($namespace,$storehash,$udomain,$uname)</span></code> : stores hash in namesp ($udomain and $uname are optional) </li> <li><code><span style='font-family:Courier'>cput($namespace,$storehash,$udomain,$uname)</span></code> : critical put ($udomain and $uname are optional) </li> <li><code><span style='font-family:Courier'>eget($namespace,$storearr,$udomain,$uname)</span></code> : returns hash with keys from array reference filled in from namesp (encrypts the return communication) ($udomain and $uname are optional) </li> <li><code><span style='font-family:Courier'>log($udom,$name,$home,$message)</span></code> : write to permanent log for user; use critical subroutine </li> </ul> <h3><a name="network_status_functions"></a><a name="_Toc421867067">Network Status Functions</a></h3> <ul type=disc> <li><code><span style='font-family:Courier'>dirlist($uri)</span></code> : return directory list based on URI </li> <li><code><span style='font-family:Courier'>spareserver()</span></code> : find server with least workload from spare.tab </li> </ul> <h3><a name="apache_request"></a><a name="_Toc421867068">Apache Request</a></h3> <ul type=disc> <li><code><span style='font-family:Courier'>ssi($url,%hash)</span></code> : server side include, does a complete request cycle on url to localhost, posts hash </li> </ul> <h3><a name="data_to_string_to_data"></a><a name="_Toc421867069">Data to String to Data</a></h3> <ul type=disc> <li><code><span style='font-family:Courier'>hash2str(%hash)</span></code> : convert a hash into a string complete with escaping and '=' and '&' separators, supports elements that are arrayrefs and hashrefs </li> <li><code><span style='font-family:Courier'>hashref2str($hashref)</span></code> : convert a hashref into a string complete with escaping and '=' and '&' separators, supports elements that are arrayrefs and hashrefs </li> <li><code><span style='font-family:Courier'>arrayref2str($arrayref)</span></code> : convert an arrayref into a string complete with escaping and '&' separators, supports elements that are arrayrefs and hashrefs </li> <li><code><span style='font-family:Courier'>str2hash($string)</span></code> : convert string to hash using unescaping and splitting on '=' and '&', supports elements that are arrayrefs and hashrefs </li> <li><code><span style='font-family:Courier'>str2array($string)</span></code> : convert string to hash using unescaping and splitting on '&', supports elements that are arrayrefs and hashrefs </li> </ul> <h3><a name="logging_routines"></a><a name="_Toc421867070">Logging Routines</a></h3> <p>These routines allow one to make log messages in the lonnet.log and lonnet.perm logfiles.</p> <ul type=disc> <li><code><span style='font-family:Courier'>logtouch()</span></code> : make sure the logfile, lonnet.log, exists </li> <li><code><span style='font-family:Courier'>logthis()</span></code> : append message to the normal lonnet.log file, it gets preiodically rolled over and deleted. </li> <li><code><span style='font-family:Courier'>logperm()</span></code> : append a permanent message to lonnet.perm.log, this log file never gets deleted by any automated portion of the system, only messages of critical importance should go in here. </li> </ul> <h3><a name="general_helper_routines"></a><a name="_Toc421867071">General File Helper Routines</a></h3> <ul type=disc> <li><code><span style='font-family:Courier'>getfile($file)</span></code> : serves up a file, returns the contents of a file or -1; replicates and subscribes to the file </li> <li><code><span style='font-family:Courier'>filelocation($dir,$file)</span></code> : returns file system location of a file based on URI; meant to be ``fairly clean'' absolute reference, $dir is a directory that relative $file lookups are to looked in ($dir of /a/dir and a file of ../bob will become /a/bob) </li> <li><code><span style='font-family:Courier'>hreflocation($dir,$file)</span></code> : returns file system location or a URL; same as filelocation except for hrefs </li> <li><code><span style='font-family:Courier'>declutter()</span></code> : declutters URLs (remove docroot, beginning slashes, 'res' etc) </li> </ul> <h3><a name="_Toc421867072">HTTP Helper Routines</a></h3> <ul type=disc> <li><code><span style='font-family:Courier'>escape()</span></code> : unpack non-word characters into CGI-compatible hex codes </li> <li><code><span style='font-family:Courier'>unescape()</span></code> : pack CGI-compatible hex codes into actual non-word ASCII character </li> </ul> </div> <h1> </h1> <h3><a