Dynamic input for logstash

Hi
I have a use case when my logstash pipeline generates output based on which I want to initiate another logstash pipeline with input based on that output.
In more details: the current pipeline uses a command input that after filtering produces JSON documents similar to this:
{key1:value1, key2:value2, etc.}.

I want to initiate another pipeline which should run a command in input like this:
input { exec { command => "curl ... http://myserver/value2"} }.

Is it possible at all? If it is, what is the way to implement this? I tried to use pipeline-to-pipeline approach but did not find how to solve it.

You cannot base the configuration of an input on fields from an event, because the configuration is done prior to receiving any events.

If you are just using exec to run curl you may be able to make the call using an http filter, which can reference fields from an event.