The cxf: component provides integration with Apache CXF for connecting to JAX-WS services hosted in CXF.

Using the JDBC based idempotent repository

Available as of Camel 2.7: In this section we will use the JDBC based idempotent repository.

First we have to create the database table which will be used by the idempotent repository. For Camel 2.7, we use the following schema:

We recommend to have a unique constraint on the columns processorName and messageId. Because the syntax for this constraint differs for database to database, we do not show it here.

Customize the JdbcMessageIdRepository

Starting with Camel 2.9.1 you have a few options to tune the org.apache.camel.processor.idempotent.jdbc.JdbcMessageIdRepository for your needs:

Parameter	Default Value	Description
createTableIfNotExists	true	Defines whether or not Camel should try to create the table if it doesn't exist.
tableExistsString	SELECT 1 FROM CAMEL_MESSAGEPROCESSED WHERE 1 = 0	This query is used to figure out whether the table already exists or not. It must throw an exception to indicate the table doesn't exist.
createString	CREATE TABLE CAMEL_MESSAGEPROCESSED (processorName VARCHAR(255), messageId VARCHAR(100), createdAt TIMESTAMP)	The statement which is used to create the table.
queryString	SELECT COUNT(*) FROM CAMEL_MESSAGEPROCESSED WHERE processorName = ? AND messageId = ?	The query which is used to figure out whether the message already exists in the repository (the result is not equals to '0'). It takes two parameters. This first one is the processor name (`String`) and the second one is the message id (`String`).
insertString	INSERT INTO CAMEL_MESSAGEPROCESSED (processorName, messageId, createdAt) VALUES (?, ?, ?)	The statement which is used to add the entry into the table. It takes three parameter. The first one is the processor name (`String`), the second one is the message id (`String`) and the third one is the timestamp (`java.sql.Timestamp`) when this entry was added to the repository.
deleteString	DELETE FROM CAMEL_MESSAGEPROCESSED WHERE processorName = ? AND messageId = ?	The statement which is used to delete the entry from the database. It takes two parameter. This first one is the processor name (`String`) and the second one is the message id (`String`).

A customized org.apache.camel.processor.idempotent.jdbc.JdbcMessageIdRepository could look like:

Using the JDBC based aggregation repository

JdbcAggregationRepository is an AggregationRepository which on the fly persists the aggregated messages. This ensures that you will not loose messages, as the default aggregator will use an in memory only AggregationRepository.
The JdbcAggregationRepository allows together with Camel to provide persistent support for the Aggregator.

< td colspan="1" rowspan="1" class="confluenceTd">

Mandatory: The name of the repository.

< tr>

Option	Type	Description
`dataSource`	`DataSource`	Mandatory: The `javax.sql.DataSource` to use for accessing the database.
`repositoryName`	`String`
`transactionManager`	`TransactionManager`	Mandatory: The `org.springframework.transaction.PlatformTransactionManager` to mange transactions for the database. The TransactionManager must be able to support databases.
`lobHandler`	`LobHandler`	A `org.springframework.jdbc.support.lob.LobHandler` to handle Lob types in the database. Use this option to use a vendor specific LobHandler, for example when using Oracle.
`returnOldExchange`	boolean	Whether the get operation should return the old existing Exchange if any existed. By default this option is `false` to optimize as we do not need the old exchange when aggregating.
`useRecovery`	boolean	Whether or not recovery is enabled. This option is by default `true`. When enabled the Camel Aggregator automatic recover failed aggregated exchange and have them resubmitted.
`recoveryInterval`	long	If recovery is enabled then a background task is run every x'th time to scan for failed exchanges to recover and resubmit. By default this interval is 5000 millis.
`maximumRedeliveries`	int	Allows you to limit the maximum number of redelivery attempts for a recovered exchange. If enabled then the Exchange will be moved to the dead letter channel if all redelivery attempts failed. By default this option is disabled. If this option is used then the `deadLetterUri` option must also be provided.
`deadLetterUri`	String	An endpoint uri for a Dead Letter Channel where exhausted recovered Exchanges will be moved. If this option is used then the `maximumRedeliveries` option must also be provided.
`storeBodyAsText`	boolean	Camel 2.11: Whether to store the message body as String which is human readable. By default this option is `false` storing the body in binary format.
`headersToStoreAsText`	`List<String>`	Camel 2.11: Allows to store headers as String which is human readable. By default this option is disabled, storing the headers in binary format.
`optimisticLocking`	`false`	Camel 2.12: To turn on optimistic locking, which often would be needed in clustered environments where multiple Camel applications shared the same JDBC based aggregation repository.
`jdbcOptimisticLockingExceptionMapper`		Camel 2.12: Allows to plugin a custom `org.apache.camel.processor.aggregate.jdbc.JdbcOptimisticLockingExceptionMapper` to map vendor specific error codes to an optimistick locking error, for Camel to p erform a retry. This requires `optimisticLocking` to be enabled.

