HTTP Pub-Sub Adapter for Publising Component Configuration

8-16 Oracle Complex Event Processing Developers Guide http-pub-sub-adapter http-pub-sub-adapter nameremoteSubscribername server-urlhttp:myhost.com:9102pubsubserver-url channelchannel3channel event-typecom.mycompany.httppubsub.PubsubEventevent-type http-pub-sub-adapter n1:config 9 Configuring Channels 9-1 9 Configuring Channels This section contains information on the following subjects: ■ Section 9.1, Overview of Channel Configuration ■ Section 9.2, Configuring a Channel ■ Section 9.3, Example Channel Configuration Files

9.1 Overview of Channel Configuration

An Oracle CEP application contains one or more channel components. A channel represents the physical conduit through which events flow between other types of components, such as between adapters and processors, and between processors and event beans business logic POJOs. You may use a channel with both streams and relations. For more information, see Section 9.1.2, Channels Representing Streams and Relations . When you create a channel in your Event Processing Network EPN, it has a default configuration. For complete details, see Section C.10, wlevs:channel . The default channel configuration is typically adequate for most applications. However, if you want to change this configuration, you must create a channel element in a component configuration file. In this channel element, you can specify channel configuration that overrides the defaults. The component configuration file channel element’s name element must match the EPN assembly file channel element’s id attribute. For example, given the EPN assembly file channel element shown in Example 9–1 , the corresponding component configuration file channel element is shown in Example 9–2 . Example 9–1 EPN Assembly File Channel Id: priceStream wlevs:channel id=priceStream event-type=PriceEvent wlevs:listener ref=filterFanoutProcessor wlevs:source ref=PriceAdapter wlevs:channel Example 9–2 Component Configuration File Channel Name: priceStream channel namepriceStreamname max-size10000max-size max-threads4max-threads channel 9-2 Oracle Complex Event Processing Developers Guide You can create a channel element in any of the following component configuration files: ■ The default Oracle CEP application configuration file by default, META-INFwlevsconfig.xml. ■ A separate configuration file. If your application has more than one channel, you can create a channel element for each of them in the default config.xml file, you can create separate XML files in META-INFwlevs for each, or create a single XML file in META-INFwlevs that contains the configuration for all channels, or even all components of your application adapters, processors, and channels. Choose the method that best suits your development environment. By default, Oracle CEP IDE for Eclipse creates one component configuration file and one EPN assembly file. Component configuration files are deployed as part of the Oracle CEP application bundle. You can later update this configuration at runtime using Oracle CEP Visualizer, the wlevs.Admin utility, or manipulating the appropriate JMX Mbeans directly. This section describes: ■ Section 9.1.1, When to Use a Channel ■ Section 9.1.2, Channels Representing Streams and Relations ■ Section 9.1.3, System-Timestamped Channels ■ Section 9.1.4, Application-Timestamped Channels ■ Section 9.1.5, Controlling Which Queries Output to a Downstream Channel: selector ■ Section 9.1.6, Batch Processing Channels ■ Section 9.1.7, EventPartitioner Channels For more information, see: ■ Section 1.1.5, Component Configuration Files ■ Section 4.3, Creating EPN Assembly Files ■ Oracle Complex Event Processing Visualizer Users Guide ■ wlevs.Admin Command-Line Reference in the Oracle Complex Event Processing Administrators Guide ■ Configuring JMX for Oracle CEP in the Oracle Complex Event Processing Administrators Guide

9.1.1 When to Use a Channel

When constructing your EPN, consider the following rules: ■ A channel is mandator when connecting an Oracle CQL processor to a down-stream stage. ■ A channel is mandatory when connecting a push source stream or relation to a processor.