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                     17: <div class=Section1><span style='font-size:12.0pt;font-family:Arial;'><b><i><br clear=ALL style='page-break-before:always'>
                     18:   </i></b></span> 
                     19:   <h2><a name="_Toc421867053">Session Three: Roles and lonnet/loncommon useful 
                     20:     functions (Guy)</a></h2>
                     21:   <h3><a name=name></a><a name="_Toc421867054">NAME</a></h3>
                     22:   <p>Apache::lonnet - Subroutines to ask questions about things in the network.</p>
                     23:   <div align=center style='text-align:center'> 
                     24:     <hr size=2 width="100%" align=center>
                     25:   </div>
                     26:   <h3><a name=synopsis></a><a name="_Toc421867055">SYNOPSIS</a></h3>
                     27:   <p>Invoked by other LON-CAPA modules, when they need to talk to or about objects 
                     28:     in the network.</p>
                     29:   <pre>&nbsp; &amp;Apache::lonnet::SUBROUTINENAME(ARGUMENTS);</pre>
                     30:   <p>Common parameters:</p>
                     31:   <ul type=disc>
                     32:     <li>$uname : an internal username (if $cname expecting a course Id specifically) 
                     33:     </li>
                     34:     <li>$udom : a domain (if $cdom expecting a course's domain specifically) </li>
                     35:     <li>$symb : a resource instance identifier </li>
                     36:     <li>$namespace : the name of a .db file that contains the data needed or being 
                     37:       set. </li>
                     38:   </ul>
                     39:   <div align=center style='text-align:center'> 
                     40:     <hr size=2 width="100%" align=center>
                     41:   </div>
                     42:   <h3><a name=introduction></a><a name="_Toc421867056">INTRODUCTION</a></h3>
                     43:   <p>This module provides subroutines which interact with the lonc/lond (TCP) 
                     44:     network layer of LON-CAPA. And Can be used to ask about - classes - users 
                     45:     - resources</p>
                     46:   <p>For many of these objects you can also use this to store data about them 
                     47:     or modify them in various ways.</p>
                     48:   <p>This is part of the LearningOnline Network with CAPA project described at 
                     49:     <a
                     50: href="http://www.lon-capa.org./">http://www.lon-capa.org.</a></p>
                     51:   <div align=center style='text-align:center'> 
                     52:     <hr size=2 width="100%" align=center>
                     53:   </div>
                     54:   <h3><a name="return_messages"></a><a name="_Toc421867057">RETURN MESSAGES</a></h3>
                     55:   <ul type=disc>
                     56:     <li>con_lost : unable to contact remote host </li>
                     57:     <li>con_delayed : unable to contact remote host, message will be delivered 
                     58:       when the connection is brought back up </li>
                     59:     <li>con_failed : unable to contact remote host and unable to save message 
                     60:       for later delivery </li>
                     61:     <li>error: : an error a occured, a description of the error follows the : 
                     62:     </li>
                     63:     <li>no_such_host : unable to fund a host associated with the user/domain that 
                     64:       was requested </li>
                     65:   </ul>
                     66:   <div align=center style='text-align:center'> 
                     67:     <hr size=2 width="100%" align=center>
                     68:   </div>
                     69:   <h3><a name="session_environment_functions"></a><a name="_Toc421867058">Session 
                     70:     Environment Functions</a></h3>
                     71:   <ul type=disc>
                     72:     <li><code><span style='font-family:
                     73:      Courier'>appenv(%hash)</span></code> : the value of %hash is written to the 
                     74:       user envirnoment file, and will be restored for each access this user makes 
1.3     ! albertel   75:       during this session, also modifies the %env for the current process </li>
1.2       bowersj2   76:     <li><code><span style='font-family:
                     77:      Courier'>delenv($regexp)</span></code> : removes all items from the session 
                     78:       environment file that matches the regular expression in $regexp. The values 
1.3     ! albertel   79:       are also delted from the current processes %env. </li>
1.2       bowersj2   80:   </ul>
                     81:   <h3><a name="user_information"></a><a name="_Toc421867059">User Information</a></h3>
                     82:   <ul type=disc>
                     83:     <li><code><span style='font-family:
                     84:      Courier'>queryauthenticate($uname,$udom)</span></code> : try to determine 
                     85:       user's current authentication scheme </li>
                     86:     <li><code><span style='font-family:
                     87:      Courier'>authenticate($uname,$upass,$udom)</span></code> : try to authenticate 
