Load balancing events to a set of servers
This setup shows load balancing the event to publish it to all three DAS/CEP receivers. The load balanced publishing is done in a Round Robin manner, sending each event to each receiver in a circular order without any priority.
It also handles fail-over cases such as, if
DAS/CEP Receiver-1 is marked as down, then the Data Agent will send the data only to
DAS/CEP Receiver-2 and
DAS/CEP Receiver-3 in a round robin manner. When
DAS/CEP Receiver-1 becomes active after some time, the Data Agent automatically detects it, adds it to the operation, and again starts to load balance between all three receivers. This functionality significantly reduces the loss of data and provides more concurrency.
Load balancing events to sets of servers
In this setup there are two sets of servers that are referred to as set-A and set-B. You can send events to both the sets. You can also carry out load balancing for both sets as mentioned in load balancing between a set of servers. This scenario is a combination of load balancing between a set of servers and sending an event to several receivers. An event is sent to both set-A and set-B. Within set-A, it will be sent either to
DAS/CEP ReceiverA-1 or
DAS/CEP ReceiverA-2. Similarly within set-B, it will be sent either to
DAS/CEP ReceiverB-1 or
DAS/CEP ReceiverB-2. In the setup, you can have any number of sets and any number of servers as required by mentioning them accurately in the server URL.
Sending all the events to several receivers
This setup involves sending all the events to more than one DAS/CEP receiver. This approach is mainly followed when you use other servers to analyze events together with DAS/CEP servers. For example, you can use the same Data Agents to publish the events to WSO2 CEP. You can use this functionality to publish the same event to both DAS and CEP servers at the same time. This is useful to perform real time analytics with CEP, to persist the data, and also to perform complex analysis with DAS in nearly real time with the same data.
When using the failover configuration in publishing events to DAS/CEP, events are sent to multiple DAS/CEP receivers in a sequential order based on priority. You can specify multiple DAS/CEP receivers so that events can be sent to the next server in the sequence in a situation where they were not successfully sent to the first server. In the scenario depicted in the above image, the events are first sent to
DAS/CEP Receiver-1. If it is unavailable, then events will be sent to
DAS/CEP Receiver-2. If
DAS/CEP Receiver-2 is also unavailable, then the events will be sent to