\contentsline {chapter}{List of Tables}{vii}
\contentsline {chapter}{List of Figures}{viii}
\contentsline {chapter}{Abstract}{x}
\contentsline {chapter}{Acknowledgments}{xii}
\contentsline {chapter}{\numberline {1}Introduction}{1}
\contentsline {section}{\numberline {1.1}Objectives}{2}
\contentsline {section}{\numberline {1.2}Research Questions}{3}
\contentsline {section}{\numberline {1.3}Significance}{3}
\contentsline {section}{\numberline {1.4}Thesis Structure}{5}
\contentsline {chapter}{\numberline {2}Background}{6}
\contentsline {section}{\numberline {2.1}Introduction}{6}
\contentsline {section}{\numberline {2.2}Distributed Objects and OO}{7}
\contentsline {subsection}{\numberline {2.2.1}Introduction to Distributed Objects}{7}
\contentsline {subsection}{\numberline {2.2.2}Why the marriage between Distributed Computing and Object-Orientation?}{9}
\contentsline {subsection}{\numberline {2.2.3}Who is currently investing in Distributed Objects?}{11}
\contentsline {subsubsection}{Microsoft's Vision of Distributed Objects}{11}
\contentsline {subsubsection}{Object Management Group's Vision of Distributed Objects}{12}
\contentsline {section}{\numberline {2.3}Distributed Object Architectures}{13}
\contentsline {subsection}{\numberline {2.3.1}Distributed Object Architectures}{13}
\contentsline {subsubsection}{Distributed Computing Environment (DCE) compared to Distributed Object Architectures}{15}
\contentsline {subsubsection}{Is the DCE framework still popular today?}{16}
\contentsline {subsection}{\numberline {2.3.2}Common Object Request Broker Architecture}{17}
\contentsline {subsubsection}{The Story behind CORBA}{17}
\contentsline {subsubsection}{CORBA's Benefits}{17}
\contentsline {section}{\numberline {2.4}CORBA's Framework and Components}{18}
\contentsline {subsection}{\numberline {2.4.1}CORBA's Framework}{18}
\contentsline {subsection}{\numberline {2.4.2}Component overview of CORBA}{19}
\contentsline {subsection}{\numberline {2.4.3}CORBA's components in Detail}{20}
\contentsline {subsubsection}{Object Request Broker}{20}
\contentsline {subsubsection}{Interface Definition Language}{21}
\contentsline {subsubsection}{Dynamic Invocation Interface}{22}
\contentsline {subsubsection}{Interface Repository}{22}
\contentsline {subsubsection}{Object Adaptors}{23}
\contentsline {subsection}{\numberline {2.4.4}Object Request Broker in Detail}{24}
\contentsline {subsubsection}{What is an Object Request Broker?}{24}
\contentsline {section}{\numberline {2.5}Amoeba Framework}{25}
\contentsline {subsection}{\numberline {2.5.1}Amoeba Design}{26}
\contentsline {subsection}{\numberline {2.5.2}Amoeba Implementation}{26}
\contentsline {section}{\numberline {2.6}ORCA Programming Language}{26}
\contentsline {section}{\numberline {2.7}Inter-Language Unification}{28}
\contentsline {subsection}{\numberline {2.7.1}ILU Implementation}{29}
\contentsline {chapter}{\numberline {3}Object Request Broker Performance}{30}
\contentsline {section}{\numberline {3.1}Performance Impact of CORBA}{30}
\contentsline {subsection}{\numberline {3.1.1}Performance Characteristics of CORBA Components}{31}
\contentsline {subsubsection}{Data Marshalling and Copying}{31}
\contentsline {subsubsection}{How does CORBA perform overall?}{33}
\contentsline {subsection}{\numberline {3.1.2}General/Inter-ORB Protocol (GIOP)}{34}
\contentsline {subsubsection}{What is a General/Inter-ORB Protocol?}{34}
\contentsline {subsubsection}{What is CDR?}{34}
\contentsline {subsubsection}{What performance does CDR provide?}{35}
\contentsline {section}{\numberline {3.2}The Current Situation}{35}
\contentsline {section}{\numberline {3.3}Performance optimisation techniques}{37}
\contentsline {subsection}{\numberline {3.3.1}Data Marshalling through Octets}{37}
\contentsline {subsection}{\numberline {3.3.2}Location of Target Server}{38}
\contentsline {subsubsection}{Server/Client in same Address Space}{38}
\contentsline {subsubsection}{Server on same Machine but unrelated processes}{39}
\contentsline {subsubsection}{Server on a Different Architecture}{39}
\contentsline {subsection}{\numberline {3.3.3}By-Passing CORBA}{40}
\contentsline {subsection}{\numberline {3.3.4}Data Packaging}{41}
\contentsline {chapter}{\numberline {4}The Packers}{42}
\contentsline {section}{\numberline {4.1}System Overview}{42}
\contentsline {section}{\numberline {4.2}Different Packing Techniques}{45}
\contentsline {subsection}{\numberline {4.2.1}Separate Component Packing}{45}
\contentsline {subsubsection}{Packing Method 1}{45}
\contentsline {subsubsection}{Packing Method 2}{45}
\contentsline {subsubsection}{Performance OverHead}{47}
\contentsline {subsubsection}{Performance of packing method 1 without including the sizes}{47}
\contentsline {subsubsection}{Performance of packing method 2}{47}
\contentsline {subsubsection}{Conclusions that can be drawn from separate component packaging}{47}
