| MINERVA applets can access the local file system
and other restricted resources according to the
Java security model, either with a policy file on
the client machine or with signed applets.
Applet handles files on local file system
This example applet shows how to read a text file,
and how to load and execute a MINERVA program
from the local machine.
Applet output goes to Java console
(This applet has no graphics or anything visible.)
Server side files
wrap.html (as this file, look at the source to see the applet tag)
Compile.sh compile command
localfile.min applet source
localfile.mbc applet object
localfile.mpk
Local machine side files (to be extracted to C:\minlocal\)
minlocal.zip archive
To install, download the zip file to C:, then unzip, so that
the files end up as
C:\minlocal\hi_world.min
and read README.txt .
Since the applet program uses this location,
you will also need to adapt the server side program if
you want to use another location.
Sample HTTP client C:\minlocal\Go.bat
appletviewer -J-Djava.security.policy=mypolicy http://www.ifcomputer.co.jp/MINERVA/ExamplePrograms/MinervaFeatures/AppletLoadsFile/wrap.html
(this must all be in one line)
Sample policy file C:\minlocal\mypolicy
grant codeBase "http://www.ifcomputer.co.jp/-" {
permission java.security.AllPermission;
};
This policy file is used explicitly in the invocation of appletviewer (see Go.bat).
Reference
http://java.sun.com/docs/books/tutorial/security1.2/tour1/step3.html
Remarks
This code was tested with Sun JDK1.3 appletviewer,
with Opera 6.05, and with Mozilla 1.1 all on Microsoft Windows98SE.
This example requires use of Sun Java, it will not work with
Microsoft Java virtual machines.
The installation of the policy file is browser dependent.
For JDK, instead of passing the policy file to appletviewer, you could edit
C:\jdk1.3.1\jre\lib\security\java.policy
For Opera, you could edit
C:\Program Files\Opera\Classes\Opera.policy
For Mozilla, you could edit
C:\Windows\.java.policy
For Internet Explorer, use the Sun Java plugin.
Signed Applets
MINERVA deployment as signed applet is same as Java signed applets.
There are 5 steps:
-
make a program that works with a policy file
a good example is the program presented here. It does not
need any modification.
-
read the friendly manual about Java signed applets
You find this in the documentation of your Java processor.
If you plan to skip this, please skip signed applets.
-
buy a certificate or make a self-signed certificate
e.g.
keytool -genkey -alias test -keypass testpassword -keystore $HOME/keystore
all in one line
-
sign the jar holding the MINERVA classes
and your own classes if any. e.g.
jarsigner -keystore $HOME/keystore -storepass mykeystore -keypass testpassword -signedjar $MINERVA_HOME/signed_minrt.jar $MINERVA_HOME/minrt.jar test
all in one line
-
change your applet tag to use the signed jar
Notes:
Some browsers including appletviewer do not accept self-signed
certificates, and they will not tell you.
This code was tested with server side Sun JDK1.4 tools on Linux,
client side Sun JDK1.4 appletviewer,
with Opera 7.23, and with Mozilla 1.1 all on Microsoft Windows98SE.
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