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RSSClient.php
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1 <?PHP
2 #
3 # FILE: RSSClient.php
4 #
5 # Part of the ScoutLib application support library
6 # Copyright 2002-2013 Edward Almasy and Internet Scout Research Group
7 # http://scout.wisc.edu/
8 #
9
13 class RSSClient {
14
15 # ---- PUBLIC INTERFACE --------------------------------------------------
16
29 function RSSClient($ServerUrl, $CacheDB = NULL, $RefreshTime = 600, $Encoding = "UTF-8", $DebugLevel = 0)
30 {
31 # set default debug level
32 $this->DebugLevel = $DebugLevel;
33
34 # set default encoding
35 $this->Encoding = $Encoding;
36
37 # save cache details
38 $this->CacheDB = $CacheDB;
39 $this->RefreshTime = $RefreshTime;
40
41 # query server (or cache) for XML text
42 $this->XmlText = $this->QueryServerWithCaching(
43 $ServerUrl, $CacheDB, $RefreshTime);
44
45 # create XML parser and parse text
46 $this->Parser = new XMLParser($this->Encoding);
47 if ($this->DebugLevel > 3) { $Parser->SetDebugLevel($this->DebugLevel - 3); }
48 $this->Parser->ParseText($this->XmlText);
49
50 if ($this->DebugLevel) { print("RSSClient->RSSClient() returned ".strlen($this->XmlText)." characters from server query<br>\n"); }
51 }
52
58 function ServerUrl($NewValue = NULL)
59 {
60 # if new RSS server URL supplied
61 if (($NewValue != NULL) && ($NewValue != $this->ServerUrl))
62 {
63 # save new value
64 $this->ServerUrl = $NewValue;
65
66 # re-read XML from server at new URL
67 $this->XmlText = $this->QueryServerWithCaching(
68 $NewValue,
69 $this->CacheDB,
70 $this->RefreshTime);
71
72 # create new XML parser and parse text
73 $this->Parser = new XMLParser();
74 if ($this->DebugLevel > 3) { $Parser->SetDebugLevel($this->DebugLevel - 3); }
75 $this->Parser->ParseText($this->XmlText);
76 }
77
78 # return RSS server URL to caller
79 return $this->ServerUrl;
80 }
81
88 function Encoding($NewValue = NULL)
89 {
90 # if new encoding supplied
91 if (($NewValue != NULL) && ($NewValue != $this->Encoding))
92 {
93 # save new value
94 $this->Encoding = $NewValue;
95
96 # re-read XML from server
97 $this->XmlText = $this->QueryServerWithCaching(
98 $this->ServerUrl,
99 $this->CacheDB,
100 $this->RefreshTime);
101
102 # create new XML parser and parse text
103 $this->Parser = new XMLParser($this->Encoding);
104 if ($this->DebugLevel > 3) { $Parser->SetDebugLevel($this->DebugLevel - 3); }
105 $this->Parser->ParseText($this->XmlText);
106 }
107
108 # return encoding to caller
109 return $this->Encoding;
110 }
111
117 function AutodetectEncoding()
118 {
119 # if neither the XML file nor the HTTP response headers specify an
120 # encoding, there is an overwhelming chance that it's ISO-8859-1, so
121 # use it as the default
122 $Encoding = "ISO-8859-1";
123
124 # only get up to the the encoding portion of the XML declartion
125 # http://www.w3.org/TR/2006/REC-xml-20060816/#sec-prolog-dtd
126 $S = '[ \t\r\n]';
127 $Eq = "{$S}?={$S}?";
128 $VersionNum = '1.0';
129 $EncName = '[A-Za-z]([A-Za-z0-9._]|-)*';
130 $VersionInfo = "{$S}version{$Eq}('{$VersionNum}'|\"{$VersionNum}\")";
131 $EncodingDecl = "{$S}encoding{$Eq}('{$EncName}'|\"{$EncName}\")";
132 $XMLDecl = "<\?xml{$VersionInfo}({$EncodingDecl})?";
133 $RegEx = "/{$XMLDecl}/";
134
135 # try to find the encoding, index 3 will be set if encoding is declared
