HADES Tutorial

Total Page:16

File Type:pdf, Size:1020Kb

HADES Tutorial Norman Hendrich HADES Tutorial version 0.90 — 15. Juli 2002 Contact: University of Hamburg Dept. Computer Science Norman Hendrich Vogt-Koelln-Str. 30 D-22527 Hamburg Germany [email protected] version 0.90 15. Juli 2002 Contents 1 Introduction 1 1.1 How to read this Tutorial ............................ 1 1.2 Concept ..................................... 1 1.3 What is Hades? ................................. 2 1.4 Related Work .................................. 4 2 Demos 5 2.1 Hamming Code ................................. 6 2.2 Carry-Lookahead Adder ............................ 7 2.3 Traffic-light controller ............................. 8 2.4 TTL-series 74xx components .......................... 9 2.5 RTLIB 16-bit counter .............................. 10 2.6 RTLIB user-defined ALU ............................ 11 2.7 D*CORE processor ............................... 12 2.8 MIDI-controller using a PIC16C84 microcontroller .............. 13 2.9 Micropipeline .................................. 14 3 Installation 15 3.1 System requirements .............................. 15 3.2 Choosing a Java virtual machine ........................ 16 3.3 Hades Download ................................ 17 3.4 Making a directory ............................... 17 3.5 Installation with JDK 1.3 ............................ 19 3.6 Installation with the Microsoft VM (jview) ................... 21 3.7 Installation with other JVMs .......................... 21 3.8 User preferences and configuration ....................... 22 3.9 Registering .hds files on Windows ....................... 23 3.10 Jython ...................................... 25 3.11 Multi-user installation .............................. 25 3.12 Applet installation and issues .......................... 26 3.13 Extending the Hades framework ........................ 27 4 Hades in a Nutshell 29 4.1 Running Hades ................................. 29 4.2 Using the Popup-Menu ............................. 29 4.3 Creating Components .............................. 31 4.4 Adding I/O-Components ............................ 32 4.5 Component Properties ............................. 33 4.6 Display Control ................................. 34 4.7 Creating Wires ................................. 35 4.8 Adding Wire Segments ............................. 35 4.9 Connecting existing Wires ........................... 36 4.10 Moving Wire Points ............................... 36 4.11 Deleting Wires or Wire Segments ....................... 37 4.12 Editor Bindkeys ................................. 37 4.13 Loading and Saving Designs .......................... 38 4.14 Digital Simulation and StdLogic1164 ..................... 38 4.15 Interactive Simulation and Switches ...................... 39 4.16 Waveforms ................................... 41 4.17 Tip: Restarting the Simulation ......................... 41 4.18 Tip: Unexpected Timing Violations ...................... 41 5 Advanced editing 43 5.1 Hierarchical Designs .............................. 43 5.2 Editor bindkeys ................................. 46 5.3 Printing and fig2dev export ........................... 46 5.4 VHDL export .................................. 48 i 6 Waveforms 51 6.1 Waveform types ................................. 52 6.2 Using the waveform viewer ........................... 52 6.3 Searching waveform data ............................ 53 6.4 Saving and loading waveform data ....................... 53 6.5 Scripting ..................................... 54 7 Model libraries 55 7.1 Model library organization ........................... 55 7.2 Browsing and accessing simulation components ................ 55 7.3 Colibri Browser ................................. 56 7.4 Label component ................................ 56 7.5 Interactive I/O .................................. 57 7.6 VCC, GND, Pullup ............................... 58 7.7 Basic and complex logic gates ......................... 58 7.8 Flipflops ..................................... 59 7.9 Register ..................................... 59 7.10 ROM ...................................... 59 7.11 RTLIB ...................................... 61 7.12 TTL 74xx series models ............................ 63 7.13 System-level components ............................ 63 7.14 PIC 16C84 microcontroller ........................... 64 7.15 MIPS IDT R3051 core ............................. 64 8 Scripting and Stimuli 65 8.1 Java-written scripts ............................... 65 8.2 Batch-mode simulation and circuit selftests .................. 67 8.3 Jython ...................................... 70 8.4 Generating simulation stimuli .......................... 71 8.5 Stimuli files and class StimuliParser ...................... 