What is preserved when persisting

JdbcAggregationRepository will only preserve any Serializable compatible data types. If a data type is not such a type its dropped and a WARN is logged. And it only persists the Message body and the Message headers. The Exchange properties are not persisted.

From Camel 2.11 onwards you can store the message body and select(ed) headers as String in separate columns.

Recovery

The JdbcAggregationRepository will by default recover any failed Exchange. It does this by having a background tasks that scans for failed Exchanges in the persi stent store. You can use the checkInterval option to set how often this task runs. The recovery works as transactional which ensures that Camel will try to recover and redeliver the failed Exchange. Any Exchange which was found to be recovered will be restored from the persistent store and resubmitted and send out again.

Header	Type	Description
`Exchange.REDELIVERED`	Boolean	Is set to true to indicate the Exchange is being redelivered.
`Exchange.REDELIVERY_COUNTER`	Integer	The redelivery attempt, starting from 1.

Only when an Exchange has been successfully processed it will be marked as complete which happens when the confirm method is invoked on the AggregationRepository. This means if the same Exchange fails again it will be kept retried until it success.

You can see some examples in the unit tests of camel-sql, for example this test.

Database

To be operational, each aggregator uses two table: the aggregation and completed one. By convention the completed has the same name as the aggregation one suffixed with "_COMPLETED". The name must be configured in the Spring bean with the RepositoryName property. In the following example aggregation will be used.

The table structure definition of both table are identical: in both case a String value is u sed as key (id) whereas a Blob contains the exchange serialized in byte array.
However one difference should be remembered: the id field does not have the same content depending on the table.
In the aggregation table id holds the correlation Id used by the component to aggregate the messages. In the completed table, id holds the id of the exchange stored in corresponding the blob field.

Here is the SQL query used to create the tables, just replace "aggregation" with your aggregator repository name.

Storing body and headers as text

You can configure the JdbcAggregationRepository to store message body and select(ed) headers as String in separate columns. For example to store the body, and the following two headers companyName and accountName use the following SQL:

Codec (Serialization)

Since they can contain any type of payload, Exchanges are not serializable by design. It is converted into a byte array to be stored in a database BLOB field. All those conversions are handled by the JdbcCodec class. One detail of the code requires your attention: the ClassLoadingAwareObjectInputStream.

The ClassLoadingAwareObjectInputStream has been reused from the Apache ActiveMQ project. It wraps an ObjectInputStream and use it with the ContextClassLoader rather than the currentThread one. The benefit is to be able to load classes exposed by other bundles. This allows the exchange body and headers to have custom types object references.

Transaction

Service (Start/Stop)

The start method verify the connection of the database and the presence of the required tables. If anything is wrong it will fail during starting.

Aggregator configuration

Depending on the targeted environment, the aggregator might need some configuration. As you already know, each aggregator should have its own repository (with the corresponding pair of table created in the database) and a data source. If the default lobHandler is not adapted to your database system, it can be injected with the lobHandler property.

Then the IN query can use a header with the key names with the dynamic values such as:

Optimistic locking

From Camel 2.12 onwards you can turn on optimisticLocking and use this JDBC based aggregation repository in a clustered environment where multiple Camel applications shared the same database for the aggregation repository. If there is a race condition there JDBC driver will throw a vendor specific exception which the JdbcAggregationRepository can react upon. To know which caused exceptions from the JDBC driver is regarded as an optimistick locking error we need a mapper to do this. Therefore there is a org.apache.camel.processor.aggregate.jdbc.JdbcOptimisticLockingExceptionMapper allows you to implement your custom logic if needed. There is a default implementation org.apache.camel.processor.aggregate.jdbc.DefaultJdbcOptimisticLockingExceptionMapper which works as follows:

You can in addition add FQN classnames, and if any of the caused exception (or any nested) equals any of the FQN class names, then its an optimistick locking error.

