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1: <html> 2: <head> 3: <meta name=Title 4: content=" Session Three: Roles and lonnet/loncommon useful functions (Guy)"> 5: <meta http-equiv=Content-Type content="text/html; charset=macintosh"> 6: <link rel=Edit-Time-Data href="Session%20Three_files/editdata.mso"> 7: <title> Session Three: Roles and lonnet/loncommon useful functions (Guy)</title> 8: <style> 14: </style> 15: </head> 16: <body bgcolor=#FFFFFF link=blue vlink=purple class="Normal" lang=EN-US> 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>  &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 75: during this session, also modifies the %ENV for the current process </li> 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 $regexp. The values 79: are also delted from the current processes %ENV. </li> 80: </ul> 81: <h3><a name="user_information"></a><a name="_Toc421867059">User Information</a></h3> 82: <ul type=disc> 83: <li><code><span style='font-family: 84: Courier'>queryauthenticate($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=>name,id=>name) </li> 99: <li><code><span style='font-family: 100: Courier'>idrget($udom,@unames)</span></code> : find the IDs behind a list 101: of usernames (returns hash: name=>id,name=>id) </li> 102: <li><code><span style='font-family: 103: Courier'>idput($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 229: course init hash, and uses $ENV('request.course.id'}</li> 230: <li><span style='font-family: 231: "Courier New"'>symbclean($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 &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 250: off of ENV values; given out to users </li> 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,$uname)</span></code> 276: : stores hash permanently for this url; hashref needs to be given and should 277: be a \%hashname; the remaining args aren't required and if they aren't passed 278: or are '' they will be derived from the ENV </li> 279: <li><code><span 280: style='font-family:Courier'>cstore($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($url,%hash)</span></code> : server side include, 339: does a complete request cycle on url to localhost, posts hash </li> 340: </ul> 341: <h3><a name="data_to_string_to_data"></a><a name="_Toc421867069">Data to String 342: to Data</a></h3> 343: <ul type=disc> 344: <li><code><span 345: style='font-family:Courier'>hash2str(%hash)</span></code> : convert a hash 346: into a string complete with escaping and '=' and '&' separators, supports 347: elements that are arrayrefs and hashrefs </li> 348: <li><code><span 349: style='font-family:Courier'>hashref2str($hashref)</span></code> : convert 350: a hashref into a string complete with escaping and '=' and '&' separators, 351: supports elements that are arrayrefs and hashrefs </li> 352: <li><code><span 353: style='font-family:Courier'>arrayref2str($arrayref)</span></code> : convert 354: an arrayref into a string complete with escaping and '&' separators, 355: supports elements that are arrayrefs and hashrefs </li> 356: <li><code><span 357: style='font-family:Courier'>str2hash($string)</span></code> : convert string 358: to hash using unescaping and splitting on '=' and '&', supports elements 359: that are arrayrefs and hashrefs </li> 360: <li><code><span 361: style='font-family:Courier'>str2array($string)</span></code> : convert string 362: to hash using unescaping and splitting on '&', supports elements that 363: are arrayrefs and hashrefs </li> 364: </ul> 365: <h3><a name="logging_routines"></a><a name="_Toc421867070">Logging Routines</a></h3> 366: <p>These routines allow one to make log messages in the lonnet.log and lonnet.perm 367: logfiles.</p> 368: <ul type=disc> 369: <li><code><span 370: style='font-family:Courier'>logtouch()</span></code> : make sure the logfile, 371: lonnet.log, exists </li> 372: <li><code><span 373: style='font-family:Courier'>logthis()</span></code> : append message to the 374: normal lonnet.log file, it gets preiodically rolled over and deleted. </li> 375: <li><code><span 376: style='font-family:Courier'>logperm()</span></code> : append a permanent 377: message to lonnet.perm.log, this log file never gets deleted by any automated 378: portion of the system, only messages of critical importance should go in 379: here. </li> 380: </ul> 381: <h3><a name="general_helper_routines"></a><a name="_Toc421867071">General File 382: Helper Routines</a></h3> 383: <ul type=disc> 384: <li><code><span 385: style='font-family:Courier'>getfile($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> </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: &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($mapname,%newhash)</span></code><span 448: style='font-family:"Courier New"'> :</span> update symbolic storage links </p> 449: <h3><a name="_Toc421867076">Coding Guidelines</a></h3> 450: <p class=H5><span style='layout-grid-mode: 451: both'>Things to keep in mind while coding handlers for LON-CAPA </span></p> 452: <p><span 453: style='font-size:14.0pt'>1.<span style='font:7.0pt "Times New Roman"'>    454: </span></span><span style='font-size:14.0pt'>DON'T write to Access machine disks 455: with permanent data, use store/restore </span></p> 456: <p><span 457: style='font-size:14.0pt'>2.<span style='font:7.0pt "Times New Roman"'>    458: </span></span><span style='font-size:14.0pt'>DON'T </span><span 459: style='font-size:14.0pt;font-family:"Courier New"'>use print()</span><span 460: style='font-size:14.0pt'>, use </span><span style='font-size:14.0pt;font-family: 461: "Courier New"'>$request->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"'>    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"'>    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"'>    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"'>    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"'>    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"'>    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"'>     </span><span 492: style='font-size:14.0pt'>DON'T use </span><span style='font-size:14.0pt; 493: font-family:"Courier New"'>&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>