Migration to Nexaweb launcher

Owned by Xuri Chen (Unlicensed)
Last updated: Jul 06, 2021 by Nilam Chand
5 min read

Oracle announced that the Java Applet and Web Start functionality, including the Applet API, Java plug-in, Java Applet Viewer, JNLP and Java Web Start including the javaws tools are all deprecated in JDK 9 and will be removed in a future release. As an alternative, our customers are recommended to use the Nexaweb Launcher to deploy and  run Nexaweb web applications. 

This step-by-step guide shows how to perform the migration of Nexaweb application to Nexaweb launcher.

  1. Nexaweb Launcher is based on an open source project GetDown. For information on GetDown project, please refer to: GetDown
  2. For more information on Nexaweb Launcher, please refer to: Nexaweb Launcher
  3. For more information on Nexaweb Standalone Client, please refer to: Standalone Client

Prerequisites:

  1. Nexaweb Platform with version 4.5.66 or higher
  2. Nexaweb Launcher Installer

You can find the installers at the Nexaweb download page. 

Step-by-step guide

To deploy a Nexaweb application using Nexaweb Launcher, the recommended approach is to use the Nexaweb Standalone Client. Here are the steps:

  1. Create a runNexaweb file for launching Nexaweb web application

    The way to create Nexaweb web application is by using a runNexaweb (Nexaweb Launching Protocol) file deployed on the server. When the user types the URL of a Nexaweb file in the browser, the application will detect that the response is a Nexaweb file and it will start Nexaweb  launcher to load the Web Start application according to the setting in the Nexaweb file. So a Nexaweb file needs to be created for the Nexaweb application.

    1. Download the latest version of Nexaweb Platform (4.5.65.0009 or later) and install it on the server
    2. Download and install Nexaweb Launcher on the client machine.
    3. Create a new Nexaweb application project
    4. Copy NexawebImages.jar,  NexawebStandaloneClient.jar,  and all other jars to WebContent directory as below:

             Note: You can find NexawebStandaloneClient.jar and NexawebImages.jar in the bin directory where Nexaweb Platform is installed

            d. Edit web.xml to add runNexaweb JSP and  /runNexaweb  URL mapping as below:

              d1.  At line #62:

             <servlet>

             <servlet-name>RunNexaweb</servlet-name>

              <display-name>RunNexaweb</display-name>

              <description/>

              <servlet-class>

               com.nexaweb.server.jnlp.replacement.RunNexawebServlet

              </servlet-class>

            </servlet>

             d2.  At line #109:

             <servlet-mapping>

              <servlet-name>RunNexaweb</servlet-name>

               <url-pattern>/runNexaweb</url-pattern>

              </servlet-mapping>

    e. Run the project on a web server, go to the URL: http://localhost:8080/nxRunNexaweb/runNexaweb, and save runNexaweb

2. Digest the jars and create digest.txt and digest2.txt and upload them to the nexaweb application

           Nexaweb launcher uses Getdown’s digester to generate jar’s digest and use the digest to check if it needs to download a new version jar file or not. So the users need to digest all jars the web application needed and put them in the same directory with GetDown.txt which is just the same file runNexaweb in a different name. After generating the digest files, they need to be added into WebContent directory too as the jars.

    a. Create a local folder called "target". Copy getdown-1.7.1-SNAPSHOT.jar from Nexaweb Launcher installation folder and paste it into the target folder

    b. Copy the runNexaweb file at step #d2 into this target folder 

    c. Create a "digesters" sub-folder under this target folder, copy runNexaweb file into this folder, and then rename it to getdown.txt (Note: please check if the file extension is .txt after renaming)

    d. Copy NexawebImages.jar, and NexawebStandaloneClient.jar in the digesters directory

    e. Copy all jars other than above jars into the ClientClassLoader directory, and the digesters directory looks as below:

    

       

                Note: the demo project uses an external jar called test.jar. It is put under ClientClassLoader directory, which is as below. If the project does not need any jars other than NexawebImages.jar and NexawebStandaloneClient.jar, you don't need to create a ClientClassLoader directory.

                

           f. Run the command below in command lines below:

             1)  Change the command prompt to D:\target folder

             2). Run command -  java -classpath getdown-1.7.1-SNAPSHOT.jar com.threerings.getdown.tools.Digester digesters

            Note: "D:\target" is the directory where getdown-1.7.1-SNAPSHOT.jar is put in and "digesters" is the directory to be digested in the above command. This command creates two digest files as the screenshot below: 

            

             

          g.  Copy these two digest files to the Nexaweb project’s WebContent folder as below :

            

            h. Restart the Nexaweb project and all the setting needed for Nexaweb launcher are done .

            Note: whenever the jar files are changed, they need to be re-digested 

3. Launch the Nexaweb web application 

 a. Start the server which was configured for the Nexaweb project
 b. Double click runNexaweb in the target folder to launch the Nexaweb web application   


Features:

1.Enable Console for debugging 

Prerequisites: the JVM's version must be greater than 1.6 

Steps: 

  1. Open the app directory. It is in  %SystemDrive%%HOMEPATH%/.nexaweb_<Server>_<Port>_<Application>_ .
    Note: the dots(.) in the server and application are replaced with underbar(_) . For example, the app directory: C:\Users\xuchen\.nexaweb\nxwb127_0_0_1_8080_myPrj4_ , where 127_0_0_1_ is the server 127.0.0.1 replaced . with _ , 8080 is port, and myPrj4 is application name 
  2. Create a  file debug.txt on it
  3. Relaunch the nexaweb web application, and the console.log will be created to catch all standard outputs   

2. Custom JVM installation and upgrade

Steps: 

  1. Create a custom JVM jar file with name java_windows.jar. It is just a zip file of the jre with the extension jar. Rename the jre folder to java_vm before you create jar

       

 2. Change runNexaweb.jsp as the screenshot below shows

   3. Follow the same instructions Step-by-step guide→ Digest the jars and create digest.txt and digest2.txt and upload them to the nexaweb application.  The digester's directory's structure looks like below


And the final web content directory's structure looks like the screenshot below:

 

Note: The nexaweb launcher uses digested code of the custom JVM to check if it needs to update the custom JVM from the Web. It means that it does not check the custom JVM version in the web. As of results, whenever there are changes for the custom JVM, it must be re-digested and redployed to the web server with all the digest files generated in order to automatically deploy it to the user's machines.



JDK 9 Release Notes Deprecated APIs, Features, and Options