73 9 Writing Components 75 9.1 Overview and Architecture ........................... 75 9.2 Simulation Overview .............................. 77 9.3 Graphics: Static Symbols ............................ 80 9.4 A Simple Example: Basic AND2 Gate ..................... 82 9.5 A D-Flipflop ................................... 86 9.6 Wakeup-Events: The Clock Generator ..................... 87 9.7 Dynamic Symbols and Animation ....................... 90 9.8 PropertySheet and SimObject User Interfaces ................. 92 9.9 Assignable .................................... 94 9.10 DesignManager ................................. 94 9.11 DesignHierarchyNavigator ........................... 95 10 FAQ, tips and tricks 97 10.1 Frequently asked questions ........................... 97 10.1.1 The documentation is wrong? ..................... 97 10.1.2 The editor hangs? ............................ 97 10.1.3 The popup menu is dead ........................ 97 10.1.4 How do I cancel a command? ..................... 97 10.1.5 I can’t get it running .......................... 97 10.1.6 How to check whether my hades.jar archive is broken? ........ 98 10.1.7 I get a ClassNotFoundError ...................... 98 10.1.8 The editor starts, but I cannot load design files ............ 98 10.1.9 The Java virtual machine crashes .................... 98 10.1.10 The editor crashes ........................... 99 10.1.11 I cannot double-click the hades.jar archive ............... 99 10.1.12 I got an OutOfMemoryError ...................... 99 10.1.13 What are those editor messages? .................... 100 10.1.14 Missing components after loading a design .............. 100 ii 10.1.15 Editor prints hundreds of messages while loading ........... 100 10.1.16 Something strange happened right now ................ 100 10.1.17 ghost components, ghost signals .................... 100 10.1.18 How can I disable the tooltips? ..................... 100 10.1.19 Why is this object off-grid? Why won’t the cursor snap to the object? 101 10.1.20 Why can’t I connect a wire to this port? ................ 101 10.1.21 Hades won’t let me delete an object .................. 101 10.1.22 Why don’t the bindkeys work? ..................... 101 10.1.23 I get timing violations from my flipflops ................ 101 10.1.24 Why won’t the editor accept to rename a component/signal? ..... 101 10.1.25 Why doesn’t the cursor represent the editor state? ........... 101 10.1.26 Operation X is slow .......................... 101 10.1.27 Remote X11-Display is very slow ................... 101 10.1.28 The simulation is suddenly very slow ................. 102 10.1.29 GND, VCC, and Pullup components do not work ........... 102 10.1.30 The simulator reports undefined values ................ 102 10.1.31 How can I automatically restore editor settings? ............ 103 10.1.32 My waveforms get overwritten? .................... 103 10.1.33 How can I edit a SimObject symbol? ................. 103 10.2 Tips and tricks .................................. 103 10.2.1 What other programs are in hades.jar? How to run them? ....... 103 10.2.2 User-settings in .hadesrc ........................ 104 10.2.3 How to enable or disable glow-mode for individual signals? ..... 104 10.2.4 What can I do to debug my circuits? .................. 104 10.2.5 I need a two-phase clock ........................ 104 10.2.6 How can I print my circuit schematics? ................ 104 10.2.7 Printing problems ............................ 105 10.2.8 How can I export my circuit schematics via fig2dev? ......... 105 10.2.9 I cannot initialize my circuit ...................... 105 10.2.10 Simulation does not appear deterministic ............... 105 10.2.11 I took a schematic from a book, but the circuit does not work ..... 105 10.2.12 VHDL export .............................. 106 10.3 Known bugs and features ............................ 106 10.3.1 How should I report bugs? ....................... 106 10.3.2 Spurious objects displayed ....................... 106 10.3.3 Repaint algorithm ........................... 107 10.3.4 Repaint bugs, DirectDraw ....................... 107 10.3.5 How to get rid of an unconnected signal? ............... 107 10.3.6 The ’run for’ simulator command may deadlock ............ 107 Bibliography 109 A SetupManager properties 110 A.1 Hades properties ................................ 110 A.2 jfig default properties .............................. 113 B Index 115 iii List of Figures 1 DCF77 radio controlled clock ......................... 2 2 Hades software architecture ........................... 3 3 Hamming code demonstration ......................... 6 4 CLA adder ................................... 7 5 Traffic-light controller ............................. 8 6 TTL circuits ................................... 9 7 RTLIB 16-bit counter .............................
