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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, $CacheTablePrefix = "", $RefreshTime = 600, $DebugLevel = 0)
    00024     {
    00025         # set default debug level
    00026         $this->DebugLevel = $DebugLevel;
    00027
    00028         # query server (or cache) for XML text
    00029         $this->XmlText = $this->QueryServerWithCaching($ServerUrl, $CacheDB, $CacheTablePrefix, $RefreshTime);
    00030
    00031         # create XML parser and parse text
    00032         $this->Parser = new XMLParser();
    00033         if ($this->DebugLevel > 3) {  $Parser->SetDebugLevel($this->DebugLevel - 3);  }
    00034         $this->Parser->ParseText($this->XmlText);
    00035
    00036         if ($this->DebugLevel) {  print("RSSClient->RSSClient() returned ".strlen($this->XmlText)." characters from server query<br>\n");  }
    00037     }
    00038
    00039     # get/set server URL
    00040     function ServerUrl($NewValue = NULL)
    00041     {
    00042         # if new RSS server URL supplied
    00043         if (($NewValue != NULL) && ($NewValue != $this->ServerUrl))
    00044         {
    00045             # save new value
    00046             $this->ServerUrl = $NewValue;
    00047
    00048             # re-read XML from server at new URL
    00049             $this->XmlText = $this->QueryServerWithCaching($NewValue);
    00050
    00051             # create new XML parser and parse text
    00052             $this->Parser = new XMLParser();
    00053             if ($this->DebugLevel > 3) {  $Parser->SetDebugLevel($this->DebugLevel - 3);  }
    00054             $this->Parser->ParseText($this->XmlText);
    00055         }
    00056
    00057         # return RSS server URL to caller
    00058         return $this->ServerUrl;
    00059     }
    00060
    00061     # retrieve RSS items (from first channel if not otherwise specified)
    00062     function GetItems($NumberOfItems = NULL, $ChannelName = NULL)
    00063     {
    00064         # start by assuming no items will be found
    00065         $Items = array();
    00066
    00067         # move parser to area in XML with items
    00068         $Parser = $this->Parser;
    00069         $Parser->SeekToRoot();
    00070         $Result = $Parser->SeekTo("rss");
    00071         if ($Result === NULL)
    00072         {
    00073             $Result = $Parser->SeekTo("rdf:RDF");
    00074         }
    00075         else
    00076         {
    00077             $Parser->SeekTo("channel");
    00078         }
    00079
    00080         # if items are found
    00081         $ItemCount = $Parser->SeekTo("item");
    00082         if ($ItemCount)
    00083         {
    00084             # for each record
    00085             $Index = 0;
    00086             do
    00087             {
    00088                 # retrieve item info
    00089                 $Items[$Index]["title"] = $Parser->GetData("title");
    00090                 $Items[$Index]["description"] = $Parser->GetData("description");
    00091                 $Items[$Index]["link"] = $Parser->GetData("link");
    00092                 $Items[$Index]["enclosure"] = $Parser->GetAttributes("enclosure");
    00093
    00094                 $Index++;
    00095             }
    00096             while ($Parser->NextItem() && (($NumberOfItems == NULL) || ($Index < $NumberOfItems)));
    00097         }
    00098
    00099         # return records to caller
    00100         return $Items;
    00101     }
    00102
    00103     # retrieve site name as given in feed
    00104     function GetChannelTitle()
    00105     {
    00106         if (!isset($this->ChannelTitle)) {  $this->LoadChannelInfo();  }
    00107         return $this->ChannelTitle;
    00108     }
    00109
    00110     # retrieve site link as given in feed
    00111     function GetChannelLink()
    00112     {
    00113         if (!isset($this->ChannelLink)) {  $this->LoadChannelInfo();  }
    00114         return $this->ChannelLink;
    00115     }
    00116
    00117     # retrieve site description as given in feed
    00118     function GetChannelDescription()
    00119     {
    00120         if (!isset($this->ChannelDescription)) {  $this->LoadChannelInfo();  }
    00121         return $this->ChannelDescription;
    00122     }
    00123
