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 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] {code} The supported transport values are currently http or netty. *Since 2.12* you can specify message name right in the URI: {code[?options] |
The supported transport values are currently http or netty.
Since 2.12 you can specify message name right in the URI:
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} avro:[transport]:[host]:[port][/messageName][?options] |
For consumers this allows you to have multiple routes attached to the same socket. Dispatching to correct route will be done by the avro component automatically. Route with no messageName specified (if any) will be used as default.
When using camel producers for avro ipc, the "in" message body needs to contain the parameters of the operation specified in the avro protocol. The response will be added in the body of the "out" message.
In a similar manner when using camel avro consumers for avro ipc, the requests parameters will be placed inside the "in" message body of the created exchange and once the exchange is processed the body of the "out" message will be send as a response.
Note: By default consumer parameters are wrapped into array. If you've got only one parameter, since 2.12 you can use singleParameter URI option to receive it direcly in the "in" message body without array wrapping.
Avro RPC URI Options
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Avro RPC Headers
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Examples
An example of using camel avro producers via http:
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{code} For consumers this allows you to have multiple routes attach to the same socket. Dispatching to correct route will be done by the avro component automatically. Route with no messageName specified (if any) will be used as default. When using camel producers for avro ipc, the "in" message body needs to contain the parameters of the operation specified in the avro protocol. The response will be added in the body of the "out" message. In a similar manner when using camel avro consumers for avro ipc, the requests parameters will be placed inside the "in" message body of the created exchange and once the exchange is processed the body of the "out" message will be send as a response. *Note:* By default consumer parameters are wrapped into array. If you've got only one parameter, *since 2.12* you can use {{singleParameter}} URI option to receive it direcly in the "in" message body without array wrapping. h3. Avro RPC URI 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 RPC Headers {div:class=confluenceTableSmall} || Name || Description || | {{CamelAvroMessageName}} | The name of the message to send. In consumer overrides message name from URI (if any)| {div} 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
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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:
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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
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the
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example
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above,
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get
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takes
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only
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one
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parameter,
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so
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singleParameter
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is
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used
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and
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getProcessor
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will
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receive
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Value
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class
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directly
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in
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body,
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while
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putProcessor
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will
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receive
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an
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array
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of
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size
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2
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with
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String
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key
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and
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Value
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value
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filled
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as
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array
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contents.
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