THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Avro
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Component
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Available
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as
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of
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Camel
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2.10
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This
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component
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provides
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a
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dataformat
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for
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avro,
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which
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allows
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serialization
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and
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deserialization
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of
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messages
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using
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Apache
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Avro's
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binary
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dataformat.
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Moreover,
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it
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provides
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support
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for
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Apache
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Avro's
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rpc,
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by
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providing
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producers
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and
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consumers
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endpoint
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for
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using
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avro
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over
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netty
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or
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http.
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Maven
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users
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will
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need
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to
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add
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the
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following
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dependency
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to
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their
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pom.xml
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for
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this
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component:
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{code:xml}
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-avro</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>
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Apache Avro Overview
Avro allows you to define message types and a protocol using a json like format and then generate java code for the specified types and messages. An example of how a schema looks like is below.
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{code} h3. Apache Avro Overview Avro allows you to define message types and a protocol using a json like format and then generate java code for the specified types and messages. An example of how a schema looks like is below. {code:xml} {"namespace": "org.apache.camel.avro.generated", "protocol": "KeyValueProtocol", "types": [ {"name": "Key", "type": "record", "fields": [ {"name": "key", "type": "string"} ] }, {"name": "Value", "type": "record", "fields": [ {"name": "value", "type": "string"} ] } ], "messages": { "put": { "request": [{"name": "key", "type": "Key"}, {"name": "value", "type": "Value"} ], "response": "null" }, "get": { "request": [{"name": "key", "type": "Key"}], "response": "Value" } } } {code} |
You
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can
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easily
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generate
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classes
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from
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a
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schema,
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using
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maven,
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ant
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etc.
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More
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details
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can
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be
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found
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at
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the
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.
However,
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it
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doesn't
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enforce
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a
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schema
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first
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approach
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and
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you
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can
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create
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schema
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for
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your
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existing
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classes.
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Since
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2.12
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you
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can
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use
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existing
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protocol
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interfaces
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to
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make
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RCP
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calls.
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You
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should
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use
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interface
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for
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the
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protocol
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itself
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and
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POJO
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beans
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or
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primitive/String
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classes
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for
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parameter
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and
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result
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types.
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Here
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is
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an
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example
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of
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the
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class
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that
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corresponds
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to
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schema
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above:
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{code:java} package org.apache.camel.avro.reflection; public interface KeyValueProtocol { void put(String key, Value value); Value get(String key); } class Value { private String value; public String getValue() { return value; } public void setValue(String value) { this.value = value; } } {code} _ |
Note:
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Existing
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classes
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can
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be
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used
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only
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for
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RPC
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(see
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below),
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not
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in
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data
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format.
Using the Avro data format
Using the avro data format is as easy as specifying that the class that you want to marshal or unmarshal in your route.
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_ h3. Using the Avro data format Using the avro data format is as easy as specifying that the class that you want to marshal or unmarshal in your route. {code:xml} <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring"> <route> <from uri="direct:in"/> <marshal> <avro instanceClass="org.apache.camel.dataformat.avro.Message"/> </marshal> <to uri="log:out"/> </route> </camelContext> {code} |
An
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alternative
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can
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be
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to
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specify
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the
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dataformat
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inside
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the
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context
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and
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reference
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it
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from
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your
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route.
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{code:xml} <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring"> <dataFormats> <avro id="avro" instanceClass="org.apache.camel.dataformat.avro.Message"/> </dataFormats> <route> <from uri="direct:in"/> <marshal ref="avro"/> <to uri="log:out"/> </route> </camelContext> {code} |
In
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the
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same
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manner
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you
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can
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umarshal
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using
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the
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avro
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data
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format.
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Using
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Avro
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RPC
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in
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Camel
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As
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mentioned
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above
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Avro
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also
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provides
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RPC
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support
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over
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multiple
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transports
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such
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as
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http
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and
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netty.
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Camel
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provides
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consumers
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and
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producers
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for
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these
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two
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transports.
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} avro:[transport]:[host]:[port][?options] {code} |
The
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supported
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transport
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values
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are
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currently
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http
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or
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netty.
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Since
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2.12
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you
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can
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specify
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message
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name
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right
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in
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the
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URI:
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} avro:[transport]:[host]:[port][/messageName][?options] {code} |
For
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consumers
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this
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allows
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you
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to
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have
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multiple
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routes
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attached
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to
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the
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same
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socket.
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Dispatching
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to
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correct
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route
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will
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be
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done
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by
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the
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avro
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component
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automatically.
