Distributed System Members
Distributed system members are programs that connect to a GemFire distributed system. You configure members to belong to a single distributed system, and you can optionally configure them to be clients or servers to members in other distributed systems, and to communicate with other distributed systems.
Distributed system members (or simply “members”) connect to the GemFire system when they create the GemFire data cache. The members’ distributed system is configured through GemFire properties. See gemfire.properties and gfsecurity.properties (GemFire Properties). GemFire properties specify all necessary information for system member startup, initialization, and communication.
Note: You cannot change a member’s properties while the member is connected to the distributed system.
Use the properties to define:
- How to find and communicate with other system members
- How to perform logging and statistics activities
- Which persistent configuration or
cache.xmlfile to use for cache and data region initialization
- Other options, including event conflation, how to handle network loss, and security settings
Every GemFire process is a member of a distributed system, even if the distributed system is defined as standalone, with just one member. You can run an individual distributed system in isolation or you can combine systems for vertical and horizontal scaling. See Topology and Communication General Concepts.
- Peer-to-Peer Distributed Systems. Members that define the same member discovery properties belong to the same distributed system and are peers to one another.
- Client/Server Installations. The client/server topology uses relationships that you configure between members of multiple distributed systems. You configure some or all of the peers in one distributed system to act as cache servers to clients connecting from outside the system. Each server can host many client processes, managing cache access for all in an efficient, vertically hierarchical cache configuration. You configure the client applications to connect to the servers, using a client cache configuration. Clients run as members of standalone GemFire distributed systems, with no peers, so all data updates and requests go to the servers.
The multi-site topology uses relationships that you configure between members of multiple distributed systems. Through this configuration, you loosely couple two or more distributed systems for automated data distribution. This is usually done for sites at geographically separate locations. You configure a subset of peers in each distributed system site with gateway senders and/or gateway receivers to manage events that are distributed between the sites.
In the context of a single distributed system, unless otherwise specified, “remote member” refers to another member of the same distributed system. In client/server and multi-site installations, “remote” generally refers to members in other distributed systems. For example, all servers are “remote” to the clients that connect to them. Each client runs standalone, with connections only to the server tier, so all servers and their other clients are “remote” to the individual client. All gateway receivers are “remote” to the gateway senders that connect to them from other distributed systems, and to those gateway senders’ peers.