IVM Full Stack Architecture

1. Internal Architecture of FORWARD
Server – Client Diff Propagation
Costas Zarifis
Web and Database Lab

2. Client-Server Communication
Server-Side
WebSocket
Module
Client-Side
Server Side
Client-Side
WebSocket
Module
Client Side
Web Socket
IVM Module Log

3. Client-Server Communication
• The Communication is initiated by the Client-Side WebSocket
Module
• After the Connection has been established the client will emit a
message of type:
(“Init Query”, Query)
• It will also start listening for messages of type: Query
• When that message is retrieved by the Server the client’s session
will be added to the group Query:
• Groups can be implemented as a hash map (Query ->
session_list):
– If the Query group already exists, the new client will simply be appended to
the group
– If it doesn’t, it will get created and added to the hash map
• The Query will be evaluated and the result will be emitted to the
client using a Construct Diff

4. Client-Server Communication
Connect
Client-Side
Server Side
Boot
Client Side
Connect
Init Query
Group by Query
Emit Construct Diff
Append to Log
Chronological
Order

5. Client-Server Communication
• The IVM Module at some point will generate a diff for a
given Query
• The WebSocket Module will utilize the hashmap to retrieve
the session ID’s of the clients that listen for changes on the
particular Query
• It will propagate the diff to them (Eager Propagation)
• Upon retrieval the client will simply add it to the log
• Keep separate logs for each type of diff (Insert, Update,
Delete)
• A Batching Module should be implemented to provide
support for Lazy Propagation

6. Client-Server Communication
Server Side Client Side
Propagate Diff(s) to Client
Append to Log
IVM Module
Diff
Find Query
Diff
Batching
Diff

7. Proposed Client-Server Architecture
• Use socket.io to enable communication between server and
client
• Ideally utilize RequireJS as a module loader on the client. On
the server-side we are somewhat flexible (RequireJS,
CommonJS etc)
• Use Karma for unit testing (as much as possible…)

8. Client-Server Communication
Server Side Client Side
NodeJS
Insert/Delete/Update
Socket.io
CommonJS
RequireJS
CommonJS
RequireJS
KarmaJS KarmaJS