Sun Standard RMI Properties

Properties that are useful to set on JVMs* that export remote objects

[b]java.rmi.activation.port (1.2 and later)[/b]
This property is used to set the TCP port number on which this VM should communicate with rmid (by default, rmid listens on port 1098, but can be set to listen on a different port by using the -port option on the rmid command line). The default value of this property is 1098, so this property only needs to be set on VMs that need to communicate with an instance of rmid that is running on a port other than 1098.

[b]java.rmi.dgc.leaseValue (1.1 and later)[/b]
The value of this property represents the lease duration (in milliseconds) granted to other JVMs that hold remote references to objects which have been exported by this JVM. Clients usually renew a lease when it is 50% expired, so a very short value will increase network traffic and risk late renewals in exchange for reduced latency in calls to Unreferenced.unreferenced. The default value of this property is 600000 milliseconds (10 minutes).

[b]java.rmi.server.codebase (1.1 and later)[/b]
This property specifies the locations from which classes that are published by this JVM (for example: stub classes, custom classes that implement the declared return type of a remote method call, or interfaces used by a proxy or stub class) may be downloaded. The value of this property is a string in URL format (or a space-separated list of URLs in 1.2 and later) that will be the codebase annotation for all classes loaded from the CLASSPATH of (and subsequently marshalled by) this JVM.

Note:This property must be set correctly in order to dynamically download classes and interfaces using RMI. If this property is not set correctly, you will likely encounter exceptions when attempting to run your server or client. For more information on this property, see Dynamic code downloading using RMI (Using the java.rmi.server.codebase Property).

[b]java.rmi.server.hostname (1.1 and later)[/b]
The value of this property represents the host name string that should be associated with remote stubs for locally created remote objects, in order to allow clients to invoke methods on the remote object. In 1.1.7 and later, the default value of this property is the IP address of the local host, in "dotted-quad" format.

[b]java.rmi.server.logCalls (1.1 and later)[/b]
If this value is true, incoming calls and exceptions thrown from incoming calls will be logged to System.err. Setting this property to true will greatly assist you in debugging your RMI programs. See also sun.rmi.server.exceptionTrace.

[b]java.rmi.server.randomIDs (1.1.8 and later)[/b]
If this value is true, object identifiers for remote objects exported by this JVM will be generated by using a cryptographically secure random number generator. The default value is false.

[b]java.rmi.server.useCodebaseOnly (1.1 and later)[/b]
If this value is true, automatic loading of classes is prohibited except from the local CLASSPATH and from the java.rmi.server.codebase property set on this JVM. Use of this property prevents client JVMs from dynamically downloading bytecodes from other codebases. This property is ignored in the implementations of 1.2 and 1.2.1 because of a bug.

[b]java.rmi.server.useLocalHostname (1.1.7 and later)[/b]
RMI now uses an IP address to identify the local host when the java.rmi.server.hostname property is not specified and a fully qualified domain name for the localhost cannot be obtained. In order to force RMI to use the fully qualified domain name by default, you need to set the this property to true.

Properties that are useful to set on JVMs that make remote method calls

[b]java.rmi.server.codebase (1.1 and later)[/b]
This property specifies the locations from which classes that are published by this JVM (for example, custom classes that implement an interface that is the declared parameter type of a remote method call) may be downloaded. The value of this property is a string in URL format (or a space-separated list of URLs in 1.2 and later) that will be the codebase annotation for all classes loaded from the CLASSPATH of (and subsequently marshalled by) this JVM.

Note: Classes that exist in both the server's codebase and the client's CLASSPATH will be loaded from the client's CLASSPATH, rather than from the server's codebase as intended. For more information on this property, see Dynamic code downloading using RMI (Using the java.rmi.server.codebase Property).

[b]java.rmi.server.disableHttp (1.1 and later)[/b]
If this value is true, HTTP tunneling is disabled, even when http.proxyHost is set. The default value is false. If you know that your program will never need to use HTTP tunneling, then by disabling HTTP tunneling, you should see shorter timeouts for failed connections.

[b]java.rmi.server.useCodebaseOnly (1.1 and later)[/b]
If this value is true, automatic loading of classes is prohibited except from the local CLASSPATH and from the java.rmi.server.codebase property set on this JVM. Use of this property prevents client JVMs from dynamically downloading bytecodes from other codebases. This property is ignored in the implementations of 1.2 and 1.2.1 because of a bug.

Properties that can be set on rmid

[b]sun.rmi.activation.execTimeout (1.2 and later)[/b]
The value of this property represents the time (in milliseconds) that the activation system will wait for a spawned activation group to start up. Setting this property gives you the ability to shorten or lengthen the maximum time that rmid will wait for an activation group to start up. The default value is 30000 milliseconds (30 seconds).

