8.2. Periodic Refresh in
XHTML MP
HTTP
refresh can be used in XHTML MP to instruct the WAP browser to
refresh the current page periodically. This is a very useful function
for mobile Internet browsing applications that provide real-time
information. In the following XHTML MP code, the page is refreshed
automatically every 15 seconds. Note that <meta
http-equiv="Cache-Control" content="no-cache"/>
is required in this XHTML MP example. If it is not included, the WAP
browser will just display the copy of the document in the cache
without connecting to the server for each refresh.
(metadataEg4.xhtml)
<?xml
version="1.0"?> <!DOCTYPE html PUBLIC
"-//WAPFORUM//DTD XHTML Mobile 1.0//EN"
"http://www.wapforum.org/DTD/xhtml-mobile10.dtd">
<html
xmlns="http://www.w3.org/1999/xhtml"> <head> <title>XHTML
MP Tutorial</title> <meta
http-equiv="Cache-Control" content="no-cache"/> <meta
http-equiv="refresh"
content="15"/> </head>
<body> <p>This
XHTML MP page will be refreshed automatically every 15
seconds.</p> </body> </html>
HTTP
refresh can also be used to instruct the WAP browser to go to another
URL after a certain period of time. You can make use of such feature
to redirect the user to another XHTML MP page or create a slide show.
The following XHTML MP example demonstrates how to redirect the user
to "helloWorldEg1.xhtml" after 15 seconds.
(metadataEg5.xhtml)
<?xml
version="1.0"?> <!DOCTYPE html PUBLIC
"-//WAPFORUM//DTD XHTML Mobile 1.0//EN"
"http://www.wapforum.org/DTD/xhtml-mobile10.dtd">
<html
xmlns="http://www.w3.org/1999/xhtml"> <head> <title>XHTML
MP Tutorial</title> <meta http-equiv="refresh"
content="15;URL=helloWorldEg1.xhtml"/> </head>
<body> <p>Hello,
you will be redirected to another XHTML MP page after 15
seconds.</p> </body> </html>
Note
that HTTP refresh is not supported on some WAP browsers. For example,
HTTP refresh works well on Openwave Mobile Browser 6.2.2, but not on
Nokia Mobile Browser 4.0, Sony Ericsson T610 and T68i mobile phone
emulators.
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