Recommended publications
  • Jpype Documentation Release 0.7.0
    JPype Documentation Release 0.7.0 Steve Menard, Luis Nell and others Jul 22, 2019 Contents 1 Parts of the documentation 3 1.1 Installation................................................3 1.2 User Guide................................................6 1.3 QuickStart Guide............................................. 17 1.4 API Reference.............................................. 27 1.5 JImport.................................................. 34 1.6 Changelog................................................ 36 1.7 Developer Guide............................................. 40 2 Indices and tables 53 Python Module Index 55 Index 57 i ii JPype Documentation, Release 0.7.0 JPype is a Python module to provide full access to Java from within Python. It allows Python to make use of Java only libraries, exploring and visualization of Java structures, development and testing of Java libraries, scientific computing, and much more. By gaining the best of both worlds using Python for rapid prototyping and Java for strong typed production code, JPype provides a powerful environment for engineering and code development. This is achieved not through re-implementing Python, as Jython/JPython has done, but rather through interfacing at the native level in both virtual machines. This shared memory based approach achieves decent computing preformance, while providing the access to the entirety of CPython and Java libraries. Contents 1 JPype Documentation, Release 0.7.0 2 Contents CHAPTER 1 Parts of the documentation 1.1 Installation JPype is available either as a pre-compiled binary for Anaconda, or may be build from source though several methods. 1.1.1 Binary Install JPype can be installed as pre-compiled binary if you are using the Anaconda Python stack. Binaries are available for Linux, OSX, ad windows are available on conda-forge.
    [Show full text]
  • Chargeurs De Classes Java (Classloader)
    http://membres-liglab.imag.fr/donsez/cours Chargeurs de classes Java (ClassLoader) Didier Donsez Université Joseph Fourier - Grenoble 1 PolyTech’Grenoble - LIG/ADELE [email protected] [email protected] 06/06/2009 Licence Cette présentation est couverte par le contrat Creative Commons By NC ND http://creativecommons.org/licenses/by-nc-nd/2.0/fr/ Didier Donsez, 2002-2009, ClassLoaders Donsez,2002-2009, Didier 2 06/06/2009 Kequoi ca un chargeur de classes ? Son rôle est 1) de charger le bytecode d’une classe depuis un artéfact (archive Java, répertoire distant …) 2) communiquer le bytecode à la machine virtuelle Didier Donsez, 2002-2009, ClassLoaders Donsez,2002-2009, Didier 4 06/06/2009 Pourquoi utiliser les chargeurs de classes Classes non présentes dans le CLASSPATH URLClassLoader, AppletClassLoader, … ex: WEB-INF/classes et WEB-INF/lib d’une WebApp ex: CODEBASE d’une applet, … Déchargement et Mise à jour du bytecode lors de l’exécution de la VM (runtime) Chargeurs de OSGi Modification du ByteCode à la volée au chargement Instrumentation AOP (Aspect Oriented Programming) BCEL, ASM Protection Chargement de ressources associées à la classe properties, images, … Recherche de Service Providers ou de Drivers META-INF/services (java.util.ServiceLoader de 6.0) Didier Donsez, 2002-2009, ClassLoaders Donsez,2002-2009, Didier 5 06/06/2009 Principe de la délégation (Java 2) Tout chargeur a un chargeur parent sauf le chargeur primordial Tout chargeur vérifie si la classe à charger n’a pas déjà été chargée par un chargeur
