Common Component Architecture (CCA) Balaprasuna Chennupati Amit Karnik 20-MAR-2002

Outline Motivation and History Relationship to Existing Standards Design Goals Architectural Overview SIDL CCA Ports CCA Services Implementations Example

Motivation High performance computing (HPC) exhibits the following Simulations are increasingly complex Acute need for code reuse and flexibility Combines multi-disciplinary expertise Rapid application development and change Dynamic attachment capabilities Requires distributed execution Fast connections and parallel interactions

History of CCA Developed by the CCA forum (NOV 98) constituted of National energy laboratories like Argonne, Lawrence Berkley, Lawrence Livermore, Los Almos, Oak Ridge, Sandia and Research laboratories from Indiana Univ. and Univ. of Utah Released Version 0.5 in Dec 1999

Relationship to Other Standards Microsoft COM and ActiveX Provides component interoperability on Windows platform with language-independence Lacks abstractions for parallel and scientific computing data types ex. Complex numbers, Dynamic multiD arrays Scientific Computing on Windows is not very popular

Relationship to Other Standards Sun JavaBeans and EJB Cross-platform component architecture based on the Java programming language Although JNI supports language interoperability - leads to intolerable performance penalty (JVM) Composition only by events/listeners CCA shares a similar event subscribe model for event-notification and provides more…

Relationship to Other Standards CORBA 2.0 Cross-language, cross-platform distributed object model Lacks an explicit component model No abstractions for scientific data types Overhead of communication through the ORB – leads to performance penalty No concept of attaching two parallel components together

Design Goals for CCA Should provide language and platform independence (esp. C, C++, Fortran) Support for tightly coupled direct & loosely coupled distributed component communication Allow dynamic component plug ability Represent the abstractions and data types such as complex nos. and dynamic multiD arrays

Architectural Overview [ARM99]

Architectural Overview Scientific IDL (SIDL) – used to define inputs/outputs for components Repository API – used to deposit and retrieve SIDL definitions CCA Ports – enable component interactions CCA Services – services provided by the framework Configuration API – supports interaction between components and builders

SIDL Scientific Interface Definition Language High level description language Provides for scientific data types Provides seamless language interoperability by hiding language dependency Currently mappings to C, C++, Fortran 77/90, Python, Java

SIDL Leverages existing IDL technologies and language mappings (CORBA, Java) Fortran mapping similar to CORBA’s C mapping except, SIDL classes and interfaces map into Fortran integers SIDL-to-language bindings use static IDL stubs and skeletons

SIDL - Example interface Component { package gov.cca void setServices(in Services svc);}; interface ComponentID{ string toString();}; }; // end package gov.cca package gov.cca { interface Port {}; interface PortInfo{ string getType(); string getName(); string getProperty(in string name);}; interface Services { Port getPort(in string name); Port getPortNonblocking(in string name); void registerUsesPort(in PortInfo name_and_type); void unregisterUsesPort(in string name); void addProvidesPort(in Port inPort, in PortInfo name); void removeProvidesPort(in string name); ComponentID getComponentID();};

Ports Based on interactions limited to pipelining I/O Define interactions between tightly coupled parallel components as well as loosely coupled remote components Fast communication and scalable performance Interaction using the very same interface in either of the connection types Support for attaching two parallel components together

Ports JavaBeans components register themselves as listeners and are notified using events CCA uses Provides/Uses design pattern CORBA 3.0 model proposes both Events and Provides/Uses interface exchange mechanism

Ports Provides/Uses interface design pattern Two types of ports Direct component interface connection for HPC Distributed connections through a proxy Two types of ports Provides port : interface that a component provides to other components Uses port : interface that has methods which the component wants to call on other components

Ports Provides ports listen to calls on their functions called by other components through their Uses ports Uses ports maintain a list of listeners Component interaction is achieved by registering the Provides port as a listener of a Uses port of another component A call on a method in the Uses port of one component results in calls to the corresponding member function on each listener resulting in zero or more invocations

Ports [ARM99]

Direct-Connect Ports Used to achieve HPC in CCA Call translates to a single function call Only overhead is incurred due to the SIDL bindings (2-3 function calls) Achieved by directly passing the Provides port supplied by one component as a Uses port for another component

Collective Ports Allows interactions between two parallel components or a serial and a parallel one Provides/Uses port interfaces are available to all threads and processes of the component CCA standard does not restrict the means of sharing (shared or distributed memory models)

Services Presents framework abstraction and defines minimal set of services for CCA compliance Provides Creation of CCA ports Access to CCA ports Additional facilities to handle naming, relationship management, error handling, querying

CCA with CORBA 3.0 CORBA 3.0 introduces the concept of the provides/uses design pattern making CCA components CORBA 3.0-compliant Thus, CCA is a potential piece to sit over CORBA 3.0 However there is no CORBA 3.0 implementation from any vendor currently

CCA Implementations CCAFFEINE from Sandia National Labs CCA Fast Framework Example In Need of Everything Assumes message passing environment Implemented in C++ and allows graphical component composition CCAT from Indian Univ. Service based architecture using Java RMI and Globus NEXUS

CCA Implementations XCAT from Indiana Univ Grid enabled framework of CCA based on Globus Uses RMI and XSOAP

Example ConsumerPort package gov.cca.eg.port; public interface StringConsumerPort extends gov.cca.Port { public void setString(String s) throws Exception; }

Example TimeProducerPort package gov.cca.eg.port; public interface TimeProducerPort extends gov.cca.Port { public String getTime(); }

Example TimeStamper package gov.cca.eg.component; public class TimeStamper implements gov.cca.Component, gov.cca.eg.port.StringConsumerPort { gov.cca.Services svc; gov.cca.eg.port.StringConsumerPort out; gov.cca.PortInfo outInfo; gov.cca.eg.port.TimeProducerPort time; gov.cca.PortInfo timeInfo; public TimeStamper(){ }

Example public void setServices(gov.cca.Services svc) { gov.cca.eg.port.StringConsumerPort stringer =(gov.cca.eg.port.StringConsumerPort) this; svc.addProvidesPort(stringer, svc.createPortInfo("in0", "StringConsumerPort", null)); svc.registerUsesPort(outInfo = svc.createPortInfo("out0", "StringConsumerPort", null)); svc.registerUsesPort(timeInfo = svc.createPortInfo("time0", "TimeProducerPort", null)); }

Example public void setString(String s) { out = (gov.cca.eg.port.StringConsumerPort)svc.getPort("out0"); time = (gov.cca.eg.port.TimeProducerPort)svc.getPort("time0"); out.setString(s+"@"+time.getTime()); svc.releasePort("out0"); svc.releasePort("time0"); }

References [ARM99] Toward a Common Component Architecture for High Performance Scientific Computing. Armstrong et al [ALL00] The CCA Core Specification In A Distributed Memory SPMD Framework. Allan et al www.cca-forum.org www.cs.ucsd.edu/classes/sp00/cse225/notes/jeff/talk.html http://www.extreme.indiana.edu/ccat/ http://www.cca-forum.org/ccafe/ccafe.html http://www.acl.lanl.gov/cca-forum/

Take-Away points Standard for interoperability among HPC components Fast connections and parallel collective interactions using Ports Scientific abstractions for specifying component interfaces using SIDL CORBA 3.0 compliant