Extreme Java G Session 2 Main Theme Java Tools and Software Engineering Techniques. Dr. Jean-Claude Franchitti

Transcription

1 Extreme Java G Session 2 Main Theme Java Tools and Software Engineering Techniques Dr. Jean-Claude Franchitti New York University Computer Science Department Courant Institute of Mathematical Sciences Agenda Summary of Previous Sessions Java Platform Architectures Java (Open Source) Development Tools Java (Client) Applications Java Support Technologies Packaging Java Applications Java Project Management Readings Class Project & Assignment #1b 2

2 Announcements Student Accounts on i5.nyu.edu Extreme Java vs. extreme Programming (XP) Homeworks & Projects Due Dates Grader Assignments Java IDEs J2EE-Compliant Application Servers Assignment #2 3 Summary of Previous Sessions Course Logistics, Structure and Objectives Java Programming Language Features Java Environment Limitations Upcoming Features in Tiger 1.5 Model Driven Architectures for Java Systems Java Enterprise Application Enabling Agile Modeling & extreme Programming Aspect-Oriented Programming & Refactoring Java Application Performance Enhancement Readings, Class Project, and Assignment #1a 4

3 Part I Java Platform Architectures 5 Key Platform Features Resources Packaging Tools Environment Open Source Solutions on the Java Platform: e.g., regexp regular expression package, log4j logging package, etc. 6

4 Java Platform Architectures Runtime Environment Architecture Byte code verifier Class loader Runtime Execution Engine / optimizer Security Manager (java.lang.securitymanager) and API class files JVM enables type-safe reference casting, structured memory access (no pointer arithmetic), automatic garbage collection (can't explicitly free allocated memory), array bounds checking, checking references for null Native platform interface libraries File Types Source code files (see Class files Serialization files Archive files Manifest files 7 Java Virtual Machine Write Once Run Anywhere (WORA) Architecture 8

5 Java Virtual Machine (JVM) (continued) Byte Code Verifier Class Loader (dynamic operation) Runtime Execution Engine Performance bottlenecks: Byte Code Execution, garbage collection, thread management, dynamic operations (i.e., class loading, bounds checking, security measures, dynamic class loading, exception handling, reflection, and native method translation) Just- in- time compiler Reduces byte-code interpretation and causes the execution workload to shift to native compilation and caching of native methods. Precompiler 9 Pre Java 2 Security 10

6 Java 2 Security 11 Java 2 Security 12

7 Part II Java Tools 13 javac jar java javadoc jdb appletviewer javahelp Traditional Java Tools 14

8 Java Interpreter Software that implements the JVM and runs Java application Standalone or part of larger application (e.g., browser) Likely written in a native, compiled language Loads Java class files and interprets the compiled bytecode Verifies compiled classes loaded from untrusted sources Can turn Java byte-code into native machine instructions (dynamic/jit compilation) java [interpreter options] class name [program arguments] 15 Using Java Class should be fully qualified class name (including class package if any) Shouldn t include.class file extension Searches for the class in current class path (-classpath option) Looks for main() method main method signature: public static void main ( String [ ] myargs ) No need for argument count parameter (int argc = myargs.length) 16

9 Class Path Piece of environment information providing a list of places to look for some resources CLASSPATH: list of locations that can be searched for packages containing Java class files Used by Java interpreter and compiler CLASSPATH includes directory names or the names of class archive files (.zip or.jar) Use colon separator (UNIX), or semicolon separator (DOS/Windows) Default paths:.:$jdk_home/classes:$jdk_home/lib/classes.zip (UNIX).;%JDK_HOME%\classes;$%JDK_HOME%\lib\classes.zip (Windows systems) 17 Java Compiler Turns Java source code into a compiled class containing JVM byte-code.java ->.class Allows one public class per file (file has same name as class) Storing the class files in alternate directory: use -d option 18

10 Java IDEs Eclipse NetBeans Sun ONE Studio JBuilder Visual Age for Java VisualCafé Codewarrior for Java WebGain Studio ModelJ J2ME Wireless Toolkit IntelliJ etc. 19 Java IDEs Selection Criteria User Interface Ease of Use IDE Customization Features Code Editing Features On-the-Fly Code Analysis Code Style, Generation, Inspection Refactoring Support J2EE Support (JSP, XML, EJB, etc.) Navigation Search and Replace JavaDoc Support Local Version Control Support Version Control System (VCS) Integrations Compiler Running/Debugging Support Debugger Other Integrated Tools Open API Written in Java / Available on All Platforms 20