    [Show full text]
  • How Java Works JIT, Just in Time Compiler Loading .Class Files The
    How Java works JIT, Just In Time Compiler ● The java compiler takes a .java file and generates a .class file ● JVM ultimately translates bytecode into native code, each time ➤ The .class file contains Java bytecodes, the assembler the same bytecodes are processed, the translation into native language for Java programs code must be made ➤ Bytecodes are executed in a JVM (java virtual machine), ➤ If we can cache translated code we can avoid re-translating the valid bytecodes are specified by Sun the same bytecode sequence • What if third parties create platform/OS specific codes? ➤ Why not just translate the entire .java program into native code? ● The JVM interprets the bytecodes ➤ JVM is platform/OS specific, must ultimately run the code ● Still need the JVM, the JIT works in conjunction with the JVM, not in place of it ➤ Different JVMs will have different performance, JITs are part of the overall JDK/Java performance ● How are classes loaded into the JVM? Can this be thwarted? Duke CPS 108 14.1 Duke CPS 108 14.2 Loading .class files The ClassLoader ● The bytecode verifier “proves theorems” about the bytecodes ● The “Primordial” loader is built-in to the JVM being loaded into the JVM ➤ Sometimes called the “default” loader, but it’s not ➤ These bytecodes may come from a non-Java source, e.g., extensible or customizable the way other loaders are compile Ada into bytecodes (why?) ➤ Loads classes from the platform on which the JVM runs ● This verification is a static analysis of properties such as: (what are loader and JVM written in?) ➤
    [Show full text]
  • An Empirical Evaluation of Osgi Dependencies Best Practices in the Eclipse IDE Lina Ochoa, Thomas Degueule, Jurgen Vinju
    An Empirical Evaluation of OSGi Dependencies Best Practices in the Eclipse IDE Lina Ochoa, Thomas Degueule, Jurgen Vinju To cite this version: Lina Ochoa, Thomas Degueule, Jurgen Vinju. An Empirical Evaluation of OSGi Dependencies Best Practices in the Eclipse IDE. 15th International Conference on Mining Software Repositories, May 2018, Gothenburg, Sweden. 10.1145/3196398.3196416. hal-01740131 HAL Id: hal-01740131 https://hal.archives-ouvertes.fr/hal-01740131 Submitted on 27 Mar 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. An Empirical Evaluation of OSGi Dependencies Best Practices in the Eclipse IDE Lina Ochoa Thomas Degueule Jurgen Vinju Centrum Wiskunde & Informatica Centrum Wiskunde & Informatica Centrum Wiskunde & Informatica Amsterdam, Netherlands Amsterdam, Netherlands Amsterdam, Netherlands [email protected] [email protected] Eindhoven University of Technology Eindhoven, Netherlands [email protected] ABSTRACT that can be implemented and tested independently. This also fos- OSGi is a module system and service framework that aims to fill ters reuse by allowing software components to be reused from one Java’s lack of support for modular development. Using OSGi, devel- system to the other, or even to be substituted by one another pro- opers divide software into multiple bundles that declare constrained vided that they satisfy the appropriate interface expected by a client.
