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<BODY>
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<A HREF="toc.html">Contents</A>
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<A HREF="61Enablingthecachesystem.html">Previous</A>
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<A HREF="63UsingthecachewithClientSideImageMaps.html">Next</A>
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<HR NOSHADE>
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<H2><A NAME="6_2">6.2 Using the cache in your script</A></H2>
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<P> To use caching in your script you must supply a suitable file name
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which will be used to store the image in the cache. You can also supply
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a timeout value indicating how many minutes the cached image should be
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considered valid.</P>
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<P> These parameters are supplied in the initial Graph() method call
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which should be among the first in your script. Instead of manually
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specifying a file name to be used you could often use the special name
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"auto". If the filename is specified as "auto" the cashed image will
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then be named the same as the image script but with the correct
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extension depending on what image format have been chosen.</P>
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<P> If you don't specify a file name no caching will be used no matter
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the settings of USE_CACHE (without a file name it is impossible!)</P>
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<P> The following call to Graph() shows a typical use of the cache.</P>
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<P><DIV class="phpscript"><CODE><FONT color="#000000"> <FONT color="#0000BB">
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$graph </FONT><FONT color="#007700">= new </FONT><FONT color="#0000BB">
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Graph</FONT><FONT color="#007700">(</FONT><FONT color="#0000BB">300</FONT><FONT
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color="#007700">,</FONT><FONT color="#0000BB">200</FONT><FONT color="#007700">
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,</FONT><FONT color="#DD0000">"auto"</FONT><FONT color="#007700">,</FONT><FONT
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color="#0000BB">60</FONT><FONT color="#007700">)</FONT><FONT color="#0000BB">
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</FONT></FONT></CODE></DIV></P>
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<P></P>
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<P> The above code will use the automatic filename and a make the cache
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valid for 60 minutes.</P>
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<P> So, how does this all work now?</P>
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<P> The first time you call your script (no cached image) everything
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will be as usual, the script will run and you will in the end send back
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the image to the browser. However if you have the caching enabled
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JpGraph will automatically have stored a copy of the generated image in
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the cache directory.</P>
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<P> The next time you call the script the first thing that happens in
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the initial Graph() is that it will go and check in the cache directory
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if the named image exists there. If this is the case it will also
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checks that the image isn't too old (as compared to the specified
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timeout value). If the image is valid then the image will be streamed
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straight back from the image file to the browser and the script will
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end it's execution.</P>
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<P> Hence, if the image is found in the cache<STRONG> no code lines
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after the initial Graph() call will be executed</STRONG></P>
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<P> The design decision behind this is that your image script code never
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has to include anything special to make full use of the cache. It will
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just automatically work.</P>
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<HR NOSHADE>
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<A HREF="toc.html">Contents</A>
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<A HREF="61Enablingthecachesystem.html">Previous</A>
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<A HREF="63UsingthecachewithClientSideImageMaps.html">Next</A>
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