org.gridgain.grid

Interface GridNode

All Superinterfaces:

GridMetadataAware, Serializable

All Known Implementing Classes:

GridTcpDiscoveryNode

public interface GridNode
extends GridMetadataAware

Interface representing a single grid node. Use attribute(String) or metrics() to get static and dynamic information about remote nodes. GridNode list, which includes all nodes within task topology, is provided to GridComputeTask.map(List, Object) method. You can also get a handle on discovered nodes by calling any of the following methods:

• Grid.localNode()

Grid Node Attributes

You can use grid node attributes to provide static information about a node. This information is initialized once within grid, during node startup, and remains the same throughout the lifetime of a node. Use GridConfiguration.getUserAttributes() method to initialize your custom node attributes at startup. Here is an example of how to assign an attribute to a node at startup:

 <bean id="grid.cfg" class="org.gridgain.grid.GridConfiguration">
     ...
     <property name="userAttributes">
         <map>
             <entry key="worker" value="true"/>
         </map>
     </property>
     ...
 </bean>
 

The system adds the following attributes automatically:

• {@link System#getProperties()} - All system properties.
• {@link System#getenv(String)} - All environment properties.
• org.gridgain.build.ver - GridGain build version.
• org.gridgain.jit.name - Name of JIT compiler used.
• org.gridgain.net.itf.name - Name of network interface.
• org.gridgain.user.name - Operating system user name.
• org.gridgain.grid.name - Grid name (see Grid.name()).
• spiName.org.gridgain.spi.class - SPI implementation class for every SPI, where spiName is the name of the SPI (see GridSpi.getName().
• spiName.org.gridgain.spi.ver - SPI version for every SPI, where spiName is the name of the SPI (see GridSpi.getName().

Note that all System and Environment properties for all nodes are automatically included into node attributes. This gives you an ability to get any information specified in System.getProperties() about any node. So for example, in order to print out information about Operating System for all nodes you would do the following:

 for (GridNode node : G.grid().nodes()) {
     System.out.println("Operating system name: " + node.getAttribute("os.name"));
     System.out.println("Operating system architecture: " + node.getAttribute("os.arch"));
     System.out.println("Operating system version: " + node.getAttribute("os.version"));
 }
 

This interface provide a system view on the node instance. All user-level APIs work with GridNode interface that provides much more functionality and extends this interface. Consult GridNode for more information.

Grid Node Metrics

Grid node metrics (see metrics()) are updated frequently for all nodes and can be used to get dynamic information about a node. The frequency of update is often directly related to the heartbeat exchange between nodes. So if, for example, default GridTcpDiscoverySpi is used, the metrics data will be updated every 2 seconds by default.

Grid node metrics provide information about other nodes that can frequently change, such as Heap and Non-Heap memory utilization, CPU load, number of active and waiting grid jobs, etc... This information can become useful during job collision resolution or GridComputeTask.map(List, Object) operation when jobs are assigned to remote nodes for execution. For example, you can only pick nodes that don't have any jobs waiting to be executed.

Local node metrics are registered as MBean and can be accessed from any JMX management console. The simplest way is to use standard jconsole that comes with JDK as it also provides ability to view any node parameter as a graph.

See Also:

GridNode

Method Summary

Methods

Modifier and Type	Method and Description
Collection<String>	addresses() Gets collection of addresses this node is known by.
<T> T	attribute(String name) Gets a node attribute.
Map<String,Object>	attributes() Gets all node attributes.
Object	consistentId() Gets consistent globally unique node ID.
Collection<String>	hostNames() Gets collection of host names this node is known by.
UUID	id() Gets globally unique node ID.
boolean	isDaemon() Tests whether or not this node is a daemon.
boolean	isLocal() Tests whether or not this node is a local node.
GridNodeMetrics	metrics() Gets metrics snapshot for this node.
long	order() Node order within grid topology.
GridProductVersion	version() Gets node version.

