A relay server accepts requests from remote clients, and forwards the requests to a cluster of servers, either Unwired Server or Afaria.
The relay-server architecture enables secure, highly available communication between remote-device clients and either Unwired Server or Afaria, and integrates with existing corporate firewall configurations and policies.
With Sybase Unwired Platform, you have two relay-server options:
- For development and testing – the Sybase Hosted Relay Service, a Web-hosted relay server that supports an Unwired Server cluster with two server installations. See Configuring a Relay Server for Development.
- For production – the Sybase Unwired Platform relay server, which supports Unwired Server and Afaria clusters with an unlimited number of servers. The remainder of this topic describes this option.
The Sybase Unwired Platform relay-server architecture includes:
- Remote devices running services and client applications that communicate with Unwired Server or Afaria.
- One or more relay servers—collectively known as a relay-server farm—running in the corporate demilitarized zone (DMZ). Each relay server runs on a separate machine.
- (Optional) A load balancer to direct requests from remote clients to a relay server. If a relay-server farm contains only one relay server, a load balancer is not required—remote clients can connect directly to the relay server. Unwired Platform does not include a load balancer; customers may install their own.
- A cluster of one or more Unwired Server installations that service client requests, running in the corporate LAN. All instances of Unwired Server must be connected to the same consolidated database (CDB), which stores the mobile business object data. A relay server can also forward client requests to a cluster of Afaria servers.
- One relay-server outbound enabler (RSOE) for each back-end server installation—Unwired Server or Afaria. The RSOE application manages all communication between the back-end server and the relay server. A collection of one or more back-end servers and their associated RSOEs is called a back-end server farm.
A relay server is implemented as a pair of Web extensions that run in a Web server. Unwired Platform supports two Web servers, IIS on Windows and Apache on Linux.
The relay server uses both HTTP and HTTPS communication protocols.
A relay server includes a client extension and a server extension. The client extension handles client requests from applications that run on remote devices. The server extension handles requests from an RSOE, on behalf of Unwired Server or Afaria. To provide a secure deployment environment, a back-end server—Unwired Server or Afaria—initiates all connections with a relay server.