This section covers the following topics:
The format used in this release is that specified in the Java Network Launching Protocol & API Specification (JSR-56) version 8.20. This document describes the most commonly used elements of a JNLP file. For a complete description of the format, refer to the specification.
Element |
Attributes |
Description |
Since |
Required |
---|---|---|---|---|
jnlp |
|
This is the main xml element for a jnlp file. Everything is contained within the jnlp element. |
1.0 |
yes |
|
spec |
The spec attribute can be 1.0, 1.5.0, 6.0, 6.0.10, 6.0.18, 7.0, 8.20, or a wildcard such as 1.0+. It denotes the minimum version of the JNLP Specification that this jnlp file can work with. |
1.0 |
|
|
codebase |
The codebase attribute specifies the base location for all relative URLs specified in href attributes in the JNLP file. |
1.0 |
|
|
href |
The href specifies the URL of the JNLP file itself. |
1.0 |
|
|
version |
The version of the application being launched, as well as the version of the JNLP file itself. |
1.0 |
|
information |
|
The information element contains other elements that describe the application and it's source. |
1.0 |
yes |
|
os |
Specifies the operating systems for which this information element should be considered. |
1.5.0 |
|
|
arch |
Specifies the architecture for which this information element should be considered |
1.5.0 |
|
|
locale |
Specifies the locale for which this information element should be considered. |
1.5.0 |
|
title |
|
The title element specifies the title of the application. |
1.0 |
yes |
vendor |
|
The vendor element specifies the provider of the application. |
1.0 |
yes |
homepage |
|
The homepage of the application. |
1.0 |
|
|
href |
A URL pointing to where more information on this application can be found. |
1.0 |
yes |
description |
|
A short statement describing the application. |
1.0 |
|
|
kind |
An indicator as to what type of description this is, legal values are one-line, short, and tooltip. |
1.0 |
|
icon |
|
Describes an icon that can be used to identify the application to the user. |
1.0 |
|
|
href |
A URL pointing to the icon file, may be in one of the following formats: gif, jpg, png, ico. |
1.0 |
yes |
|
kind |
Indicates the suggested use of the icon; can be: default, splash, or shortcut. |
1.0 |
|
|
width |
Can be used to indicate the resolution of the image. |
1.0 |
|
|
height |
Can be used to indicate the resolution of the image. |
1.0 |
|
|
depth |
Can be used to indicate the resolution of the image. |
1.0 |
|
offline-allowed |
|
Indicates that this application can operate when the client system is disconnected from the network. |
1.0 |
|
shortcut |
|
The shortcut element can be used to indicate an application's preferences for desktop integration. |
1.5.0 |
|
|
online |
Can be used to describe the application's preference for creating a shortcut to run online or offline. |
1.5.0 |
|
|
install |
The optional install attribute can be used in a shortcut element to describe the application's preference for being considered "installed". If the value is "true" the application prefers to be considered installed. The default value of the install attribute is "false". On Windows, this determines if the application appears in the Add and Remove Programs panel. |
7.0 |
|
desktop |
|
Can be used to indicate an application's preference for putting a shortcut on the users desktop. |
1.5.0 |
|
menu |
|
Can be used to indicate an application's preference for putting a menu item in the users start menus. |
1.5.0 |
|
|
sub-menu |
Can be used to indicate an application's preference for where to place the menu item. |
1.5.0 |
|
association |
|
Can be used to hint to the JNLP client that it wishes to be registered with the operating system as the primary handler of certain extensions and a certain mime-type. If this element is included, either the offline-allowed element must also be included, or the href attribute must be set for the jnlp element. |
1.5.0 |
|
|
extensions |
