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# RSSClient.php

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    00001 <?PHP
    00002
    00003 #
    00004 #   FILE:  Scout--RSSClient.php
    00005 #
    00006 #   METHODS PROVIDED:
    00007 #       RSSClient()
    00008 #           - constructor
    00009 #       SomeMethod($SomeParameter, $AnotherParameter)
    00010 #           - short description of method
    00011 #
    00012 #   AUTHOR:  Edward Almasy
    00013 #
    00014 #   Copyright 2005 Internet Scout Project
    00015 #   http://scout.wisc.edu
    00016 #
    00017
    00018 class RSSClient {
    00019
    00020     # ---- PUBLIC INTERFACE --------------------------------------------------
    00021
    00022     # object constructor
    00023     function RSSClient($ServerUrl, $CacheDB = NULL, $RefreshTime = 600, $Encoding = "UTF-8", $DebugLevel = 0)
    00024     {
    00025         # set default debug level
    00026         $this->DebugLevel = $DebugLevel;
    00027
    00028         # set default encoding
    00029         $this->Encoding = $Encoding;
    00030
    00031         # save cache details
    00032         $this->CacheDB = $CacheDB;
    00033         $this->RefreshTime = $RefreshTime;
    00034
    00035         # query server (or cache) for XML text
    00036         $this->XmlText = $this->QueryServerWithCaching(
    00037             $ServerUrl, $CacheDB, $RefreshTime);
    00038
    00039         # create XML parser and parse text
    00040         $this->Parser = new XMLParser($this->Encoding);
    00041         if ($this->DebugLevel > 3) {  $Parser->SetDebugLevel($this->DebugLevel - 3);  }
    00042         $this->Parser->ParseText($this->XmlText);
    00043
    00044         if ($this->DebugLevel) {  print("RSSClient->RSSClient() returned ".strlen($this->XmlText)." characters from server query<br>\n");  }
    00045     }
    00046
    00047     # get/set server URL
    00048     function ServerUrl($NewValue = NULL)
    00049     {
    00050         # if new RSS server URL supplied
    00051         if (($NewValue != NULL) && ($NewValue != $this->ServerUrl))
    00052         {
    00053             # save new value
    00054             $this->ServerUrl = $NewValue;
    00055
    00056             # re-read XML from server at new URL
    00057             $this->XmlText = $this->QueryServerWithCaching(
    00058                 $NewValue,
    00059                 $this->CacheDB,
    00060                 $this->RefreshTime);
    00061
    00062             # create new XML parser and parse text
    00063             $this->Parser = new XMLParser();
    00064             if ($this->DebugLevel > 3) {  $Parser->SetDebugLevel($this->DebugLevel - 3);  }
    00065             $this->Parser->ParseText($this->XmlText);
    00066         }
    00067
    00068         # return RSS server URL to caller
    00069         return $this->ServerUrl;
    00070     }
    00071
    00072     # get/set encoding
    00073     function Encoding($NewValue = NULL)
    00074     {
    00075         # if new encoding supplied
    00076         if (($NewValue != NULL) && ($NewValue != $this->Encoding))
    00077         {
    00078             # save new value
    00079             $this->Encoding = $NewValue;
    00080
    00081             # re-read XML from server
    00082             $this->XmlText = $this->QueryServerWithCaching(
    00083                 $this->ServerUrl,
    00084                 $this->CacheDB,
    00085                 $this->RefreshTime);
    00086
    00087             # create new XML parser and parse text
    00088             $this->Parser = new XMLParser($this->Encoding);
    00089             if ($this->DebugLevel > 3) {  $Parser->SetDebugLevel($this->DebugLevel - 3);  }
    00090             $this->Parser->ParseText($this->XmlText);
    00091         }
    00092
    00093         # return encoding to caller
    00094         return $this->Encoding;
    00095     }
    00096
    00102     function AutodetectEncoding()
    00103     {
    00104         # if neither the XML file nor the HTTP response headers specify an
    00105         # encoding, there is an overwhelming chance that it's ISO-8859-1, so
    00106         # use it as the default
    00107         $Encoding = "ISO-8859-1";
    00108
    00109         # only get up to the the encoding portion of the XML declartion
    00110         # http://www.w3.org/TR/2006/REC-xml-20060816/#sec-prolog-dtd
    00111         $S = '[ \t\r\n]';
    00112         $Eq = "{$S}?={$S}?";
    00113         $VersionNum = '1.0';
    00114         $EncName = '[A-Za-z]([A-Za-z0-9._]|-)*';
    00115         $VersionInfo = "{$S}version{$Eq}('{$VersionNum}'|\"{$VersionNum}\")";
    00116         $EncodingDecl = "{$S}encoding{$Eq}('{$EncName}'|\"{$EncName}\")";
    00117         $XMLDecl = "<\?xml{$VersionInfo}({$EncodingDecl})?";
    00118         $RegEx = "/{$XMLDecl}/";
    00119
    00120         # try to find the encoding, index 3 will be set if encoding is declared
    00121         preg_match($RegEx, $this->XmlText, $Matches);
    00122
    00123         # give precedence to the encoding specified within the XML file since
    00124         # a RSS feed publisher might not have access to HTTP response headers
