Mercurial > hg > digilib-old
diff webapp/doc/website/tips.html @ 922:8251cc7888fb
slightly updated website.
removed links to berlios wiki, made tips page instead.
still quite ugly...
| author | robcast |
|---|---|
| date | Fri, 09 Dec 2011 20:33:24 +0100 |
| parents | |
| children | 45effb9c9bed |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/webapp/doc/website/tips.html Fri Dec 09 20:33:24 2011 +0100 @@ -0,0 +1,194 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> +<title>digilib -- Digital Image Library</title> +</head> +<body> + <table border="0" cellspacing="0" cellpadding="10"> + <tr> + <td bgcolor="#a0a0a0"> </td> + <td> + <img src="images/digilib-logo-big.png" align="left" /> + <h1> + <tt>digilib</tt> + -- a versatile image viewing environment for the internet + </h1> + </td> + </tr> + <tr> + <td bgcolor="#a0a0a0" valign="top" align="right"> + <p> + <b><a href="index.html">Info</a> + </b> + </p> + <p> + <b><a href="http://developer.berlios.de/projects/digilib/">Project</a> + </b> + </p> + <p> + <b><a href="http://developer.berlios.de/project/showfiles.php?group_id=251">Download</a> + </b> + </p> + <p> + <b><a href="http://developer.berlios.de/docman/?group_id=251">Docs</a> + </b> + </p> + <p> + <b><a href="tips.html">Tips</a> + </b> + </p> + <p> + <b><a href="http://hg.berlios.de/repos/digilib">Source</a> + </b> + </p> + </td> + <td> + + + <p>Some tips for running digilib</p> + <ul> + <li> + <a href="#vm_settings">Java VM settings for digilib</a> + </li> + <li> + <a href="#prescaled_images">Prescaled images</a> + </li> + <li> + <a href="installing_jai">Installing JAI</a> + </li> + </ul> + + <h1 id="vm_settings">Java VM settings for digilib</h1> + + <p>The Java virtual machine (Java-VM) only uses a fixed amount of memory for + its operations. When an operation needs more memory than available it aborts + with an error ("out of memory error").</p> + <p>digilib can need a lot of memory depending on the size and type of images. + Since digilib runs as a servlet under Tomcat its in the same VM as the Tomcat + server.</p> + <p>The amount of memory Tomcat (version 5.0) uses is configured by creating a + "setenv.sh" script with a line</p> + <pre> CATALINA_OPTS="-Xmx512m" +</pre> + <p>in Tomcat's "bin" directory (giving 512MB in this case).</p> + <p> + You can check the amount of memory your digilib instance has available on the + bottom of the web page /server/dlConfig.jsp in your digilib instance (e.g. <a + href="http://digilib.mpiwg-berlin.mpg.de/digitallibrary/server/dlConfig.jsp" + class="external free" rel="nofollow">http://digilib.mpiwg-berlin.mpg.de/digitallibrary/server/dlConfig.jsp</a>). + </p> + + <h1 id="prescaled_images">Prescaled images</h1> + + <p>You can provide any number of scaled-down versions of your images that + digilib uses when a smaller version of an image is requested. Since less data + has to be read and processed this can speed up digilib's performance quite a + lot.</p> + <p>The actual process is that the client requests a certain target size, + digilib scans all available scaled-down versions of the same image, selects the + smallest image that is larger than the requested size and scales it down to the + requested size.</p> + <p>The scaled-down versions of the image have to have the same file name as + the original hi-res file. They can have a different type and extension (e.g. + img002.jpg for img002.TIFF)</p> + <p>The scaled down images have to be in the same subdirectory (the part that + shows up in digilib's "fn" parameter) as the hi-res file. The first part of each + directory tree is configured by the basedir-list parameter in + digilib-config.xml.</p> + <p>The sequence of directories in basedir-list is from hi-res to lo-res. + Images must be present in the hires directory but they need not be present in + all lower-res directories.