The EQUIP Platform

1
The EQUIP Platform

• Chris GreenhalghUniversity of Nottingham

2
Contents

• Goals
• Runtime support
• Core services
• Dataspaces
• Structure
• Distribution and replication

3
Goals

• Cross-language
• Java prototyping, GUIs, smaller devices
• C performance (3D), integration
• CORBA IDL cross-language class defn
• Broadly applicable
• Extensible
• Clear semantics

4
Runtime support

• Java-like facilities for C
• Dynamic class (module) loading
• Serialisation (cross-language)
• Object value-equality
• (limited) introspection
• Socket API
• Matches operation

5
Core Services

• Trader
• c.f. RMI registry
• Dataspace server
• General purpose data (object and event) sharing
• Appliction-specific services

6
Dataspace Structure(single process)
Events
Dataspace
API
Callbacks(Events)
Pattern(s)
ItemEvents
Other Events
PseudoEvents
SimpleQueries
Data Items
7
Event Types

• State-related events
• Add Item
• Update (replace) Item
• Delete Item
• Pseudo-events
• Add Item Present (item already present)
• Delete Item Present (item still present)
• Other events user-extensible hierarchy

8
Dataspace Distributionevents only, pattern
replication
1. Client pattern
X
X
3. Creates remote pattern
Serverpattern

X
2. Item represents pattern X
Client
Server
9
Dataspace Distributionevents only, event
distribution
Event X1
X1
X1
X
X

X
Client
Server
10
Dataspace Distributiondata item replication
Dataspace Distributiondata item replication
4a.AddItemY1
Add Y
Add Y
3. Add Item Y1 pseudo-event

2. Add Item Y1 pseudo-event
Y1
Y1
1. Item Y1 exists
4. Replica of Y1
Client
Server
11
Future Issues

• Management, configuration, service discovery
• Space, uncertainty, content, sessions and links
• Persistence (including activity persistence)
• (More) disconnected and wireless access
• Scaling up
• Extensibility and evolution