11 Cactus Software Tools for XP Test framework for unit testing server-side java code (Servlets, EJBs, Tag Libs, Filters, ) Cactus uses JUnit and extends it JUnit is a regression testing framework written by Erich Gamma and Kent Beck. It is used by the developer who implements unit tests in Java provides a packaged and simple mechanism based on Ant to automate server-side testing 21 Software Tools for XP (continued) 22

12 Part III Java (Client) Applications 23 Type of Java Applications Standalone Java application Runs independently Applet (embeddable program module) Part of a larger application Compatible with mainstream browsers (Netscape, IE), and the Java appletviewer JWS (Java Web Start) Applications A component model for deployable client software Subsumes the Applet component model 24

13 Java Web Start (JWS) Technology See Applications do not require a browser once downloaded Files are cached on the client Checks are performed with the web server to ensure that the latest version of the application is being used (ZAC!) Built on top of Java 2 Security Links point to JNLP files which syntax is defined as part of a Java Community Process specification 25 JWS Application Launching 26

14 Sample JNLP File <?xml version="1.0" encoding="utf-8"?> <jnlp spec="1.0+" codebase=" href="swingset2.jnlp"> <information> <title>swingset2 Demo Application</title> <vendor>sun Microsystems, Inc.</vendor> <homepage href="docs/help.html"/> <description>swingset2 Demo App</description> <description kind="short">a demo</description> <icon href="images/swingset2.jpg"/> <offline-allowed/> </information> <security> <all-permissions/> </security> <resources> <j2se version="1.3"/> <jar href="lib/swingset2.jar"/> </resources> <application-desc main-class="swingset2"/> </jnlp> 27 JNLP Element to Launch an Applet <applet-desc documentbase=" name="timepilot" main-class="timepilot.timepilotapp" width="527" height="428"> <param name="key1" value="value1"/> <param name="key2" value="value2"/> </applet-desc> 28

15 BasicService ClipboardService DownloadService FileOpenService FileSaveService PrintService PersistenceService JNLP API 29 Applet Tag <applet attribute [attribute] > [<param parameter>] [<param parameter>] [HTML for non Java aware browsers] </applet> 30

16 Applet Tag ( attributes: width, height, code / object (serialized representation of applet) parameter: <param name=zone value=gmt> Applets can also be launched via the OBJECT or EMBED tag 31 Applet Plug-In Needed for RSA signed applet verification Provides enhanced applet debugging and management features Java Plug-in included as part of the JRE JDK 1.3.1_01 was the first version to include Java Plug-in (1.3) software Consult the Java Plug-in documentation Using the HTML APPLET tag converter ml_converter.html 32

17 Java 2 Plugin Architecture ( 33 Open JVM Interface (OJI) Allows any Sun-Compliant JVM (implementing OJI) to become the default JVM for a browser Supports Applet, Embed, and Object tags Supports Java-JavaScript bidirectional communication Supports RSA signed applet verification 34

18 Applet Security Java Plug-In Security Reference Security Features RSA signed applet (jar signing in the JDK) HTTPS (handled via browser) Liveconnect for Java-JavaScript bidirectional communication Origin of HTML page must be same as that of applet JavaScript must be signed and UniversalBrowserRead permission must be enabled for JavaScript (default is local Java policy) 35 Java 2 Security 36

19 Java 2 Security (secure application distribution using Java cryptography API) Secure Application Distribution Applications stored as a self-executing encrypted file Only class file data is encrypted Main executable file must be distinguishable Four Phases Packaging Encryption/Decryption Loading Execution 37 Part IV Java Support Technologies 38

20 MDA OMG's MDA (Model-Driven Architecture) specification describes: a PIM - platform-independent models (i.e. business design) PSMs - the mapping of a PIM to one or more platform-specific model MDA => Model Once, Generate Everywhere Review MDA presentations: 39 UML Model (PIM) Auto Color : String Door : Integer Engine : Integer M O F MDA (continued) XMI X M I XMI Document (PSM) <Auto> <Color> Red </Color> <Door> 4 </Door> <Engine> 2 </Engine> </Auto> IDL, Java (PSM) interface Auto { Class Auto }; {public String color; public int Door; public int Engine; } XMI DTD, Schema (PSM) <!Element Auto (Color*, Door*, Engine*)> 40