                     88:       user from domain's lib servers (first use the current one), $upass should 
                     89:       be the users password </li>
                     90:     <li><code><span style='font-family:
                     91:      Courier'>homeserver($uname,$udom)</span></code> : find the server which has 
                     92:       the user's directory and files (there must be only one) . This caches the 
                     93:       answer and also caches if there is an error.</li>
                     94:     <li><code><span style='font-family:
                     95:      Courier'>idget($udom,@ids)</span></code> : find the usernames behind a list 
                     96:       of IDs (IDs are a unique resource in a domain, there must be only 1 ID per 
                     97:       username, and only 1 username per ID in a specific domain) (returns hash: 
                     98:       id=&gt;name,id=&gt;name) </li>
                     99:     <li><code><span style='font-family:
                    100:      Courier'>idrget($udom,@unames)</span></code> : find the IDs behind a list 
                    101:       of usernames (returns hash: name=&gt;id,name=&gt;id) </li>
                    102:     <li><code><span style='font-family:
                    103:      Courier'>idput($udom,%ids)</span></code> : store away a list of names and 
                    104:       associated IDs </li>
                    105:     <li><code><span style='font-family:
                    106:      Courier'>rolesinit($udom,$username,$authhost)</span></code> : get user privileges 
                    107:     </li>
                    108:     <li><code><span style='font-family:
                    109:      Courier'>usection($udom,$uname,$cname)</span></code> : finds the section 
                    110:       of student in the course $cname, return section name/number or '' for ``not 
                    111:       in course'' and '-1' for ``no section'' </li>
                    112:     <li><code><span style='font-family:
                    113:      Courier'>userenvironment($udom,$uname,@what)</span></code> : gets the values 
                    114:       of the keys passed in @what from the requested user's environment, returns 
                    115:       a hash </li>
                    116:   </ul>
                    117:   <h3><a name="user_roles"></a><a name="_Toc421867060">User Roles</a></h3>
                    118:   <ul type=disc>
                    119:     <li><code><span style='font-family:
                    120:      Courier'>allowed($priv,$uri)</span></code> : check for a user privilege; 
                    121:       returns codes for allowed actions F: full access U,I,K: authentication modes 
                    122:       (cxx only) '': forbidden 1: user needs to choose course 2: browse allowed 
                    123:     </li>
                    124:     <li><code><span style='font-family:
                    125:      Courier'>definerole($rolename,$sysrole,$domrole,$courole)</span></code> : 
                    126:       define role; define a custom role rolename set privileges in format of lonTabs/roles.tab 
                    127:       for system, domain, and course level </li>
                    128:     <li><code><span style='font-family:
                    129:      Courier'>plaintext($short)</span></code> : return value in %prp hash (rolesplain.tab); 
                    130:       plain text explanation of a user role term </li>
                    131:   </ul>
                    132:   <h3><a name="user_modification"></a><a name="_Toc421867061">User Modification</a></h3>
                    133:   <ul type=disc>
                    134:     <li><code><span
                    135:      style='font-family:Courier'>assignrole($udom,$uname,$url,$role,$end,$start)</span></code> 
                    136:       : assign role; give a role to a user for the level given by URL. Optional 
                    137:       start and end dates (leave empty string or zero for ``no date'') </li>
                    138:     <li><span style='font-family:
                    139:      "Courier New"'>changepass($uname,$udom,$currentpass,$newpass,$server):</span> 
                    140:       attempts to change a users, password, possible return values are: <span
                    141:      style='font-family:"Courier New"'>ok, pwchange_failure, non_authorized, auth_mode_error, 
                    142:       unknown_user, refused</span></li>
                    143:     <li><code><span
                    144:      style='font-family:Courier'>modifyuserauth($udom,$uname,$umode,$upass)</span></code> 
                    145:       : modify user authentication </li>
                    146:     <li><code><span
                    147:      style='font-family:Courier'>modifyuser($udom,$uname,$uid,$umode,$upass,$first,$middle,$last,$gene)</span></code> 
                    148:       : modify user </li>
                    149:     <li>modifystudent($udom,$uname,$uid,$umode,$upass,$first,$middle,$last,$gene,$usec, 
                    150:       $end,$start) : modify student </li>
                    151:     <li><code><span
                    152:      style='font-family:Courier'>assigncustomrole($udom,$uname,$url,$rdom,$rnam,$rolename,$end,$start)</span></code> 
