Middleware fourth unit
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This document discusses middleware and remote procedure calls (RPC). It explains that middleware makes client-server programming easier, faster, less error-prone, and more reliable by automating tasks like network communication and connection management. RPC is a popular middleware paradigm that uses standard procedure calls to divide a program between client and server sides, generating communication stubs to enable remote calls. Object-oriented middleware similarly allows for remote invocation of object methods across systems.
Middleware fourth unit
- 1. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 1 Part 4 Other Topics RPC & Middleware
- 2. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 2 Middleware Tools to help programmers Makes client-server programming Easier Faster Makes resulting software Less error-prone More reliable
- 3. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 3 Middleware Approach Allow programmer to work with familiar language constructs Provide tools to help programmer Special translators Libraries Automatically generate code for Network communication Connection management
- 4. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 4 Remote Procedure Call Uses standard procedure call paradigm Divides program along procedure call boundaries Main program and procedures for user interaction in client side Other procedures in server side
- 5. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 5 Reason for Remote Procedure Call If a programmer follows the same procedure call paradigm used to build conventional programs when building client and server software, the programmer will find the task easier and will make fewer mistakes
- 6. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 6 Illustration of Conventional Procedure Call Graph Arrow denotes procedure call
- 7. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 7 Procedure Call Graph Divided Into Client and Server Division occurs on call boundary Main program in client piece
- 8. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 8 Communication Stubs Inserted to enable remote “call” Automatically generated Use original call interface Allow calling and called procedure to remain unchanged
- 9. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 9 Illustration of Client and Server Stubs Original call in (a) Same interface with stubs in (b)
- 10. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 10 Creating Stubs Programmer writes Code for a program Specification of procedure interfaces using Interface Definition Language (IDL) Middleware generates Client and server stub code Necessary socket calls Data translation
- 11. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 11 Data Representation Network can connect heterogeneous computers Two computers may use different Integer representations Character codes Floating point representations Translation required
- 12. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 12 Possible Data Translation Schemes Use receiver’s representation Sender translates all outgoing data Use sender’s representation Receiver translates all incoming data Use external representation (popular) Sender translates to external form before sending Receiver translates from external form after reception
- 13. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 13 Middleware Technologies That Use Remote Procedure Call ONC RPC Open Network Computing IETF standard Popular in Unix world DCE RPC Distributed Computing Environment Open Group Standard
- 14. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 14 Middleware Technologies That Use Remote Procedure Call (continued) MSRPC Microsoft Variant of DCE RPC
- 15. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 15 Object-Oriented Middleware Designed for use with object-oriented programming languages Same general scheme as RPC Interface Definition Language Tool to build stubs Libraries to handle network communication Uses method invocation instead of procedure call
- 16. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 16 Middleware Technologies That Use Remote Object Invocation CORBA Common Object Request Broker Architecture Well known object-oriented middleware MSRPC2 Microsoft Also called Object RPC (ORPC)
- 17. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 17 Middleware Technologies That Use Remote Object Invocation COM / DCOM Also from Microsoft Component Object Model (COM) Used on single computer Provides mechanism for inter-object references Distributed Component Object Model Used across multiple computers Includes communication stubs
- 18. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 18 Middleware Technologies That Use Remote Object Invocation RMI From Sun Microsystems Methods of remote Java objects can be invoked from other Java virtual machines on different hosts Jini Also from Sun; based on Java Provides an environment for creating dynamically networked components, applications, and services that scale
- 19. FALL 2005 CSI 4118 – UNIVERSITY OF OTTAWA 19 Summary (continued) Middleware Tools to help build client and server Automates routine tasks Two popular paradigms Remote procedure call Object invocation Generates communication stubs
Editor's Notes
- #2: Westmont College CS 140 Chapters 32-35