Flink
Since Camel 2.18
Only producer is supported
This documentation page covers the Apache Flink component for the Apache Camel. The camel-flink component provides a bridge between Camel components and Flink tasks.
This Camel Flink component provides a way to route message from various transports, dynamically choosing a flink task to execute, use incoming message as input data for the task and finally deliver the results back to the Camel pipeline.
Maven users will need to add the following dependency to their pom.xml for this component:
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-flink</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>URI Format
Currently, the Flink Component supports only Producers. One can create DataSet, DataStream jobs.
flink:dataset?dataset=#myDataSet&dataSetCallback=#dataSetCallback flink:datastream?datastream=#myDataStream&dataStreamCallback=#dataStreamCallback
Configuring Options
Camel components are configured on two separate levels:
-
component level
-
endpoint level
Configuring Component Options
The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.
Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.
Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.
Configuring Endpoint Options
Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.
Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java.
A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.
The following two sections lists all the options, firstly for the component followed by the endpoint.
Component Options
The Flink component supports 5 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
Function performing action against a DataSet. | DataSetCallback | ||
DataStream to compute against. | DataStream | ||
Function performing action against a DataStream. | DataStreamCallback | ||
Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | boolean | |
Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. | true | boolean |
Endpoint Options
The Flink endpoint is configured using URI syntax:
flink:endpointType
with the following path and query parameters:
Query Parameters (6 parameters)
| Name | Description | Default | Type |
|---|---|---|---|
Indicates if results should be collected or counted. | true | boolean | |
DataSet to compute against. | DataSet | ||
Function performing action against a DataSet. | DataSetCallback | ||
DataStream to compute against. | DataStream | ||
Function performing action against a DataStream. | DataStreamCallback | ||
Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | boolean |
Message Headers
The Flink component supports 4 message header(s), which is/are listed below:
| Name | Description | Default | Type |
|---|---|---|---|
| Constant: | The dataset. | Object | |
CamelFlinkDataSetCallback (producer) Constant: | The dataset callback. | DataSetCallback | |
CamelFlinkDataStream (producer) Constant: | The data stream. | Object | |
CamelFlinkDataStreamCallback (producer) Constant: | The data stream callback. | DataStreamCallback |
Flink DataSet Callback
@Bean
public DataSetCallback<Long> dataSetCallback() {
return new DataSetCallback<Long>() {
public Long onDataSet(DataSet dataSet, Object... objects) {
try {
dataSet.print();
return new Long(0);
} catch (Exception e) {
return new Long(-1);
}
}
};
}Flink DataStream Callback
@Bean
public VoidDataStreamCallback dataStreamCallback() {
return new VoidDataStreamCallback() {
@Override
public void doOnDataStream(DataStream dataStream, Object... objects) throws Exception {
dataStream.flatMap(new Splitter()).print();
environment.execute("data stream test");
}
};
}Camel-Flink Producer call
CamelContext camelContext = new SpringCamelContext(context);
String pattern = "foo";
try {
ProducerTemplate template = camelContext.createProducerTemplate();
camelContext.start();
Long count = template.requestBody("flink:dataSet?dataSet=#myDataSet&dataSetCallback=#countLinesContaining", pattern, Long.class);
} finally {
camelContext.stop();
}Spring Boot Auto-Configuration
When using flink with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:
<dependency>
<groupId>org.apache.camel.springboot</groupId>
<artifactId>camel-flink-starter</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>The component supports 6 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. | true | Boolean | |
Function performing action against a DataSet. The option is a org.apache.camel.component.flink.DataSetCallback type. | DataSetCallback | ||
DataStream to compute against. The option is a org.apache.flink.streaming.api.datastream.DataStream type. | DataStream | ||
Function performing action against a DataStream. The option is a org.apache.camel.component.flink.DataStreamCallback type. | DataStreamCallback | ||
Whether to enable auto configuration of the flink component. This is enabled by default. | Boolean | ||
Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | Boolean |