                    153:       : assign custom role; give a custom role to a user for the level given by 
                    154:       URL. Specify name and domain of role author, and role name </li>
                    155:     <li><code><span
                    156:      style='font-family:Courier'>revokerole($udom,$uname,$url,$role)</span></code> 
                    157:       : revoke a role for url </li>
                    158:     <li><code><span
                    159:      style='font-family:Courier'>revokecustomrole($udom,$uname,$url,$role)</span></code> 
                    160:       : revoke a custom role </li>
                    161:   </ul>
                    162:   <h3><a name="course_infomation"></a><a name="_Toc421867062">Course Infomation</a></h3>
                    163:   <ul type=disc>
                    164:     <li><code><span style='font-family:
                    165:      Courier'>coursedescription($courseid)</span></code> : course description 
                    166:     </li>
                    167:     <li><span style='font-family:
                    168:      "Courier New"'>courseresdata($coursenum,$coursedomain,@which) :</span> request 
                    169:       for current parameter setting for a specific course, @what should be a list 
                    170:       of parameters to ask about. This routine caches answers for 5 minutes.</li>
                    171:   </ul>
                    172:   <h3><a name="course_modification"></a><a name="_Toc421867063">Course Modification</a></h3>
                    173:   <ul type=disc>
                    174:     <li><code><span
                    175:      style='font-family:Courier'>writecoursepref($courseid,%prefs)</span></code> 
                    176:       : write preferences (environment database) for a course </li>
                    177:     <li><code><span
                    178:      style='font-family:Courier'>createcourse($udom,$description,$url)</span></code> 
                    179:       : make/modify course </li>
                    180:   </ul>
                    181:   <h3><a name="resource_subroutines"></a><a name="_Toc421867064">Resource Subroutines</a></h3>
                    182:   <ul type=disc>
                    183:     <li><code><span style='font-family:
                    184:      Courier'>subscribe($fname)</span></code> : subscribe to a resource, returns 
                    185:       URL if possible (probably should use repcopy instead) </li>
                    186:     <li><code><span style='font-family:
                    187:      Courier'>repcopy($filename)</span></code> : subscribes to the requested file, 
                    188:       and attempts to replicate from the owning library server, Might return HTTP_SERVICE_UNAVAILABLE, 
                    189:       HTTP_NOT_FOUND, FORBIDDEN, OK, or HTTP_BAD_REQUEST, also attempts to grab 
                    190:       the metadata for the resource. Expects the local filesystem pathname (/home/httpd/html/res/....) 
                    191:     </li>
                    192:   </ul>
                    193:   <h3><a name="resource_information"></a><a name="_Toc421867065">Resource Information</a></h3>
                    194:   <ul type=disc>
                    195:     <li>EXT($varname,$symb,$udom, $uname) : evaluates and returns the value of 
                    196:       a vairety of different possible values, $varname should be a request string, 
                    197:       and the other parameters can be used to specify who and what one is asking 
                    198:       about. </li>
                    199:   </ul>
                    200:   <p><span style='font-size:10.0pt'>Possible values for $varname are environment.lastname 
                    201:     (or other item from the environment hash), user.name (or someother aspect 
                    202:     about the user), resource.0.maxtries (or some other part and parameter of 
                    203:     a resource)</span></p>
                    204:   <ul type=disc>
                    205:     <li><code><span
                    206:      style='font-family:Courier'>directcondval($number)</span></code> : get current 
                    207:       value of a condition; reads from a state string </li>
                    208:     <li><code><span
                    209:      style='font-family:Courier'>condval($condidx)</span></code> : value of condition 
                    210:       index based on state </li>
                    211:     <li><code><span
                    212:      style='font-family:Courier'>metadata($uri,$what,$liburi,$prefix,$depthcount)</span></code> 
                    213:       : request a resource's metadata, $what should be either a specific key, 
                    214:       or either 'keys' (to get a list of possible keys) or 'packages' to get a 
                    215:       list of packages that this resource currently uses, the last 3 arguments 
                    216:       are only used internally for recursive metadata. This function automatically 
                    217:       caches all requests</li>
                    218:     <li><code><span
                    219:      style='font-family:Courier'>metadata_query($query,$custom,$customshow)</span></code> 
                    220:       : make a metadata query against the network of library servers; returns 