    00125         if (count($Matches) >= 4)
    00126         {
    00127             # also need to strip off the quotes
    00128             $Encoding = trim($Matches[3], "'\"");
    00129         }
    00130
    00131         # then give precedence to the charset parameter in the Content-Type
    00132         # response header
    00133         else if ($this->CacheDB)
    00134         {
    00135             # create cache table if it doesn't exist
    00136             $DB = $this->CacheDB;
    00137             $ServerUrl = addslashes($this->ServerUrl);
    00138
    00139             # get the cache value
    00140             $DB->Query("
    00141                 SELECT * FROM RSSClientCache
    00142                 WHERE ServerUrl = '".$ServerUrl."'");
    00143             $Exists = ($DB->NumRowsSelected() > 0);
    00144             $Cache = $DB->FetchRow();
    00145
    00146             # if cached and charset parameter was given in the response headers
    00147             if ($Exists && strlen($Cache["Charset"]))
    00148             {
    00149                 $Encoding = $Cache["Charset"];
    00150             }
    00151         }
    00152
    00153         $this->Encoding($Encoding);
    00154     }
    00155
    00156     # retrieve RSS items (from first channel if not otherwise specified)
    00157     function GetItems($NumberOfItems = NULL, $ChannelName = NULL)
    00158     {
    00159         # start by assuming no items will be found
    00160         $Items = array();
    00161
    00162         # move parser to area in XML with items
    00163         $Parser = $this->Parser;
    00164         $Parser->SeekToRoot();
    00165         $Result = $Parser->SeekTo("rss");
    00166         if ($Result === NULL)
    00167         {
    00168             $Result = $Parser->SeekTo("rdf:RDF");
    00169         }
    00170         else
    00171         {
    00172             $Parser->SeekTo("channel");
    00173         }
    00174
    00175         # if items are found
    00176         $ItemCount = $Parser->SeekTo("item");
    00177         if ($ItemCount)
    00178         {
    00179             # for each record
    00180             $Index = 0;
    00181             do
    00182             {
    00183                 # retrieve item info
    00184                 $Items[$Index]["title"] = $Parser->GetData("title");
    00185                 $Items[$Index]["description"] = $Parser->GetData("description");
    00186                 $Items[$Index]["link"] = $Parser->GetData("link");
    00187                 $Items[$Index]["enclosure"] = $Parser->GetAttributes("enclosure");
    00188
    00189                 $Index++;
    00190             }
    00191             while ($Parser->NextItem() && (($NumberOfItems == NULL) || ($Index < $NumberOfItems)));
    00192         }
    00193
    00194         # return records to caller
    00195         return $Items;
    00196     }
    00197
    00198     # retrieve site name as given in feed
    00199     function GetChannelTitle()
    00200     {
    00201         if (!isset($this->ChannelTitle)) {  $this->LoadChannelInfo();  }
    00202         return $this->ChannelTitle;
    00203     }
    00204
    00205     # retrieve site link as given in feed
    00206     function GetChannelLink()
    00207     {
    00208         if (!isset($this->ChannelLink)) {  $this->LoadChannelInfo();  }
    00209         return $this->ChannelLink;
    00210     }
    00211
    00212     # retrieve site description as given in feed
    00213     function GetChannelDescription()
    00214     {
    00215         if (!isset($this->ChannelDescription)) {  $this->LoadChannelInfo();  }
    00216         return $this->ChannelDescription;
    00217     }
    00218
    00219     # tell caller whether client is using cached data
    00220     function UsedCachedData()
    00221     {
    00222         return $this->CachedDataWasUsed;
    00223     }
    00224
    00225
    00226     # ---- PRIVATE INTERFACE -------------------------------------------------
    00227
    00228     var $CacheDB;
    00229     var $RefreshTime;
    00230     var $ServerUrl;
    00231     var $MetadataPrefix;
    00232     var $SetSpec;
    00233     var $DebugLevel;
    00234     var $Encoding;
    00235     var $XmlText;
    00236     var $Parser;
    00237     var $ChannelTitle;
    00238     var $ChannelLink;
    00239     var $ChannelDescription;
    00240     var $CachedDataWasUsed;
    00241
    00242     # set current debug output level (0-9)
    00243     function SetDebugLevel($NewLevel)
    00244     {
    00245         $this->DebugLevel = $NewLevel;
    00246     }
    00247
    00257     function GetXmlInfo($Url)
    00258     {
    00259         $Text = @file_get_contents($Url);
    00260         $Type = NULL;
    00261         $Charset = NULL;
    00262
    00263         # get the type and charset if the fetch was successful
    00264         if ($Text !== FALSE)
    00265         {
    00266             # this must come after file_get_contents() and before any other remote
    00267             # fetching is done
    00268             $Headers = $http_response_header;
    00269
    00270             # http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.17
