Document revision: 2023-02-22
Refers to EQWS version: 1.0.0
The EQWS utility is a simple and lightweight alternative to Java Webstart
(javaws) which is no longer included in Oracle™ Java since
EQWS is compatible with existing JNLP files
and handles multiple JAR files and/or extension JNLP files, for example
to use JDLG plugins.
Similar to Java Webstart, EQWS maintains a local cache where JNLP and JAR
files are downloaded as necessary. EQWS then starts a local Java VM process,
providing the main JAR file along with any properties and additional arguments
specified in the JNLP file(s).
If multiple JAR files are specified (e.g., to use JDLG plugins), EQWS creates
a "launcher JAR file" providing the necessary Java class path.
- EQWS requires Java version 7 or newer.
- Unlike Java webstart, the current EQWS implementation does not require
code-signed JAR file(s), i.e., it does not check the JAR file certificates
and code signatures.
As a consequence, EQWS should not be configured as general JNLP
file handler because this could cause unknown JAR files to be started.
- Two Java VM processes are used, one for EQWS and another to run the
application. The additional memory usage should be less than 30 MB.
- The application's working directory is set to the cache subdirectory
containing the main JAR file. The jnlp.codebase Java property
is set to the codebase of the main JNLP file.
- EQWS does not provide the
Download EQWS and copy
the eqws.jar file to a local directory or a shared subdirectory.
The usage examples below assume that eqws.jar has been copied to
the local C:\Util directory on a Windows PC.
Command line usage:
usage: java -jar eqws.jar [options] JNLP-URL
java -jar eqws.jar -help
java -jar eqws.jar -version
java -jar eqws.jar -c
-a ARGUMENT - additional Java VM argument
-c - clear cache, delete cache directory
-j JVM-FILE - absolute path to Java VM executable file
default: use EQWS_JVM env variable or 'java'
-v[vv] - output additional information
The following example assumes that Java Webstart
is used to start JDLG with a command line like below:
Assuming that eqws.jar is located in the local C:\Util
directory on a Windows PC, it can equivalently be used to start JDLG:
java -jar C:\Util\eqws.jar http://intranet/jdlg/jdlg.jnlp
Command line options:
- The -a command line option may be used to specify additional
Java VM arguments.
For example, to use
JDLG drag & drop with Java 9 or newer,
the following VM arguments must be specified:
The preferred way to specify them is by adding the java-vm-args
attribute to the <j2se ...> tag in the
Alternatively, they can be specified with the EQWS -a command
java -jar C:\Util\eqws.jar -a--add-opens=java.desktop/javax.swing=ALL-UNNAMED -a--add-opens=java.desktop/javax.swing.plaf.basic=ALL-UNNAMED http://intranet/jdlg/jdlg.jnlp
- The -c command line option may be used to clear the local
cache, so that all locally cached JNLP and JAR files are deleted.
The cache automatically recognizes when a remote file has been updated,
therefore using the -c command line option should never be
- The -j command line option, or the EQWS_JVM environment
variable, may be used to invoke a specific Java VM executable.
By default, java is invoked.
For example, if JDLG should run in a specific Java VM
(here: Zulu OpenJDK 8 on Windows):
java -jar C:\Util\eqws.jar -j "C:\Program Files\Zulu\zulu-8\bin\java.exe" http://intranet/jdlg/jdlg.jnlp
Or, on Windows, if javaw should be used, for example in a
desktop link, to avoid that a console window is opened:
javaw -jar C:\Util\eqws.jar -jjavaw http://intranet/jdlg/jdlg.jnlp
Please note that when using javaw, any output of EQWS and/or
the application is suppressed, which could complicate error diagnostics.
If javaw is used and EQWS does not appear to work as expected,
java should be used in a Command Prompt console window to analyze
what causes the problem.
Also, javaw output can be redirected to a log file, like:
javaw -jar C:\Util\eqws.jar ... >>%TEMP%\eqws.log 2>&1
- The -v (verbose) command line option causes EQWS to output
additional information, depending on the verbosity level.
-v (verbosity level 1) outputs which files are downloaded to the
local cache. It also outputs the title of the main JNLP file.
Starting: 'Eloquence JDLG with Plugins'
-vv (verbosity level 2) in addition outputs the location of the
cache directory and which cached files are used.
Cache directory: '/tmp/eqws/mary/'
Starting: 'Eloquence JDLG with Plugins'
-vvv (verbosity level 3) in addition outputs the Java VM command
line. If EQWS fails, a stack trace is output.