Compressing Files

• Gzip File
• pack200 Compression

Gzip File

If you deploy your Nexaweb application to a server that supports gzip compressed files, you can use gzip to compress any files associated with your Nexaweb application.

Nexaweb platform includes a servlet, servlet com.nexaweb.server.servlet.CompressedFileServlet, to serve gzip files to clients from a Tomcat server. For other types of servers, you need to create your own servlet to provide gzip files to a Nexaweb application client.

servlet com.nexaweb.server.servlet.CompressedFileServlet does the following:

Checks whether the incoming client request supports gzip encoded responses.

- If not: the servlet forwards the file request directly to the web server.

- If so:

• The servlet gets the appropriate mime-type for the file being requested (the original file request).
• Checks for a .gz (gzipped) version of the file.
  - If found: returns the .gz version of the file.
    This response indicates the original file's mime-type and a content-encoding header specifiying gzip.

    For example, for the file: js.gz, you see the following:

    Content-Encoding: gzip
    Content-Type: application/x-javascript

  - If not found: forwards the file request directly to the web server. 

The platform seed web.xml file maps the path to this file as: /CompressedFileServlet.

To utilize this, use:
/CompressedFileServlet/path/to/file

pack200 Compression

Requires Platform 4.2+

• pack200 compressed JAR files transfer significantly faster over a network than other JAR files
• Nexaweb compresses NexawebClient.and Nexaweb-nfc JARs using pack200
• You can now use pack200 to compress JARs containing libraries pre-loaded into your application’s client.

• Use pack200 compression for deploying Nexaweb applications
• Use with JAR files containing pre-loaded client libraries
• Use with unsigned JAR files
  Note: For information on how to us pack200 with signed JAR files, see Sun’s Java Documentation including:
  http://java.sun.com/j2se/1.5.0/docs/guide/deployment/deployment-guide/pack200.html#pack200_compression.  

• Creating a pack200 compressed file
• Adding a pack200 attribute entry into the Nexaweb client configuration file 

1. Package pre-loaded library files in an unsigned JAR file.
   Note: To use signed files, see Java documentation on how to repackage a signed JAR.
2. Locate the pack200 utility in JRE_HOME or JAVA_HOME bin directory.
3. Copy the JAR file that you want to compress into the same bin directory as pack2000.
4. Type the following command in a command window: pack200 MyLibrary.jar.pack.gz MyLibrary.jar
   where:
   - MyLibrary.jar.pack.gz is the name of the compressed JAR file that pack200 creates
   - MyLibrary.jar is the name of the original uncompressed file
5. Copy both the compressed and uncompressed JARs (for example, MyLibrary.jar.pack.gz and MyLibrary.jar) into the directory where you save pre-loaded client libraries for your application. This process does not change the original MyLibrary.jar file, so if a copy of it already exists in this directory, you do not need to copy it into the directory again.

pack200Path="/WEB-INF/client/lib/foo.jar"
pack200Url=http://blah:18/foo.jar

1. Locate the nexaweb-client.xml file for the Nexaweb application in the application’s WebContent\WEB-INF directory.
2. Open nexaweb-client.xml file with a text editor.

3. Locate the <pre-loaded-in-applet-def> section of the nexaweb-client.xml file, similar to the following:

   <client-classpath> 
     <pre-loaded-in-applet-def> 
        <archive name="MyLibrary.jar" 
           path="/WEB-INF/client/lib/MyLibrary.jar" /> 
      </pre-loaded-in-applet-def>
   </client-classpath>

4. Add a pack200Path or pack200Url attribute, similar to the following:

    <client-classpath> 
        <pre-loaded-in-applet-def> 
          <archive name=" MyLibrary.jar " 
           path="/WEB-INF/client/lib/ MyLibrary.jar " 
           pack200Path="/WEB-INF/client/lib/ MyLibrary.jar.pack.gz"/> 
        </pre-loaded-in-applet-def>
    </client-classpath>

• Using a network monitor
• Using Nexaweb platform’s service console

• HTTP traffic
• Resources requested
• Resources returned

• Library name and location mappings
• Counters

1. Enter the following address in a Web browser location bar: http://server:port/yourapp/Nexaweb/Services/index.jsp
2. Click right menu on ClientClassService.