Overview

This section describes GigaSpaces clustering capabilities. It explains the built-in clustering topologies GigaSpaces support and how to use these; clustering concepts and their GigaSpaces implementation; discusses how to configure a cluster and maintain it; and provides a step-by-step guide detailing how to build a common cluster configuration.

For details on how a network of processors elects a unique processor (a leader), and how to avoid split-brain scenarios, refer to the Active Election and Avoiding Split-Brain Scenarios section.

Cluster Schema Options

The cluster XML schema configuration file includes tags that define the replication, load-balancing, and failover parameters and policies.

Each cluster has an XML schema configuration file that defines:

• The cluster name, which is unique in the environment. Clients can connect the cluster via its name regardless the actual machines running the cluster spaces.
• Space members and their location – each space member is identified as a 'container:space' pair, for example container1:space1. You may have spaces defined within the configuration file even if they don't exist yet.
• Groups and policies – space members should be grouped; A cluster may have several groups; groups have policies that determine whether clustered spaces perform replication, failover, or load-balancing between them.

For more details on the Cluster Schema, refer to: Cluster Construction Cluster Name Cluster Members Cluster Groups Replication Group Load-Balancing Group Failover Group

Managing Clusters

It can be difficult to understand the structure and settings of a cluster from its configuration file. The GigaSpaces Browser offers a graphic representation of cluster groups, the spaces within them, and the relationships between spaces. The cluster viewer also shows persistency, load balancing and failover settings for any space you click on.

To learn how to use the cluster viewer in the GigaSpaces Browser, see Cluster View.

The Space Browser allows you to manipulate cluster members easily.

Right click the Cluster Icon in the right tree side of the main window. This displays the following options:

• Start Cluster – this starts a stopped cluster. All cluster members are restarted. If some of the cluster members fail to start, you get an appropriate indication.
• Stop Cluster – this stops all cluster members. If some of the cluster members fail to stop, you get an appropriate indication.
• Restart Cluster – this stops and starts all cluster members. If some of the cluster members fail to start, you get an appropriate indication.
• Clean Cluster – this deletes all Entries and their class definitions from all cluster members.

Replication Filters

When constructing a replicated space topology you may need to call some business logic when data is replicated. GigaSpaces provides the IReplicationFilter plug-in interface (com.j_spaces.core.cluster.IReplicationFilter; see Javadoc) that allows you to build business logic that will be called when data is sent through the replication channel. The IReplicationFilter methods are called before data is sent to the replication channel from the source space (output mode) and after coming out from the replication channel - i.e. before written to the target space (input mode). The replication filter should implement the com.j_spaces.core.cluster.IReplicationFilter interface methods.
The replication filter may be used to monitor or alter the data passed through the replication channel. The replication channel passing Replication Filter Entry objects that stores the replicated data.
The cluster schema should include the class name for input and output mode that implements the IReplicationFilter and some free text parameter you may pass into the replication filter. You may use the same replication filter implementation class for both input and output replication modes.

For more details, refer to: Replication Filters

Creating Static Cluster

This section explains how to create a cluster from scratch using the Cluster Wizard in the GigaSpaces Browser. The following section shows the overall workflow, and the following sections provide step-by-step procedures on how to create the cluster.

An example of a cluster using static cluster configuration can be found at: <GigaSpaces Root>\examples\Advanced\Data_Grid\multi-site.

For more details on how to create a cluster, refer to: Static Cluster Planning Defining cluster name and spaces Creating groups Defining a replication policy Defining a load balancing policy Defining a failover policy Creating spaces