    [Show full text]
  • Kawa - Compiling Dynamic Languages to the Java VM
    Kawa - Compiling Dynamic Languages to the Java VM Per Bothner Cygnus Solutions 1325 Chesapeake Terrace Sunnyvale CA 94089, USA <[email protected]> Abstract: in a project in conjunction with Java. A language im- plemented on top of Java gives programmers many of Many are interested in Java for its portable bytecodes the extra-linguistic benefits of Java, including libraries, and extensive libraries, but prefer a different language, portable bytecodes, web applets, and the existing efforts especially for scripting. People have implemented other to improve Java implementations and tools. languages using an interpreter (which is slow), or by translating into Java source (with poor responsiveness The Kawa toolkit supports compiling and running vari- for eval). Kawa uses an interpreter only for “simple” ous languages on the Java Virtual Machine. Currently, expressions; all non-trivial expressions (such as function Scheme is fully supported (except for a few difficult fea- definitions) are compiled into Java bytecodes, which are tures discussed later). An implementation of ECMA- emitted into an in-memory byte array. This can be saved Script is coming along, but at the time of writing it is for later, or quickly loaded using the Java ClassLoader. not usable. Kawa is intended to be a framework that supports mul- Scheme [R RS] is a simple yet powerful language. It tiple source languages. Currently, it only supports is a non-pure functional language (i.e. it has first-class Scheme, which is a lexically-scoped language in the Lisp functions, lexical scoping, non-lazy evaluation, and side family. The Kawa dialect of Scheme implements almost effects).
    [Show full text]
  • Components: Concepts and Techniques
    Software Engineering 2005 Components: Concepts and Techniques Martin Bravenboer Department of Information and Computing Sciences Universiteit Utrecht [email protected] October 19, 2005 1 Concepts 2 Component-based Software Engineering Developing a software system from prefabricated parts • From custom-made to standard software • Required in all industries • No replication: different configurations • Cross-cuts the software engineering: – Requirements, deployment, versioning, configuration, building, maintenance, architecture, design • Aspects: both technical and market-related – Time to market, competitiveness. – Stimulation of marketplace 3 Dreaming in Components • Maturity of software engineering • Components of different vendors working together – Requires protocols between components • Marketplace – Sell components – Provide services – Infrastructure – Service provider • Reduce need for skilled system programmers – Component architects, assemblers Has taken almost 40 years to take off! 4 Components according to Czarnecki “Building blocks from which different software systems can be composed.” • Component is a natural concept – Not constructed, artificial – Definition is futile. • Component is part of a production process • What a component is, depends on the production process. – e.g. not necessarily binary Economic pressure towards standardized solutions 5 Components according to Szyperski Very strict definition of software component 1. Unit of composition 2. Unit of independent deployment 3. Contractually specified interfaces • Deployment,
    [Show full text]
  • Towards Integrating Modeling and Programming Languages: the Case of UML and Java⋆
    Towards Integrating Modeling and Programming Languages: The Case of UML and Java? Patrick Neubauer, Tanja Mayerhofer, and Gerti Kappel Business Informatics Group, Vienna University of Technology, Austria {neubauer, mayerhofer, gerti}@big.tuwien.ac.at Abstract. Today, modeling and programming constitute separate activities car- ried out using modeling respectively programming languages, which are neither well integrated with each other nor have a one-to-one correspondence. As a con- sequence, platform and implementation details, such as the usage of existing software components and libraries, are usually introduced on code level only. This impedes accurate model-level analyses that take platform-specific decisions into account as well as the direct deployment of executable models on the target platform. In this work we present an approach for integrating existing software libraries with fUML models—an executable variant of UML models for which a standardized virtual machine exists—not only at design time but also at runtime. As a result of that, the modeler is empowered with the capabilities provided by existing software libraries on model level. Our approach is evaluated based on unit tests and initial case studies available in the ReMoDD repository that assess the correctness, performance, and completeness of our implementation. 1 Introduction Back in 1966, the first object-oriented programming language was born. Its name is SIMULA and it combined modeling and programming in a unified approach, that is one of the strengths provided by object-orientation [4]. Carrying this idea further, the language BETA, which was developed based on SIMULA and DELTA, was designed for supporting both designing and programming systems.
