Dictionary

The dictionary entity forms the backbone of the coordination of information between nodes in the cluster. This entity is fully replicated to all nodes that are interested in it -- it is not a "distributed" dictionary where every node has partial data.

Major Features

Most major features can be selected at object creation time to optimize for speed or for utility

• Replicated: Replicated efficiently to multiple nodes

• Nested: Dictionary values can be unique identifiers that resolve to another Dictionary

• Persistent: Dictionaries can automatically store themselves to disk (Persistence)

• Notifiable: You can subscribe to get notified of changes to dictionaries (Event)

• Shared memory: For efficiency, a single service per node can maintain coherency (with the rest of the cluster) of a dictionary. To do this the dictionary is stored in shared memory

• Transactional: Dictionary operations can be wrapped in a Transaction

Design

In this document the term "Dictionary" will be used to refer to the entire replicated Dictionary abstraction. The term "local replica" will be used to refer to a particular copy of the dictionary.

Process Access

A Dictionary can be located in process private memory, or in shared memory based on an option when the Dictionary is created.

If a dictionary needs

Internode Replication and Communication

Discovery

A dictionary will be registered with the Group service. It is identified by a well-known ClusterUniqueId or by the ClusterUniqueId returned by the Group registration. It may also be identified by a string entry in the Name service and APIs will accept either a ClusterUniqueId or a string name.

Replication