    00271             $LWS = '([ \t]*|\r\n[ \t]+)';
    00272             $Token = '[!\x23-\x27*+-.\x30-\x39\x41-\x5A\x5E-\x7A|~]+';
    00273             $QuotedPair = '\\[\x00-\x7F]';
    00274             $QdText = "([^\\x00-\\x1F\\x7F\"]|{$LWS})";
    00275             $QuotedString = "\"({$QdText}|{$QuotedPair})*\"";
    00276             $Value = "({$Token}|{$QuotedString})";
    00277             $Parameter = "{$Token}{$LWS}={$LWS}{$Value}";
    00278
    00279             # these make the Content-Type regex specific to Content-Type
    00280             # values with charset parameters in them, but make capturing
    00281             # the charset much easier
    00282             $BasicParameter = "(;{$LWS}{$Parameter})*";
    00283             $CharsetParameter = "(;{$LWS}charset{$LWS}={$LWS}{$Value})";
    00284             $ModParameter = "{$BasicParameter}{$CharsetParameter}{$BasicParameter}";
    00285             $MediaType = "({$Token}{$LWS}\\/{$LWS}{$Token}){$LWS}{$ModParameter}";
    00286
    00287             # back to the spec
    00288             $ContentType = "Content-Type{$LWS}:{$LWS}{$MediaType}{$LWS}";
    00289             $RegEx = "/^{$ContentType}$/i";
    00290
    00291             foreach ($Headers as $Header)
    00292             {
    00293                 preg_match($RegEx, $Header, $Matches);
    00294
    00295                 if (isset($Matches[3]) && isset($Matches[19]))
    00296                 {
    00297                     $Type = $Matches[3];
    00298                     $Charset = $Matches[19];
    00299                     break;
    00300                 }
    00301             }
    00302         }
    00303
    00304         return array($Text, $Type, $Charset);
    00305     }
    00306
    00307     # load RSS XML from server or cache
    00308     function QueryServerWithCaching($ServerUrl, $CacheDB, $RefreshTime)
    00309     {
    00310         # save RSS server URL
    00311         $this->ServerUrl = $ServerUrl;
    00312
    00313         # save caching info (if any)
    00314         if ($CacheDB)
    00315         {
    00316             $this->CacheDB = $CacheDB;
    00317         }
    00318
    00319         # if caching info was supplied
    00320         if ($this->CacheDB)
    00321         {
    00322             $DB = $this->CacheDB;
    00323
    00324             # look up cached information for this server
    00325             $QueryTimeCutoff = date("Y-m-d H:i:s", (time() - $RefreshTime));
    00326             $DB->Query("
    00327                 SELECT * FROM RSSClientCache
    00328                 WHERE ServerUrl = '".addslashes($ServerUrl)."'
    00329                 AND LastQueryTime > '".$QueryTimeCutoff."'");
    00330
    00331             # if we have cached info that has not expired
    00332             if ($CachedXml = $DB->FetchField("CachedXml"))
    00333             {
    00334                 # use cached info
    00335                 $QueryResult = $CachedXml;
    00336                 $this->CachedDataWasUsed = TRUE;
    00337             }
    00338             else
    00339             {
    00340                 $this->CachedDataWasUsed = FALSE;
    00341
    00342                 # query server for XML text
    00343                 list($Text, $Type, $Charset) = $this->GetXmlInfo($ServerUrl);
    00344                 $QueryResult = "";
    00345
    00346                 # if query was successful
    00347                 if ($Text !== FALSE)
    00348                 {
    00349                     $QueryResult = $Text;
    00350
    00351                     # clear out any old cache entries
    00352                     $DB->Query("
    00353                         DELETE FROM RSSClientCache
    00354                         WHERE ServerUrl = '".addslashes($ServerUrl)."'");
    00355
    00356                     # save info in cache
    00357                     $DB->Query("
    00358                         INSERT INTO RSSClientCache
    00359                         (ServerUrl, CachedXml, Type, Charset, LastQueryTime)
    00360                         VALUES (
    00361                             '".addslashes($ServerUrl)."',
    00362                             '".addslashes($Text)."',
    00363                             '".addslashes($Type)."',
    00364                             '".addslashes($Charset)."',
    00365                             NOW())");
    00366                 }
    00367             }
    00368         }
    00369
    00370         # return query result to caller
    00371         return $QueryResult;
    00372     }
    00373
    00374     function LoadChannelInfo()
    00375     {
    00376         $Parser = $this->Parser;
    00377         $Parser->SeekToRoot();
    00378         $Result = $Parser->SeekTo("rss");
    00379         if ($Result === NULL)
    00380         {
    00381             $Result = $Parser->SeekTo("rdf:RDF");
    00382         }
    00383         $Parser->SeekTo("channel");
    00384         $this->ChannelTitle = $Parser->GetData("title");
    00385         $this->ChannelLink = $Parser->GetData("link");
    00386         $this->ChannelDescription = $Parser->GetData("description");
    00387     }
    00388 }

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