Methods inherited from interface org.gridgain.grid.GridMetadataAware

addMeta, addMetaIfAbsent, addMetaIfAbsent, allMeta, copyMeta, copyMeta, hasMeta, hasMeta, meta, putMetaIfAbsent, putMetaIfAbsent, removeMeta, removeMeta, replaceMeta

Method Detail

id

UUID id()

Gets globally unique node ID. A new ID is generated every time a node restarts.

Returns:

Globally unique node ID.

consistentId

Object consistentId()

Gets consistent globally unique node ID. Unlike id() method, this method returns consistent node ID which survives node restarts.

Returns:

Consistent globally unique node ID.

attribute

@Nullable
<T> T attribute(String name)

Gets a node attribute. Attributes are assigned to nodes at startup via GridConfiguration.getUserAttributes() method.

The system adds the following attributes automatically:

• {@link System#getProperties()} - All system properties.
• {@link System#getenv(String)} - All environment properties.
• All attributes defined in GridNodeAttributes

Note that attributes cannot be changed at runtime.

Type Parameters:

T - Attribute Type.

Parameters:

name - Attribute name. Note that attribute names starting with org.gridgain are reserved for internal use.

Returns:

Attribute value or null.

metrics

GridNodeMetrics metrics()

Gets metrics snapshot for this node. Note that node metrics are constantly updated and provide up to date information about nodes. For example, you can get an idea about CPU load on remote node via GridNodeMetrics.getCurrentCpuLoad() method and use it during GridComputeTask.map(List, Object) or during collision resolution.

Node metrics are updated with some delay which is directly related to heartbeat frequency. For example, when used with default GridTcpDiscoverySpi the update will happen every 2 seconds.

Returns:

Runtime metrics snapshot for this node.

attributes

Map<String,Object> attributes()

Gets all node attributes. Attributes are assigned to nodes at startup via GridConfiguration.getUserAttributes() method.

The system adds the following attributes automatically:

• {@link System#getProperties()} - All system properties.
• {@link System#getenv(String)} - All environment properties.
• All attributes defined in GridNodeAttributes

Note that attributes cannot be changed at runtime.

Returns:

All node attributes.

addresses

Collection<String> addresses()

Gets collection of addresses this node is known by.

If GridConfiguration.getLocalHost() value isn't null node will try to use that address for all communications and returned collection will contain only that address. If it is null then local wildcard address will be used, and GridGain will make the best effort to supply all addresses of that node in returned collection.

Returns:

Collection of addresses.

hostNames

Collection<String> hostNames()

Gets collection of host names this node is known by.

If GridConfiguration.getLocalHost() value isn't null node will try to use the host name of that resolved address for all communications and returned collection will contain only that host name. If that host name can not be resolved then ip address returned by method addresses() is used.

If GridConfiguration.getLocalHost() value is null then local wildcard address will be used, and this method returns host names of all addresses of that node.

Returns:

Collection of host names.

order

long order()

Node order within grid topology. Discovery SPIs that support node ordering will assign a proper order to each node and will guarantee that discovery event notifications for new nodes will come in proper order. All other SPIs not supporting ordering may choose to return node startup time here.

NOTE: in cases when discovery SPI doesn't support ordering GridGain cannot guarantee that orders on all nodes will be unique or chronologically correct. If such guarantee is required - make sure use discovery SPI that provides ordering.

Returns:

Node startup order.

version

GridProductVersion version()

Gets node version.

Returns:

Node version.

isLocal

boolean isLocal()

Tests whether or not this node is a local node.

Returns:

True if this node is a local node, false otherwise.

isDaemon

boolean isDaemon()

Tests whether or not this node is a daemon.

Daemon nodes are the usual grid nodes that participate in topology but not visible on the main APIs, i.e. they are not part of any projections. The only way to see daemon nodes is to use GridProjection.forDaemons() method.

Daemon nodes are used primarily for management and monitoring functionality that is build on GridGain and needs to participate in the topology but should be excluded from "normal" topology so that it won't participate in task execution or in-memory database.

Application code should never use daemon nodes.

Returns:

True if this node is a daemon, false otherwise.