Here is an example, where we define 2 extra FQN class names from the JDBC vendor.

See Also

Test Component

The test component extends the Mock component to support pulling messages from another endpoint on startup to set the expected message bodies on the underlying Mock endpoint. That is, you use the test endpoint in a route and messages arriving on it will be implicitly compared to some expected messages extracted from some other location.

So you can use, for example, an expected set of message bodies as files. This will then set up a properly configured Mock endpoint, which is only valid if the received messages match the number of expected messages and their message payloads are equal.

Maven users will need to add the following dependency to their pom.xml for this component when using Camel 2.8 or older:

The query can also be specified in the endpoint instead of being externalized (notice that externalizing makes maintaining the SQL queries easier)

Using the JDBC based idempotent repository

Available as of Camel 2.7: In this section we will use the JDBC based idempotent repository.

From Camel 2.9 onwards there is an abstract class org.apache.camel.processor.idempotent.jdbc.AbstractJdbcMessageIdRepository you can extend to build custom JDBC idempotent repository.

First we have to create the database table which will be used by the idempotent repository. For Camel 2.7, we use the following schema:

CREATE TABLE CAMEL_MESSAGEPROCESSED ( processorName VARCHAR(255), messageId VARCHAR(100) )

CREATE TABLE CAMEL_MESSAGEPROCESSED ( processorName VARCHAR(255), messageId VARCHAR(100), createdAt TIMESTAMP )

The SQL Server TIMESTAMP type is a fixed-length binary-string type. It does not map to any of the JDBC time types: DATE, TIME, or TIMESTAMP.

We recommend to have a unique constraint on the columns processorName and messageId. Because the syntax for this constraint differs for database to database, we do not show it here.

Second we need to setup a javax.sql.DataSource in the spring XML file:{snippet:id=e1|lang=xml|url=camel/trunk/components/camel-s
 ql/src/test/resources/org/apache/camel/processor/idempotent/jdbc/spring.xml}

And finally we can create our JDBC idempotent repository in the spring XML file as well:{snippet:id=e2|lang=xml|url=camel/trunk/components/camel-sql/src/test/resources/org/apache/camel/processor/idempotent/jdbc/spring.xml}

Starting with Camel 2.9.1 you have a few options to tune the org.apache.camel.processor.idempotent.jdbc.JdbcMessageIdRepository for your needs:

Defines whether or not Camel should try to create the table if it doesn't exi
 st.

This query is used to figure out whether the table already exists or not. It must throw an exception to indicate the table doesn't exist.

CREATE TABLE CAMEL_MESSAGEPROCESSED (processorName VARCHAR(255), messageId VARCHAR(100), createdAt TIMESTAMP)

SELECT COUNT(*) FROM CAMEL_MESSAGEPROCESSED WHERE processorName = ? AND messageId = ?

The query which is used to figure out whether the message already exists in the repository (the result i
 s not equals to '0'). It takes two parameters. This first one is the processor name (String) and the second one is the message id (String).

INSERT INTO CAMEL_MESSAGEPROCESSED (processorName, messageId, createdAt) VALUES (?, ?, ?)

The statement which is used to add the entry into the table. It takes three parameter. The first one is the processor name (String), the second one is the message id (String) and the third one is the timestamp (java.sql.Timestamp) when this entry was added to the repository.

The statement which is used to delete the entry from the dat
 abase. It takes two parameter. This first one is the processor name (String) and the second one is the message id (String).

A customized org.apache.camel.processor.idempotent.jdbc.JdbcMessageIdRepository could look like:{snippet:id=e1|lang=xml|url=camel/trunk/components/camel-sql/src/test/resources/org/apache/camel/processor/idempotent/jdbc/customized-spring.xml}

In Camel 2.6, the JdbcAggregationRepository is provided in the camel-jdbc-aggregator component. From Camel 2.7 onwards, the JdbcAggr
 egationRepository is provided in the camel-sql component.

JdbcAggregationRepository is an AggregationRepository which on the fly persists the aggregated messages. This ensures that you will not loose messages, as the default aggregator will use an in memory only AggregationRepository.
 The JdbcAggregationRepository allows together with Camel to provide persistent support for the Aggregator.

Mandatory: The org.springframework.transaction.PlatformTransactionManager to mange transactions for the database. The TransactionManager must be able to support databases.