                    221:       file handle of where SQL and regex results will be stored for query</li>
                    222:     <li><code><span
                    223:      style='font-family:Courier'>symbread($filename)</span></code> : return symbolic 
                    224:       list entry (filename argument optional); returns the data handle </li>
                    225:     <li><span style='font-family:
                    226:      "Courier New"'>symbverify($symb,$thisfn):</span> verifies that $symb actually 
                    227:       exists and is a possible symb for the URL in $thisfn, returns a 1 on success, 
                    228:       0 on failure, user must be in a course, as it assumes the existance of the 
1.3     ! albertel  229:       course init hash, and uses $env('request.course.id'}</li>
1.2       bowersj2  230:     <li><span style='font-family:
                    231:      "Courier New"'>symbclean($symb):</span> removes versions numbers from a symb, 
                    232:       returns the cleaned symb</li>
                    233:     <li><span style='font-family:
                    234:      "Courier New"'>is_on_map($uri) :</span> checks if the $uri is somewhere on 
                    235:       the current course map, user must be in a course for it to work</li>
                    236:     <li><code><span
                    237:      style='font-family:Courier'>numval($salt)</span></code> : return random seed 
                    238:       value (addend for rndseed) </li>
                    239:     <li><code><span
                    240:      style='font-family:Courier'>rndseed($symb,$courseid,$udom,$username)</span></code> 
                    241:       : create a random sum; returns a random seed, all arguments are optional, 
                    242:       if they aren't sent it uses the environment to derive them. Note: if symb 
                    243:       isn't sent and it can't get one from &amp;symbread it will use the current 
                    244:       time as its return value </li>
                    245:     <li><code><span
                    246:      style='font-family:Courier'>ireceipt($funame,$fudom,$fucourseid,$fusymb)</span></code> 
                    247:       : return unique, unfakeable, receipt </li>
                    248:     <li><code><span
                    249:      style='font-family:Courier'>receipt()</span></code> : API to ireceipt working 
1.3     ! albertel  250:       off of env values; given out to users </li>
1.2       bowersj2  251:     <li><code><span
                    252:      style='font-family:Courier'>countacc($url)</span></code> : count the number 
                    253:       of accesses to a given URL </li>
                    254:     <li><code><span
                    255:      style='font-family:Courier'>checkout($symb,$tuname,$tudom,$tcrsid)</span></code> 
                    256:       : creates a record of a user having looked at an item, most likely printed 
                    257:       out or otherwise using a resource </li>
                    258:     <li><code><span
                    259:      style='font-family:Courier'>checkin($token)</span></code> : updates that 
                    260:       a resource has beeen returned (a hard copy version for instance) and returns 
                    261:       the data that $token was Checkout with ($symb, $tuname, $tudom, and $tcrsid) 
                    262:     </li>
                    263:     <li><code><span
                    264:      style='font-family:Courier'>expirespread($uname,$udom,$stype,$usymb)</span></code> 
                    265:       : set expire date for spreadsheet </li>
                    266:     <li><code><span
                    267:      style='font-family:Courier'>devalidate($symb)</span></code> : devalidate 
                    268:       temporary spreadsheet calculations, forcing spreadsheet to reevaluate the 
                    269:       resource scores next time. </li>
                    270:   </ul>
                    271:   <h3><a name="storing/retreiving_data"></a><a name="_Toc421867066"><span
                    272: style='"storing\/retreiving_data"'>Storing/Retrieving Data</span></a></h3>
                    273:   <ul type=disc>
                    274:     <li><code><span
                    275:      style='font-family:Courier'>store($storehash,$symb,$namespace,$udom,$uname)</span></code> 
                    276:       : stores hash permanently for this url; hashref needs to be given and should 
                    277:       be a \%hashname; the remaining args aren't required and if they aren't passed 
1.3     ! albertel  278:       or are '' they will be derived from the env </li>
1.2       bowersj2  279:     <li><code><span
                    280:      style='font-family:Courier'>cstore($storehash,$symb,$namespace,$udom,$uname)</span></code> 
                    281:       : same as store but uses critical subroutine </li>
                    282:     <li><code><span
                    283:      style='font-family:Courier'>restore($symb,$namespace,$udom,$uname)</span></code> 
                    284:       : returns hash for this symb; all args are optional </li>
                    285:     <li><code><span
                    286:      style='font-family:Courier'>tmpstore($storehash,$symb,$namespace,$udom,$uname)</span></code> 
