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Defending Against Software Engineering Quagmire: JML

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Shows how the Java Modeling Language can keep code clean and efficient. The Java Modeling Language (JML) is a notation for formally specifying the behavior and interfaces of Java classes and methods. – PowerPoint PPT presentation

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Title: Defending Against Software Engineering Quagmire: JML


1
Defending Against Quagmire and Failure JML in
Formal Analysis
  • The New Java Modeling Language (JML) System
    Addresses the Essence of the Software Problem.

by Christopher Balz 7/3/2004
2
JML Is for You.
  • JML specifies modules and works with general
    specification languages
  • Have you ever worked on a team with individuals
    implementing pieces that do not fit together, and
    that thus must be re-engineered to work?
  • JML is the first to automate your program testing
    using a runtime assertion checker.
  • JML is an exciting advance towards automatic
    programming.

3
JML A Practical Specification Language
  • JML builds on the Larch Eiffel traditions.
  • Built for specifying program modules, as
    distinguished from whole systems.
  • JML replaces Larchs math notations by taking
    Eiffels approach for reduced learning curve.
  • JML can specify precise conditions for
    exceptions.
  • JML comes with a powerful toolset.

4
JML Tools Fill Practicality Gap
  • Other specification languages (Z, B notation)
    specify entire systems.
  • Reaching actual code is difficult from these
    languages.
  • jmlunit, jmlc, and jmldoc dynamically connect
    specification and actual code.

5
JML Specification With Implementation
  • Specification is and should be distinct from
    implementation.
  • But specification can be used to check
    implementation.
  • JML with its tools automatically generates and
    runs unit tests from JUnit, and more.

6
Specification With Implementation How and What
  • jmlunit specified module behavior is monitored
    at runtime to determine test pass or fail.
  • JMLs jmlc and jmldoc make enforced up-to-date
    documentation.
  • Specification of private and protected elements.
  • Allows effective implementation of extending
    classes.
  • JML will offer even more soon.

7
My Experience with JML
  • Read the main JML System documentation.
  • For the PET v2 system, implemented a simple
    specification and a few pre- and post- condition
    module checks.
  • Ran jmlunit tool on code to generate JUnit tests.
  • Performed dry-run runtime assertion checking.
  • My skill level still rates as beginner with JML!

8
Drilling Down JML Code Fig. 1
  • The power sets of the whole system are defined
  • public class PetCycleForm
  • extends JFrame
  • /_at_
  • _at_ public ghost JMLObjectSet JMLLifecycles
    new JMLObjectSet()
  • _at_ public ghost JMLObjectSet
    JMLLifecyclePhases new JMLObjectSet()
  • _at_ public ghost JMLObjectSet JMLProjects
    new JMLObjectSet()
  • _at_ public invariant JMLLifecycles ! null
    JMLLifecyclePhases ! null
  • _at_/

9
Drilling Down JML Code Fig. 2
  • public class ProjectPhases
  • private ArrayList moPD_BOs new ArrayList()
  • private ProjectPhasesDO moPP_DO new
    ProjectPhasesDO()
  • /_at_
  • _at_ public ghost JMLObjectSet
    JMLProjectPhases new JMLObjectSet()
  • _at_ public ghost JMLObjectSet
    JMLProjectDeliverables new JMLObjectSet()
  • _at_ public ghost JMLObjectSet
    JMLLifeCycleDeliverables new JMLObjectSet()
  • _at_ public invariant JMLLifeCycleDeliverables
    ! null
  • _at_ public initially ( See 'PetCycleForm'
    for power set definitions.
  • _at_ JMLProjectDeliverables
    contains the set of ProjectDeliverables
  • _at_ belonging to the
    current ProjectPhase and JMLLifeCycleDeliverables
  • _at_ contains the set of
    LifeCycleDeliverables belonging to the current
  • _at_ phase. )
  • _at_/

10
Drilling Down JML Code Fig. 3
  • JML checks pre- and post- conditions at a Java
    method
  • From ProjectPhases.java
  • /_at_
  • _at_ requires aoPD_BO ! null
    !JMLProjectDeliverables.has(aoPD_BO)
  • _at_
    JMLLifeCycleDeliverables.has(aoPD_BO)
  • _at_ ensures JMLProjectDeliverables.has(aoPD_BO
    )
  • _at_/
  • public boolean createPD(ProjectDeliverable
    aoPD_BO)

11
JML Tomorrow
  • The JML system finished in February 2004.
  • Automatic generation of test data is next for
    jmlunit.
  • Already adequate documentation will be improved.
  • Already easy-to-use GUI tools will be improved.

12
JML and The Essence of the Software Problem
  • Fred Brooks No Silver Bullet Essence and
    Accidents of Software Engineering.
  • Automatic programming a false hope.
  • Too many implementation choices the
    generalization barrier
  • JML powerfully enables software quality.
  • JML breaks through the generalization barrier!
  • Solidly connects code to specification through
    runtime test.
  • But leaves many implementation choices.

13
JML and the Immediate Future
  • Improved Quality
  • Increased ability to test (white box and black
    box) and to take test-first approach.
  • More accurate and effective documentation.
  • Traversing Quagmire Mozilla.
  • Sinking into Failure Netscape.
  • Improved Efficiency
  • Microsoft Massive resources.
  • Build big-company software with small-company
    resources.

14
JML and System Development
High-Level Specification
Low-Level Specification
Z, B
Shorthands
UML
IDEs
JML
Components (J2EE, .NET, Others)
Implementation Code
15
JML and the Future
  • Automatic programming 30,000 above the
    quagmire.
  • JML offers a new kind of abstraction to specify
    implementation, floating just above
    implementation.
  • But implementation must be informed as well from
    the use case/whole-system (high-level).
  • Z, B enable specific whole-system view.
  • IDE and component (e.G., J2EE) state-of-the-art
    already make many implementation choices.
  • Gap still exists between IDE tip and JML tip.
  • A.I. techniques can make the remaining
    implementation choices.

16
JML and You
  • JML represents a genuinely new, exciting approach
    to software development.
  • JML is ready for use, is free, and will be
    improving.
  • JML can make your work much more fun, effective,
    and easier.
  • Visit http//jmlspecs.org
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