AWS SSM port forwarding session using AWS-SDK

Hello,

I am curious whether it is possible to open and maintain SSM port forwarding session using @aws-sdk ssm client. I have seen examples using AWS CLI, but I have not seen examples using SDK.

What I would like is to do something like this:

const { SessionId } = await ssmClient.send(
      new StartSessionCommand({
        Target: 'i-0af865f7bb036b35c', // jump host
        DocumentName: 'AWS-StartPortForwardingSessionToRemoteHost',
        Parameters: {
          host: ['bastion-tst2-myslsdb.cluster-xxxxxxxxx.eu-west-1.rds.amazonaws.com'],  // remote db I try connect to
          portNumber: ['5432'],
          localPortNumber: ['5432']
        }
      })
    );

**This should open tunnel from my local port through the jumphost to the database. ** In my case, the session starts, but no local port seems to be open on my localhost. The session then terminates automatically in about 20 seconds.