Evaluation and Comparison of CORBA (Object Request Broker) Implementations

Diplomarbeit von Roland Gelbmann

Abstract:

Common Object Request Broker Architecture (CORBA), a standard from the Object Management Group (OMG), defines a vendor-independent architecture and infrastructure for distributed systems. Further CORBA species a client-server platform as well as an object-oriented programming model for distributed computing.The Object Request Broker (ORB) implements the part of CORBA which manages communication and data exchange between objects. CORBA-based applications often have to communicate with ORBs from different vendors. Therefore testing the interoperability is one important point in this work.

Six actually available ORB implementations are shown and compared at given features. If a problem has to be solved with CORBA, it is necessary to choose the best ORB implementation for that purpose, because they differ often at significant points. Important details for decision are Standard Conformity, Robustness, Functionality as well as Functional Range or Interoperability. Exactly these properties are to be examined in this work. The investigation is performed on six, at the web available ORBs indeed Jacorb 1.4 beta 2, Orbacus 4.1.0, Orbix E2A 2.0, OpenORB 1.2.0, J2SE ORB 1.4.0 as well as TAO 1.2.1 all in their most actual released version.

Additionally to these properties the correct implementation of the most important CORBA Services is checked. They are Event Service, Notification Service, Name Service and Transaction Service. The ORBs are compared at this given properties.It shows that the ORBs differ very much from each other and that the CORBA Services are often implemented incorrectly. Further a high costly implementation is no guarantee for best quality at all points. The evaluation shows that a freely available ORB can be as good as or better than a commercial one.

Table of Contents:

1.	Introduction
1.1	Motivation	1
1.2	Project Objectives	1
1.3	Related Work	2
1.4	Content of the following Sections	2
2.	CORBA Basics
2.1	Overview	5
2.2	Major Parts of an ORB	9
2.2.1	Core Compnents	9
2.2.2	Object Adaptors	11
2.3	CORBA Services	12
2.4	OMG Interface Definition Language	21
2.5	BOA to POA Migration	23
3.	ORB Evaluation and Comparison
3.1	Chosen ORBs	25
3.1.1	Jacorb1.4 beta2	25
3.1.2	Orbacus 4.1.0	25
3.1.3	OrbixE2A 2.0	25
3.1.4	OpenORB 1.2.0	26
3.1.5	J2SEORB 1.4.0	26
3.1.6	TAO The Ace ORB 1.2.1	26
3.2	Evaluation-Environment	26
3.3	Installation	27
3.4	Standard Conformity	30
3.4.1	Interface Definition Language	30
3.4.2	Basic Remote Invocation	32
3.4.3	Dynamic Type Manipulation	33
3.4.4	Repositories	34
3.5	Throughput- and Robustness-Tests	36
3.5.1	Test-Environment	36
3.5.2	Test-Description	38
3.5.3	Test-Results	41
3.5.4	Reactivation Mechanism for Crashed Servers	46
3.6	Functionality	46
3.7	Functional Range	48
3.8	Interoperability	51
3.9	CORBA Services	56
3.9.1	Event Service	56
3.9.2	Notification Service	57
3.9.3	Name Service	58
3.9.4	Transaction Service	59
3.10	Miscellanea	60
3.10.1	Requirenments	60
3.10.2	Development	61
3.10.3	Documentation	62
3.10.4	Vendor	64
4.	Conclusion
4.1	Essential ORB Decision-Contributing Features	66
4.2	Summary	67
A.	Appendix
A.1	Class-Diagrams for the generated Java Classes	69
A.2	Stock Example IDL-Listing