Basic ActiveSpaces Terms

This section defines basic terms for ActiveSpaces, which are used in the discussion of ActiveSpaces concepts.

ActiveSpaces Terms
Term	Definition
Metaspace	A logical group of spaces—a cluster of hosts and processes that share the same metaspace name and set of discovery transport attributes. The hosts and processes in a metaspace work together by joining the same spaces.
Space	A shared, virtual entity that functions as a container for a collection of entries consisting of a tuple and associated metadata. Applications become members of a space in order to execute operations on the space. Spaces are contained in a metaspace.
Tuple	A sequence of named elements called fields (similar to the columns in a database table) that contain values of a specific type.
Seeder	A space member that can execute operations on spaces that it is connected to and which also plays an active role in maintaining the space by providing CPU and RAM. The service of storing the data contained in a space and handling requests to read and write this data is implemented in a distributed peer-to-peer manner by one or more seeders.
Leech	A space member that can execute operations on spaces that it is connected to but which does not contribute memory or CPU time to maintenance of the space.
Replication	An ActiveSpaces process that backs up data from one seeder to one or more additional seeders, to enable fault tolerance.
Persistence	An ActiveSpaces feature that allows you to persist data to disk storage and recover data if data loss occurs or there is a problem with cluster startup. ActiveSpaces allows the distribution of data replicates on different peers for fault tolerance. If a seeder suddenly fails, the replicate is immediately promoted to seeder, and the new seeder creates new replicates. This optimizes system performance
Browser	A mechanism to iterate through a series of tuples retrieved from a space using filters. Unlike a traditional iterator that works only on a snapshot of the data to be iterated through, the space browser is continuously updated according to the changes in the data contained in the space being browsed.
Listener	A mechanism that allows an application to monitor events that represent changes to the tuples stored in a space through a callback routines that are automatically called when specific events occur in a space.