    00124     # tell caller whether client is using cached data
    00125     function UsedCachedData()
    00126     {
    00127         return $this->CachedDataWasUsed;
    00128     }
    00129
    00130
    00131     # ---- PRIVATE INTERFACE -------------------------------------------------
    00132
    00133     var $ServerUrl;
    00134     var $MetadataPrefix;
    00135     var $SetSpec;
    00136     var $DebugLevel;
    00137     var $XmlText;
    00138     var $Parser;
    00139     var $ChannelTitle;
    00140     var $ChannelLink;
    00141     var $ChannelDescription;
    00142     var $CachedDataWasUsed;
    00143
    00144     # set current debug output level (0-9)
    00145     function SetDebugLevel($NewLevel)
    00146     {
    00147         $this->DebugLevel = $NewLevel;
    00148     }
    00149
    00150     # load RSS XML from server or cache
    00151     function QueryServerWithCaching($ServerUrl, $CacheDB, $CacheTablePrefix, $RefreshTime)
    00152     {
    00153         # save RSS server URL
    00154         $this->ServerUrl = $ServerUrl;
    00155
    00156         # save caching info (if any)
    00157         if ($CacheDB)
    00158         {
    00159             $this->CacheDB = $CacheDB;
    00160         }
    00161         $this->CacheTablePrefix = $CacheTablePrefix;
    00162
    00163         # if caching info was supplied
    00164         if ($this->CacheDB)
    00165         {
    00166             # create cache table if it doesn't exist
    00167             $DB = $this->CacheDB;
    00168             $TableName = $CacheTablePrefix."RSSClientCache";
    00169             $DB->Query("CREATE TABLE IF NOT EXISTS ".$TableName." ("
    00170                     ."ServerUrl      TEXT,"
    00171                     ."CachedXml      TEXT,"
    00172                     ."LastQueryTime  DATETIME"
    00173                     .");");
    00174
    00175             # look up cached information for this server
    00176             $QueryTimeCutoff = date("Y-m-d H:i:s", (time() - $RefreshTime));
    00177             $DB->Query("SELECT * FROM ".$TableName." WHERE ServerUrl = '".addslashes($ServerUrl)."'"
    00178                     ." AND LastQueryTime > '".$QueryTimeCutoff."'");
    00179
    00180             # if we have cached info that has not expired
    00181             if ($CachedXml = $DB->FetchField("CachedXml"))
    00182             {
    00183                 # use cached info
    00184                 $QueryResult = $CachedXml;
    00185                 $this->CachedDataWasUsed = TRUE;
    00186             }
    00187             else
    00188             {
    00189                 # query server for XML text
    00190                 $QueryResult = ($Text = @file_get_contents($ServerUrl))
    00191                     ? $Text : "";
    00192                 $this->CachedDataWasUsed = FALSE;
    00193
    00194                 # if query was successful
    00195                 if (strlen($QueryResult))
    00196                 {
    00197                     # clear out any old cache entries
    00198                     $DB->Query("DELETE FROM ".$TableName." WHERE ServerUrl = '".addslashes($ServerUrl)."'");
    00199
    00200                     # save info in cache
    00201                     $DB->Query("INSERT INTO ".$TableName." (ServerUrl, CachedXml, LastQueryTime)"
    00202                             ." VALUES ('".addslashes($ServerUrl)."', '".addslashes($QueryResult)."', NOW())");
    00203                 }
    00204             }
    00205         }
    00206
    00207         # return query result to caller
    00208         return $QueryResult;
    00209     }
    00210
    00211     function LoadChannelInfo()
    00212     {
    00213         $Parser = $this->Parser;
    00214         $Parser->SeekToRoot();
    00215         $Result = $Parser->SeekTo("rss");
    00216         if ($Result === NULL)
    00217         {
    00218             $Result = $Parser->SeekTo("rdf:RDF");
    00219         }
    00220         $Parser->SeekTo("channel");
    00221         $this->ChannelTitle = $Parser->GetData("title");
    00222         $this->ChannelLink = $Parser->GetData("link");
    00223         $this->ChannelDescription = $Parser->GetData("description");
    00224     }
    00225 }
    00226
    00227
    00228 ?>

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