Homework 5

Enforcing rules // Observing // Security

Due Feb 12, 2002

Consider the incomplete banking application in directory bank.
Compile with: ajc *.java
Run with: java Main

PART 1:

Write an aspect that checks the rule: all objects should
be created by parsing. Objects should not be created 
outside the parser. Print a message if this happens.
Can you write a pointcut designator that detects violations
already at compile time?


PART 2:

Write an aspect that measures and prints out to a log file
how long each call to method addBusinessUnit lasts.


PART 3:

Write a simple security aspect that checks that users
who add a BusinessUnit are properly authorized.
When a call to addBusinessUnit happens,
the caller must know a secret password, such as 673489.
Only when the caller knows this secret, will the business
unit be added.


PART 4: Combining AspectJ and Demeter

THIS PART DOES NOT HAVE TO BE COMPLETED THIS WEEK.
Do a first growth phase only: From 1 to 2.1.


The task is to write a translator from a language L1 to a language L2. The language L1 consists of all of Java
plus a traversal language T. 
The output language consists of a small subset of AspectJ. 
The purpose of the translation is to translate high-level 
traversal specifications to Java traversal methods.

The code is in:
/proj/adaptive2/course/com1205/w02/project-prep/testing

Example input:

Java:

class Basket {
  Fruit f;
  Pencil p;
}
class Fruit { Weight w;}
class Orange extends Fruit {
  Color c;
}
class Pencil {}
class Color {
  String s;
}
class Weight{
  int i;
}
class Main {
  static public void main(String args[]) throws Exception {
  }
}


T:
aspect Traversals {
  declare traversal t1 = Basket to *;
  declare traversal t2 = Basket to Weight;
}

output:


aspect TraveralsImplementation {
  void Basket.t1(){ if (f != null) t1_f(); if (p != null) t1_p();}
  void Basket.t1_f(){f.t1();}
  void Basket.t1_p(){p.t1();}
  void Fruit.t1(){t1_w();}
  void Fruit.t1_w(){w.t1();}
  void Orange.t1(){t1_c(); super.t1();}
  void Orange.t1_c(){c.t1();}
  void Pencil.t1(){};
  void Color.t1(){};
  void Weight.t1(){};

  void Basket.t2(){t2_f();}
  void Basket.t2_f(){f.t2();}
  void Fruit.t2(){t2_w();}
  void Fruit.t2_w(){w.t2();}
  void Orange.t2(){super.t2();}
  void Weight.t2(){};
}


aspect TraversalsTest {
  pointcut mainCall() : call(void main(..));
  before() : mainCall() { 
    // create Basket b
    Basket b = new Basket();
    b.f = new Orange();
    b.t1();
    b.t2();
  
  pointcut nodeTraversals(Object o): 
    call(void t1()) && target(o);
  pointcut edgeTraversals(Object s, Object t): 
    withincode(void t1_*(..)) && call(void t1()) && 
      this(s) && target(t);
  before(Object o) : nodeTraversals(o) {
    System.out.println("traversing node " + o);
  }
  before(Object s, Object t) : edgeTraversals(s, t) {
    System.out.println(
      "traversing edge: source= " + s + " target= " + t);
    System.out.println(thisJoinPoint);
  }
  // same but replace t1 by t2
}



The project consists of the following steps:

1. Produce the class graph cg from the Java program.
2. For cg and a fixed traversal strategy produce the traversal graph.
2.1. Generate the traversal graph for each strategy appearing in T.
     Translate the T file, into a list of strategies and print
     them to a file. Read from this file to construct the 
     traversal graphs using DJ.
     
3. Generate the traversal code from a fixed 
    traversal graph using the interface of the AP Library available in DJ.
4. Test the generated traversal code manually.
5. Automate 2./3./4.: Read in traversal graphs from file 
Traversals.java and translate them into a file that, 
when compiled by AspectJ and executed, will produce 
the file TraversalsImplementation.java 
(containing the traversal code) and TraversalsTest.java 
(containing the test code). 

Note:

Artan has a better way to generate the traversal:

aspect TraveralsImplementation {
  void Basket.t1(){ 
    if (f != null) crossing_f(f); 
    if (p != null) crossing_p(p);}
    // use if throughout
  void Basket.crossing_f(Fruit f){f.t1();}
  void Basket.crossing_p(Pencil p){p.t1();}

The we can define pointcuts like:

pointcut crossing_fFromBasket(Basket b, Fruit f):
  call(void Basket.crossing_f(..)) && this(b) && args(f);