CHAIMS January 1999 CHAIMS

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

Shift in Programming Tasks I n t e g r a t i o n C o d i n g 1970 1990 2010 January 1999 CHAIMS 2

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

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

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

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

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

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

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

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

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

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

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

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

CHAIMS January 1999 CHAIMS