extending RichSinkFunction doesn't force to implement any of its methods

[Siddhesh Kalgaonkar <ka...@gmail.com>]

I have implemented a Cassandra sink and when I am trying to call it from
another class via DataStream it is not calling any of the methods. I tried
extending other interfaces like ProcessFunction and it is forcing me to
implement its methods whereas. when it comes to RichSinkFunction it doesn't
force me to do it. Is my problem due to this? or there is something else to
it?

https://stackoverflow.com/questions/70592174/richsinkfunction-for-cassandra-in-flink/70593375

Re: extending RichSinkFunction doesn't force to implement any of its methods

[Siddhesh Kalgaonkar <ka...@gmail.com>]

Hi Caizhi,

Thanks for your reply. Much appreciated. I understood the difference now.
Also, I have a flow like Kafka Sink Datastream -> Process Function
(Separate Class) -> Cassandra Sink(Separate Class).

Process Function returns me the output as a string and now I want to create
a DataStream out of the string variable so that I can call something like
ds.addSink(new CassandraSink()). For that, I used the StreamExecution
variable as a global /method variable but I am not able to create it
properly. Could you please refer to my StackOverflow post mentioned in the
main thread?
What is happening is, if I don't create a data stream properly it doesn't
call the sink properly because it doesn't execute the methods under the
Cassandra Sink class.

What should I do?

On Thu, Jan 6, 2022 at 7:58 AM Caizhi Weng <ts...@gmail.com> wrote:

> Hi!
>
> This is because ProcessFunction#processElement is a must while all methods
> in SinkFunction are not mandatory (for example you can create a sink which
> just discards all records by directly implementing SinkFunction). However
> if you want your sink to be more useful you'll have to see which methods in
> SinkFunction you need to implement. For example you can deal with the
> records fed to the sink in the invoke method or clean up the resources in
> the finish method.
>
> Siddhesh Kalgaonkar <ka...@gmail.com> 于2022年1月6日周四 03:11写道：
>
>> I have implemented a Cassandra sink and when I am trying to call it from
>> another class via DataStream it is not calling any of the methods. I tried
>> extending other interfaces like ProcessFunction and it is forcing me to
>> implement its methods whereas. when it comes to RichSinkFunction it doesn't
>> force me to do it. Is my problem due to this? or there is something else to
>> it?
>>
>>
>> https://stackoverflow.com/questions/70592174/richsinkfunction-for-cassandra-in-flink/70593375
>>
>

Re: extending RichSinkFunction doesn't force to implement any of its methods

[Caizhi Weng <ts...@gmail.com>]

Hi!

This is because ProcessFunction#processElement is a must while all methods
in SinkFunction are not mandatory (for example you can create a sink which
just discards all records by directly implementing SinkFunction). However
if you want your sink to be more useful you'll have to see which methods in
SinkFunction you need to implement. For example you can deal with the
records fed to the sink in the invoke method or clean up the resources in
the finish method.

Siddhesh Kalgaonkar <ka...@gmail.com> 于2022年1月6日周四 03:11写道：

> I have implemented a Cassandra sink and when I am trying to call it from
> another class via DataStream it is not calling any of the methods. I tried
> extending other interfaces like ProcessFunction and it is forcing me to
> implement its methods whereas. when it comes to RichSinkFunction it doesn't
> force me to do it. Is my problem due to this? or there is something else to
> it?
>
>
> https://stackoverflow.com/questions/70592174/richsinkfunction-for-cassandra-in-flink/70593375
>