1. CHAIMS
January 1999
CHAIMS

2. CHAIMS: Compiling High-level Access Interfaces for Multi-site Software
Stanford University
CHAIMS
Objective: Investigate new approaches to large-scale software composition.
Approach: Develop and validate a composition-only language, a protocol for large, distributed, heterogeneous and autonomous megamodules, and a supporting system.
January 1999
CHAIMS

3. Shift in Programming Tasks
I n t e g r a t i o n
C o d i n g
January 1999
CHAIMS 2

4. Typical Scenario - Logistics
A general has to ship troops and/or various material from L.A. to Chicago:
different kind of material, not every airport equally suited
congestion, prices, weather constraints
exact due or ready dates
different transport service providers
Today: · calling different companies, looking up information on the web, reservations by hand
· hand coded systems
Future: fast system development by tools supporting automated composition
January 1999
CHAIMS

5. What CHAIMS does: Composition of megamodules
by a composition only language (CLAM)
that also provides run-time cost estimation
and allows automatic run-time invocation scheduling.
Composition is automated
by using the protocol CPAM on top of several distribution systems
by hiding protocol details in CLAM,
and by providing a compiler for CLAM.
January 1999
CHAIMS

6. Megamodules - Definition
Megamodules are large, autonomous, distributed, heterogeneous services or processes.
from different providers: several services from different providers available for similar tasks
autonomous: maintenance of megamodule and control over resources remains with provider
heterogeneous: accessible by various distribution protocols like RMI, DCE, CORBA
distributed: to be used by more than one client
large: computation intensive, data intensive, ongoing processes
January 1999
CHAIMS

7. Examples of Megamodules
Travel information:
Computing all possible routes between two cities
Computing the air and ground cost for each route given data about the goods to be transported
RoutePlan
- AllRoutes
- ...
RouteCost
- OneRoute- Cost
- ...
Calculating optimal routes
Two megamodules from different suppliers offering similar services
BestPick
- Optimum
- ...
RouteChoose
- BestRoute
- ...
General I/O-megamodule
InputOutput
- write
- ask
- ...
January 1999
CHAIMS

8. Process - Providing Megamodules
Megamodule Providers
writes CPAM compliant megamodule d
CHAIMS
Repository
add information to
Wrapper
Templates a
wrap legacy megamodules
DCE e
RM I c b
CORBA
MEGA Modules
January 1999
CHAIMS

9. Process - Composing Megamodules
Composers
Megaprogram
write in CLAM
CHAIMS
Repository
read
CHAIMS
Compiler
generates
Client Side Run Time
compiled megaprograms
information
January 1999
CHAIMS

10. Process - Running a Megaprogram
Client Side Run Time
located
on the client
Distribution System (CORBA, RMI, …) with CPAM Protocol b
CORBA e c a
DCE d
MEGA Modules
located on
several servers
January 1999
CHAIMS

11. Process - Summary b d e a c server side client side Megamodule
writes
Composer
Client Side Run Time
Megaprogram
CHAIMS
Compiler
generates
server side
client side e d a b c
MEGA Modules
CHAIMS
Repository
adds information to
Megamodule
Provider
provides
megamodules
Wrapper
Templates
Distribution Systems (CORBA, RMI…)
January 1999
CHAIMS

12. CHAIMS - Special Features
CHAIMS supports megamodule heterogeneity:
The CHAIMS compiler ensures that clients support the various megamodule distribution systems
The CHAIMS data encoding-rules facilitates heterogeneous data transmission between megamodules
CHAIMS preserves megamodule autonomy:
The CHAIMS repository contains the information necessary to access megamodules
Run-time cost estimation allows to leave control over resources to providers
CHAIMS enables optimized composition:
Parallelism, invocation monitoring, and cost estimation allow clients to optimize the invocation sequence to megamodules
Global pre-setting of parameters and partial extraction of results allow minimized data flow between megamodules
January 1999
CHAIMS

13. Primitives in CHAIMS Pre-invocation:
SETUP: set up a connection to a megamodule
SET-, GETPARAM: preset / get parameters in a megamodule
ESTIMATE: get cost estimation for optimization
Invocation and result gathering:
INVOKE: start a specific method
EXAMINE: test status and progress of an invoked method
EXTRACT: extract results from an invoked method
Termination:
TERMINATE: terminate a method invocation
TERMINATEALL: terminate the connection to a megamodule
January 1999
CHAIMS

14. CHAIMS proves that ...
» We can do composition in a high-level language and hide technical details
» Large-scale composition can be automated
» Run-time cost estimation is essential for invocation scheduling optimization.
January 1999
CHAIMS

15. Focus for Future Applying CHAIMS to a larger real-life example.
Automated scheduling of invocations and extractions, automatic optimization of dataflows.
Automatic generation of direct dataflows between megamodules.
Flexible interaction with megamodules; extracting and handling overview results.
Enhancing CHAIMS language CLAM and complementing it by graphical front-end.
January 1999
CHAIMS

16. CHAIMS
January 1999
CHAIMS