Esper

The Esper component supports the Esper Library for Event Stream Processing. The camel-esper library is provided by the Camel Extra project which hosts all *GPL related components for Camel.

URI format

esper:name[?options]

When consuming from an Esper endpoint you must specify a pattern or eql statement to query the event stream.

Pattern example:

from("esper://cheese?pattern=every event=MyEvent(bar=5)")
  .to("activemq:Foo");

EQL example:

from("esper://esper-dom?eql=insert into DomStream select * from org.w3c.dom.Document")
  .to("log://esper-dom?level=INFO");
from("esper://esper-dom?eql=select childNodes from DomStream")
  .to("mock:results");

Options

Name

Default Value

Description

configured

false

Available as of camel-extra 2.11.3:
If flag is set to 'true' the default Esper configuration file (esper.cfg.xml) will be used. 
To configure Esper via a configuration file, please refer to the Esper documentation

pattern

 

The Esper Pattern expression as a String to filter events

eql

 

The Esper EQL expression as a String to filter events

You can append query options to the URI in the following format, ?option=value&option=value&...

EsperMessage

From Camel 2.12 onwards the esper consumer stores new and old events in the org.apacheextras.camel.component.esper.EsperMessage message as the input Message on the Exchange. You can get access to the esper event beans from java code with:

  EventBean newEvent = exchange.getIn(EsperMessage.class).getNewEvent();
  EventBean oldEvent = exchange.getIn(EsperMessage.class).getOldEvent();

By default if you get the body of org.apacheextras.camel.component.esper.EsperMessage it returns the new EventBean as in previous versions.

Demo

There is a demo which shows how to work with ActiveMQ, Camel and Esper in the Camel Extra project