    [Show full text]
  • Analysing Class Loading Conflicts on Weblogic
    Class Loading Conflicts in JVM This guide shows how to analyze and avoid potential problems caused by class loading conflicts. The content is structured in the following sections, the first one gives a little introduction to the Classloader model in Weblogic [1], following the installation of Classloader Analysis Tool (CAT) [1] is shown and then two examples that shows the use of CAT on a real application is presented. Class loading in Weblogic Summarizing the class loading process in just some lines is hard so in this guide the focus is talking about hierarchies and the delegation model. Concept Definition Hierarchies The classloader in an application server such as Weblogic is based on the model defined by the JVM, which means a hierarchical model that on Weblogic is organized as a tree with these levels: bootstrap class loader, extension class loader, system classpath classloader, application specific classloaders (this includes Weblogic server) [1]. In the previous tree, bootstrap class loader is the root and application specific classloaders are the leaves [1]. Delegation model A common question that arises when Java application servers are used is why is my application using the wrong class? This is because the delegation model, which states “The classloader implementation first checks its cache to see if the requested class has already been loaded. This class verification improves performance in that its cached memory copy is used instead of repeated loading of a class from disk. If the class is not found in its cache, the current classloader asks its parent for the class. Only if the parent cannot load the class does the classloader attempt to load the class.
    [Show full text]
  • Understanding the Java Classloader Skill Level: Introductory
    Understanding the Java ClassLoader Skill Level: Introductory Greg Travis ([email protected]) Programmer 24 Apr 2001 This tutorial provides an overview of the Java ClassLoader and takes you through the construction of an example ClassLoader that automatically compiles your code before loading it. You'll learn exactly what a ClassLoader does, and what you need to do to create your own. Section 1. Tutorial tips Should I take this tutorial? The Java ClassLoader is a crucial, but often overlooked, component of the Java run-time system. It is the class responsible for finding and loading class files at run time. Creating your own ClassLoader lets you customize the JVM in useful and interesting ways, allowing you to completely redefine how class files are brought into the system. This tutorial provides an overview of the Java ClassLoader and takes you through the construction of an example ClassLoader that automatically compiles your code before loading it. You'll learn exactly what a ClassLoader does and what you need to do to create your own. A basic understanding of Java programming, including the ability to create, compile, and execute simple command-line Java programs, as well as an understanding of the class file paradigm is sufficient background to take this tutorial. Upon completion of this tutorial, you will know how to: Understanding the Java ClassLoader © Copyright IBM Corporation 1994, 2005. All rights reserved. Page 1 of 19 developerWorks® ibm.com/developerWorks • Expand the functionality of the JVM • Create a custom ClassLoader • Learn how to integrate a custom ClassLoader into your Java application • Modify your ClassLoader to accommodate the Java 2 release Section 2.
    [Show full text]
  • Supporting Resource Awareness in Managed Runtime Environment Inti Yulien Gonzalez Herrera
    Supporting resource awareness in managed runtime environment Inti Yulien Gonzalez Herrera To cite this version: Inti Yulien Gonzalez Herrera. Supporting resource awareness in managed runtime environment. Soft- ware Engineering [cs.SE]. Université Rennes 1, 2015. English. NNT : 2015REN1S090. tel-01308660 HAL Id: tel-01308660 https://tel.archives-ouvertes.fr/tel-01308660 Submitted on 28 Apr 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. ANNÉE 2015 THÈSE / UNIVERSITÉ DE RENNES 1 sous le sceau de l’Université Européenne de Bretagne pour le grade de DOCTEUR DE L’UNIVERSITÉ DE RENNES 1 Mention : Informatique École doctorale Matisse présentée par Inti Yulien GONZALEZ HERRERA préparée à l’unité de recherche INRIA Rennes Bretagne Atlantique Thèse soutenue à Rennes Supporting le 14 Décembre 2015 devant le jury composé de : Vivien QUÉMA resource awareness LIG laboratory – Grenoble INP/ENSIMAG / Rapporteur Gilles MULLER in managed runtime Whisper team – LIP6 / Rapporteur Gaël THOMAS environments. Samovar Laboratory – Telecom SudParis / Examinateur Laurent RÉVEILLÈRE LaBRI – Université de Bordeaux / Examinateur Isabelle PUAUT IRISA – Université de Rennes 1 / Examinatrice Olivier BARAIS Professor, IRISA – Université de Rennes 1 / Directeur de thèse Johann BOURCIER Maître de conférences, IRISA – Université de Rennes 1 / Co-directeur de thèse Hay una historia familiar que me impactó muchísimo.