[b]sun.rmi.activation.snapshotInterval (1.2 and later)[/b]
This property controls the number of updates for which the activation system will wait before it serializes a snapshot of its state to the rmid log file on disk. An "update" refers to a persistent change in the state of the activation system (for example, the registration of an Activatable object) since the last snapshot was taken. Changing the value of this property can be used to make rmid re-start more quickly (by taking snapshots of the log more often) or to make rmid more efficient (by taking snapshots of the log less often). The value of this property is a positive integer value. The default value is 200.

[b]sun.rmi.log.debug (1.2 and later)[/b]
If this value is true, details of rmid's logging activity are sent to System.err.

[b]sun.rmi.rmid.maxstartgroup (1.2 and later)[/b]
The value of this property represents the maximum number of activation group VMs that rmid will allow to be in the "spawning but not yet active" state simultaneously. If more VMs need to be started, they will queue up until one of the current spawn attempts either succeeds or times out. Note that this property does not limit the maximum number of active VMs; it is intended to smooth out sudden spikes of activity to avoid reaching operating system limits. While setting the value of this property to a lower number may result in a longer start-up time for rmid, and setting the value to a higher number could shorten the start-up time, setting this value too high can crash rmid, because your system may run out of resources. The default value is 3.

[b]sun.rmi.server.activation.debugExec (1.2 and later)[/b]
If this value is true, the activation system will print out debugging information to the command line that is used for spawning activation groups. By default, the value is false, so debugging information is not printed.

Properties that are useful to set on JVMs* that export remote objects

[b]sun.rmi.dgc.ackTimeout (1.4 and later)[/b]
The value of this property represents the length of time (in milliseconds) that the server-side RMI runtime will strongly refer to a remote object (or a reference to a remote object) that has been returned from the current virtual machine as part of the result of a remote method call, until it receives positive acknowledgment from the client that the remote reference has been fully received and processed. This timeout only applies to failure situations (in which the client fails to send the acknowledgment). Setting the value too low can increase the risk of a remote object being prematurely garbage collected when the only known reference to the remote object is the one in transit as part of the remote method call result. The maximum value is Long.MAX_VALUE. The default value is 300000 (five minutes).

[b]sun.rmi.dgc.checkInterval (1.1 and later)[/b]
The value of this property represents (in milliseconds) how often the RMI runtime checks for expired DGC leases. The default value is 300000 milliseconds (5 minutes).

[b]sun.rmi.dgc.logLevel (1.1 and later)[/b]
This property controls the logging of incoming and outgoing calls related to DGC lease granting, renewing, and expiration. It sends output to the "dgc" log.

[b]sun.rmi.dgc.server.gcInterval (1.2 and later)[/b]
When it is necessary to ensure that unreachable remote objects are unexported and garbage collected in a timely fashion, the value of this property represents the maximum interval (in milliseconds) that the RMI runtime will allow between garbage collections of the local heap. The default value is 60000 milliseconds (60 seconds).

[b]sun.rmi.loader.logLevel (1.2 and later)[/b]
This property controls the logging of each class name and codebase, whenever the RMI runtime attempts to load a class as a result of unmarshalling either an argument or return value. This property sends output to the "loader" log.

Please note in 1.3 that while the codebase that is printed is the annotated codebase, it may not necessarily be the actual codebase from which the class gets loaded; the RMI class loader defers the class loading to the current thread's context class loader, which may load the class from the CLASSPATH, rather than the annotated codebase. This issue no longer exists in 1.4.

[b]sun.rmi.server.exceptionTrace (1.2 and later)[/b]
This property controls the output of server-side stack traces from exceptions and errors that are thrown by dispatched, incoming remote calls. If this value is true, exception stack traces will be printed. By default (false), exception and error stack traces are not printed.

[b]sun.rmi.server.suppressStackTraces (1.4 and later)[/b]
If this value is true, the server-side RMI runtime implementation will clear the stack traces of all exceptions thrown from the current virtual machine as the result of remote calls. This property is useful for certain RMI server applications that may wish to prevent any server-side stack trace data from accompanying an exception to be marshalled out as the result of an incoming remote call (as part of the exception's default serialized form in J2SE 1.4), perhaps for reasons of performance or confidentiality.

[b]sun.rmi.transport.logLevel (1.1 and later)[/b]
This property controls detailed logging throughout the transport layer. It sends output to the "transport" log.

[b]sun.rmi.transport.tcp.localHostNameTimeOut (1.1.7 and later)[/b]
The value of this property represents the time (in milliseconds) that the RMI runtime will wait to obtain a fully qualified domain name for the local host. The default value is 10000 milliseconds (10 seconds).

[b]sun.rmi.transport.tcp.logLevel (1.1 and later)[/b]
This property provides detailed logging for the TCP-specific transport sub-layer. It sends output to the "tcp" log.