A org.springframework.jdbc.support.lob.LobHandler to handle Lob types in the database. Use this
  option to use a vendor specific LobHandler, for example when using Oracle.

Whether the get operation should return the old existing Exchange if any existed. By default this option is false to optimize as we do not need the old exchange when aggregating.

Whether or not recovery is enabled. This option is by default true. When enabled the Camel Aggregator automatic recover failed aggregated exchange and have them resubmitted.

If recovery is enabled then a background task is run every x'th time to scan for failed exchanges to recover and resubmit. By default this interval is 5000 millis.

Allows you to limit the maximum number of redelivery attempts for a recovered exchange. If enabled then the Exchange will be moved to the dead letter channel if all redelivery attempts failed. By default this option is disabled. If this option is used then the deadLetterUri option must also be provided.

An endpoint uri for a Dead Letter Channel where exhausted recovered Exchanges will be moved. 
 If this option is used then the maximumRedeliveries option must also be provided.

Camel 2.11: Whether to store the message body as String which is human readable. By default this option is false storing the body in binary format.

Camel 2.11: Allows to store headers as String which is human readable. By default this option is disabled, storing the headers in binary format.

Camel 2.12: To turn on optimistic locking, which often would be needed in clustered environments where multiple Camel applications shared the same JDBC based aggregation repository.

Camel 2.12: Allows to plugin a custom org.apache.camel.processor.aggregate.jdbc.JdbcOptimisticLockingExceptionMapper to map vendor specific error codes to an optimistick locking error, for Camel to perform a retry. This requires optimisticLocking to be enabled.

JdbcAggregationRepository will only preserve any Serializable compatible data types. If a data type is not such a type its dropped and a WARN is logged. And it only persists the Message body and 
 the Message headers. The Exchange properties are not persisted.

From Camel 2.11 onwards you can store the message body and select(ed) headers as String in separate columns.

The JdbcAggregationRepository will by default recover any failed Exchange. It does this by having a background tasks that scans for failed Exchanges in the persistent store. You can use the checkInterval option to set how often this task runs. The recovery works as transactional which ensures that Camel will try to recover and redeliver the failed Exchange. Any Exchange which was found to be recovered will be restored from the persistent store and resubmitted and send out again.

Only when an Exchange has been successfully processed it will be marked as complete which happens when the confirm method is invoked on the AggregationRepository. This means if the s
 ame Exchange fails again it will be kept retried until it success.

You can use option maximumRedeliveries to limit the maximum number of redelivery attempts for a given recovered Exchange. You must also set the deadLetterUri option so Camel knows where to send the Exchange when the maximumRedeliveries was hit.

You can see some examples in the unit tests of camel-sql, for example this test.

To be operational, each aggregator uses two table: the aggregation and completed one. By convention the completed has the same name as the aggregation one suffixed with "_COMPLETED". The name must be configured in the Spring bean with the RepositoryName property. In the following example aggregation will be used.

The table structure definition of both table are identical: in both case a String value is used as key (id) whereas a Blob contains the exchange serialized in byte array.
 However one difference should be remembered: the id field does not have the same content depending on the table.
 In the aggregation table id holds the correlation Id used by the component to aggregate the messages. In the completed table, id holds the id of the exchange stored in corresponding the blob field.

Here is the SQL query used to create the tables, just replace "aggregation" with your aggregator repository name.

CREATE TABLE aggregation ( id varchar(255) NOT NULL, exchange blob NOT NULL, constraint aggregation_pk PRIMARY KEY (id) ); CREATE TABLE aggregation_completed ( id varchar(255) NOT NULL, exchange blob NOT NULL, constraint aggregation_completed_pk PRIMARY KEY (id) );

You can configure the JdbcAggregationRepository to store message body and select(ed) headers as String in separate columns. For example to store the body, and the following two headers companyName and accountName use the following SQL:

CREATE TABLE aggregationRepo3 ( id varchar(255) NOT NULL, exchange blob NOT NULL, body varchar(1000), companyName varchar(1000), accountName varchar(1000), constraint aggregationRepo3_pk PRIMARY KEY (id) ); CREATE TABLE aggregationRepo3_completed ( id varchar(255) NOT NULL, exchange blob NOT NULL, body varchar(1000), companyName varchar(1000), accountName varchar(1000), constraint aggregationRepo3_completed_pk PRIMARY KEY (id) );

