platform-update-home/doc/working/site-performance-enhancement.html

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revision 1.1, Mon Apr 3 22:06:04 2006 UTC revision 1.2, Tue Apr 4 01:21:54 2006 UTC
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15  install anything from the site. A solution is needed to reduce the number of  install anything from the site. A solution is needed to reduce the number of
16  connections simply to browse or search the update site.</p>  connections simply to browse or search the update site.</p>
17  <p>Once the features to install have been selected, Update needs to physically  <p>Once the features to install have been selected, Update needs to physically
18  download plug-in JARs onto user's machine. At this point, payload size seizes to  download plug-in JARs onto user's machine. At this point, payload size ceases to
19  be trivial - a full Callisto download is several hundred megabytes. A technique  be trivial - a full Callisto download is several hundred megabytes. A technique
20  to reduce the payload size would benefit users who are downloading the full  to reduce the payload size would benefit users who are downloading the full
21  Callisto set.</p>  Callisto set.</p>
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71  digestLocales</b> attribute listing all the locales for which a digest has just  digestLocales</b> attribute listing all the locales for which a digest has just
72  been generated. If <b>pack200</b> is present, it will cause the utility to call  been generated. If <b>pack200</b> is present, it will cause the utility to call
73  pack200.exe on each plug-in or fragment archive (say, com.example.xyz.jar) and  pack200.exe on each plug-in or fragment archive (say, com.example.xyz.jar) and
74  generate a packed version (com.example.xyz.jar.gz).</p>  generate a packed version (com.example.xyz.jar.pack.gz).</p>
75  <p>It is the responsibility of the utility caller to ensure that it is run  <p>It is the responsibility of the utility caller to ensure that it is run
76  regularly in order to keep the generated content in sync with the source.  regularly in order to keep the generated content in sync with the source.
77  Failure to do so will result in stale content and browsing or installation  Failure to do so will result in stale content and browsing or installation
78  errors.</p>  errors. Digest generator portion of the utility can be simple and always
79    generate all the files if it does not take too much time. On the other hand,
80    pack200 portion must be incremental in order to avoid packing jars that have not
81    changed.</p>
82  <h3>Update site digests</h3>  <h3>Update site digests</h3>
83  <p>The goal of the update site digests is to minimize the number of files that  <p>The goal of the update site digests is to minimize the number of files that
84  need to be downloaded in order to browse or search the update site. Digests are  need to be downloaded in order to browse or search the update site. Digests are
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97  for small and simple sites.</p>  for small and simple sites.</p>
98  <h3>Support for Pack200</h3>  <h3>Support for Pack200</h3>
99  <p>If Pack200 is indicated in site.xml, Eclipse Update will first try to  <p>If Pack200 is indicated in site.xml, Eclipse Update will first try to
100  download &quot;com.example.xyz.jar.gz&quot; when downloading &quot;com.example.xyz.jar&quot;  download &quot;com.example.xyz.jar.pack.gz&quot; when downloading &quot;com.example.xyz.jar&quot;
101  archive. If found, it will be downloaded and unpacked at the client machine. The  archive. If found, it will be downloaded and unpacked at the client machine. The
102  rest of the process will be as usual. If the file is not present, &quot;com.example.xyz.jar&quot;  rest of the process will be as usual. If the file is not present, &quot;com.example.xyz.jar&quot;
103  will be downloaded instead. This may actually slow down the installation due to  will be downloaded instead. This may actually slow down the installation due to
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110  Manager will check if it can unpack Pack200 archives before downloading them.  Manager will check if it can unpack Pack200 archives before downloading them.
111  For this reason, update sites must have normal versions of the archives in  For this reason, update sites must have normal versions of the archives in
112  addition to the packed versions.</p>  addition to the packed versions.</p>
113    <p>The location of the unpack200 executable can be specified to update using a
114    system property &quot;org.eclipse.update.jarprocessor.pack200&quot;. The value can be one
115    of:</p>
116    <ul>
117            <li>&quot;@jre&quot; - find unpack200 in java.home/bin</li>
118            <li>&quot;@path&quot; - find unpack200 on the search path</li>
119            <li>&quot;@none&quot; - don't use unpack200, just download the .jar</li>
120            <li>&quot;path/to/dir&quot; - path to the directory containing the unpack200
121            executable</li>
122    </ul>
123    <p>If the property is not set, we will look for unpack200.exe first in java.home/bin,
124    then on the system path. If that fails, unpack will not be used.</p>
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