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This section contains information on the following subjects:
Oracle Complex Event Processing, or Oracle CEP for short, provides a number of Spring tags that you use in the EPN assembly file of your application to register event types, declare the components of the event processing network and specify how they are linked together. The EPN assembly file is an extension of the standard Spring context file.
The following graphic describes the hierarchy of the Oracle CEP Spring tags.
The following sample EPN assembly file from the HelloWorld application shows how to use many of the Oracle CEP tags:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:osgi="http://www.springframework.org/schema/osgi"
xmlns:wlevs="http://www.bea.com/ns/wlevs/spring"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/osgi
http://www.springframework.org/schema/osgi/spring-osgi.xsd
http://www.bea.com/ns/wlevs/spring
http://www.bea.com/ns/wlevs/spring/spring-wlevs.xsd">
<!-- First, create and register the adapter (and factory) that generates hello world messages -->
<osgi:service interface="com.bea.wlevs.ede.api.AdapterFactory">
<osgi:service-properties>
<prop key="type">hellomsgs</prop>
</osgi:service-properties>
<bean class="com.bea.wlevs.adapter.example.helloworld.HelloWorldAdapterFactory" />
</osgi:service>
<wlevs:event-type-repository>
<wlevs:event-type type-name="HelloWorldEvent">
<wlevs:class>com.bea.wlevs.event.example.helloworld.HelloWorldEvent</wlevs:class>
</wlevs:event-type>
</wlevs:event-type-repository>
<!-- Assemble EPN (event processing network) -->
<!-- The adapter id is used by the configuration system, so needs to be well-known -->
<wlevs:adapter id="helloworldAdapter" provider="hellomsgs" manageable="true">
<!-- This property is also configure by dynamic config -->
<wlevs:instance-property name="message" value="HelloWorld - the currenttime is:"/>
</wlevs:adapter>
<!-- The processor id is used by the configuration system, so needs to be well-known -->
<wlevs:processor id="helloworldProcessor" manageable="true" />
<wlevs:stream id="helloworldInstream" manageable="true">
<wlevs:listener ref="helloworldProcessor"/>
<wlevs:source ref="helloworldAdapter"/>
</wlevs:stream>
<!-- Manageable is so that we can monitor the event throughput -->
<wlevs:stream id="helloworldOutstream" manageable="true">
<wlevs:listener>
<!-- Create business object -->
<bean class="com.bea.wlevs.example.helloworld.HelloWorldBean"/>
</wlevs:listener>
<wlevs:source ref="helloworldProcessor"/>
</wlevs:stream>
</beans>
Use this tag to declare an adapter component to the Spring application context.
The wlevs:adapter Spring tag supports the following child tags:
The following table lists the attributes of the wlevs:adapter Spring tag.
The following example shows how to use the wlevs:adapter tag in the EPN assembly file:
<wlevs:adapter id="helloworldAdapter" provider="hellomsgs">
<wlevs:instance-property name="message"
value="HelloWorld - the current time is:"/>
</wlevs:adapter>
In the example, the adapter’s unique identifier is helloworldAdapter. The provider is an OSGi service, also registered in the EPN assembly file, whose reference is hellomsgs. The adapter has a static property called message, which implies that the adapter Java file has a setMessage() method.
Use this tag to declare a cache to the Spring application context.
The wlevs:cache Spring tag supports the following child tags.
wlevs:caching-system—Specifies the caching system to which this cache belongs. | Note: | This child tag is different from the wlevs:caching-system tag used to declare a caching system. The child tag of the wlevs:cache tag takes a single attribute, ref, that references the id attribute of a declared caching system. |
The following table lists the attributes of the wlevs:cache Spring tag.
The following example shows how to use the wlevs:cache tag in the EPN assembly file:
<wlevs:cache id="cache-id" name="alternative-cache-name">
<wlevs:caching-system ref="caching-system-id"/>
<wlevs:listener ref="tradeListener" />
</wlevs:cache>
In the example, the cache’s unique identifier is cache-id and its alternate name is alternative-cache-name. The caching system to which the cache belongs has an id of caching-system-id. The cache has a listener to which the cache sends events; the component that listens to it has an id of tradeListener.
Specifies the caching system used by the application.
The wlevs:caching-system Spring tag supports the following child tag:
The following table lists the attributes of the wlevs:caching-system Spring tag.
