Configuring Your System for Continuous Querying

The continuous query (CQ) functionality requires standard client/server distributed system and cache configuration settings.

  • The client region must use a pool with subscription-enabled set to true .
  • If you want your CQs to be highly available, configure your servers for high availability as described in Configuring Highly Available Servers in the server documentation. When your servers are highly available, CQs are registered on primary and secondary servers, and server failover is performed without any interruption to CQ messaging. CQ events messaging uses the same queues used for server-to-client messaging. Note: When CQ is used with high availability, the overhead for CQs is higher than for the key-based interest list registration. CQs are executed on the primary and all secondary servers, so they require more overall server processing.

  • To obtain a list of all durable CQs registered on the server, use the QueryService.getAllDurableCqsFromServer API.

  • If you want your CQs to be durable, configure your native clients for durable messaging. When your clients are durable, you can create durable CQs whose events are maintained during client disconnects and replayed for the client when it reconnects. The process and data flow particular to durable CQs is described in Durable Client Messaging.