136 preg_match($RegEx, $this->XmlText, $Matches);
137
138 # give precedence to the encoding specified within the XML file since
139 # a RSS feed publisher might not have access to HTTP response headers
140 if (count($Matches) >= 4)
141 {
142 # also need to strip off the quotes
143 $Encoding = trim($Matches[3], "'\"");
144 }
145
146 # then give precedence to the charset parameter in the Content-Type
147 # response header
148 else if ($this->CacheDB)
149 {
150 # create cache table if it doesn't exist
151 $DB = $this->CacheDB;
152 $ServerUrl = addslashes($this->ServerUrl);
153
154 # get the cache value
155 $DB->Query("
156 SELECT * FROM RSSClientCache
157 WHERE ServerUrl = '".$ServerUrl."'");
158 $Exists = ($DB->NumRowsSelected() > 0);
159 $Cache = $DB->FetchRow();
160
161 # if cached and charset parameter was given in the response headers
162 if ($Exists && strlen($Cache["Charset"]))
163 {
164 $Encoding = $Cache["Charset"];
165 }
166 }
167
168 $this->Encoding($Encoding);
169 }
170
179 function GetItems($NumberOfItems = NULL, $ChannelName = NULL)
180 {
181 # start by assuming no items will be found
182 $Items = array();
183
184 # move parser to area in XML with items
185 $Parser = $this->Parser;
186 $Parser->SeekToRoot();
187 $Result = $Parser->SeekTo("rss");
188 if ($Result === NULL)
189 {
190 $Result = $Parser->SeekTo("rdf:RDF");
191 }
192 else
193 {
194 $Parser->SeekTo("channel");
195 }
196
197 # if items are found
198 $ItemCount = $Parser->SeekTo("item");
199 if ($ItemCount)
200 {
201 # for each record
202 $Index = 0;
203 do
204 {
205 # retrieve item info
206 $Items[$Index]["title"] = $Parser->GetData("title");
207 $Items[$Index]["description"] = $Parser->GetData("description");
208 $Items[$Index]["link"] = $Parser->GetData("link");
209 $Items[$Index]["enclosure"] = $Parser->GetAttributes("enclosure");
210
211 $Index++;
212 }
213 while ($Parser->NextItem() && (($NumberOfItems == NULL) || ($Index < $NumberOfItems)));
214 }
215
216 # return records to caller
217 return $Items;
218 }
219
224 function GetChannelTitle()
225 {
226 if (!isset($this->ChannelTitle)) { $this->LoadChannelInfo(); }
227 return $this->ChannelTitle;
228 }
229
234 function GetChannelLink()
235 {
236 if (!isset($this->ChannelLink)) { $this->LoadChannelInfo(); }
237 return $this->ChannelLink;
238 }
239
244 function GetChannelDescription()
245 {
246 if (!isset($this->ChannelDescription)) { $this->LoadChannelInfo(); }
247 return $this->ChannelDescription;
248 }
249
254 function UsedCachedData()
255 {
256 return $this->CachedDataWasUsed;
257 }
258
259 # ---- PRIVATE INTERFACE -------------------------------------------------
260
261 var $CacheDB;
262 var $RefreshTime;
263 var $ServerUrl;
264 var $MetadataPrefix;
265 var $SetSpec;
266 var $DebugLevel;
267 var $Encoding;
268 var $XmlText;
269 var $Parser;
270 var $ChannelTitle;
271 var $ChannelLink;
272 var $ChannelDescription;
273 var $CachedDataWasUsed;
274
280 function SetDebugLevel($NewLevel)
281 {
282 $this->DebugLevel = $NewLevel;
283 }
284
294 function GetXmlInfo($Url)
295 {
296 $Text = @file_get_contents($Url);
297 $Type = NULL;
298 $Charset = NULL;
299
300 # get the type and charset if the fetch was successful
301 if ($Text !== FALSE)
302 {
303 # this must come after file_get_contents() and before any other remote
304 # fetching is done
305 $Headers = $http_response_header;
306