name="underlying_communication_routines_(shoul"></a><a name="_Toc421867073">Private: Underlying communication routines (Shouldn't call)</a></h3> <ul type=disc> <li><code><span style='font-family: Courier'>subreply()</span></code> : tries to pass a message to lonc, returns con_lost if incapable </li> <li><code><span style='font-family: Courier'>reply()</span></code> : uses subreply to send a message to remote machine, logs all failures </li> <li><code><span style='font-family: Courier'>critical()</span></code> : passes a critical message to another server; if cannot get through then place message in connection buffer directory and returns con_delayed, if incapable of saving message, returns con_failed </li> <li><code><span style='font-family: Courier'>reconlonc()</span></code> : tries to reconnect lonc client processes. </li> </ul> <h3><a name="resource_access_logging"></a><a name="_Toc421867074">Private: Resource Access Logging</a></h3> <ul type=disc> <li><code><span style='font-family: Courier'>flushcourselogs()</span></code> : flush (save) buffer logs and access logs </li> <li><code><span style='font-family: Courier'>courselog($what)</span></code> : save message for course in hash </li> <li><code><span style='font-family: Courier'>courseacclog($what)</span></code> : save message for course using &courselog(). Perform special processing for specific resource types (problems, exams, quizzes, etc). </li> <li><code><span style='font-family: Courier'>goodbye()</span></code> : flush course logs and log shutting down; it is called in srm.conf as a PerlChildExitHandler </li> </ul> <h3><a name=other></a><a name="_Toc421867075">Private: Other</a></h3> <p><code><span style='font-family:"Courier New"'>symblist($mapname,%newhash)</span></code><span style='font-family:"Courier New"'> :</span> update symbolic storage links </p> <h3><a name="_Toc421867076">Coding Guidelines</a></h3> <p class=H5><span style='layout-grid-mode: both'>Things to keep in mind while coding handlers for LON-CAPA </span></p> <p><span style='font-size:14.0pt'>1.<span style='font:7.0pt "Times New Roman"'>    </span></span><span style='font-size:14.0pt'>DON'T write to Access machine disks with permanent data, use store/restore </span></p> <p><span style='font-size:14.0pt'>2.<span style='font:7.0pt "Times New Roman"'>    </span></span><span style='font-size:14.0pt'>DON'T </span><span style='font-size:14.0pt;font-family:"Courier New"'>use print()</span><span style='font-size:14.0pt'>, use </span><span style='font-size:14.0pt;font-family: "Courier New"'>$request->print()</span><span style='font-size:14.0pt'> </span></p> <p><span style='font-size:14.0pt'>3.<span style='font:7.0pt "Times New Roman"'>    </span></span><span style='font-size:14.0pt'>DON'T launch children </span></p> <p><span style='font-size:14.0pt'>4.<span style='font:7.0pt "Times New Roman"'>    </span></span><span style='font-size:14.0pt'>DO use </span><span style='font-size:14.0pt;font-family:"Courier New"'>$Apache::lonnet::perlvar{'lonDaemons'}/tmp</span><span style='font-size:14.0pt'> for temporary data. </span></p> <p><span style='font-size:14.0pt'>5.<span style='font:7.0pt "Times New Roman"'>    </span></span><span style='font-size:14.0pt'>DO query the return value of every file operation. </span></p> <p><span style='font-size:14.0pt'>6.<span style='font:7.0pt "Times New Roman"'>    </span></span><span style='font-size:14.0pt'>DO </span><span style='font-size: 14.0pt;font-family:"Courier New"'>use strict;</span><span style='font-size: 14.0pt'> </span></p> <p><span style='font-size:14.0pt'>7.<span style='font:7.0pt "Times New Roman"'>    </span></span><span style='font-size:14.0pt'>DO </span><span style='font-size: 14.0pt;font-family:"Courier New"'>use strict;</span><span style='font-size: 14.0pt'> </span></p> <p><span style='font-size:14.0pt'>8.<span style='font:7.0pt "Times New Roman"'>    </span></span><span style='font-size:14.0pt'>DO familiarize your self with the functions in </span><span style='font-size:14.0pt;font-family:"Courier New"'>lonnet.pm</span><span style='font-size:14.0pt'> and use them to communicate with other servers and when you handler needs to ask questions. </span></p> <p>9.<span style='font:7.0pt "Times New Roman"'>     </span><span style='font-size:14.0pt'>DON'T use </span><span style='font-size:14.0pt; font-family:"Courier New"'>&Apache::lonnet::reply()</span><span style='font-size:14.0pt'> </span></p> <br clear=ALL style='page-break-before:always;'> <div class=Section2> </div> </body> </html>