Architecture issues

[celluloid]

Architecture issues

[spangenberg]

I had the same question two weeks ago when I dived into the project.

I think there was this directory functionality in the gossip adapter, correct me when I'm wrong.

But currently there is only a stuped single point of failure registry as a key value store.

I'm digging into it and try to create a new registry which lives on every node and tries to set up a routing table, checks health of node and so on ...

Maybe we should talk together, sounds like you have similar needs.

Best
Daniel

[vgololobov]

IMHO - routing table (more likely DHT) is overcomplicated for this task and makes it hard to have a clusters of nodes

Currently each node sends a heartbeat message every 10 seconds and to have a Directory node which will coordinate all connected nodes is a good idea

In case if it fall off, the only thing you will lose - is ability to find out connected to cluster nodes, all existing communications will remain functional

Couple thing I think will be great to add:

• connection timeout
• connection state tracking (using heartbeats)
• ability to create different types of connections, like pub/sub (like claimed in wiki)
• load balanced cluster of nodes

[tarcieri]

The issue tracker is for bugs, not open-ended discussion. I guess I'm going to call this a dupe of #6?

Can you broach these issues on the mailing list? You seem to be missing quite a bit from the codebase as well: DCell most certainly has a heartbeat system for detecting downed nodes.

https://github.com/celluloid/dcell/blob/master/lib/dcell/node.rb#L108

[vgololobov]

This was not a discussion.
Issues are:

• Directory is not functional at all (duplicates registry calls )
• Detecting down nodes not functional , the only thing it does is just

        Celluloid::Logger.warn "Communication with #{id} interrupted" 

I just said that DCell has a heartbeat system but not use it

[tarcieri]

Okay, so this is just a dupe of #6 then, or what?

[vgololobov]

No, issue addressed to this ticket is not down nodes
Is about what to do with Directory service and node clustering ?

Add functionality according to wiki or remove it as a dup of Registry

[tarcieri]

Okay, I'm a bit confused because you're telling me a lot of different things in this ticket so I'm having trouble nailing down anything specific...

The issue is: the code in Directory merely delegates to the active Registry and is therefore unnecessary? Probably.

DCell uses heartbeats to determine the liveliness of nodes. Every node is a Celluloid::FSM, and the heartbeat system triggers state transitions which mark the node as down.

When nodes are marked as down, existing DCell RPC calls are cancelled, and new ones will fail until the nodes are marked back up. If you are having trouble with this behavior, I suggest you open another issue.

[vgololobov]

The issue is: the code in Directory merely delegates to the active Registry and is therefore unnecessary? 

This is the point of this ticket

Remove or rewrite it to handle clustering as it described in wiki