provided.rmiUtils

Class RMIUtils

java.lang.Object

provided.rmiUtils.RMIUtils

All Implemented Interfaces:

IRMIUtils

public class RMIUtils
extends java.lang.Object
implements IRMIUtils

Concrete implementaion of the IRMIUtils, which are utilities to make it easier to start/stop the RMI system, access local/remote Registries and get the local IP address. It is NOT recommended that students write their own RMI management code as this code has been thoroughly tested and should satify all the needs of the project.

Author:

swong

Field Summary

Fields

Modifier and Type	Field and Description
private ClassFileServer	classFileServer A class file server to enable remote dynamic class loading of the ICompute object.
private java.util.function.Consumer<java.lang.String>	errMsgStrategy Strategy to display an error message.
private java.util.function.Consumer<java.lang.String>	infoMsgStrategy Strategy to display an informational message.
private java.lang.String	last_addr The last address selected for use.
private boolean	privateAddrOnly If true, then only detects private IP addresses.

Constructor Summary

Constructors

Constructor and Description
RMIUtils(java.util.function.Consumer<java.lang.String> outputCmd) Constructor for the class.
RMIUtils(java.util.function.Consumer<java.lang.String> outputCmd, boolean privateAddrOnly) Auxiliary constructor used to set the getLocalAddress() method to return non-private addresses, e.g.

Method Summary

Modifier and Type	Method and Description
private void	addPrivateAddr(java.lang.String hostAddress, java.util.ArrayList<java.lang.String> addr_choices) Adds the given host address to the addr_choices ArrayList if the host address is a private address, i.e.
private void	configRMIProperties(int classServerPort) Sets the java.rmi.server.hostname and java.rmi.server.codebase system properties which control the automatic remote dynamic class loading.
private void	configSecurityManager() Sets the java.security.policy system property to point at the location of the security policy file, which is assumed to be at "provided\rmiUtils\server.policy" (file separators adjusted to match operating system).
java.lang.String	getLocalAddress() This method is designed to reliably return the actual local IP address across multiple platforms, particularly Linux.
java.rmi.registry.Registry	getLocalRegistry() Returns the Registry on the local machine on port IRMI_Defs.REGISTRY_PORT, as a server would require.
java.rmi.registry.Registry	getRemoteRegistry(java.lang.String host) Returns the Registry on the given machine on port IRMI_Defs.REGISTRY_PORT, as a client would require.
protected void	showErrorMsg(java.lang.String msg) Encapsulated behavior to show an error message
protected void	showInfoMsg(java.lang.String msg) Encapsulated behavior to show an informational message
private void	startClassFileServer(int classServerPort) Start the class file server to support remote dynamic class loading.
void	startRMI(int classServerPort) Start up the RMI system.
private void	stopClassFileServer() Stop the class file server and reset the reference to it, "classFileServer", to null.
void	stopRMI() Performs all necessary work to shut the RMI system down, such as shut the class server down.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

privateAddrOnly

private boolean privateAddrOnly

If true, then only detects private IP addresses. Should be set false for server use (i.e. non-private addresses). See auxiliary constructor.

last_addr

private java.lang.String last_addr

The last address selected for use.

infoMsgStrategy

private java.util.function.Consumer<java.lang.String> infoMsgStrategy

Strategy to display an informational message. Defaults to System.out.println()

errMsgStrategy

private java.util.function.Consumer<java.lang.String> errMsgStrategy

Strategy to display an error message. Defaults to System.err.println()

classFileServer

private ClassFileServer classFileServer

A class file server to enable remote dynamic class loading of the ICompute object.

Constructor Detail

RMIUtils

public RMIUtils(java.util.function.Consumer<java.lang.String> outputCmd)

Constructor for the class. Combines the given output command with the internal default commands to send status info to both the view connected to by the input outputCmd as well as standard out and error.

Parameters:

outputCmd - command used to output status and error information

RMIUtils

public RMIUtils(java.util.function.Consumer<java.lang.String> outputCmd,
                boolean privateAddrOnly)

Auxiliary constructor used to set the getLocalAddress() method to return non-private addresses, e.g. when used on a server rather than a wireless laptop.

Parameters:

outputCmd - command used to output status and error information

privateAddrOnly - If false, will look for non-private IP addresses as well.

