Server Roles

Primary

The primary servers (green cluster circle) form the central hub within a family of affiliated servers.

• Servers in the primary cluster function as interchangeable peers.
• Primary servers operate within a local network.
• A client application process can specify a list of server URLs, and it can attempt to connect to any of them. Nonetheless, each client process needs and maintains a connection to exactly one FTL server at a time.
• Each client sends monitoring and log data to its server (more precisely, to the realm service that the server provides).
• The servers in a localized cluster (any circle) present the same status view, as their realm services share client monitoring and log data. However, servers do not share client data outside their cluster circle.
• Administrators can update the realm definition at any of the primary servers. The primaries share that definition with one another so they all remain up to date. The primaries deploy updates to their clients and to affiliated satellite servers.

Satellite

Optional satellite servers (blue circles) provide local service to clients that are geographically distant from the primaries, or clients that are insulated from the primaries (to fulfill enterprise requirements).

• Servers in a satellite cluster function as interchangeable peers within a local network.
• Separate satellite clusters (separate blue circles) do not intercommunicate.
• Several remote satellite clusters can connect to any primary. A cluster cannot be a satellite of another satellite.
• A client application process can specify a list of server URLs, and it can attempt to connect to any of them. Nonetheless, each client process needs and maintains a connection to exactly one FTL server at a time.
• A satellite server does not accept client connection requests until it first receives a realm definition from a primary server.
• Each client sends monitoring and log data to its server.
• The servers in a localized cluster (any circle) present the same status view, as their realm services share client monitoring and log data. However, servers do not share client data outside their cluster circle.
• A satellite initiates a TCP connection to a primary server, and not the reverse.
• A satellite receives the realm definition from a primary. When an administrator deploys an updated realm definition, the primaries push the deployment to the satellites. (Administrators cannot deploy updates directly to a satellite server.)
• A satellite is loosely coupled to a primary. If one of them became inoperative, or the connection between them broke, the primary would not take any restorative action. Rather, the satellite would attempt to reconnect to a primary, continuing to serve its local clients in the interim. Primaries can deploy a new realm definition while satellites are disconnected (but see Disconnected Satellite).

Disaster Recovery

Optional disaster recovery servers (grey cluster circle) provides a remote failover point in case a disaster disrupts service at the main site.

For background information and details, see Disaster Recovery.

Auxiliary

Optional auxiliary servers (outside any cluster circle) are servers that you designate for a special purpose.

For details, see Auxiliary Servers.

Obsolete: Backup

The concept of a backup server is obsolete as of Release 6.0. Instead, localized clusters provide backup through full redundancy.