                    287:       : storage that works very similar to store/cstore, but all data is stored 
                    288:       in a temporary location and can be reset using tmpreset, $storehash should 
                    289:       be a hash reference, returns nothing on success </li>
                    290:     <li><code><span
                    291:      style='font-family:Courier'>tmprestore($symb,$namespace,$udom,$uname)</span></code> 
                    292:       : storage that works very similar to restore, but all data is stored in 
                    293:       a temporary location and can be reset using tmpreset. Returns a hash of 
                    294:       values on success, error string otherwise. </li>
                    295:     <li><code><span
                    296:      style='font-family:Courier'>tmpreset($symb,$namespace,$udom,$uname)</span></code> 
                    297:       : temporary storage reset, deltes all keys for $symb form the temporary 
                    298:       storage hash. </li>
                    299:     <li><code><span
                    300:      style='font-family:Courier'>get($namespace,$storearr,$udom,$uname)</span></code> 
                    301:       : returns hash with keys from array reference filled in from namesp ($udomain 
                    302:       and $uname are optional) </li>
                    303:     <li><code><span
                    304:      style='font-family:Courier'>del($namespace,$storearr,$udom,$uname)</span></code> 
                    305:       : deletes keys out of array from namesp ($udomain and $uname are optional) 
                    306:     </li>
                    307:     <li><code><span
                    308:      style='font-family:Courier'>dump($namespace,$udom,$uname,$regexp)</span></code> 
                    309:       : dumps the complete (or key matching regexp) namespace into a hash ($udomain, 
                    310:       $uname and $regexp are optional) </li>
                    311:     <li><code><span
                    312:      style='font-family:Courier'>put($namespace,$storehash,$udomain,$uname)</span></code> 
                    313:       : stores hash in namesp ($udomain and $uname are optional) </li>
                    314:     <li><code><span
                    315:      style='font-family:Courier'>cput($namespace,$storehash,$udomain,$uname)</span></code> 
                    316:       : critical put ($udomain and $uname are optional) </li>
                    317:     <li><code><span
                    318:      style='font-family:Courier'>eget($namespace,$storearr,$udomain,$uname)</span></code> 
                    319:       : returns hash with keys from array reference filled in from namesp (encrypts 
                    320:       the return communication) ($udomain and $uname are optional) </li>
                    321:     <li><code><span
                    322:      style='font-family:Courier'>log($udom,$name,$home,$message)</span></code> 
                    323:       : write to permanent log for user; use critical subroutine </li>
                    324:   </ul>
                    325:   <h3><a name="network_status_functions"></a><a name="_Toc421867067">Network Status 
                    326:     Functions</a></h3>
                    327:   <ul type=disc>
                    328:     <li><code><span
                    329:      style='font-family:Courier'>dirlist($uri)</span></code> : return directory 
                    330:       list based on URI </li>
                    331:     <li><code><span
                    332:      style='font-family:Courier'>spareserver()</span></code> : find server with 
                    333:       least workload from spare.tab </li>
                    334:   </ul>
                    335:   <h3><a name="apache_request"></a><a name="_Toc421867068">Apache Request</a></h3>
                    336:   <ul type=disc>
                    337:     <li><code><span
                    338:      style='font-family:Courier'>ssi($url,%hash)</span></code> : server side include, 
                    339:       does a complete request cycle on url to localhost, posts hash </li>
                    340:   </ul>
                    341:   <h3><a name="data_to_string_to_data"></a><a name="_Toc421867069">Data to String 
                    342:     to Data</a></h3>
                    343:   <ul type=disc>
                    344:     <li><code><span
                    345:      style='font-family:Courier'>hash2str(%hash)</span></code> : convert a hash 
                    346:       into a string complete with escaping and '=' and '&amp;' separators, supports 
                    347:       elements that are arrayrefs and hashrefs </li>
                    348:     <li><code><span
                    349:      style='font-family:Courier'>hashref2str($hashref)</span></code> : convert 
                    350:       a hashref into a string complete with escaping and '=' and '&amp;' separators, 
                    351:       supports elements that are arrayrefs and hashrefs </li>
                    352:     <li><code><span
                    353:      style='font-family:Courier'>arrayref2str($arrayref)</span></code> : convert 
                    354:       an arrayref into a string complete with escaping and '&amp;' separators, 