Contains a list of file extensions (separated by spaces) that the application requests it be registered to handle. |
1.5.0 |
|
|
mime-type |
Contains the mime-type that the application requests it be registered to handle. |
1.5.0 |
|
related-content |
|
Describes an additional piece of related content that may be integrated with the application. |
1.5.0 |
|
|
href |
A URL pointing to the related content. |
1.5.0 |
yes |
update |
|
The update element is used to indicate the preferences for how application updates should be handled by the JNLP Client. |
6.0 |
|
|
check |
Indicates the preference for when the JNLP Client should check for updates. It can be always, timeout, or background.. |
6.0 |
|
|
policy |
Indicates the preference for how the JNLP Client should handle an application update when it is known an update is available before the application is launched. It can be always, prompt-update, or prompt-run. |
6.0 |
|
security |
|
This element can be used to request enhanced permissions. |
1.0 |
|
all-permissions |
|
Requests that the application be run with all permissions. |
1.0 |
|
j2ee-application-client-permissions |
|
Requests that the application be run with a permission set that meets the security specifications of the J2EE Application Client environment. |
1.0 |
|
resources |
|
Describes all the resources that are needed for an application. |
1.0 |
yes |
|
os |
Specifies the operating system for which the resources element should be considered. |
1.0 |
|
|
arch |
Specifies the architecture for which the resources element should be considered. |
1.0 |
|
|
locale |
Specifies that the locales for which the resources element should be considered. |
|
|
java (or j2se) |
|
Specifies what version(s) of Java to run the application with. |
6.0 (java) |
|
|
version |
Describes an ordered list of version ranges to use. |
1.0 |
yes |
|
href |
The URL denoting the supplier of this version of java, and where it may be downloaded from. |
1.0 |
|
|
java-vm-args |
Indicates an additional set of standard and non-standard virtual machine arguments that the application would prefer the JNLP Client to use when launching Java. Note: Arguments are used only if they are considered secure. See the secure properties Note. |
1.0 |
|
|
initial-heap-size |
Indicates the initial size of the Java heap. |
1.0 |
|
|
max-heap-size |
Indicates the maximum size of the Java heap. |
1.0 |
|
jar |
|
Specifies a JAR file that is part of the application's classpath. |
1.0 |
yes |
|
href |
The URL of the jar file. |
1.0 |
yes |
|
version |
The requested version of the jar file. Requires using the version-based download protocol |
1.0 |
|
|
main |
Indicates if this jar contains the class containing the main method of the application. |
1.0 |
|
|
download |
Can be used to indicate this jar may be downloaded eagerly, lazily, or for progress indication. |
1.0 (6.0.18) |
|
|
size |
Indicates the downloadable size of the jar file in bytes. |
1.0 |
|
|
part |
Can be used to group resources together so they will be downloaded at the same time. |
1.0 |
|
nativelib |
|
Specifies a JAR file that contains native libraries in it's root directory. |
1.0 |
|
|
href |
The URL of the jar file. |
1.0 |
yes |
|
version |
The requested version of the jar file. Requires using the version-based download protocol |
1.0 |
|
|
download |
Can be used to indicate this jar may be downloaded lazily. |
1.0 |
|
|
size |
Indicates the downloadable size of the jar file in bytes. |
1.0 |
|
|
part |
Can be used to group resources together so they will be downloaded at the same time. |
1.0 |
|
extension |
|
Contains pointer to an additional component-desc or installer-desc to be used with this application. |
1.0 |
|
|
href |
The URL to the additional extension jnlp file. |
1.0 |
yes |
|
version |
The version of the additional extension jnlp file. |
1.0 |
|
|
name |
The name of the additional extension jnlp file |
1.0 |
|
ext-download |
|
Can be used in an extension element to denote the parts contained in a component-extension. |
1.0 |
|
|
ext-part |