Method Detail

getLocalRegistry

public java.rmi.registry.Registry getLocalRegistry()

Returns the Registry on the local machine on port IRMI_Defs.REGISTRY_PORT, as a server would require. Creates the Registry if it isn't already running. Returns null system if unable to create a Registry if needed.

Specified by:

getLocalRegistry in interface IRMIUtils

Returns:

the Registry or null if no Registry could be made or found.

getRemoteRegistry

public java.rmi.registry.Registry getRemoteRegistry(java.lang.String host)

Returns the Registry on the given machine on port IRMI_Defs.REGISTRY_PORT, as a client would require.

Specified by:

getRemoteRegistry in interface IRMIUtils

Parameters:

host - the IP address or host name of the remote machine.

Returns:

The remote Registry or null if it could not be located.

getLocalAddress

public java.lang.String getLocalAddress()
                                 throws java.net.SocketException,
                                        java.net.UnknownHostException

This method is designed to reliably return the actual local IP address across multiple platforms, particularly Linux. This method is a replacement for "java.net.InetAddress.getLocalHost().getHostAddress()" which will return the loopback address in Linux, not the actual IP address. Also, Java tends to report many virtual network adapters as "non-virtual". This method only returns IPv4 addresses, not IPv6 addresses, which are non-loopback, operational and non-virtual, as reported by Java. By default, privateAddrOnly is set to true, so only private IP addresses are detected. If privateAddr = false (having used the auxiliary constructor) then all valid addresses are detected. If multiple potentially valid addresses are detected, then a dialog box will pop up to ask the user to select the proper address. The selected address is cached so the next call to getLocalAddress() will simply return the cached address value.

Specified by:

getLocalAddress in interface IRMIUtils

Returns:

A non-loopback, non-virtual IPv4 address found for the system.

Throws:

java.net.SocketException - thrown when there is a problem retrieving the network interfaces.

java.net.UnknownHostException - thrown when the local host address cannot be found.

addPrivateAddr

private void addPrivateAddr(java.lang.String hostAddress,
                            java.util.ArrayList<java.lang.String> addr_choices)

Adds the given host address to the addr_choices ArrayList if the host address is a private address, i.e. 10.x.x.x, 192.188.x.x or 172.16.x.x-172.31.x.x

Parameters:

hostAddress - The host address to check and possibly add

addr_choices - The ArrayList to add the host address to if it is a private address

startRMI

public void startRMI(int classServerPort)

Start up the RMI system. This method should be called before any other activity with that involves RMI. This method configures the system properties RMI needs, starts the security manager and starts the class server.
Typical classServerPort values are:
IRMI_Defs.CLASS_SERVER_PORT_SERVER and
IRMI_Defs.CLASS_SERVER_PORT_CLIENT

Specified by:

startRMI in interface IRMIUtils

Parameters:

classServerPort - the port that the class server will use

configRMIProperties

private void configRMIProperties(int classServerPort)

Sets the java.rmi.server.hostname and java.rmi.server.codebase system properties which control the automatic remote dynamic class loading. This must be called before starting the class server.

Parameters:

classServerPort - The port the class server will use.

configSecurityManager

private void configSecurityManager()

Sets the java.security.policy system property to point at the location of the security policy file, which is assumed to be at "provided\rmiUtils\server.policy" (file separators adjusted to match operating system). the security manager is then started. This method must be called before starting the class server.

startClassFileServer

private void startClassFileServer(int classServerPort)

Start the class file server to support remote dynamic class loading. This method must be called after configSecurityManager() and configRMIProperties(). If the reference to the class file server, "classFileServer" is null, it is assumed that the class file server is not runnng.

Parameters:

classServerPort - the port the class file server will use.

stopClassFileServer

private void stopClassFileServer()

Stop the class file server and reset the reference to it, "classFileServer", to null.

stopRMI

public void stopRMI()

Performs all necessary work to shut the RMI system down, such as shut the class server down. This method MUST be called before exiting the system or phantom processes may persist.

Specified by:

stopRMI in interface IRMIUtils

showInfoMsg

protected void showInfoMsg(java.lang.String msg)

Encapsulated behavior to show an informational message

Parameters:

msg - Message to show.

showErrorMsg

protected void showErrorMsg(java.lang.String msg)

Encapsulated behavior to show an error message

Parameters:

msg - Message to show.