307 # http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.17
308 $LWS = '([ \t]*|\r\n[ \t]+)';
309 $Token = '[!\x23-\x27*+-.\x30-\x39\x41-\x5A\x5E-\x7A|~]+';
310 $QuotedPair = '\\[\x00-\x7F]';
311 $QdText = "([^\\x00-\\x1F\\x7F\"]|{$LWS})";
312 $QuotedString = "\"({$QdText}|{$QuotedPair})*\"";
313 $Value = "({$Token}|{$QuotedString})";
314 $Parameter = "{$Token}{$LWS}={$LWS}{$Value}";
315
316 # these make the Content-Type regex specific to Content-Type
317 # values with charset parameters in them, but make capturing
318 # the charset much easier
319 $BasicParameter = "(;{$LWS}{$Parameter})*";
320 $CharsetParameter = "(;{$LWS}charset{$LWS}={$LWS}{$Value})";
321 $ModParameter = "{$BasicParameter}{$CharsetParameter}{$BasicParameter}";
322 $MediaType = "({$Token}{$LWS}\\/{$LWS}{$Token}){$LWS}{$ModParameter}";
323
324 # back to the spec
325 $ContentType = "Content-Type{$LWS}:{$LWS}{$MediaType}{$LWS}";
326 $RegEx = "/^{$ContentType}$/i";
327
328 foreach ($Headers as $Header)
329 {
330 preg_match($RegEx, $Header, $Matches);
331
332 if (isset($Matches[3]) && isset($Matches[19]))
333 {
334 $Type = $Matches[3];
335 $Charset = $Matches[19];
336 break;
337 }
338 }
339 }
340
341 return array($Text, $Type, $Charset);
342 }
343
354 function QueryServerWithCaching($ServerUrl, $CacheDB, $RefreshTime)
355 {
356 # save RSS server URL
357 $this->ServerUrl = $ServerUrl;
358
359 # save caching info (if any)
360 if ($CacheDB)
361 {
362 $this->CacheDB = $CacheDB;
363 }
364
365 # if caching info was supplied
366 if ($this->CacheDB)
367 {
368 $DB = $this->CacheDB;
369
370 # look up cached information for this server
371 $QueryTimeCutoff = date("Y-m-d H:i:s", (time() - $RefreshTime));
372 $DB->Query("
373 SELECT * FROM RSSClientCache
374 WHERE ServerUrl = '".addslashes($ServerUrl)."'
375 AND LastQueryTime > '".$QueryTimeCutoff."'");
376
377 # if we have cached info that has not expired
378 if ($CachedXml = $DB->FetchField("CachedXml"))
379 {
380 # use cached info
381 $QueryResult = $CachedXml;
382 $this->CachedDataWasUsed = TRUE;
383 }
384 else
385 {
386 $this->CachedDataWasUsed = FALSE;
387
388 # query server for XML text
389 list($Text, $Type, $Charset) = $this->GetXmlInfo($ServerUrl);
390 $QueryResult = "";
391
392 # if query was successful
393 if ($Text !== FALSE)
394 {
395 $QueryResult = $Text;
396
397 # clear out any old cache entries
398 $DB->Query("
399 DELETE FROM RSSClientCache
400 WHERE ServerUrl = '".addslashes($ServerUrl)."'");
401
402 # save info in cache
403 $DB->Query("
404 INSERT INTO RSSClientCache
405 (ServerUrl, CachedXml, Type, Charset, LastQueryTime)
406 VALUES (
407 '".addslashes($ServerUrl)."',
408 '".addslashes($Text)."',
409 '".addslashes($Type)."',
410 '".addslashes($Charset)."',
411 NOW())");
412 }
413 }
414 }
415
416 # return query result to caller
417 return $QueryResult;
418 }
419
424 function LoadChannelInfo()
425 {
426 $Parser = $this->Parser;
427 $Parser->SeekToRoot();
428 $Result = $Parser->SeekTo("rss");
429 if ($Result === NULL)
430 {
431 $Result = $Parser->SeekTo("rdf:RDF");
432 }
433 $Parser->SeekTo("channel");
434 $this->ChannelTitle = $Parser->GetData("title");
435 $this->ChannelLink = $Parser->GetData("link");
436 $this->ChannelDescription = $Parser->GetData("description");
437 }
438
439 }
RSSClient\UsedCachedData
UsedCachedData()
Determine whether the RSS client is using cached data.