Describes the name of a part that can be expected to be found in the extension. |
1.0 |
yes |
|
download |
Can be used to indicate this extension may be downloaded eagerly or lazily. |
1.0 |
|
|
part |
Denotes the name of a part in this jnlp file to include the extension in. |
1.0 |
|
package |
|
Can be used to indicate to the JNLP Client which packages are implemented in which JAR files. |
1.0 |
|
|
name |
Package name contained in the jar files of the given part. |
1.0 |
yes |
|
part |
Part name containing the jar files that include the given package name. |
1.0 |
yes |
|
recursive |
Can be used to indicated that all package names beginning with the given name, can be found in the given part. |
1.0 |
|
property |
|
Defines a system property that will be available through the System.getProperty and System.getProperties methods. Note: System properties set in an unsigned JNLP file are set by Java Web Start only if they are considered secure. See the secure properties Note. |
1.0 |
|
|
name |
Name of the system property. |
1.0 |
yes |
|
value |
Value it will be set to. |
1.0 |
yes |
application-desc |
|
Denotes this is the jnlp file for an application. |
1.0 |
Note: A jnlp file must contain one of application-desc, applet-desc, component-desc, or installer-desc |
|
main-class |
The name of the class containing the public static void main(String[]) method of the application. |
1.0 |
yes |
|
progress-class |
The name of the class containing the implementation of DownloadServiceListener, that may be used to indicate download progress. |
6.0.18 |
|
argument |
|
Each argument contains (in order) an additional argument to be passed to main. |
1.0 |
|
applet-desc |
|
Denotes this is the jnlp file for an applet. |
1.0 |
Note: A jnlp file must contain one of application-desc, applet-desc, component-desc, or installer-desc |
|
main-class |
This is the name of the main Applet class. |
1.0 |
yes |
|
documentbase |
The document base for the Applet as a URL. |
1.0 |
|
|
name |
Name of the Applet. |
1.0 |
yes |
|
width |
The width of the applet in pixels. |
1.0 |
yes |
|
height |
The height of the applet in pixels |
1.0 |
yes |
|
progress-class |
The name of the class containing the implementation of DownloadServiceListener, that may be used to indicate download progress. |
6.0.18 |
|
param |
|
A set of parameters that can be passed into the applet. |
1.0 |
|
|
name |
The name of this parameter |
1.0 |
yes |
|
value |
The value of this parameter |
1.0 |
yes |
component-desc |
|
Denotes this is the jnlp file for a component extension. |
1.0 |
Note: A jnlp file must contain one of application-desc, applet-desc, component-desc, or installer-desc |
|
progress-class |
The name of the class containing the implementation of DownloadServiceListener, that may be used to indicate download progress. |
6.0.18 |
|
installer-desc |
|
Denotes this is the jnlp file for an installed extension. |
1.0 |
Note: A jnlp file must contain one of application-desc, applet-desc, component-desc, or installer-desc |
|
main-class |
The name of the class containing the public static void main(String[]) method of the installer. |
1.0 |
yes |
For a basic application that does not require a lot of customization, the JNLP file can be simple. For more complex applications, additional elements can be added to the JNLP file.
The elements are described in JNLP Elements.
This example shows a simple JNLP file. The root element is jnlp
, which has two subelements: resources
and application-desc
.
<?xml version="1.0" encoding="utf-8"?> <jnlp spec="8"> <resources> <jar href="https://docs.oracle.com/javase/tutorialJWS/samples/deployment/NotepadJWSProject/Notepad.jar" /> </resources> <application-desc main-class="Notepad"/> </jnlp>
This example shows the basic outline of the JNLP file with settings for application attributes. The root element is jnlp
, which has four subelements: information
, security
, resources
, and application-desc
. In addition, Java Web Start also supports launching applets by using the applet-desc
element.