                    355:       supports elements that are arrayrefs and hashrefs </li>
                    356:     <li><code><span
                    357:      style='font-family:Courier'>str2hash($string)</span></code> : convert string 
                    358:       to hash using unescaping and splitting on '=' and '&amp;', supports elements 
                    359:       that are arrayrefs and hashrefs </li>
                    360:     <li><code><span
                    361:      style='font-family:Courier'>str2array($string)</span></code> : convert string 
                    362:       to hash using unescaping and splitting on '&amp;', supports elements that 
                    363:       are arrayrefs and hashrefs </li>
                    364:   </ul>
                    365:   <h3><a name="logging_routines"></a><a name="_Toc421867070">Logging Routines</a></h3>
                    366:   <p>These routines allow one to make log messages in the lonnet.log and lonnet.perm 
                    367:     logfiles.</p>
                    368:   <ul type=disc>
                    369:     <li><code><span
                    370:      style='font-family:Courier'>logtouch()</span></code> : make sure the logfile, 
                    371:       lonnet.log, exists </li>
                    372:     <li><code><span
                    373:      style='font-family:Courier'>logthis()</span></code> : append message to the 
                    374:       normal lonnet.log file, it gets preiodically rolled over and deleted. </li>
                    375:     <li><code><span
                    376:      style='font-family:Courier'>logperm()</span></code> : append a permanent 
                    377:       message to lonnet.perm.log, this log file never gets deleted by any automated 
                    378:       portion of the system, only messages of critical importance should go in 
                    379:       here. </li>
                    380:   </ul>
                    381:   <h3><a name="general_helper_routines"></a><a name="_Toc421867071">General File 
                    382:     Helper Routines</a></h3>
                    383:   <ul type=disc>
                    384:     <li><code><span
                    385:      style='font-family:Courier'>getfile($file)</span></code> : serves up a file, 
                    386:       returns the contents of a file or -1; replicates and subscribes to the file 
                    387:     </li>
                    388:     <li><code><span
                    389:      style='font-family:Courier'>filelocation($dir,$file)</span></code> : returns 
                    390:       file system location of a file based on URI; meant to be ``fairly clean'' 
                    391:       absolute reference, $dir is a directory that relative $file lookups are 
                    392:       to looked in ($dir of /a/dir and a file of ../bob will become /a/bob) </li>
                    393:     <li><code><span
                    394:      style='font-family:Courier'>hreflocation($dir,$file)</span></code> : returns 
                    395:       file system location or a URL; same as filelocation except for hrefs </li>
                    396:     <li><code><span
                    397:      style='font-family:Courier'>declutter()</span></code> : declutters URLs (remove 
                    398:       docroot, beginning slashes, 'res' etc) </li>
                    399:   </ul>
                    400:   <h3><a name="_Toc421867072">HTTP Helper Routines</a></h3>
                    401:   <ul type=disc>
                    402:     <li><code><span
                    403:      style='font-family:Courier'>escape()</span></code> : unpack non-word characters 
                    404:       into CGI-compatible hex codes </li>
                    405:     <li><code><span
                    406:      style='font-family:Courier'>unescape()</span></code> : pack CGI-compatible 
                    407:       hex codes into actual non-word ASCII character </li>
                    408:   </ul>
                    409: </div>
                    410: <h1>&nbsp;</h1>
                    411: <h3><a name="underlying_communication_routines_(shoul"></a><a
                    412: name="_Toc421867073">Private: Underlying communication routines (Shouldn't call)</a></h3>
                    413: <ul type=disc>
                    414:   <li><code><span style='font-family:
                    415:      Courier'>subreply()</span></code> : tries to pass a message to lonc, returns 
                    416:     con_lost if incapable </li>
                    417:   <li><code><span style='font-family:
                    418:      Courier'>reply()</span></code> : uses subreply to send a message to remote 
                    419:     machine, logs all failures </li>
                    420:   <li><code><span style='font-family:
                    421:      Courier'>critical()</span></code> : passes a critical message to another 
                    422:     server; if cannot get through then place message in connection buffer directory 
                    423:     and returns con_delayed, if incapable of saving message, returns con_failed 
                    424:   </li>
                    425:   <li><code><span style='font-family:
                    426:      Courier'>reconlonc()</span></code> : tries to reconnect lonc client processes. 