21 AspectJ Locking Sample Creating a new aspect called lock with introduce and advise cross- cuts 01 aspect Lock { 03 Data shareddatainstance; 04 Lock( Data d ) { 05 shareddatainstance = d; 06 } 08 introduce Lock Data.lock; advise Data() { 11 static after { 12 thisobject.lock = new Lock( thisobject ); 13 } 14 } 17 } 41 AspectJ Locking Sample (continued) Advising classes that work with the data (note that all the locking code is included in an aspect!) 15 boolean locked = false; advise Worker.perform*(..), AnotherWorker.perform*(..) { 18 before { 19 if ( thisobject.shareddatainstace.lock.locked ) // enqueue, wait 20 thisobject.shareddatainstace.lock.locked = true; 21 } 22 after { 23 thisobject.shareddatainstace.lock.locked = false; 24 } 25 } 26 } 42

22 Design Patterns and Refactoring Refactoring improves code design without adding new behavior A design pattern is the description of a design problem and of its solution, which comes with certain benefits and liabilities See Do design patterns drive refactoring or are design patterns discovered in the refactoring result? See Refactoring to Patterns 43 Part V Packaging Java Applications Also See Session 2 Handout: How to Submit Projects in Zip or Jar Files 44

23 Packaging: Java Archive (JAR) Files Can compress with ZLIB compression Can use pkzip to create and maintain JAR files jar is the java archive utility JAR file advantages: compression and access time 45 JAR Utility See handout on how to submit projects using zip/jar jar -cvf jarfile path [path] [ ] jar -tvf jarfile [path] [ ] jar -xvf jarfile [path] [ ] Alternatives: Mobile Object and Agents GUI Jar utility (MOAJar), etc. 46

24 JAR Utility (continued) jar adds META-INF/MANIFEST.MF packing list naming files along with cryptographic checksums jar -cvmf mymanifest.mf spaceblaster.jar spaceblaster Use javakey to sign a JAR file (see digital signature / certificate) 47 Java 2 Security (secure application distribution using Java cryptography API) Secure Application Distribution Applications stored as a self-executing encrypted file Only class file data is encrypted Main executable file must be distinguishable Four Phases Packaging Encryption/Decryption Loading Execution 48

25 Part VI Java Project Management Also See Session 2 Sub-Topic 1 Presentation on: Java Project Management 49 Java Project Management Approach Refer to the links on extreme Programming (see Session1 main slide set, and corresponding bullets under Announcements on the course Web site). See Java Tools for extreme Programming: Mastering Open Source Tools, including Ant, Junit, and Cactus (Richard Hightower, Nicholas Lesiecki, ISBN: X, 11/2001) Regression testing framework: Ant build tool and Cactus server-side unit testing: See Sub-Topic 1 presentation on Java Project Management 50

26 extreme Programming (XP) Map 51 XP Iteration Planning 52

27 XP Unit Testing 53 CMM & TSP The Capability Maturity Model for Software (SW- CMM) is used by organization to guide their software process improvement efforts The Team Software ProcessSM (TSPSM) was designed to implement effective, high-maturity processes for project teams If all projects in an organization are using the TSP, does the organization exhibit the characteristics of high process maturity, as described in the SW-CMM? 54

28 SEI s IDEALModel IDEAL is an organizational improvement model 55 Part VII Readings and Assignment 56

29 Assignment Readings Mastering Java 2: Part 2 Chapter 17 & Appendix B Expert One-on-One: Chapter 2-4 as applicable Selected readings mentioned in class or referenced in the handouts Handouts posted on the course web site Assignment #1b: (submit report and implementation archive) Implement a sample application and test it using Cactus Hint: use and extend the sample application provided in the Cactus distribution Extra Credit: Implement and test the sample application using Cactus on top of a JVM that supports behavioral reflection Project Framework Setup Java Plug-in, Java Web Start, Apache s Xerces/Xalan J2SE 1.3.1, or (SDK) IDE: Eclipse, NetBeans, Sun ONE Studio, JBuilder, Visual Age, Visual Café, Codewarrior, WebGain Studio, Oracle JDeveloper, etc. Editors: JCreator, UltraEdit, etc. 57