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Overview Phase 10 Introduction Notations Java Implementation of modules Module Tests Procedure Example - TLC Example - SBC Phase 11 Phase 12 Summary Overview Phase 10 Introduction Notations Java Implementation of modules Module Tests Procedure Example - TLC Example - SBC Phase 11 Phase 12 Summary Solution: Synchronize public class SharedMemSum { private int[] x; public SharedMemSum () { x = new int [3] ; x[0]=0; x[1]=0; x[2]=0; } synchronized int getSum() { int a,b,c; a=x[0]; b=x[1]; c=x[2]; return a+b+c; } synchronized void setVal(int a, int b, int c) { x[0] = a; x[1] = b; x[1] = c; } } The statement synchronized makes a method non-interruptable. Implementation of modules / software components II Interfaces can be implemented using directly called methods, methods in interface classes, or messages, e.g. delegates in C♯, events in Java, signals and slots in C++ with the Qt-library, messages in the Windows API. Messages usually allow asynchronous communication (with queuing) and in some frameworks multiple consumers are allowed. 21 / 89 23 / 89 Overview Phase 10 Introduction Notations Java Implementation of modules Module Tests Procedure Example - TLC Example - SBC Phase 11 Phase 12 Summary Overview Phase 10 Introduction Notations Java Implementation of modules Module Tests Procedure Example - TLC Example - SBC Phase 11 Phase 12 Summary Implementation of modules / software components I Amodulehasprovidedandrequiredinterfacesthatcanbe connected with other modules A module only uses functionality from the provided interfaces, from the programming language, and a limited set of operations of the operating system (e.g., tasks, threads, memory allocation, timers, messages, synchronization mechanisms). Active components are implemented using threads. Implementation of interfaces I Loose and tight coupling is possible for interfaces between components. Tight (directly called methods) coupling is used if methods of a class and not of an object are called. Tight coupling of objects can only be implemented if the called object is created by the calling class. For loose coupling (methods in interface classes) the objects are created by a different class. The object that uses an interface of another object needs a reference to the used object. The reference can be provided in the constructororinanadditionalmethodtoconnectthe objects. 22 / 89 24 / 89
Overview Phase 10 Introduction Notations Java Implementation of modules Module Tests Procedure Example - TLC Example - SBC Phase 11 Phase 12 Summary Overview Phase 10 Introduction Notations Java Implementation of modules Module Tests Procedure Example - TLC Example - SBC Phase 11 Phase 12 Summary Implementation of interfaces II Tight coupling usually need less resources and can also be implemented using non-oo languages. With loose coupling, the object can be implemented independently of its environment. The object becomes a component. Messages implement a loose coupling. Loose coupling is better for the implementation of module tests. Implementation of provided interfaces in Java Each provided interface is defined as a interface class, e.g.: public interface LineIn { public void transmitMusic(); } public interface PowerSupply { public void powerOn(); } A component can implement / provide several interfaces, e.g.: 25 / 89 public class AmplifierAndSpeeker implements LineIn, PowerSupply public AmplifierAndSpeeker (){} //constructor public void transmitMusic() { Play;} public void powerOn() { Action2;} } All provided operations must be implemented as methods. 27 / 89 Overview Phase 10 Introduction Notations Java Implementation of modules Module Tests Procedure Example - TLC Example - SBC Phase 11 Phase 12 Summary Overview Phase 10 Introduction Notations Java Implementation of modules Module Tests Procedure Example - TLC Example - SBC Phase 11 Phase 12 Summary Implementation of interfaces in Java ≪ interface ≫ if name method 1 (par1: Integer) method 2():String package project_name; public interface if_name { public void method_1 (int par1); public String method_2 (); } The project name should be added as a package. Otherwise additional parameters are necessary to compile the project. Note: int is a simple data type and and String is a class. Implementation of used interfaces in Java I A component can use / require several interfaces, defined as interface classes. public class Tuner implements PowerSupply { private LineIn outputDevice; public Tuner(){ outputDevice = NULL; } public void connectTo(LineIn par) {outputDevice = par;} } public void powerOn() { while (true) { if (outputDevice!=NULL) outputDevice.transmitMusic(); } 26 / 89 28 / 89
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