<bean id="repo3" class="org.apache.camel.processor.aggregate.jdbc.JdbcAggregationRepository"> <property name="repositoryName" value="aggregationRepo3"/> <property name="transactionManager" ref="txManager3"/> <property name="dataSource" ref="dataSource3"/> <!-- configure to store the message body and following headers as text in the repo --> <property name="storeBodyAsText" value="true"/> <property name="headersToStoreAsText"> <list> <value>companyName</value> <value>accountName</value> </list> </property> </bean>

Since they can contain any type of payload, Exchanges are not serializable by design. It is converted into a byte array to be stored in a database BLOB field. All those conversions are handled by the JdbcCodec class. One detail of the code requires your attention: the ClassLoadingAwareObjectInputStream.

The ClassLoadingAwareObjectInputStream has been reused from the Apache ActiveMQ project. It wraps an ObjectInputStream and use it with the ContextClassLoader rather than the currentThread one. The benefit is to be able to load classes exposed by other bundles. This allows the exchange body and headers to have custom types object references.

The start method verify the connection of the database and the presence of the required tables. If anything is wrong it will fail during starting.

Depending on the targeted environment, the aggregator might need some configuration. As you already know, each aggregator should have its own repository (with the correspo
 nding pair of table created in the database) and a data source. If the default lobHandler is not adapted to your database system, it can be injected with the lobHandler property.

<bean id="lobHandler" class="org.springframework.jdbc.support.lob.OracleLobHandler"> <property name="nativeJdbcExtractor" ref="nativeJdbcExtractor"/> </bean> <bean id="nativeJdbcExtractor" class="org.springframework.jdbc.support.nativejdbc.CommonsDbcpNativeJdbcExtractor"/> <bean id="repo" class="org.apache.camel.processor.aggregate.jdbc.JdbcAggregationRepository"> <property name="transactionManager" ref="transactionManager"/> <property name="repositoryName" value="aggregation"/> <property name="dataSource" ref="dataSource"/> <!-- Only with Oracle, else use default --> <property name="lobHandler" ref="lobHandler"/> </bean>

From Camel 2.12 onwards you can turn on optimisticLocking and use this JDBC based aggregation repository in a clustered environment where multiple Camel applications shared the same database for the aggregation r
 epository. If there is a race condition there JDBC driver will throw a vendor specific exception which the JdbcAggregationRepository can react upon. To know which caused exceptions from the JDBC driver is regarded as an optimistick locking error we need a mapper to do this. Therefore there is a org.apache.camel.processor.aggregate.jdbc.JdbcOptimisticLockingExceptionMapper allows you to implement your custom logic if needed. There is a default implementation org.apache.camel.processor.aggregate.jdbc.DefaultJdbcOptimisticLockingExceptionMapper which works as follows:

If the caused exception is an SQLException then the SQLState is checked if starts with 23.

optional checking for FQN class name matches if any class names has been co
 nfigured

You can in addition add FQN classnames, and if any of the caused exception (or any nested) equals any of the FQN class names, then its an optimistick locking error.

Here is an example, where we define 2 extra FQN class names from the JDBC vendor.

<bean id="repo" class="org.apache.camel.processor.aggregate.jdbc.JdbcAggregationRepository"> <property name="transactionManager" ref="transactionManager"/> <property name="repositoryName" value="aggregation"/> <property name="dataSource" ref="dataSource"/> <property name"jdbcOptimisticLockingExceptionMapper" ref="myExceptionMapper"/> </bean> <!-- use the default mapper with extra FQN class names from our JDBC driver --> <bean id="myExceptionMapper" class="org.apache.camel.processor.aggregate.jdbc.DefaultJdbcOptimisticLockingExceptionMapper"> <property name="classNames"> <util:set> <value>com.foo.sql.MyViolationExceptoion</value> <value>com.foo.sql.MyOtherViolationExceptoion</value> </util:set> </property> </bean>

See Also

CXF Component

Using the JDBC based idempotent repository

Customize the JdbcMessageIdRepository

Using the JDBC based aggregation repository

What is preserved when persisting

Recovery

Database

Storing body and headers as text

Codec (Serialization)

Transaction

Service (Start/Stop)

Aggregator configuration

Optimistic locking

See Also

Test Component

`Using the JDBC based idempotent repository`

`See Also`

Test Component