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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> &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>
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