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 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. However, it doesn't enforce a schema first approach and you can create schema for your existing classes. 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, it doesn't enforce a schema first approach and you can create schema for your existing classes. Since 2.12 you can use existing protocol interfaces to make RCP calls. You should use interface for the protocol itself and POJO beans or primitive/String classes for parameter and result types. Here is an example of the class that corresponds to schema above:
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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; }
}
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Note: Existing classes can be used only for RPC (see below), not in data 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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documentation|http://avro.apache.org/docs/current/]. 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 the same manner you can umarshal using the avro data format. h3. Using Avro RPC in Camel As mentioned above Avro also provides RPC support over multiple transports such as http and netty. Camel provides consumers and producers for these two transports. {code} |
In the same manner you can umarshal using the avro data format.
Using Avro RPC in Camel
As mentioned above Avro also provides RPC support over multiple transports such as http and netty. Camel provides consumers and producers for these two transports.
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avro:[transport]:[host]:[port][?options]
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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]
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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}
The supported transport values are currently http or netty.
When using camel producers for avro ipc, the "in" message body needs to contain the arguments of the operation sepcified 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 arguments 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.
h3. Avro RPC URI Options
{div:class=confluenceTableSmall}
|| Name || Description ||
| {{protocolClassName}} | The class name of the avro protocol. |
{div}
h3. Avro RPC Headers
{div:class=confluenceTableSmall}
|| Name || Description ||
| {{CamelAvroMessageName}} | The name of the message to send. |
{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>
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In the example above you need to fill CamelAvroMessageName header. Since 2.12 you can use following syntax to call constant messages:
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<route>
<from uri="direct:start"/>
<to uri="avro:http:localhost:{{avroport}}/put?protocolClassName=org.apache.camel.avro.generated.KeyValueProtocol"/>
<to uri="log:avro"/>
</route>
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An example of consuming messages using camel avro consumers via netty:
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{code} An example of consuming messages using camel avro consumers via netty: {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> |
Since 2.12 you can set up two distinct routes to perform the same task:
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<route> <from uri="avro:netty:localhost:{{avroport}}/put?protocolClassName=org.apache.camel.avro.generated.KeyValueProtocol"> <process ref="putProcessor"/> </route> {code} <route> <from uri="avro:netty:localhost:{{avroport}}/get?protocolClassName=org.apache.camel.avro.generated.KeyValueProtocol&singleParameter=true"/> <process ref="getProcessor"/> </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.