<?xml version="1.0" encoding="utf-8"?> <!-- JNLP File for SwingSet2 Demo Application --> <jnlp spec="6.0+" codebase="http://my_company.com/jaws/apps" href="swingset2.jnlp"> <information> <title>SwingSet2 Demo Application</title> <vendor>Sun Microsystems, Inc.</vendor> <homepage href="docs/help.html"/> <description>SwingSet2 Demo Application</description> <description kind="short">A demo of the capabilities of the Swing Graphical User Interface.</description> <icon href="images/swingset2.jpg"/> <icon kind="splash" href="images/splash.gif"/> <offline-allowed/> <association mime-type="application-x/swingset2-file" extensions="swingset2"/> <shortcut online="false" install="false"> <desktop/> <menu submenu="My Corporation Apps"/> </shortcut> </information> <information os="linux"> <title> SwingSet2 Demo on Linux </title> <homepage href="docs/linuxhelp.html"> </information> <security> <all-permissions/> </security> <resources> <j2se version="1.6+" java-vm-args="-esa -Xnoclassgc"/> <jar href="lib/SwingSet2.jar"/> </resources> <application-desc main-class="SwingSet2"/> </jnlp>
jnlp
Elementspec
attribute: This attribute
must be 1.0 or higher to work with this release. The default
value is "1.0+". Thus, it can typically be omitted. Note that
this version supports spec versions 1.0, 1.5.0, 6.0, 6.0.10,
6.0.18, 7.0, and 8.20. A jnlp file specifying
spec="8.20+"
will work with this version, but not
previous versions of Java Web Start.
codebase
attribute: All relative URLs
specified in href attributes in the JNLP file are using
this URL as a base.
href
attribute: This is a URL pointing to
the location of the JNLP file itself.
information
Elementos
attribute: This attribute contains a
list of operating system names for this element. Read the
discussion of the resources
element later for a full
discussion of the os
attribute.
title
element: The name of the
application.
vendor
element: The name of the vendor of
the application.
homepage
element: Contains a single
attribute, href, which is a URL locating the home page
for the Application. It is used by the Java Application Cache
Viewer to point the user to a Web page where more information
about the application can be found.
description
element: A short statement
about the application. Description elements are optional. The
kind attribute defines how the description should be
used. It can have one of the following values:
Only one description element of each kind can be specified. A
description element without a kind is used as a default value.
Thus, if Java Web Start needs a description of kind
short
, and it is not specified in the JNLP file,
then the text from the description without an attribute is
used.
All descriptions contain plain text. No formatting, such as with HTML tags, is supported.
icon
element: Contains an HTTP URL to an
image file in either GIF, JPEG, ICO, or PNG format. The icons are
used to represents the application
A 64x64 icon is shown during download; in the Java Application Cache Viewer and in desktop shortcuts a 32x32 icon is used. Java Web Start automatically resizes an icon to the appropriate size.
Optional width and height attributes can be used to indicate the size of the images.
The optional kind attribute can have one of the following values:
A JNLP file can contain multiple icon elements that differ by their kind attribute. This enables you to specify different icon images for your application.
offline-allowed
element: The optional
offline-allowed element indicates if the application can
be launched offline.
If offline-allowed is specified, then the application can be launched offline by the Java Application Cache Viewer, and shortcuts can be created which launch the application offline.
If an application is launched offline, it will not check for
updates and the API call BasicService.isOffline()
will return true
.
The offline-allowed element also controls how Java Web Start checks for an update to an application. If the element is not specified—i.e., the application is required to be online to run—Java Web Start will always check for an updated version before launching the application. And if an update is found, the new application will be downloaded and launched. Thus, it is guaranteed that the user always runs the latest version of the application. The application, however, must be run online.
If offline-allowed is specified, Java Web Start will also check to see if an update is available. However, if the application is already downloaded the check will timeout after a few seconds, in which case the cached application will be launched instead. Given a reasonably fast server connection, the latest version of the application will usually be run, but it is not guaranteed. The application, however, can be run offline.
shortcut
element: The optional shortcut element can be
used to indicate an application's preferences for desktop
integration. The shortcut element and its sub-elements provide
hints that the JNLP Client may or may not use. The shortcut
element can contain the optional online
and
install
attributes, and the two optional
sub-elements, desktop
and menu
.
association
element: The optional association element is a
hint to the JNLP client that it wishes to be registered with the
operating system as the primary handler of certain extensions and
a certain mime-type. The association element must have the
extensions and mime-type attributes. If the association element
is included, either the offline-allowed element must also be
included, or the href
attribute must be set for the
jnlp element to ensure that the application can be located and
run.
related-content
element: The optional related-content element
describes an additional piece of related content, such as a
readme file, help pages, or links to registration pages, as a
hint to a JNLP Client. The application is asking that this
content be included in its desktop integration. The
related-content element has a mandatory href and title attribute.