</p> + <p>e.g. if digilib-config.xml contains</p> + <pre> <parameter name="basedir-list" value="/images:/scaled:/thumb" /> +</pre> + <p>and a user requests the image "books/book1/page0002" digilib looks for</p> + <pre> /thumb/books/book1/page0002.* + /scaled/books/book1/page002.* + /images/books/book1/page002.* +</pre> + <p>and uses the first image that is bigger than or equal to the requested + size.</p> + <p> + For batch-prescaling our images we use a script called "scale-o-mat" that uses a + lot of freely available imaging libraries (ImageMagick, libtiff, netpbm) and is + available in our public CVS <a + href="http://itgroup.mpiwg-berlin.mpg.de/cgi-bin/cvsweb.cgi/scaleomat/" + class="external autonumber" rel="nofollow">[1]</a>. The script is given a + hi-res base directory, a destination base directory, a destination size and a + starting directory. It then processes all files in the starting directory and + all its subdirectories and creates scaled images in corresponding directories + under the destination base directory. + </p> + <p>We currently use prescaled thumbnails of 100 pixels and images for browser + display of 1500 pixels. Remember that the prescaled image has to be larger (or + the same size) than the requested image size!</p> + <p>There is another optimization in digilib: if the requested image is exactly + the same size and type as the prescaled image then the prescaled image is sent + unmodified to the client which is a lot faster. So it makes sense to produce + thumbnails of exactly 90 pixels width when they are used in an HTML page where + all images are 90 pixels wide.</p> + + + <h1 id="installing_jai">Installing JAI</h1> + + <p> + In principle you can install the <a + href="http://java.sun.com/javase/technologies/desktop/media/jai/" + class="external text" rel="nofollow">Java Advanced Imaging</a> JAR files (and + native library files if available) in the /WEB-INF/lib/ directory of the digilib + web application. + + </p> + <p>I found that in some cases digilib stopped reading TIFF files after a + period of running. In these cases it helped to install the JAI files directly in + the local Java installation (i.e. in the Java's /jre/lib/ext/ directory on + linux).</p> + + + <h1 id="mpiwg_setup">Sample setup</h1> + + <p>The current digilib setup at the MPIWG (as of November 2005):</p> + <ul> + <li> + One frontend server running the lightweight web-multiplexer <a + href="http://www.apsis.ch/pound/" class="external text" rel="nofollow">pound</a> + on port 80 that distributes requests to two servers runnning digilib + </li> + <li> + the two servers run digilib under <a + href="http://tomcat.apache.org/index.html" class="external text" + rel="nofollow">Tomcat</a> on port 8080 without Apache + <ul> + <li>one server is the same machine as the frontend server (Linux, Dual + 2.4GHz Xeon, 2GB RAM)</li> + <li>the other server is a separate, newer machine (Linux, Dual 1.8GHz + Opteron, 2GB RAM)</li> + </ul> + </li> + <li> + the digilib instances (digilib 1.5.9c as of 22.11.2005) run on Tomcat on Java + 1.5.0_05 (or 1.4.2_06) with 1GB of <a href="#vm_settings">Java VM memory + for digilib</a> (-Xmx1024m) with JAI (1.1.2_01) and JAI-ImageIO (1.0_01) <a + href="#installing_jai">installed in the JRE</a>(!) + </li> + <li>both digilib servers access all image files over NFS (over GBit + Ethernet) from a central file server (Solaris 8, Sun Fire 480, multiple RAIDs + on Fibrechannel)</li> + </ul> + + </td> + </tr> + <tr> + <td style="padding: 0px" align="left"> + <a href="http://developer.berlios.de"> <img + src="http://developer.berlios.de/bslogo.php?group_id=0&type=1" width="124" + height="32" border="0" alt="BerliOS Logo" /> </a> + </td> + <td></td> + </tr> + </table> + +</body> +</html> \ No newline at end of file