rmid - RMI activation system daemon
The daemon can be started by executing the rmid command, and specifying a security policy file, as follows:
example% rmid -J-Djava.security.policy=rmid.policy
Note: When running Sun's implementation of rmid, by default you will need to specify a security policy file so that rmid can verify whether or not the information in each ActivationGroupDesc is allowed to be used to launch a JVM for an activation group. Specifically, the command and options specified by the CommandEnvironment and any Properties passed to an ActivationGroupDesc's constructor must now be explicitly allowed in the security policy file for rmid. The value of the sun.rmi.activation.execPolicy property dictates the policy that rmid uses to determine whether or not the information in an ActivationGroupDesc may be used to launch a JVM for an activation group.
Executing rmid by default
To specify an alternate port for the registry, you must specify the -port option when starting up rmid. For example,
rmid -J-Djava.security.policy=rmid.policy -port 1099
starts the activation system daemon and a registry on the registry's default port, 1099.
rmid -C-Dsome.property=value
This ability to pass command-line arguments o child processes can be useful for debugging. For example, the following command:
rmid -C-Djava.rmi.server.logCalls=true
will enable server-call logging in all child JVMs.
rmid -J-Djava.security.policy=rmid.policy
rmid launches a JVM for an activation group using the information in the group's registered activation group descriptor, an ActivationGroupDesc. The group descriptor specifies an optional ActivationGroupDesc.CommandEnvironment which includes the command to execute to start the activation group as well as any command line options to be added to the command line. By default, rmid uses the java command found in java.home. The group descriptor also contains properties overrides that are added to the command line as options defined as:
-Dproperty=value
The permission com.sun.rmi.rmid.ExecPermission is used to grant rmid permission to execute a command, specified in the group descriptor's CommandEnvironment to launch an activation group. The permission com.sun.rmi.rmid.ExecOptionPermission is used to allow rmid to use command-line options, specified as properties overrides in the group descriptor or as options in the CommandEnvironment, when launching the activation group.
When granting rmid permission to execute various commands and options, the permissions ExecPermission and ExecOptionPermission need to be granted universally (that is, granted to all code sources).
Syntax
The name of an
ExecPermission
is the path name of a command to grant
rmid
permission to execute.
A path name that ends in "/*" indicates
all the files contained in that directory (where "/"
is the file-separator character,
File.separatorChar).
A path name that ends with "/-" indicates
all files and subdirectories contained in that directory (recursively).
A path name consisting of
the special token "<<ALL FILES>>" matches
any
file.
Note: A path name consisting of a single "*" indicates all the files in the current directory, while a path name consisting of a single "-" indicates all the files in the current directory and (recursively) all files and subdirectories contained in the current directory.
Syntax
Options support a limited wildcard scheme.
An asterisk signifies a wildcard match, and it may
appear as the option name itself
(that is, it matches any option),
or an asterisk may appear at the end
of the option name only if the
asterisk follows either a "." or "=".
For example: "*" or "-Dfoo.*" or "-Da.b.c=*" is valid; "*foo" or "-Da*b" or "ab*" is not.
An example policy file that grants various execute permissions to rmid is:
grant { permission com.sun.rmi.rmid.ExecPermission "/files/apps/java/jdk1.2.2/bin/java"; permission com.sun.rmi.rmid.ExecPermission "/files/apps/rmidcmds/*"; permission com.sun.rmi.rmid.ExecOptionPermission "-Djava.security.policy=/files/policies/group.policy"; permission com.sun.rmi.rmid.ExecOptionPermission "-Djava.security.debug=*"; permission com.sun.rmi.rmid.ExecOptionPermission "-Dsun.rmi.*"; };
The first permission granted allow rmid to execute the 1.2.2 version of the java command, specified by its explicit path names. Note that by default, the version of the java command found in java.home is used (the same one that rmid uses), and does not need to be specified in the policy file. The third permission allows rmid to execute any command in the directory /files/apps/rmidcmds.
The fourth permission granted, an ExecOptionPermission, allows rmid to launch an activation group that defines the security policy file to be /files/policies/group.policy. The next permission allows the java.security.debug property to be used by an activation group. The last permission allows any property in the sun.rmi property name hierarchy to be used by activation groups.
To start rmid with a policy file, the java.security.policy property needs to be specified on rmid's command line. For example:
rmid -J-Djava.security.policy=rmid.policy
If the default behavior is not flexible enough, an administrator can provide, when starting rmid, the name of a class whose checkExecCommand method is executed in order to check commands to be executed by rmid.
The policyClassName specifies a public class with a public, no-argument constructor and an implementation of the following checkExecCommand method:
public void checkExecCommand(ActivationGroupDesc desc, String[] command) throws SecurityException;
Before launching an activation group, rmid calls the policy's checkExecCommand method, passing it the activation group descriptor and an array containing the complete command to launch the activation group. If the checkExecCommand throws a SecurityException, rmid will not launch the activation group and an ActivationException will be thrown to the caller attempting to activate the object.
If the sun.rmi.activation.execPolicy property value is "none", then rmid will not perform any validation of commands to launch activation groups.
import java.rmi.*; import java.rmi.activation.*; ActivationSystem system; system = (ActivationSystem) Naming.lookup("//:port/java.rmi.activation.ActivationSystem");
example% .:/usr/local/java/classes
See (or search java.sun.com) for the following:
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