It can contain any of the following two sub-elements:
description
element: A short description
of the related content.icon
element: The icon can be used by the
JNLP Client to identify the related content to the user.security
ElementEach sandbox application is run in a restricted execution environment, similar to the Applet sandbox. The security element can be used to request unrestricted access.
If the all-permissions element is specified, the application will have full access to the client machine and local network. All JAR files must be signed. The user is prompted to accept the certificate and agree to run the application.
update
ElementThe update element is used to indicate the preferences for how application updates should be handled by Java Web Start.
The update element can contain the following two optional attributes:
check attribute:
The check attribute
indicates the preference for when the JNLP Client should check
for updates, and can have one of the three values: "always",
"timeout", and "background"
A value of "always" means to always check for updates before launching the application.
A value of "timeout" (default) means to check for updates until timeout before launching the application. If the update check is not completed before the timeout, the application is launched, and the update check will continue in the background.
A value of "background" means to launch the application while checking for updates in the background.
policy attribute:
The policy attribute
indicates the preference for how the JNLP Client should handle an
application update when it is known an update is available before
the application is launched, and can have one of the following
three values: "always", "prompt-update", and "prompt-run"
A value of "always" (default) means to always download updates without any prompt.
A value of "prompt-update" means to ask the user if he/she wants to download and run the updated version, or launch the cached version.
A value of "prompt-run" means to ask the user if he/she wants to download and run the updated version, or cancel and abort running the application.
For example:
<update check="always" policy="prompt-update">resources
ElementThe resources element is used to specify all the resources, such as Java class files, native libraries, and system properties, that are part of the application. A resource definition can be restricted to a specific operating system, architecture, or locale using the os, arch, and locale attributes.
The os
attribute contains a list of operating
system names for a resource. For example, you could use multiple
resources
definitions, with different
os
attributes, to supply a native library for
multiple operating systems.
The os
attribute contains a list of operating
system names separated by spaces. At runtime, the os
values are compared with the beginning of the
os.name
system property to find a match. For
example, an os
attribute value of "Windows" matches
both "Windows 8" and "Windows 10" operating systems.
If you wish to list an operating system whose name contains a space, use a backslash to indicate that the space is part of the operating system name. The following example will specifically match "Windows 8" and "Windows 10":
<resources os="Windows\ 8 Windows\ 10"> <jar href="hello.jar"/> </resources>
The resources
element has six different possible
subelements: jar, nativelib, j2se,
property, package, and extension. The
package and extension elements are not
discussed in this developer's guide.
A jar element specifies a JAR file that is part of the application's classpath. For example:
<jar href="myjar.jar"/>
The jar file will be loaded into the JVM using a ClassLoader object. The jar file will typically contain Java classes that contain the code for the particular application, but can also contain other resources, such as icons and configuration files, that are available through the getResource mechanism.
A nativelib element specifies a JAR file that contains native libraries. For example:
<nativelib href="lib/windows/corelib.jar"/>
The JNLP client must ensure that each file entry in the root
directory of the JAR file (i.e., /
) can be loaded
into the running process using the System.loadLibrary
method. Each entry must contain a platform-dependent shared
library with the correct naming convention, e.g.,
*.dll
on Windows or lib*.so
on
Solaris/Linux. The application is responsible for doing the
actual call to System.loadLibrary.
Native libraries would typically be included in a resources element that is geared toward a particular operating system and architecture. For example:
<resources os="SunOS" arch="sparc"> <nativelib href="lib/solaris/corelibs.jar"/> </resources>
By default, jar and nativelib resources will be downloaded eagerly, i.e., they are downloaded and available locally to the JVM running the application before the application is launched. The jar and nativelib elements also allow a resource to be specified as lazy. This means the resource does not have to be downloaded onto the client system before the application is launched.