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Route
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with
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no
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messageName
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specified
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(if
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any)
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will
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be
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used
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as
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default.
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When
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using
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camel
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producers
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for
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avro
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ipc,
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the
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"in"
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message
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body
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needs
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to
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contain
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the
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parameters
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of
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the
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operation
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specified
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in
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the
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avro
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protocol.
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The
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response
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will
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be
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added
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in
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the
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body
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of
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the
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"out"
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message.
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In
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a
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similar
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manner
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when
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using
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camel
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avro
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consumers
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for
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avro
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ipc,
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the
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requests
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parameters
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will
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be
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placed
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inside
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the
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"in"
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message
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body
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of
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the
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created
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exchange
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and
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once
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the
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exchange
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is
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processed
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the
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body
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of
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the
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"out"
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message
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will
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be
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send
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as
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a
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response.
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Note:
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By
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default
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consumer
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parameters
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are
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wrapped
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into
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array.
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If
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you've
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got
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only
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one
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parameter,
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since
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2.12
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you
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can
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use
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singleParameter
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URI
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option
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to
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receive
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it
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direcly
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in
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the
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"in"
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message
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body
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without
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array
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wrapping
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.
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Avro
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RPC
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URI Options
| Wiki Markup |
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Options {div:class=confluenceTableSmall} || Name || Version || Description || | {{protocolClassName}} | | The class name of the avro protocol. | | {{singleParameter}} | 2.12 | If true, consumer parameter won't be wrapped into array. Will fail if protocol specifies more then 1 parameter for the message | | {{protocol}} | | Avro procol object. Can be used instead of {{protocolClassName}} when complex protocol needs to be created. One cane used #name notation to refer beans from the Registry | | {{reflectionProtocol}} | 2.12 | If protocol object provided is reflection protocol. Should be used only with {{protocol}} parameter because for {{protocolClassName}} protocol type will be autodetected | {div} h3. |
Avro
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RPC Headers
| Wiki Markup |
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Headers
{div:class=confluenceTableSmall}
|| Name || Description ||
| {{CamelAvroMessageName}} | The name of the message to send. In consumer overrides message name from URI (if any)|
{div} |
Examples
An example of using camel avro producers via http:
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h3. Examples An example of using camel avro producers via http: {code:xml} <route> <from uri="direct:start"/> <to uri="avro:http:localhost:{{avroport}}?protocolClassName=org.apache.camel.avro.generated.KeyValueProtocol"/> <to uri="log:avro"/> </route> {code} |
In
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the
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example
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above
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you
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need
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to
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fill
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CamelAvroMessageName
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header.
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Since
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2.12
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you
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can
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use
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following
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syntax
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to
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call
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constant
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messages:
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{code:xml} <route> <from uri="direct:start"/> <to uri="avro:http:localhost:{{avroport}}/put?protocolClassName=org.apache.camel.avro.generated.KeyValueProtocol"/> <to uri="log:avro"/> </route> {code} |
An
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example
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of
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consuming
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messages
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using
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camel
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avro
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consumers
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via
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netty:
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{code:xml} <route> <from uri="avro:netty:localhost:{{avroport}}?protocolClassName=org.apache.camel.avro.generated.KeyValueProtocol"/> <choice> <when> <el>${in.headers.CamelAvroMessageName == 'put'}</el> <process ref="putProcessor"/> </when> <when> <el>${in.headers.CamelAvroMessageName == 'get'}</el> <process ref="getProcessor"/> </when> </choice> </route> {code} *Since |
Since 2.12
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you
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can
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set
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up
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two
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distinct
...
routes
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to
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perform
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the
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same
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task:
| Code Block | ||||
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{code:xml} <route> <from uri="avro:netty:localhost:{{avroport}}/put?protocolClassName=org.apache.camel.avro.generated.KeyValueProtocol"> <process ref="putProcessor"/> </route> <route> <from uri="avro:netty:localhost:{{avroport}}/get?protocolClassName=org.apache.camel.avro.generated.KeyValueProtocol&singleParameter=true"/> <process ref="getProcessor"/> </route> {code} In the example above, get takes only one parameter, so {{singleParameter}} is used and {{getProcessor}} will receive Value class directly in body, while {{putProcessor}} will receive an array of size 2 with String key and Value value filled as array contents. route> |
In the example above, get takes only one parameter, so singleParameter is used and getProcessor will receive Value class directly in body, while putProcessor will receive an array of size 2 with String key and Value value filled as array contents.