Applications Messaging - Initial Questions for the Community
To spark off the discussion of what we want from an Applications Messaging System, we've prepared some questions and topics for discussion. If you have opinions on these issues, then please add your views to the appropriate page. Following this we'll try to distill people's views into some sort of consensus (if possible!), considering what is achievable in the time we have.
Questions to kick off the IVOA Applications Messaging discussion
General Questions
Infrastructure
- Which set of platforms/languages should be able to access the messaging system?
- Do we need....?
- Security?
- Encryption?
- Guaranteed delivery?
- Guaranteed ordering?
- Queuing of messages?
- Transactions?
- Everything changes: How do we deal with versioning of the protocol?
- Should the system be dynamic (apps discover each other at runtime), or static (apps can be discovered even when not running?)
- Is there/should there be a mechanism to start non-running apps?
Messages
- Who should define messages?
- How do we balance the need for messages to be general enough for max interop, with the specicifity needed to exploit the full power of an app?
- Do we need to be concerned with obsolescence of messages?
- In a Hub-based architecture, should the hub have any concept of the meaning of messages?
- Do we need to share access to data (rather than passing references and each app making a copy)?
Intradesktop messaging Questions
- Is a hub-based architecture best or should it be peer to peer?
PLASTIC-specific Questions
Compatibility
- Can your application send and receive messages via PLASTIC?
- Could you embed a PLASTIC Hub in your application?
- If not, what's stopping you?
Ease of use
- Should PLASTIC have more underlying transport protocols?
- Should PLASTIC have fewer underlying transport protocols?
- What would you change in the PLASTIC API?
- How do we deal with a multi Hub world?
- Do we need a protocol for "handover" as one hub shuts down?
- PLASTIC supports request-response style and asynchronous messages. Are both styles necessary?
Power
- Is the PLASTIC model of a message as a simple string accompanied by arguments, with "method call"-like semantics adequate?
- Can PLASTIC cope with the widely different capabilities of different applications?
Beyond the desktop
- Is there a demand for collaborative data exploration?
- What technologies are there that could facilitate this, and cope with firewalls, NATS etc?
- Is this any of our business or is this a GWS issue?
And finally...
- What should our target be for May?
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JohnTaylor - 01 Feb 2007