The following example shows the simplest use of the wlevs:caching-system tag in the EPN assembly file:
<wlevs:caching-system id="caching-system-id"/>
The following example shows how to specify a third-party implementation that uses a factory as a provider:
<wlevs:caching-system id ="caching-system-id"
provider="caching-provider"/>
<factory id="factory-id" provider-name="caching-provider">
<class>the.factory.class.name</class>
</factory>
In the example, the.factory.class.name is a factory for creating some third-party caching system; the provider attribute of wlevs:caching-system in turn references it as the caching system implementation for the application.
Specifies the fully qualified JavaBean classname that implements a particular event type.
This tag is used only as a child of wlevs:event-type.
This tag has no child tags and no attributes
The following example shows how to use the wlevs:class tag in the EPN assembly file:
<wlevs:event-type type-name="HelloWorldEvent"><wlevs:class>com.bea.wlevs.event.example.helloworld.HelloWorldEvent</wlevs:class></wlevs:event-type>
In the example, the <wlevs:class> tag specifies the class (com.bea.wlevs.event.example.helloworld.HelloWorldEvent) that defines the HelloWorldEvent event type.
Use this tag to declare to the Spring application context that an event bean is part of your event processing network (EPN). Event beans are managed by the Oracle CEP container, analogous to Spring beans that are managed by the Spring framework. In many ways, event beans and Spring beans are similar so it is up to a developer which one to use in their EPN. Use a Spring bean for legacy integration to Spring. Use an event bean if you want to take full advantage of the additional capabilities of Oracle CEP.
For example, you can monitor an event bean using the Oracle CEP monitoring framework, make use of the Configuration framework metadata annotations, and record and playback events that pass through the event bean. An event-bean can also participate in the Oracle CEP bean lifecycle by specifying methods in its EPN assembly file declaration, rather than by implementing Oracle CEP API interfaces.
The wlevs:event-bean Spring tag supports the following child tags:
The following table lists the attributes of the wlevs:event-bean Spring tag.
The following example shows how to use the wlevs:event-bean tag in the EPN assembly file:
<wlevs:event-bean id="myBean" class="com.customer.SomeEventBean" >
<wlevs:listener ref="myProcessor" />
</wlevs:event-bean>
In the example, the event bean called myBean is implemented with the class com.customer.SomeEventBean. The component called myProcessor receives events from the myBean event bean.
Use this tag to group together one or more wlevs:event-type tags, each of which is used to register an event type used throughout the application.
This tag does not have any attributes.
The wlevs:event-type-repository Spring tag supports the following child tag:
The following example shows how to use the wlevs:event-type-repository tag in the EPN assembly file:
<wlevs:event-type-repository><wlevs:event-type type-name="HelloWorldEvent">
<wlevs:class>com.bea.wlevs.event.example.helloworld.HelloWorldEvent</wlevs:class>
</wlevs:event-type></wlevs:event-type-repository>
In the example, the <wlevs:event-type-repository> tag groups a single <wlevs:event-type> tag to declare a single event type: HelloWorldEvent. See wlevs:event-type for additional details.
Specifies the definition of an event type used in the Oracle CEP application. Once you define the event types of the application, you can reference them in the adapter and business class POJO, as well as the EPL rules.
You can define an event type in the following ways:
You can specify one of either wlevs:class or wlevs:metadata as a child of wlevs:event-type, but not both.
You can also use the wlevs:property child tag to specify a custom property to apply to the event type.
Oracle recommends that you define your event type by using the wlevs:class child tag because you can them reuse the specified JavaBean class, and you control exactly what the event type looks like.
The wlevs:event-type Spring tag supports the following child tags:
The following table lists the attributes of the wlevs:event-type Spring tag.
The following example shows how to use the wlevs:event-type tag in the EPN assembly file:
<wlevs:event-type-repository><wlevs:event-type type-name="HelloWorldEvent"></wlevs:event-type-repository>
<wlevs:class>com.bea.wlevs.event.example.helloworld.HelloWorldEvent</wlevs:class>
</wlevs:event-type>
In the example, the name of the event type is HelloWorldEvent and its definition is determined by the com.bea.wlevs.event.example.helloworld.HelloWorldEvent JavaBean class.
Use this tag to register a factory class as a service. Use of this tag decreases the dependency of your application on Spring-OSGi interfaces.
The Java source of this factory must implement the com.bea.wlevs.ede.api.Factory interface.