\contentsline {subsection}{\numberline {4.2.2}Schema Transmission}{47}
\contentsline {subsubsection}{Performance Overheads when transmitting the Schema}{48}
\contentsline {subsubsection}{Performance Overhead on the first transmission}{48}
\contentsline {subsubsection}{Performance Overhead on the second transmission}{48}
\contentsline {subsubsection}{Interesting Issues Raised by transmitting the Schema}{49}
\contentsline {subsection}{\numberline {4.2.3}RPC Transmission}{49}
\contentsline {subsubsection}{Problems with RPC Transmission}{49}
\contentsline {subsection}{\numberline {4.2.4}Character transmission of class}{50}
\contentsline {subsubsection}{Problems with Character Transmission}{51}
\contentsline {subsection}{\numberline {4.2.5}Sharing a common schema}{51}
\contentsline {subsubsection}{Sharing through Shared Memory}{52}
\contentsline {subsubsection}{Sharing through a NFS Mount}{53}
\contentsline {subsubsection}{Sharing through a socket structure}{54}
\contentsline {subsubsection}{Sharing through CORBA}{55}
\contentsline {section}{\numberline {4.3}The Packers Packing Types}{55}
\contentsline {subsection}{\numberline {4.3.1}Standard CORBA Marshalling}{55}
\contentsline {subsection}{\numberline {4.3.2}Octet Marshalling}{57}
\contentsline {subsection}{\numberline {4.3.3}Low Level TCP/IP Communication Marshalling}{58}
\contentsline {chapter}{\numberline {5}Experimental Investigation}{62}
\contentsline {section}{\numberline {5.1}Standard CORBA implementation}{62}
\contentsline {subsection}{\numberline {5.1.1}Overview}{62}
\contentsline {subsection}{\numberline {5.1.2}Hypothesis}{62}
\contentsline {subsection}{\numberline {5.1.3}Expected Results}{63}
\contentsline {subsection}{\numberline {5.1.4}Actual Results}{63}
\contentsline {subsection}{\numberline {5.1.5}Results Discussion}{63}
\contentsline {section}{\numberline {5.2}Octet Data marshalling/packaging mechanism}{67}
\contentsline {subsection}{\numberline {5.2.1}Overview}{67}
\contentsline {subsection}{\numberline {5.2.2}Hypothesis}{68}
\contentsline {subsection}{\numberline {5.2.3}Expected Results}{68}
\contentsline {subsection}{\numberline {5.2.4}Actual Results}{68}
\contentsline {subsection}{\numberline {5.2.5}Results Discussion}{69}
\contentsline {section}{\numberline {5.3}Low Level communication mechanism (TCP/IP Socket)}{70}
\contentsline {subsection}{\numberline {5.3.1}Overview}{70}
\contentsline {subsection}{\numberline {5.3.2}Hypothesis}{70}
\contentsline {subsection}{\numberline {5.3.3}Expected Results}{70}
\contentsline {subsection}{\numberline {5.3.4}Actual Results}{70}
\contentsline {subsection}{\numberline {5.3.5}Results Discussion}{71}
\contentsline {chapter}{\numberline {6}Implementation}{72}
\contentsline {section}{\numberline {6.1}Experimental Environment}{72}
\contentsline {subsection}{\numberline {6.1.1}Hardware/Platform}{72}
\contentsline {subsection}{\numberline {6.1.2}Software}{72}
\contentsline {section}{\numberline {6.2}Experimental Design}{73}
\contentsline {subsection}{\numberline {6.2.1}Test Data}{73}
\contentsline {subsection}{\numberline {6.2.2}Design and Implementation of Experiments}{74}
\contentsline {subsubsection}{Interface Definition Language Specification}{74}
\contentsline {subsubsection}{Class Proxies/Stubs}{74}
\contentsline {subsubsection}{Marshalling Techniques}{75}
\contentsline {subsubsection}{Server Implementation Code}{75}
\contentsline {subsection}{\numberline {6.2.3}Validation of Experiments}{84}
\contentsline {section}{\numberline {6.3}Experimental Limitation}{85}
\contentsline {chapter}{\numberline {7}Conclusion}{87}
\contentsline {section}{\numberline {7.1}Solutions to Research Questions}{89}
\contentsline {section}{\numberline {7.2}Future Work}{90}
\contentsline {subsection}{\numberline {7.2.1}Object Request Broker Comparison}{90}
\contentsline {subsection}{\numberline {7.2.2}Functionality in the Octet Marshalling Stream}{90}
\contentsline {subsection}{\numberline {7.2.3}Deep Marshalling}{91}
\contentsline {chapter}{Appendix\ A\ Interface Definition for the Packers}{92}
\contentsline {chapter}{Appendix\ B\ Implementation Header for the Packers}{94}
\contentsline {chapter}{Appendix\ C\ Implementation Code for the Packers}{100}
\contentsline {chapter}{Appendix\ D\ Implementation Header for the Buffer}{121}
\contentsline {chapter}{Appendix\ E\ Implementation Code for the Buffer}{127}
\contentsline {chapter}{Appendix\ F\ Implementation Code for Standard Marshalling}{157}
\contentsline {chapter}{Appendix\ G\ Implementation Code for Structure Marshalling}{162}
\contentsline {chapter}{Appendix\ H\ Implementation Code for Socket Marshalling (server)}{166}
\contentsline {chapter}{Appendix\ I\ Implementation Code for Socket Marshalling (client)}{169}
\contentsline {chapter}{Appendix\ J\ Implementation Code for Octet Marshalling}{173}