A relay rule evaluates an inbound event by the port it was received on and any other source criteria defined in the rule. When the criteria is met, the rule dictates how the event should be processed.
To handle a few standard inbound event types, all relays have four predefined rules that are assigned to fixed ports - these ports cannot be used for any custom rules.
For all event processing not covered by the default rules, you will create custom rules. Custom relay rules are primarily designed to perform two types of processing: applying Devo tags or filtering out data that you don't want to save in Devo. Read more about custom rules in Defining a relay rule and 5 common relay rule scenarios.
To see a list of the custom rules defined on a relay, go to Administration → Relays, then click the relay name to see the list of rules.
Since a single relay can have multiple rules, it's important to consider the order in which they should be applied, especially the rules that are defined on the same Source Port. The run order is determined by the order the rules appear in this list, starting from the top. To reorder a rule, just select and drag the rule to its new position.
Golden rules for relay rules
- Respect the default ports. Ports 12999, 13000, 13001, and 13002 are reserved for very specific types of events and processing. They cannot be used for custom rules. More information.
- One event source per port. Otherwise, things have the potential to get very messy.
- Filtering rules first. When you have multiple rules for events arriving on the same port, be sure that the filtering rules - those designed to identify and drop specific events - come first.
- Stop processing after every filter. If you don't, the event will move on the next rule and might end up being forwarded to the Devo repository.
- Using regex in relay rules
- Defining a relay rule
- The 4 predefined relay rules
- 5 common relay rule scenarios