The factory tag does not allow you to specify service properties. If you need to specify service properties, then you must use the Spring- OSGi <osgi:service> tag instead.
This tag does not have any child tags.
The following table lists the attributes of the wlevs:factory Spring tag.
The following example shows how to use the wlevs:factory tag in the EPN assembly file:
<wlevs:factory provider-name="myEventSourceFactory"
class="com.customer.MyEventSourceFactory" />
In the example, the factory implemented by the com.customer.MyEventSourceFactory goes by the provider name of myEventSourceFactory.
Use this tag to specify a bean that contains user-defined functions for a processor.
This tag does not have any child tags.
The following table lists the attributes of the wlevs:function Spring tag.
The following example shows how to use the wlevs:function tag in the EPN assembly file:
No documentation available for Beta.
Specifies the properties that apply to the create stage instance of the component to which this is a child tag. This allows declarative configuration of user-defined stage properties.
This tag is used only as a child of wlevs:adapter, wlevs:processor, wlevs:stream, or wlevs:caching-system.
The wlevs:instance-property tag is defined as the Spring propertyType type; for additional details of this Spring data type, the definition of the allowed child tags, and so on, see the
Spring 2.0 XSD.
You can specify one of the following standard Spring tags as a child tag of the wlevs:instance-property tag:
The following table lists the attributes of the wlevs:instance-property Spring tag.
The following example shows how to use the wlevs:instance-property tag in the EPN assembly file:
<wlevs:adapter id="helloworldAdapter" provider="hellomsgs"><wlevs:instance-property name="message" value="HelloWorld - the current time is:"/></wlevs:adapter>
In the example, the bean that implements the helloworldAdapter adapter component expects an instance property called message; the sample wlevs:instance-property tag above sets the value of this property to HelloWorld - the current time is:.
Specifies the component that listens to the component to which this tag is a child. A listener can be an instance of any other component. You can also nest the definition of a component within a particular wlevs:listener component to specify the component that listens to the parent.
| WARNING: | Nested definitions are not eligible for dynamic configuration or monitoring. |
This tag is always a child of wlevs:adapter, wlevs:processor, wlevs:stream, wlevs:event-bean, or wlevs:cache.
The following table lists the attributes of the wlevs:listener Spring tag.
The following example shows how to use the wlevs:listener tag in the EPN assembly file:
<wlevs:processor id="helloworldProcessor"><wlevs:listener ref="helloworldOutstream"/></wlevs:processor>
In the example, the hellworldOutstream component listens to the helloworldProcessor component. It is assumed that the EPN assembly file also contains a declaration for a <wlevs:adapter>, <wlevs:stream>, or <wlevs:processor> component whose unique identifier is helloworldOustream.
Specifies the Spring bean that implements an object that loads data into a cache.
This tag is always a child of wlevs:cache.
The following table lists the attributes of the wlevs:loader Spring tag.
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The Spring bean must implement the com.bea.cache.jcache.CacheLoader interface.
|
The following example shows how to use the wlevs:loader tag in the EPN assembly file:
<wlevs:cache id="cache-id" name="alternative-cache-name">
<wlevs:caching-system ref="caching-system-id"/>
<wlevs:loader ref="cache-loader-id" />
</wlevs:cache>
...
<bean id="cache-loader-id" class="wlevs.example.MyCacheLoader"/>
In the example, the cache-loader-id Spring bean, implemented with the wlevs.example.MyCacheLoader class that in turn implements the com.bea.cache.jcache.CacheLoader interface, is a bean that loads data into a cache. The cache specifies this loader by pointing to it with the ref attribute of the <wlevs:loader> child element.
Specifies the definition of an event type by listing its fields as a group of Spring entry tags. When you define an event type this way, Oracle CEP automatically generates the Java class for you.
Use the key attribute of the entry tag to specify the name of a field and the value attribute to specify the Java class that represents the field’s data type.
This tag is used only as a child of wlevs:event-type.
The wlevs:metadata tag is defined as the Spring mapType type; for additional details of this Spring data type, see the
Spring 2.0 XSD.
The wlevs:metadata tag can have one or more standard
Spring entry child tags.
The following table lists the attributes of the wlevs:metadata Spring tag.
The following example shows how to use the wlevs:metadata tag in the EPN assembly file:
<wlevs:event-type type-name="ForeignExchangeEvent"><wlevs:metadata>...
