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CS428/9: Software Engineering II

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  1. CS428/9: Software Engineering II Darko Marinov (slides from Ralph Johnson)

  2. Topics after Spring Break • Covered • Component-based software engineering • Client-server software engineering • Web software engineering • Reengineering and maintenance • Reverse engineering • Today • CASE and model-driven software engineering 428-22

  3. CASE Computer Aided Software Engineering • Computer tools for helping a software engineer • Modeling tools, with code generators, simulators, test generators, etc. 428-22

  4. Tools for software engineering • Compilers • Editors • Debuggers • Configuration management • Test suite management • Middleware (CORBA, EJB, MTS) 428-22

  5. Integrated CASE environment • Provide a mechanism for sharing SE information among all tools in the environment • Enable a change to one item of information to be tracked by related information items • Provide version control and configuration management for all SE information 428-22

  6. Integrated CASE environmnet • Allow non-sequential access to any tool • Support the software process • Provide a consistent look and feel • Support communication among software engineers • Collect both management and technical metrics 428-22

  7. CASE in industry • Tools advertised as “CASE” usually focus on analysis and design • CASE tools usually support pictures, but also generate code • Rational Rose • Together (http://www.borland.com/together/index.html) 428-22

  8. Together • Modeling • UML • Patterns • Development • Java/C++/other • “Round trip engineering” (a bit of holy grail) • GUI builder 428-22

  9. Together projects • System is made of one or more projects • Many people can work on one project • Project contains a directory for code and diagrams • Can convert code into package diagram and class diagram for the project • Can convert diagrams into code 428-22

  10. Modeling • Supports all UML diagrams • Most support for class diagram, structure diagram • Library of patterns • Applying a pattern can add class, association, or method 428-22

  11. Code generation • Class diagrams can generate code • Class template describes what is included with each class. • Special templates, e.g. for EJB • Method in diagram includes code for method 428-22

  12. Round trip engineering • Programmers can edit program • “Together” will update diagrams • Solves problem of out of date diagrams 428-22

  13. Together as an example of CASE • Variety of tools • Common project “database” • Changes propagated from code to diagrams • Version control • Multiuser • Some metrics 428-22

  14. Together as an example of CASE • Focus on pictures • UML - general purpose modeling language • Code generation • Patterns - the latest thing • Round-trip engineering, demanded by customers 428-22

  15. Failure of CASE • 1980: CASE will revolutionize software! • Problems • No feedback • Diagrams get out of date • Slow progress without improving quality • “Fool with a tool is still a fool” • 2005-10: CASE used modestly 428-22

  16. Success of CASE • Many kinds of code generators • Compilers • Finite state machines • User interfaces 428-22

  17. Rules for code generation • Never edit generated code • Specify procedures to call • Specify code to include • Generate superclasses, write code in subclasses • Don’t look at generated code • Usually very ugly 428-22

  18. Potential future of CASE • Model-driven architecture (MDA)http://www.omg.org/mdahttp://www.omg.org/docs/omg/03-06-01.pdf • Claim: models will be more reusable than code • A vision, not yet a technology or a process • Describe system with UML + extra info • Generate all code from model 428-22

  19. Example of MDA • Wells Fargo • Big systems, lots of legacy code, many technologies • A UML model of all the business objects • Can generate IDL for CORBA, SOAP, COM from the UML model 428-22

  20. Division of labor • Business Object Services group maintains the model and helps other people understand it • Projects usually have people from client group, BOS group, and backend data group • Model used to generate interfaces for client group 428-22

  21. Reality of MDA • Model defines data and interfaces • Model controls middleware • Model does not describe all the behavior • Use conventional programming languages • UML not good at precise behavioral specification • Many attempts to extend UML so it will be better at specifying behavior 428-22

  22. Promise of MDA • Platform Independent Model (PIM) is transformed to Platform Specific Model (PSM) • A normal UML model is “marked” with extra information to guide code generation • Behavior is described with an “action language” 428-22

  23. Problems of MDA • UML is a modeling language to help you think and talk to other people • UML is not a programming language • How can you make UML be precise while still letting it be easy to use? 428-22