                    427:   </li>
                    428: </ul>
                    429: <h3><a name="resource_access_logging"></a><a name="_Toc421867074">Private: Resource 
                    430:   Access Logging</a></h3>
                    431: <ul type=disc>
                    432:   <li><code><span style='font-family:
                    433:      Courier'>flushcourselogs()</span></code> : flush (save) buffer logs and access 
                    434:     logs </li>
                    435:   <li><code><span style='font-family:
                    436:      Courier'>courselog($what)</span></code> : save message for course in hash 
                    437:   </li>
                    438:   <li><code><span style='font-family:
                    439:      Courier'>courseacclog($what)</span></code> : save message for course using 
                    440:     &amp;courselog(). Perform special processing for specific resource types (problems, 
                    441:     exams, quizzes, etc). </li>
                    442:   <li><code><span style='font-family:
                    443:      Courier'>goodbye()</span></code> : flush course logs and log shutting down; 
                    444:     it is called in srm.conf as a PerlChildExitHandler </li>
                    445: </ul>
                    446: <h3><a name=other></a><a name="_Toc421867075">Private: Other</a></h3>
                    447: <p><code><span style='font-family:"Courier New"'>symblist($mapname,%newhash)</span></code><span
                    448: style='font-family:"Courier New"'> :</span> update symbolic storage links </p>
                    449: <h3><a name="_Toc421867076">Coding Guidelines</a></h3>
                    450: <p class=H5><span style='layout-grid-mode:
                    451: both'>Things to keep in mind while coding handlers for LON-CAPA </span></p>
                    452: <p><span
                    453: style='font-size:14.0pt'>1.<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; 
                    454:   </span></span><span style='font-size:14.0pt'>DON'T write to Access machine disks 
                    455:   with permanent data, use store/restore </span></p>
                    456: <p><span
                    457: style='font-size:14.0pt'>2.<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; 
                    458:   </span></span><span style='font-size:14.0pt'>DON'T </span><span
                    459: style='font-size:14.0pt;font-family:"Courier New"'>use print()</span><span
                    460: style='font-size:14.0pt'>, use </span><span style='font-size:14.0pt;font-family:
                    461: "Courier New"'>$request-&gt;print()</span><span style='font-size:14.0pt'> </span></p>
                    462: <p><span
                    463: style='font-size:14.0pt'>3.<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; 
                    464:   </span></span><span style='font-size:14.0pt'>DON'T launch children </span></p>
                    465: <p><span
                    466: style='font-size:14.0pt'>4.<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; 
                    467:   </span></span><span style='font-size:14.0pt'>DO use </span><span
                    468: style='font-size:14.0pt;font-family:"Courier New"'>$Apache::lonnet::perlvar{'lonDaemons'}/tmp</span><span
                    469: style='font-size:14.0pt'> for temporary data. </span></p>
                    470: <p><span
                    471: style='font-size:14.0pt'>5.<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; 
                    472:   </span></span><span style='font-size:14.0pt'>DO query the return value of every 
                    473:   file operation. </span></p>
                    474: <p><span
                    475: style='font-size:14.0pt'>6.<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; 
                    476:   </span></span><span style='font-size:14.0pt'>DO </span><span style='font-size:
                    477: 14.0pt;font-family:"Courier New"'>use strict;</span><span style='font-size:
                    478: 14.0pt'> </span></p>
                    479: <p><span
                    480: style='font-size:14.0pt'>7.<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; 
                    481:   </span></span><span style='font-size:14.0pt'>DO </span><span style='font-size:
                    482: 14.0pt;font-family:"Courier New"'>use strict;</span><span style='font-size:
                    483: 14.0pt'> </span></p>
                    484: <p><span
                    485: style='font-size:14.0pt'>8.<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp; 
                    486:   </span></span><span style='font-size:14.0pt'>DO familiarize your self with the 
                    487:   functions in </span><span style='font-size:14.0pt;font-family:"Courier New"'>lonnet.pm</span><span
                    488: style='font-size:14.0pt'> and use them to communicate with other servers and when 
                    489:   you handler needs to ask questions. </span></p>
                    490: <p>9.<span
                    491: style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp; </span><span
                    492: style='font-size:14.0pt'>DON'T use </span><span style='font-size:14.0pt;
                    493: font-family:"Courier New"'>&amp;Apache::lonnet::reply()</span><span
                    494: style='font-size:14.0pt'> </span></p>
                    495: <br
                    496: clear=ALL style='page-break-before:always;'>
                    497: <div class=Section2> </div>
                    498: </body>
                    499: </html>

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