com.gemstone.gemfire.distributed
Class Locator

java.lang.Object
  com.gemstone.gemfire.distributed.Locator

public abstract class Locator
extends Object

Represents a distribution locator server that provides discovery information to members of a GemFire distributed system. In most GemFire distributed cache architectures, distribution locators are run in their own process. A stand-alone locator process is managed using the GemFire console, administration API, or the gemfire command line utility:

 $ gemfire start-locator
 

The stand-alone locator configuration provides high-availability of the membership information.

This class allows a GemFire application VM to host a distribution locator. Such a configuration minimizes the number of processes that are required to run GemFire. However, hosting distribution locators is not generally recommended because if the application VM exits, the primary membership list for the distributed system would be lost and it would not be possible for new applications to connect to the distributed system.

It is important to remember that an application that hosts a distribution locator must start its locator before it (or any other potentialy member) connects to the distributed system.

Since:

4.0

Constructor Summary

Locator()

Method Summary

InetAddress	getBindAddress() Returns the IP address to which this locator's listening socket is bound.
abstract DistributedSystem	getDistributedSystem() Returns the distributed system started by this locator, if any
static Collection	getLocators() Returns an unmodifiable collection of all of the Locators that are hosted by this VM.
File	getLogFile() Returns the log file to which this locator's output is written
int	getPort() Returns the port on which this locator runs
static boolean	hasLocators() Examine the size of the collection of locators running in this VM
static void	main(String[] args) Starts a distribution locator from the command line.
static Locator	startLocator(int port, File logFile) Starts a new distribution locator host by this VM.
static Locator	startLocator(int port, File logFile, InetAddress bindAddress) Starts a new distribution locator host by this VM.
static Locator	startLocatorAndDS(int port, File logFile, InetAddress bindAddress, Properties dsProperties) Starts a new distribution locator host by this VM that binds to the given network address.
static Locator	startLocatorAndDS(int port, File logFile, Properties distributedSystemProperties) Starts a new distribution locator host by this VM, and an admin distributed system controlled by the locator.
abstract void	stop() Stops this distribution locator.
String	toString() Returns a brief description of this Locator

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Locator

public Locator()

Method Detail

startLocator

public static Locator startLocator(int port,
                                   File logFile)
                            throws IOException

Starts a new distribution locator host by this VM. The locator's listening sockets will bind to all network addresses. The locator will look for a gemfire.properties file, or equivalent system properties to fill in the gaps in its configuration. If you are using multicast communications, the locator should be configured with the same settings that your applications will use.

The locator will not start a distributed system.

Parameters:

port - The port on which the locator will listen for membership information requests from new members

logFile - The file to which the locator logs information. The directory that contains the log file is used as the output directory of the locator (see -dir option to the gemfire command).

Throws:

IllegalArgumentException - If port is not in the range 0 to 65536

SystemIsRunningException - If another locator is already running in outputDir

GemFireIOException - If the directory containing the logFile does not exist or cannot be written to

IOException - If the locator cannot be started

startLocatorAndDS

public static Locator startLocatorAndDS(int port,
                                        File logFile,
                                        Properties distributedSystemProperties)
                                 throws IOException

Starts a new distribution locator host by this VM, and an admin distributed system controlled by the locator. The locator's listening sockets will bind to all network addresses. The locator will use the given properties to start an AdminDistributedSystem.

The locator starts a AdminDistributedSystem configured with the given properties to provide the system with a long-running process that can be relied on for stable membership information.

Parameters:

port - The port on which the locator will listen for membership information requests from new members

logFile - The file to which the locator logs information. The directory that contains the log file is used as the output directory of the locator (see -dir option to the gemfire command).

distributedSystemProperties - The properties used to configure the locator's distributed system. If there are multiple locators in the system, this should note them in the "locators" setting. If The distributed system is using multicast, the "mcast-port" should also be set.

Throws:

IllegalArgumentException - If port is not in the range 0 to 65536

SystemIsRunningException - If another locator is already running in outputDir

GemFireIOException - If the directory containing the logFile does not exist or cannot be written to

IOException - If the locator cannot be started

Since:

5.0

startLocator

public static Locator startLocator(int port,
                                   File logFile,
                                   InetAddress bindAddress)
                            throws IOException

Starts a new distribution locator host by this VM. The locator will look for a gemfire.properties file, or equivalent system properties to fill in the gaps in its configuration.

The locator will not start a distributed system.

Parameters:

port - The port on which the locator will listen for membership information requests from new members

logFile - The file to which the locator logs information. The directory that contains the log file is used as the output directory of the locator (see -dir option to the gemfire command).

bindAddress - The IP address to which the locator's socket binds

Throws:

IllegalArgumentException - If port is not in the range 0 to 65536

SystemIsRunningException - If another locator is already running in outputDir

GemFireIOException - If the directory containing the logFile does not exist or cannot be written to

IOException - If the locator cannot be started

startLocatorAndDS

public static Locator startLocatorAndDS(int port,
                                        File logFile,
                                        InetAddress bindAddress,
                                        Properties dsProperties)
                                 throws IOException

Starts a new distribution locator host by this VM that binds to the given network address.

The locator starts a AdminDistributedSystem configured with the given properties to provide the system with a long-running process that can be relied on for stable membership information.

Parameters:

port - The port on which the locator will listen for membership information requests from new members

logFile - The file to which the locator logs information. The directory that contains the log file is used as the output directory of the locator (see -dir option to the gemfire command).

bindAddress - The IP address to which the locator's socket binds

dsProperties - The properties used to configure the locator's DistributedSystem. If there are multiple locators, the "locators" property should be set. If multicast is being used, the "mcast-port" property should be set.

Throws:

IllegalArgumentException - If port is not in the range 0 to 65536

SystemIsRunningException - If another locator is already running in outputDir

GemFireIOException - If the directory containing the logFile does not exist or cannot be written to

IOException - If the locator cannot be started

Since:

5.0

getLocators

public static Collection getLocators()

Returns an unmodifiable collection of all of the Locators that are hosted by this VM.

hasLocators

public static boolean hasLocators()

Examine the size of the collection of locators running in this VM

Returns:

the number of locators running in this VM

getPort

public int getPort()

Returns the port on which this locator runs

getDistributedSystem

public abstract DistributedSystem getDistributedSystem()

Returns the distributed system started by this locator, if any

getLogFile

public File getLogFile()

Returns the log file to which this locator's output is written

getBindAddress

public InetAddress getBindAddress()

Returns the IP address to which this locator's listening socket is bound.

stop

public abstract void stop()

Stops this distribution locator.

toString

public String toString()

Returns a brief description of this Locator

Overrides:

toString in class Object

main

public static void main(String[] args)

Starts a distribution locator from the command line.

8 This method of starting the locator is provided as an alternative to the gemfire start-locator command to give you complete control over the java virtual machine's configuration.

The gemfire stop-locator command can be used to stop a locator that is started with this class.

java com.gemstone.gemfire.distributed.Locator port [bind-address] [gemfire-properties-file]

port - the tcp/ip port that the locator should listen on. This is the port number that applications will refer to in their locators property in gemfire.properties

bind-address - the tcp/ip address that the locator should bind to. This can be missing or be an empty string, which causes the locator to listen on all host addresses.

gemfire-properties-file - the location of a gemfire.properties file to be used in configuring the locator's distributed system.

Since:

5.0