  24. More OMG standards • Finance • Health care • Telecom • E-commerce • Transportation • Space • … 428-22

  25. More details of MDA • Record analysis and design models • Generate as much code as possible from them • Reduces cost of generating code • Change to model quickly can be reflected in code • Models become more accurate • Reuse models for different platforms 428-22

  26. MDA • Based on UML • Focuses more on middleware than on business logic • Aimed at three-tier business systems. 428-22

  27. MDA • Use UML to define a Platform Indendent Model (PIM) • Add “marking” and “annotation” to PIM • Marking is platform independent • Annotation is platform specific • Generate a Platform Specific Model (PSM) and all the IDL for various middleware 428-22

  28. PIM to PSM mapping process PIM Marked PIM Mapping Platform PSM Annotations 428-22

  29. What is a platform? • Operating system • Programming language • Database system • Web server • CORBA/DCOM/SOAP/RMS • Any software package 428-22

  30. Persistence • Are objects stored in a RDBMS or in a flat file? XML? • How do we fetch an object? Does it have an ID? • When do we store it? • UML does not have enough information 428-22

  31. Extending UML • Stereotype – a label on a class, attribute, operation, or other model element • Profile – a set of related stereotypes 428-22

  32. Persistence Profile • <entity> - class that is persistent • <key> - attribute • <get><set> - attribute • <add><remove> - attribute • <generated> 428-22

  33. Vehicle class diagram Garage Vehicle garage capacity: Integer dateAcquired: Date make: String model: String year: Integer price: Float computeAmortizedValue() vehicles 428-22

  34. Stereotypes <entity>Vehicle <entity>Garage garage <key,generated> oid:String <get,set>dateAcquired: Date <get,set>make: String <get,set>model: String <get,set>year: Integer <get,set>price: Float <get,set>/garage:Garage computeAmortizedValue() <generated>Create(): Vehicle capacity: Integer <key,generated> oid: String <generated> Create(): Garage <generated> FindByKey(oid: String) Garage vehicles 428-22

  35. Process of MDA to define application • Define class diagram • Mark class diagram • Specify the target of PSM • Customize PIM with annotation • Generate PSM 428-22

  36. Example mapping to XML Specify the target of PSM XML – JavaXMLMapper Customize PIM with annotation Specify file for each class Default is “garage.xml” for Garage objects, “vehicle.xml” for Vehicle objects Specify tag for each attribute 428-22

  37. Result of storing to XML <?xml version=“1.0” encoding=“UTF-8”?> <java version=“1.4.1_02” Class=“java.beans.XMLDecoder”> <object class =“vehicle.Garage”> <capacity> 2 </capacity> <oid> 342 </oid> <vehicles> <reference oid=“922”> </vehicles> </object> </java> 428-22

  38. EJB as target • Use same marked class diagram • Will create • A Bean interface for each entity class • A Bean class for each entity class • A Bean key class for each entity class • A Home interface for each entity class • A deployment descriptor container 428-22

  39. Annotation for EJB • Information needed • EJB container vendor • Vendor specific information such as session timeout, bean and data cache settings, and local transaction settings • Database • Will create DDL if tables do not exist • Provide mapping to existing tables 428-22

  40. Other profiles • We’ve seen a profile for persistence • Other profiles for • Distribution • Transactions (builds on persistence) • Security 428-22

  41. Transformer • Transformer for each profile/target platform • Transformer is a program • Each new target platform requires a new transformer for each profile 428-22

  42. Impact on organization • Two types of developers • Modelers • Understand the problem domain • Create UML models • Write algorithms in Java/action language/?? • Transformation writers • Understand platform • Write transformations 428-22

  43. Problems • Profiles have to be standardized • Class diagrams get cluttered • Transformations interact • Writing transformers can be hard • UML gets complex • Do we really achieve portability? 428-22

  44. Summary • CASE: Computer-aided Software Engineering • Computer tools for helping in software engineering tasks (modeling tools, with code generators, simulators, test generators, etc.) • MDA: Model-driven Architecture • Write Platform Independent Models (PIM) • Generate Platform Specific Models (PSM) • Limited success in several domains 428-22