Supporting Pubsub/Event Driven for long-running tools

[Omer-N]

While ADK's event-loop design is powerful and intuitive, it poses challenges for long-running tools. Having a generator function waiting to yield an event makes it difficult to scale ADK instances up and down reliably, since the execution time can exceed a reasonable grace period.

I'm curious to figure out how others are handling this.
For example, could long-running tools publish a message to a Pub/Sub topic once complete, and have that message pushed into the event loop?

Maybe I'm missing something but I think in order to scale robustly we will need to figure out a way to make the event-driven design support events that aren't just in memory?

(same question of course for AgentTool)

I think it is similar to:
#165 (comment)

WDYT?

[boyangsvl]

If you use long running tools (https://google.github.io/adk-docs/tools/function-tools/#2-long-running-function-tool), it will end the event loop and give you the info about the tool. After a few minutes, hours or days, you can resume the conversation by sending the tool response to the agent. This is working sort like a pub/sub system.