Research Issues in
CORBA
What keeps CORBA people
awake at Night!
Peter de Jong
H
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Contents
 CORBA Introduction
 Issues
 1. Language Heterogeneity
 2. Components
 3. Transports
 4. Application Coordination
 5. Reuse of Services
 6. Interoperability
 7. Interworking
 8. Tracking Computation
 9. Tracking Resources
 10. Scale
H
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Software Bus
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Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
CORBA 2.0 Architecture
Object Services
Naming
Trading
Transactions
Security
Interface
Repository
Object
Adapter
Client
DII
H
Stub
Server
O
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B
RPC
IIOP-RPC
DCE-RPC
IDL
Compiler
O
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Skeleton
DSI
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
OMG IDL
 C++ like
 Mappings to multiple
languages
C
 C++
 Java
 Ada
 SmallTalk
 Cobol
 ILU (Xerox Parc)
 Common Lisp
 Python
H
 Basic types
 long, unsigned long
 short, unsigned short
 long long, unsigned long
long
 fixed
 float, double, long double
 char, wchar
 boolean
 octet
 any
 Constructed types
 union, enum, structure
 sequence, string, array,
Research Issues in CORBA
Peter de Jong Hewlett-Packard
wstring
Usenix 8/12/97
IDL Operations and Inheritance




Operation Attribute
Return value
Operation
Parameter
direction
 User exception
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Research Issues in CORBA
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Peter de Jong Hewlett-Packard
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Usenix 8/12/97
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Usenix 8/12/97
Object References
Client
Server
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Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 1 - Language Heterogeneity
 IDL to Java Mapping
 Multiple Inheritance
 Class slot - corba
object class
 Rest are interfaces
 Out parameters
 Holder classes
 Any
 Helper classes
 Exceptions
 java exceptions
 Object Reference
 Java class reference
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Research Issues in CORBA
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Peter de Jong Hewlett-Packard
Usenix 8/12/97
Binary Compatibility in Java Mapping
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Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Other Language Issues
 Pseudo Code (Almost IDL)
 Local Objects (ORB API's)
 Native Language Constructs
 Local By-Pass (inproc)
 Direct to IDL
 Java to IDL rather than IDL to Java
 Objects by Value
 Object state (Not described in IDL)
 Migrating implementations
 Scripting Languages
 Language specification rather than IDL specification
H
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 2 - Components
 Component CORBA
 Absorb Java Soft RMI into CORBA




Java to IDL mapping (OMG RFP)
Objects-by-Value (OMG Submissions being merged)
Distributed Garbage Collection
Migration of object implementation (Information in java serialization, not in IIOP)
 Component RFP





Component identity
Properties
Interfaces for component-events
Introspection
Mapping to Java Beans
 Related Object Services
 IIOP Firewall (OMG RFP)
 Scripting Language (OMG RFP)
 Java Script
 Object locality constrains (getting rid of PIDL)
 Multiple interfaces
H
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 3 - Transports
 Type
 RPC
 Async Message
 Streams
 Multi-cast
 Quality
 Load Balance
 Highly Available
 Transactional
 Secure
 Real-time
 Embedded
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A
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
The Next IIOP?
 IIOP 2.0? (Proposals by Bill Janssen, Xerox Parc)
 Minimize information transfer via Caching
 Efficient type negotiation
 Port Mapper
 Transfer Syntax changes (alignment, any)
 MUX (http://www.w3.org.pub/Protocols/MUX)
 Multiple protocols multiplexed over the same connection
IIOP, HTTP run over the socket built over protocol
 128 sessions per TCP/IP connection
 MUX handles fragmentation for all protocols
 HTTP-NG (http://www.w3.org.pub//Protocols/HTTP-NG)
 Possible future replacement for IIOP
H
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 4 - Application Coordination
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Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 5 - Reuse of Services
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Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 6 - Interoperability/Portability
 Interoperability (CORBA
2.0)
 IIOP (Compliance point)
 Transactions
 Security
General Architecture
Kerberos (compliance point )
SSL
 Portability
 Pseudo Objects
Portable Object Adaptor
 Language Mappings
 Research Problems
 Implementations more
detailed then specs
Revision Task Forces
Compliance tests
written by XOPEN
Proposals for Semantic
specifications
 Balance between
implementation freedom
and conformance
Special purpose ORBs
 Profiles and Conformance
 Embedded ORBs
H
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 7 - Interworking
C
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/
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H
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 8 - Tracking Computation
 Distributed debugging
 Distributed profiling
 Distributed Administration
 Bootstrap
 Install and Configure
 Object Locator, Persistent
servers
 CORBA object services
servers - Naming, Event,
Trading, Security,
Transactions
 Discover distributed
executing objects
 Monitor execution
 Start, Stop, Modify object
operation
H
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B
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 9 - Tracking Resources
 Distributed Garbage Collection
 Distributed Scheduling
 Real-Time constraints
 Parallel searching
 Agents
 Copy and transmission constraints
 Killing
 Error handling
 At most once semantics
 Network partitioning
 Computation continuing in one partition
 Error recovery in the other
 Versioning
H
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97
Issue 10 - Scale
 Integration of all Services
 Security, Transactions, Fault tolerant, Real-Time, Persistent
storage, Messaging, ...
 One Object distributed system which does everything well
 Massively Distributed Systems
 Integrate with the organizational Applications
 Track organizational change
 Goal of Object Bus - Integration vs execution
 Integration
Legacy applications, multiple - object models, standards, OS,
languages
 Execution
High performance, secure distributed computation
H
Research Issues in CORBA
Peter de Jong Hewlett-Packard
Usenix 8/12/97