Notification Down Under

1
Notification Down Under

• Ideology and Implementation

2
Introduction

• What is a notification service (IMHO)?
• Why we think that?
• Features vs Simplicity

3
Ideology

• "In its most general form a notification
  service supports anonymous interactions between
  loosely coupled parties. Where distributed object
  models typically assume that interacting parties
  know about each other, a notification service
  does routing based on message content. The
  producer of a notification isn't generally
  interested in who or how many clients receives a
  notification and a consumer isn't interested in
  where it comes from." Keryx (HP research labs,
  Bristol)

4
What is a notification service?

• Publish-subscribe
• Content-based addressing
• Loosely coupled
• Asynchronous

5
Background
6
Background
7
Data Representation

• Requirements
• Simplicity
• Content-based addressing
• How do we structure data?
• Subject and payload
• Objects
• Set of named values

8
Subscribing

• Requirements
• Dynamic
• Scalable
• Powerful
• How?
• Channels, Templates, Registered Callbacks
• Boolean expressions

9
Internet Notification Services

• Simplicity
• Standards
• Federation and Scalability
• Security

10
Security

• Privacy and Integrity
• Anonymous Access Control
• Key Management

11
Scalability and Federation

• Retrofitting will not work
• Performance matters
• Traffic control (fan-out)

12
Scalability Requirements

• Redundant links between servers
• Boundaries
• Organizational
• Enterprise
• Defined semantics

13
Additions

• Persistence
• Reliability
• Causal Ordering
• Correlation

14
Simplicity

• Building
• Using
• Efficiency

15
More information

• http//www.dstc.edu.au/Elvin
• elvin_at_dstc.edu.au