    [Show full text]
  • CICS JVM Server Application Isolation
    CICS JVM Server Application Isolation Masterarbeit Lehrstuhl für Technische Informatik Wilhelm-Schickard-Institut für Informatik Mathematisch-Naturwissenschaftliche Fakultät Universität Tübingen Dipl.-Ing. (FH) Robert Harbach Betreuer: Prof. Dr.-Ing. Wilhelm G. Spruth Tag der Anmeldung: 1. Oktober 2011 Tag der Abgabe: 30. März 2012 Executive Summary The Java Virtual Machine (JVM) is able to host multiple simultaneously execut- ing transaction programs. Since a JVM is not capable to provide full application isolation however, the common practice found in most Java application servers implies to run one JVM per program. Due to the fact, that this implies an overhead of computational resources, several, most often proprietary, solutions for application isolation in JVMs have been proposed in the past. This paper outlines isolation properties of a new Java Virtual Machine (JVM) type, called a JVM Server, which implements the OSGi framework, and is in- tegrated into the System z architecture Customer Control Information System (CICS). It is shown that this approach resolves two application isolation issues: The CICS environment enables transaction safe execution of tasks. In addition, inclusion of the OSGi Framework provides namespace isolation based on class loading. However, several issues remain unsolved. They arise from the use of Java system classes, OSGi specific functions, resource exhaustion, and the use of the Java Native Interface (JNI). This paper proposes solutions to these isolation exposures. Some employ func- tions of the OSGi security layer. Others utilise existing CICS services for pro- gram control which would have to be implemented differently on other Java Transaction Servers. 1 Erklärung Hiermit bestätige ich, dass ich diese Masterarbeit selbstständig und nur mit Hilfe der angegebenen Quellen und Hilfsmittel verfasst habe.
    [Show full text]
  • How Java Works
    How Java works ● The java compiler takes a .java file and generates a .class file ➤ The .class file contains Java bytecodes, the assembler language for Java programs ➤ Bytecodes are executed in a JVM (java virtual machine), the valid bytecodes are specified by Sun • What if third parties create platform/OS specific codes? ● The JVM interprets the bytecodes ➤ JVM is platform/OS specific, must ultimately run the code ➤ Different JVMs will have different performance, JITs are part of the overall JDK/Java performance Duke CPS 108 14.1 JIT, Just In Time Compiler ● JVM ultimately translates bytecode into native code, each time the same bytecodes are processed, the translation into native code must be made ➤ If we can cache translated code we can avoid re-translating the same bytecode sequence ➤ Why not just translate the entire .java program into native code? ● Still need the JVM, the JIT works in conjunction with the JVM, not in place of it ● How are classes loaded into the JVM? Can this be thwarted? Duke CPS 108 14.2 Loading .class files ● The bytecode verifier “proves theorems” about the bytecodes being loaded into the JVM ➤ These bytecodes may come from a non-Java source, e.g., compile Ada into bytecodes (why?) ● This verification is a static analysis of properties such as: ➤ .class file format (including magic number 0xCAFEBABE) ➤ Methods/instances used properly, parameters correct ➤ Stack doesn’t underflow/overflow ➤ … ● Verification is done by the JVM, not changeable as is, for example, the ClassLoader http://securingjava.com http://java.sun.com/sfaq/verifier.html
    [Show full text]