The download attribute is used to control whether a resource is downloaded eagerly, lazily, or contains a custom progress implementation. For example:
<jar href="sound.jar"
download="lazy"/>
<nativelib href="native-sound.jar"
download="eager"/>
<jar href="progress.jar"
download="progress"/>
A jar denoted with download="progress" will be downloaded eagerly, and may be used to indicate progress while downloading other resources.
The j2se element specifies what Java Platform Standard Edition Runtime Environment (JRE) versions an application is supported on, as well as standard parameters to the Java Virtual Machine. If several JREs are specified, this indicates a prioritized list of the supported JREs, with the most preferred version first. For example:
<j2se version="1.3"
initial-heap-size="64m"
max-heap-size="128m"/>
<j2se version="1.4.2+"
href="http://java.sun.com/products/autodl/j2se"
java-vm-args="-esa -Xnoclassgc"/>
The version
attribute refers, by default, to a platform
version (specification version) of the Java Platform Standard
Edition. Currently defined platform versions are 1.2, 1.3, 1.4,
1.5, 1.6, 1.7, and 1.8. (A platform version will not normally
contain a micro version number; e.g., 1.4.2.)
Exact product versions (implementation versions) may also be
specified. by including the href
attribute. For
example, 1.3.1_07, 1.4.2, or 1.5.0-beta2 by Sun Microsystems,
Inc. For example,
<j2se version="1.4.2" href="http://java.sun.com/products/autodl/j2se"/
or
<j2se version="1.4.2_04" href="http://java.sun.com/products/autodl/j2se"/>
If a platform version is specified (i.e., no href
attribute is provided), Java Web Start will not consider an
installed non-FCS (i.e., milestone) JRE as a match. E.g., a
request of the form
<j2se version="1.4+"/>
would not consider an installed 1.4.1-ea or 1.4.2-beta JRE as
a match for the request. Starting with 1.3.0, a JRE from Sun
Microsystems, Inc., is by convention a non-FCS (milestone) JRE if
there is a dash (-
) in the version string.
The java-vm-args
attribute of the j2se element specifies a
preferred set of virtual machine arguments to use when launching
java.
Note: Arguments are used only if they are considered secure. See the secure properties Note.
The following java-vm-args are supported by this version:
-d32 /* use 32-bit data model if available */ -client /* to select the "client" VM */ -server /* to select the "server" VM */ -verbose /* enable verbose output */ -version /* print product version and exit */ -showversion /* print product version and continue */ -help /* print this help message */ -X /* print help on non-standard options */ -ea /* enable assertions */ -enableassertions /* enable assertions */ -da /* disable assertions */ -disableassertions /* disable assertions */ -esa /* enable system assertions */ -enablesystemassertions /* enable system assertions */ -dsa /* disable system assertions */ -disablesystemassertions /* disable system assertions */ -Xmixed /* mixed mode execution (default) */ -Xint /* interpreted mode execution only */ -Xnoclassgc /* disable class garbage collection */ -Xincgc /* enable incremental gc. */ -Xbatch /* disable background compilation */ -Xprof /* output cpu profiling data */ -Xdebug /* enable remote debugging */ -Xfuture /* enable strictest checks */ -Xrs /* reduce use of OS signals */ -XstartOnFirstThread -XX:+CMSClassUnloadingEnabled /* It needs to be combined with -XX:+CMSPermGenSweepingEnabled */ -XX:+CMSIncrementalPacing /* Automatic adjustment of the incremental mode duty cycle */ -XX:+CrashOnOutOfMemoryError /* When enabled, when an out-of-memory error occurs, the JVM crashes and produces text and binary crash files if core files are enabled. */ -XX:+DisableExplicitGC /* Disable calls to System.gc() */ -XX:+ExitOnOutOfMemoryError /* When enabled, the JVM exits on the first occurrence of an out-of-memory error. Use it if you prefer restarting an instance of the JVM rather than handling out-of-memory errors. */ -XX:+ForceTimeHighResolution /* use high resolution timer */ -XX:-ForceTimeHighResolution /* use low resolution (default) */ -XX:+HeapDumpOnOutOfMemoryError -XX:-ParallelRefProcEnabled -XX:+PrintStringDeduplicationStatistics -XX:+PrintGCDetails /* Gives some details about the GCs */ -XX:+PrintGCTimeStamps /* Prints GCs times happen to the start of the application */ -XX:+PrintHeapAtGC /* Prints detailed GC info including heap occupancy */ -XX:+PrintTenuringDistribution /* Gives the aging distribution of the allocated objects */ -XX:+TraceClassUnloading /* Display classes as they are unloaded */ -XX:-TransmitErrorReport -XX:+UseConcMarkSweepGC /* Turns on concurrent garbage collection */ -XX:+UseG1GC -XX:+UseGCTimeLimit -XX:-UseGCTimeLimit -XX:+UseGCOverheadLimit -XX:-UseGCOverheadLimit -XX:+UseParallelOldGC -XX:-UseParallelOldGC -XX:+UseParallelOldGCCompacting -XX:-UseParallelOldGCCompacting -XX:+UseParallelGC -XX:-UseParallelGC -XX:+UseParallelScavenge -XX:-UseParallelScavenge -XX:+UseStringDeduplication -XX:+ScavengeBeforeFullGC -XX:-ScavengeBeforeFullGC
Plus any argument starting with one of the following:
-ea: /* enable assertions for classes ... */ -enableassertions: /* enable assertions for classes ... */ -da: /* disable assertions for classes ... */ -disableassertions: /* disable assertions for classes ... */ -verbose: /* enable verbose output */ -Xmn /* set the young gen size; this is an unspecified and undocumented JVM option being added here only as a convenience to end users */ -Xms /* set initial Java heap size */ -Xmx /* set maximum Java heap size */ -Xss /* set java thread stack size */ -XX:NewRatio /* set Ratio of new/old gen sizes */ -XX:NewSize /* set initial size of new generation */ -XX:MaxNewSize /* set max size of new generation */ -XX:PermSize /* set initial size of permanent gen */ -XX:MaxPermSize /* set max size of permanent gen */ -XX:MaxHeapFreeRatio /* heap free percentage (default 70) */ -XX:MinHeapFreeRatio /* heap free percentage (default 40) */ -XX:-UseSerialGC /* use serial garbage collection */ -XX:ThreadStackSize /* thread stack size (in KB) */ -XX:MaxInlineSize /* set max num of bytecodes to inline */ -XX:ReservedCodeCacheSize /* Reserved code cache size (bytes) */ -XX:MaxDirectMemorySize /* set maximum direct memory size */ -XX:PrintCMSStatistics /* If > 0, Print statistics about the concurrent collections */ -XX:SurvivorRatio /* Sets the ratio of the survivor spaces */ -XX:MaxTenuringThreshold /* Determines how much the objects may age */ -XX:CMSMarkStackSize -XX:CMSMarkStackSizeMax -XX:CMSIncrementalDutyCycleMin /* The percentage which is the lower bound on the duty cycle */ -XX:ParallelCMSThreads -XX:ParallelGCThreads /* Sets the number of parallel GC threads */ -XX:CMSInitiatingOccupancyFraction /* Sets the threshold percentage of the used heap */ -XX:+UseCompressedOops /* Enables compressed references in 64-bit JVMs */ -XX:GCPauseIntervalMillis -XX:MaxGCPauseMillis /* A hint to the virtual machine to pause times */ -XX:+CMSIncrementalMode /* Enables the incremental mode */ -XX:MaxMetaspaceSize /* Sets an upper limit on memory used for class metadata */ -XX:StringDeduplicationAgeThreshold -XX:GCTimeLimit -XX:GCHeapFreeLimit
The property element defines a system property that will be available through the System.getProperty and System.setProperties methods. It has two required attributes: name and value. For example:
<property name="key" value="overwritten"/>Properties set in the JNLP file will normally be set by Java Web Start after the VM is started but before the application is invoked. Some properties are considered "secure" properties and can be passed as -Dkey=value arguments on the java invocation command line. The following properties are predefined secure properties and will be passed to the VM in this way:
apple.laf.useScreenMenuBar awt.useSystemAAFontSettings com.sun.management.jmxremote.local.only http.agent http.keepAlive java.awt.Window.locationByPlatform java.awt.smartInvalidate java.awt.syncLWRequests java.net.preferIPv4Stack java.util.Arrays.useLegacyMergeSort javaplugin.lifecycle.cachesize javaws.cfg.jauthenticator jdk.jar.maxSignatureFileSize jdk.map.althashing.threshold sun.awt.disableMixing sun.awt.enableExtraMouseButtons sun.awt.erasebackgroundonresize sun.awt.keepWorkingSetOnMinimize sun.awt.noerasebackground sun.java2d.d3d sun.java2d.dpiaware sun.java2d.noddraw sun.java2d.opengl sun.lang.ClassLoader.allowArraySyntax sun.locale.formatasdefault sun.nio.ch.bugLevel sun.nio.ch.disableSystemWideOverlappingFileLockCheck swing.boldMetal swing.metalTheme swing.noxp swing.useSystemFontSettings
New secure properties can also be defined as needed by prefixing the property name with "jnlp." or "javaws.".
