Hi Toletum,

You can initialize a JDBC connection with RichSinkFunction [1]. There are two 
methods, `open` and `close`. The `open` method is called once before calling 
`invoke` method. The `close` method is called lastly.

Note that you should add `transient` keyword to the JDBC connection object.

Regards,
Chiwan Park

[1]: 
https://ci.apache.org/projects/flink/flink-docs-master/api/java/org/apache/flink/streaming/api/functions/sink/RichSinkFunction.html

> On Mar 7, 2016, at 10:08 PM, [email protected] wrote:
> 
> Hi!
> I'm doing a process which reads from kafka, makes some things... and after 
> writes on Database (NEO4J). I can read from kafka, and make some things.... 
> But... I have problems with write on Database (JDBC).
> I tried use a SinkFunction.... It works, but it create a connection each 
> invoke method is called.
> 
> 
> --------
> DataStream<String> messageStream = this.env.addSource(new 
> FlinkKafkaConsumer082<>(properties.getProperty("topic"), new 
> SimpleStringSchema(), properties));
> 
> 
> messageStream.map(new StreamingCrimeSplitter 
> .filter(new filterFunction())
> .keyBy(1);
> .addSink(new sinkFunction());
> 
> 
> --------
> --------
> public class sinkFunction
> implements SinkFunction<Tuple7<String, String, String, String, String, 
> String,String>> {
>         private static final long serialVersionUID = 2859601213304525959L;
>         @Override
>         public void invoke(Tuple7<String, String, String, String, String, 
> String, String> crime) throws Exception {
>                 System.out.println(crime.f0);
> //JDBC connection
>         }
> }
> --------
> 
> 
> Somebody knows how I could do just one connection? I tried to do in the 
> Constructor but the JDBC is not serializable.
> 
> 
> Thanks
> Toletum
> 
> 

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