Java bug: Object tag and archive attribute

[Walter Gabrielsen Iii]

I think that I have found a bug in Java itself, not a browser bug, regarding the Object tag, the 'archive' attribute of the Object tag, and the archive attribute's interaction with Java's internal AppletClassLoader.


I think a little background detail is needed here. Java applets were first embeded into web pages with the APPLET tag and the "archive" attribute on the APPLET tag was a comma-separated list -- this part is important! The replacement for APPLET is supposed to be the Object tag which also has an "archive" attribute but this version of the "archive" attribute takes a space-separated list of values.


So, to the bug, I open the Java Console, trigger logging mode, set trace to level 5, and then open a page with an applet, embeded with the Object tag, using the attribute:

archive="myApplet.class archive1.jar archive2.jar"

(the full version is found below).

This is what appears in the Java Console using Object's version of the archive attribute:
Plugin2ClassLoader.addURL parent called for file:/C:/Desktop/applet/applet/myApplet.class archive1.jar archive2.jar

-- Java thinks it has a single file name: "myApplet.class archive1.jar archive2.jar"

-- Java should have seen three files and cached at least two (the jar files):
1 myApplet.class
2 archive1.jar
3 archive2.jar


Okay, so then, after that, I added a Param tag, formatted using a comma-separated list, just like the APPLET tag uses: <param name="archive" value="archive1.jar, archive2.jar" valuetype="ref">.

Java's new output:

Plugin2ClassLoader.addURL parent called for file:/C:/Desktop/applet/applet/archive1.jar
Plugin2ClassLoader.addURL parent called for file:/C:/Desktop/applet/applet/archive2.jar

Now it works. Java's applet class loader found the jar files and called them.

So, it appears, that Java's internal class loader is broken -- it only takes a comma-separated list for reading an archive attribute's value. This conflicts with Object's specification of the archive tag which is space-separated. Yet what happens is that Java can't read Object's archive attribute correctly if its longer than 1 item long because Java only reads comma-separated lists of archives.

Run using Java Plug-in 1.6.0_32, that's Java SE 1.6.0_32 release (the current latest version from http://www.java.com).

Just so you know, if you try to recreate this, this is how I sorted my File Locations:
C:\Desktop\applet -- where the html file using the Object tag is located.
C:\Desktop\applet\applet -- where the applet's *.class and .jar files are located.

The full object code (and this was intentionally made verbose for maximum use and browser support) (Note: the code is html 4.01 not xhtml, so remember to close the param tags with slash-bracket "/>" if you copy this code into an xhtml file):

<object type="application/x-java-applet" codetype="application/x-java-applet" codebase="applet/" data="myApplet.class" classid="java:myApplet.class" width="176" height="220" archive="myApplet.class archive1.jar archive2.jar" > <!-- APPLET § codebase : uri This attribute specifies the base URI for the applet. If this attribute is not specified, then it defaults the same base URI as for the current document. Values for this attribute may only refer to subdirectories of the directory containing the current document. --> <param name="codebase" value="applet/" valuetype="ref" > <!-- APPLET § code : cdata : case-sensitive This attribute specifies either the name of the class file that contains the applet's compiled applet subclass or the path to get the class, including the class file itself. It is interpreted with respect to the applet's codebase. One of code or object must be present. --> <param name="code" value="myApplet.class" valuetype="data" type="application/x-java-applet" > <!-- APPLET § name : cdata : case-sensitive This attribute specifies a name for the applet instance, which makes it possible for applets on the same page to find (and communicate with) each other. --> <param name="name" value="myApplet" valuetype="data" > <!-- APPLET § archive : uri-list : comma-separated This attribute specifies a comma-separated list of URIs for archives containing classes and other resources that will be "preloaded". The classes are loaded using an instance of an AppletClassLoader with the given codebase. Relative URIs for archives are interpreted with respect to the applet's codebase. Preloading resources can significantly improve the performance of applets. --> <!-- disabled param <param name="archive" value="archive1.jar, archive2.jar" valuetype="ref" >--> <!-- APPLET § object : cdata : case-sensitive This attribute names a resource containing a serialized representation of an applet's state. It is interpreted relative to the applet's codebase. The serialized data contains the applet's class name but not the implementation. The class name is used to retrieve the implementation from a class file or archive. --> <!-- disabled param. <param name="object" value="" valuetype="data" > --> no java. </object>

[Andrew Thompson]

Walter Gabrielsen Iii wrote:..The replacement for APPLET is supposed to be the Object tag ..

Oracle currently supports the Deployment Toolkit Script.

[Tim Moores]

Yeah, don't use OBJECT or EMBED. The APPLET tag works fine in my experience, though, but it doesn't handle checking for a particular Java version being installed, and steering the user to download it if necessary.

[Walter Gabrielsen Iii]

Yes using the Applet tag, or the script, does work. So does overloading Object with param values.

I just find it odd that Java can choke up over the difference between a space and a comma. It must be Java's rendering engine that chokes because I'm following its messages through the Java Console in multiple browsers.