Note: To be considered secure, property names and values must meet the following requirements:
System properties set in an unsigned JNLP file will only be set by Java Web Start if they are considered secure.
For information about properties that affect the behavior of Java Web Start applications, see Properties That Affect the Behavior of Rich Internet Applications.
application-desc
ElementThe application element indicates that the JNLP file is launching an application (as opposed to an applet). The application element has an optional attribute, main-class, which can be used to specify the name of the application's main class, i.e., the class that contains the public static void main(String argv[]) method where execution must begin.
The main-class
attribute can be omitted if the first JAR file
specified in the JNLP file contains a manifest file containing
the main
class.
Arguments can be specified to the application by including one or more nested argument elements. For example:
<application-desc
main-class="Main">
<argument>arg1</argument>
<argument>arg2</argument>
</application-desc>
The (optional) progress-class
attribute can be used to indicate that the class
of this name implements the javax.jnlp.DownloadServiceListener
interface. This class may be loaded first and used to indicate
the progress of other resources being downloaded and
verified.
applet-desc
ElementJava Web Start has support for launching Java applets. This support provides easy migration of existing code to Java Web Start.
An applet is launched using the applet-desc element instead of the application-desc element. For example:
<applet-desc
documentBase="http://..."
name="TimePilot"
main-class="TimePilot.TimePilotApp"
width="527"
height="428">
<param name="key1"
value="value1"/>
<param name="key2"
value="value2"/>
</applet-desc>
The JAR files that make up the applet are described using the resources element as for applications. The documentBase must be provided explicitly since a JNLP file is not embedded in an HTML page. The rest of the attributes correspond to the respective HTML applet tag elements.
The main-class attribute is used instead of the code attribute. The main-class attribute is assigned the name of the Applet class (without the .class extension). This attribute can be omitted if the Applet class can be found from the Main-Class manifest entry in the main JAR file.
The (optional) progress-class
attribute can be used to indicate that the class
of this name implements the javax.jnlp.DownloadServiceListener
interface. This class may be loaded first and used to indicate
the progress of other resources being downloaded and
verified.
Note: Applets must be packaged in JAR files in order to work with Java Web Start.
component-desc
ElementThe component-desc element denotes that this jnlp file is not an application or an applet but an extension that can be used as a resource in an application, applet or another extension.
A component extension is typically used to factor out a set of resources that are shared between multiple applications or that have separate security needs.
The (optional) progress-class
attribute can be used to indicate that the class
of this name implements the javax.jnlp.DownloadServiceListener
interface. This class may be loaded first and used to indicate
the progress of other resources being downloaded and
verified.
installer-desc
ElementThe installer-desc element denotes that this jnlp file is an installer extension that defines an application that will be run only once, the first time this extension jnlp file is used in an application, applet or another extension.
An installer extension is typically used to install platform specific native code that requires a more complicated setup than simply loading a native library into the VM.