[b]sun.rmi.transport.tcp.readTimeout (1.2.2 and later)[/b]
The value of this property represents the time (in milliseconds) used as an idle timeout for incoming RMI-TCP connections. The value is passed to java.net.Socket.setSoTimeout. This property is used only for cases where a client has not dropped an unused connection as it should (see sun.rmi.transport.connectionTimeout). The default value is 2*3600*1000 milliseconds (2 hours).

Properties that are useful to set on JVMs that make remote method calls

[b]sun.rmi.client.logCalls (1.4 and later)[/b]
If the value of this property is true, the sun.rmi.client.call logger will be set to the level Level.FINER. Remote calls are logged at the level Level.FINER, and exceptions from remote calls are logged at the level Level.FINE.

[b]sun.rmi.dgc.cleanInterval (1.1 and later)[/b]
The value of this property represents the maximum length of time (in milliseconds) that the RMI runtime will wait before retrying a failed DGC "clean" call. The default value is 180000 milliseconds (3 minutes).

[b]sun.rmi.dgc.client.gcInterval (1.2 and later)[/b]
When it is necessary to ensure that DGC clean calls for unreachable remote references are delivered in a timely fashion, the value of this property represents the maximum interval (in milliseconds) that the RMI runtime will allow between garbage collections of the local heap. The default value is 60000 milliseconds (60 seconds).

[b]sun.rmi.loader.logLevel (1.2 and later)[/b]
This property controls the logging of each class name and codebase, whenever the RMI runtime attempts to load a class as a result of unmarshalling either an argument or return value. This property sends output to the "loader" log.

Please note in 1.3 that while the codebase that is printed is the annotated codebase, it may not necessarily be the actual codebase from which the class gets loaded; the RMI class loader defers the class loading to the current thread's context class loader, which may load the class from the CLASSPATH, rather than the annotated codebase. This issue no longer exists in 1.4.

[b]sun.rmi.server.logLevel (1.1 and later)[/b]
This property controls the logging of information related to outgoing calls, including some connection-reuse information. It sends output to the "transport" log.

[b]sun.rmi.transport.connectionTimeout (1.1.6 and later)[/b]
The value of this property represents the period (in milliseconds) for which RMI socket connections may reside in an "unused" state, before the RMI runtime will allow those connections to be freed (closed). The default value is 15000 milliseconds (15 seconds). See also sun.rmi.transport.tcp.readTimeout.

[b]sun.rmi.transport.logLevel (1.1 and later)[/b]
This property controls detailed logging throughout the transport layer. It sends output to the "transport" log.

[b]sun.rmi.transport.proxy.connectTimeout (1.1 and later)[/b]
The value of this property represents the maximum length of time (in milliseconds) that the RMI runtime will wait for a connection attempt (createSocket) to complete, before attempting to contact the server using HTTP. This property is only used when the http.proxyHost property is set and the value of java.rmi.server.disableHttp is false. The default value is 15000 milliseconds (15 seconds).

[b]sun.rmi.transport.proxy.eagerHttpFallback (1.4.1 and later)[/b]
If this value is true and the java.rmi.server.disableHttp system property is not set, then RMI's default socket factory will fall back to HTTP tunneling when any java.net.SocketException is thrown from an initial (direct) connection attempt, as opposed to the default behavior of falling back to HTTP tunneling only if an initial connection attempt throws a java.net.UnknownHostException or java.net.NoRouteToHostException.

This setting can be useful when dealing with firewalls that deny (instead of ignore) connection attempts to unauthorized ports, resulting in java.net.ConnectionExceptions inside the client's default RMI socket factory. If this system property is not enabled, then such ConnectionExceptions will not trigger HTTP fallback, since they are neither UnknownHostExceptions nor NoRouteToHostExceptions. However, if this system property is enabled, then the ConnectionExceptions will cause HTTP fallback to occur, because ConnectionException is a subclass of SocketException.

[b]sun.rmi.transport.proxy.logLevel (1.1 and later)[/b]
This property controls the logging of events (createSocket and createServerSocket) when the default RMISocketFactory class is used. This type of logging is likely to be useful for applications that use RMI over HTTP. Events in custom socket factories are not logged by this property. It sends some messages to the "proxy" log, and others to the "transport" log.

[b]sun.rmi.transport.tcp.handshakeTimeout (1.4 and later)[/b]
The value of this property represents the length of time (in milliseconds) that the client-side RMI runtime will use as a socket read timeout when reading initial handshake data (protocol acknowledgment) when establishing a new JRMP connection. This property is used to configure how long the RMI runtime will wait before deciding that a TCP connection accepted by a remote server cannot actually be used, either because the entity listening on the remote host's port is not actually an RMI server, or because the server is somehow not functioning correctly. The maximum value is Integer.MAX_VALUE, and a value of zero indicates an infinite timeout. The default value is 60000 (one minute).

[b]sun.rmi.transport.tcp.logLevel (1.1 and later)[/b]
This property provides detailed logging for the TCP-specific transport sub-layer. It sends output to the "tcp" log.