Tunnels - fjåge version of UnetStack wormholes

[mchitre]

Implements tunnels that allow multiple fjåge universes to be connected over TCP/IP.

Example usage

fjåge container 1:

> container.add 't1', new org.arl.fjage.remote.Tunnel(12345);
> subscribe topic('sharedTopic')

fjåge container 2:

> container.add 't2', new org.arl.fjage.remote.Tunnel('localhost', 12345);
> subscribe topic('sharedTopic')
> t2.agents = [agent('t1'), topic('sharedTopic')]
[t1, sharedTopic]

> agent('t1')       // access agent t1 through the tunnel
« Tunnel »

Tunnel listening on port 12345 (1 connection)

[org.arl.fjage.remote.TunnelParam]
  agents = []
  ip ⤇ null
  port ⤇ 12345

> send new Message(recipient: topic('sharedTopic'))
true
shell >> INFORM

You should see that message in container 1 too:

fjåge container 1:

shell@1 >> INFORM

Additional notes

• Server and client can be started in any order.
• Client will reconnect to server if it loses connections (retries every 5 seconds).
• @id suffix is added to remote agent names to avoid confusion with similar named local agents. The id is auto-generated and has no user-facing semantics other than to make agentIDs unique in each container.
• ip and port can only be setup when loading the agent and cannot be modified during runtime. An agent can be killed and re-loaded, if a different IP or port is desired.
• To get detailed logs of every message exchange, do: logLevel 'org.arl.fjage.remote', FINE

[Copilot]

Pull request overview

This PR introduces a new Tunnel agent to bridge selected agents/topics between multiple fjåge containers over TCP/IP, conceptually similar to UnetStack “wormholes”.

Changes:

• Added org.arl.fjage.remote.Tunnel agent to forward messages over newline-delimited JSON/TCP connections.
• Added TunnelParam enum to expose tunnel parameters (ip, port, agents) via the existing parameter mechanism.
• Simplified TcpConnector.connections() implementation.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 11 comments.

File	Description
src/main/java/org/arl/fjage/remote/TunnelParam.java	Defines tunnel parameter names for parameter messaging.
src/main/java/org/arl/fjage/remote/Tunnel.java	Implements TCP-based tunneling/forwarding logic between containers.
src/main/java/org/arl/fjage/connectors/TcpConnector.java	Refactors connections() method formatting/flow.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 6 comments.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

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