GLASS provides a share-everything architecture for scaling Seaside applications. It uses GemStone/S, which allows for a shared-everything approach within a single image and shared-nothing across multiple VMs. This allows Seaside applications built for Squeak to run on GLASS without modification, providing transparent persistence and scalability through approaches like persistent session state or one session per VM. GLASS provides tools for transparent development across multiple images.

1. Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
e
GLASS: A Share Everything
Architecture for Seaside
Dale Henrichs
8/28/2008

2. 2 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
What is GLASS?
GemStone, Linux, Apache, Seaside,
Smalltalk
 Persistence and scalability for Seaside
applications
 FREE for commercial use
• http://seaside.gemstone.com/downloads.html

3. 3 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
What is GLASS?
GLASS
 self-contained development environment
for GemStone/S
• Monticello for source code control
• OminiBrowser-based development tools
 Easy to move apps from Squeak to GLASS
 FREE for commercial use

4. 4 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
What is GLASS?
Appliance
 VMWare running an instance of GLASS
• 3 Seaside VMs
• 1 Maintenance VM
• 1 (or more) development Vms connected to
Squeak
 FREE for commercial use

5. 5 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Share Nothing Architecture
Scaling Story
 Every time you need data, you hit the data
base
 Distributed computing and distributed data
• add additional resources to meet demand
 Well suited to stateless web servers and
uncomplicated data models

6. 6 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Share Nothing Architecture
Drawbacks
 Scaling limited by available electricity
 distributed data constrains model
complexity

7. 7 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Share Nothing Architecture
Smalltalk is not Share Nothing

8. 8 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Share Everything
Smalltalk is
 Share Everything inside the image
 Share Nothing outside the image

9. 9 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
GemStone/S
GemStone/S is designed for
 very large images
 shared between multiple VMs
 running on multiple computers
GemStone/S is the perfect vehicle for
doing Share Everything with Share
Nothing scalability

10. 10 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Seaside Scalability Options
Persistent Session State
Optional _s and _k
One Session per VM

11. 11 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Scalability – Persistent Session State
Scaling Story
 store/share Seaside session state in
repository
 deploy any number of VMs
 round robin requests without session
affinity

12. 12 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Scalability – Persistent Session State
Drawbacks
 request rate limited by commit rate
• depending upon hardware limit kicks in at about
10-100 commits/second
 scaling requires investment in more
sophisticated hardware
• NOT commodity hardware

13. 13 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Scalability – Optional _k _s
Scaling Story
 Avoid saving 'unnecessary' session state
• reduce commit rate
 Performance Potential
• 7K requests/second
• 128 VMs
• 72 CPUs
• 7 machines

14. 14 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Scalability – Optional _k _s
Drawbacks
 application must be changed (RESTful)

15. 15 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Scalability – One Session per VM
Scaling Story
 session state in temporary memory
 VM dedicated to session for its lifetime
 performance similar to Optional _k _s

16. 16 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Scalability – One Session per VM
Drawbacks
 need more characterization work
 swap/real memory limitiations
• need to characterize tradeoffs

17. 17 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
GLASS
A Seaside application written to run in
Squeak can be ported to GLASS
'without modification'
 Transparent Persistence
 Transparent Scalability
• persistent session state
• one session per vm

18. 18 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Transparent Development
Multi-image development support
 auto commit
 object log
 debugging
• breakpoints
 profiling

19. 19 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Demo

20. 20 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Futures
GemStone 3.0
 non-Tranlogged objects
 Native code generation
 Improved Exception Handling
 Foreign Function Interface
...and Beyond?
 sharding for GemStone/S

21. 21 Copyright © 2008, GemStone Systems Inc. All Rights Reserved.
Questions?
http://seaside.st
http://seaside.gemstone.com
http://gemstonesoup.wordpress.com