<entry key="symbol" value="java.lang.String"/>
<entry key="price" value="java.lang.Double"/>
<entry key="fromRate" value="java.lang.String"/>
<entry key="toRate" value="java.lang.String"/>
</wlevs:metadata>
</wlevs:event-type>
In the example, the wlevs:metadata tag groups together four standard Spring entry tags that represent the four fields of the ForeignExchangeEvent: symbol, price, fromRate, and toRate. The data types of the fields are java.lang.String, java.lang.Double, java.lang.String, and java.lang.String, respectively.
Use this tag to declare a processor to the Spring application context.
The wlevs:processor Spring tag supports the following child tags:
The following table lists the attributes of the wlevs:processor Spring tag.
Specifies whether Oracle CEP should lazily initialize the underlying Spring bean that implements this component.
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The following example shows how to use the wlevs:processor tag in the EPN assembly file:
<wlevs:processor id="spreader" />
The example shows how to declare a processor with ID spreader. This means that in the processor configuration file that contains the EPL rules for this processor, the <name> element must contain the value spreader. This way Oracle CEP knows which EPL rules it must file for this particular processor.
Specifies a custom property to apply to the event type.
This tag is used only as a child of wlevs:event-type, wlevs:adapter, wlevs:processor, wlevs:stream, or wlevs:caching-system.
The wlevs:property tag is defined as the Spring propertyType type; for additional details of this Spring data type, the definition of the allowed child tags, and so on, see the
Spring 2.0 XSD.
You can specify one of the following standard Spring tags as a child element of the wlevs:property tag:
The following table lists the attributes of the wlevs:property Spring tag.
The following example shows how to use the wlevs:property tag in the EPN assembly file:
<wlevs:event-type type-name="ForeignExchangeEvent">
<wlevs:metadata>
<entry key="symbol" value="java.lang.String"/>
<entry key="price" value="java.lang.Double"/>
</wlevs:metadata><wlevs:property name="builderFactory"></wlevs:event-type>
<bean id="builderFactory"
class="com.bea.wlevs.example.fx.ForeignExchangeBuilderFactory"/>
</wlevs:property>
In the example, the wlevs:property tag defines a custom property of the ForeignExchangeEvent called builderFactory. The property uses the standard Spring bean tag to specify the Spring bean used as a factory to create ForeignExchangeEvents.
Specifies an event source for this component, or in other words, the component which the events are coming from. Specifying an event source is equivalent to specifying this component as an event listener to another component.
You can also nest the definition of a component within a particular wlevs:source component to specify the component source.
| WARNING: | Nested definitions are not eligible for dynamic configuration or monitoring. |
This tag is a child of wlevs:stream or wlevs:processor.
The following table lists the attributes of the wlevs:source Spring tag.
The following example shows how to use the wlevs:source tag in the EPN assembly file:
<wlevs:stream id="helloworldInstream">
<wlevs:listener ref="helloworldProcessor"/><wlevs:source ref="helloworldAdapter"/></wlevs:stream>
In the example, the component with id helloworldAdapter is the source of the helloworldInstream stream component.
Specifies the Spring bean that implements a custom store that is responsible for writing data from the cache to a backing store, such as a table in a database.
This tag is always a child of wlevs:cache.
The following table lists the attributes of the wlevs:store Spring tag.
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The Spring bean must implement the com.bea.cache.jcache.CacheStore interface.
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The following example shows how to use the wlevs:store tag in the EPN assembly file:
<wlevs:cache id="cache-id" name="alternative-cache-name">
<wlevs:caching-system ref="caching-system-id"/>
<wlevs:store ref="cache-store-id" />
</wlevs:cache>
...
<bean id="cache-store-id" class="wlevs.example.MyCacheStore"/>
In the example, the cache-store-id Spring bean, implemented with the wlevs.example.MyCacheStore class that in turn implements the com.bea.cache.jcache.CacheStore interface, is a bean for the custom store, such as a database. The cache specifies this store by pointing to it with the ref attribute of the <wlevs:store> child element.
Use this tag to declare a stream to the Spring application context.
The wlevs:stream Spring tag supports the following child tags:
The following table lists the attributes of the wlevs:stream Spring tag.
Specifies whether Oracle CEP should lazily initialize the underlying Spring bean that implements this component.
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The following example shows how to use the wlevs:stream tag in the EPN assembly file:
<wlevs:stream id="fxMarketAmerOut" />
The example shows how to declare a stream service with unique identifier fxMarketAmerOut.
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