Definition: RSSClient.php:254
RSSClient\GetItems
GetItems($NumberOfItems=NULL, $ChannelName=NULL)
Retrieve the RSS items from the RSS feed.
Definition: RSSClient.php:179
RSSClient\GetChannelTitle
GetChannelTitle()
Retrieve the channel title as given in the RSS feed.
Definition: RSSClient.php:224
RSSClient
Implements an RSS client for fetching, parsing, and caching RSS feeds.
Definition: RSSClient.php:13
RSSClient\$ChannelTitle
$ChannelTitle
Definition: RSSClient.php:270
RSSClient\$ChannelDescription
$ChannelDescription
Definition: RSSClient.php:272
RSSClient\GetChannelLink
GetChannelLink()
Retrive the URL to the site of the channel in the RSS feed.
Definition: RSSClient.php:234
RSSClient\ServerUrl
ServerUrl($NewValue=NULL)
Get or set the RSS feed URL.
Definition: RSSClient.php:58
RSSClient\$DebugLevel
$DebugLevel
Definition: RSSClient.php:266
RSSClient\$CacheDB
$CacheDB
Definition: RSSClient.php:261
RSSClient\$ChannelLink
$ChannelLink
Definition: RSSClient.php:271
RSSClient\$ServerUrl
$ServerUrl
Definition: RSSClient.php:263
RSSClient\$SetSpec
$SetSpec
Definition: RSSClient.php:265
RSSClient\$RefreshTime
$RefreshTime
Definition: RSSClient.php:262
RSSClient\$Encoding
$Encoding
Definition: RSSClient.php:267
RSSClient\RSSClient
RSSClient($ServerUrl, $CacheDB=NULL, $RefreshTime=600, $Encoding="UTF-8", $DebugLevel=0)
Object constructor.
Definition: RSSClient.php:29
PHP
PHP
Definition: OAIClient.php:39
RSSClient\Encoding
Encoding($NewValue=NULL)
Get or set the character encoding of the RSS feed.
Definition: RSSClient.php:88
RSSClient\$CachedDataWasUsed
$CachedDataWasUsed
Definition: RSSClient.php:273
RSSClient\SetDebugLevel
SetDebugLevel($NewLevel)
Set the current level of verbosity for debug output.
Definition: RSSClient.php:280
XMLParser
Definition: XMLParser.php:18
RSSClient\LoadChannelInfo
LoadChannelInfo()
Load information from the current RSS channel.
Definition: RSSClient.php:424
RSSClient\AutodetectEncoding
AutodetectEncoding()
Try to automatically detect and set the encoding of the RSS feed.
Definition: RSSClient.php:117
RSSClient\QueryServerWithCaching
QueryServerWithCaching($ServerUrl, $CacheDB, $RefreshTime)
Load the XML of an RSS feed from the cache, if available, or from the server.
Definition: RSSClient.php:354
RSSClient\GetXmlInfo
GetXmlInfo($Url)
Get the XML text at the given URL, along with the type and character encoding of the text...
Definition: RSSClient.php:294
RSSClient\$XmlText
$XmlText
Definition: RSSClient.php:268
RSSClient\GetChannelDescription
GetChannelDescription()
Get the description of the channel as given in the RSS feed.
Definition: RSSClient.php:244
RSSClient\$MetadataPrefix
$MetadataPrefix
Definition: RSSClient.php:264
RSSClient\$Parser
$Parser
Definition: RSSClient.php:269
$Items
$Items
Definition: RSSClient--Test.php:26