You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@apex.apache.org by Yogi Devendra <yo...@apache.org> on 2015/12/16 12:19:31 UTC
DAG with a single operator
Hi,
I am writing a Test application which does some validations on the HDFS
file.
Practically, I have single operator in my DAG which extends
AbstractFileInputOperator to do the necessary validation check.
public class OutputValidator extends AbstractFileInputOperator<String>
My output is just about writing log message saying SUCCESS or FAILURE
(which I can grep to find the status). I do not need any port, streams for
this operator.
Essentially, my DAG is just a single operator. Here is the code snippet for
populateDAG
@Override
public void populateDAG(DAG dag, Configuration conf)
{
dag.addOperator("OutputValidator", new OutputValidator());
}
While launching this application; I am getting following error:
javax.validation.ValidationException: At least one output port must be
connected: OutputValidator
at com.datatorrent.stram.plan.logical.LogicalPlan.validate(LogicalPlan.java:1720)
at com.datatorrent.stram.StramClient.<init>(StramClient.java:140)
at com.datatorrent.stram.client.StramAppLauncher.launchApp(StramAppLauncher.java:508)
at com.datatorrent.stram.cli.DTCli$LaunchCommand.execute(DTCli.java:1928)
at com.datatorrent.stram.cli.DTCli.launchAppPackage(DTCli.java:3382)
at com.datatorrent.stram.cli.DTCli.access$7200(DTCli.java:109)
at com.datatorrent.stram.cli.DTCli$LaunchCommand.execute(DTCli.java:1765)
at com.datatorrent.stram.cli.DTCli$3.run(DTCli.java:1329)
Looks like, this is invalid DAG as per the platform definition.
Obviously, I can do some work around by adding some dummy port, stream.
But, my question is:
*Why should we call a DAG with a single operator as invalid*?
~ Yogi
Re: DAG with a single operator
Posted by Yogi Devendra <yo...@apache.org>.
Question resolved.
I had one output port in OutputValidator which I forgot to remove.
Removing it allowed me to launch the application.
~ Yogi
On 16 December 2015 at 16:49, Yogi Devendra <yo...@apache.org> wrote:
> Hi,
>
> I am writing a Test application which does some validations on the HDFS
> file.
>
> Practically, I have single operator in my DAG which extends
> AbstractFileInputOperator to do the necessary validation check.
>
> public class OutputValidator extends AbstractFileInputOperator<String>
>
> My output is just about writing log message saying SUCCESS or FAILURE
> (which I can grep to find the status). I do not need any port, streams
> for this operator.
>
> Essentially, my DAG is just a single operator. Here is the code snippet
> for populateDAG
>
> @Override
> public void populateDAG(DAG dag, Configuration conf)
> {
> dag.addOperator("OutputValidator", new OutputValidator());
> }
>
> While launching this application; I am getting following error:
>
> javax.validation.ValidationException: At least one output port must be connected: OutputValidator
> at com.datatorrent.stram.plan.logical.LogicalPlan.validate(LogicalPlan.java:1720)
> at com.datatorrent.stram.StramClient.<init>(StramClient.java:140)
> at com.datatorrent.stram.client.StramAppLauncher.launchApp(StramAppLauncher.java:508)
> at com.datatorrent.stram.cli.DTCli$LaunchCommand.execute(DTCli.java:1928)
> at com.datatorrent.stram.cli.DTCli.launchAppPackage(DTCli.java:3382)
> at com.datatorrent.stram.cli.DTCli.access$7200(DTCli.java:109)
> at com.datatorrent.stram.cli.DTCli$LaunchCommand.execute(DTCli.java:1765)
> at com.datatorrent.stram.cli.DTCli$3.run(DTCli.java:1329)
>
> Looks like, this is invalid DAG as per the platform definition.
>
> Obviously, I can do some work around by adding some dummy port, stream.
>
> But, my question is:
> *Why should we call a DAG with a single operator as invalid*?
>
> ~ Yogi
>
>