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SOEN 343 Software Design Computer Science and Software Engineering Department Concordia University Fall 2004 Instructor: Patrice Chalin
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Agenda – Lecture 6a Review & renew Design principles Servlets, JSPs
(Homework) Solutions to Exercise Set 4. UML: visibility Design principles Encapsulation and information hiding. GRASP: Controller. Servlets, JSPs MVC 4/21/2019 SOEN 343, © P.Chalin,
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Homework was … Planned (e.g. MDD) vs. Evolutionary (e.g. XP)
How does each approach address: No doc. produced. Increased gap: design vs. implementation. Add-on syndrome. 4/21/2019 SOEN 343, © P.Chalin,
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Homework Planned (e.g. MDD) vs. Evolutionary (e.g. XP)
How does each approach address: No doc. produced: MDD: design documentation is the code. XP: code is the design documentation . Increased gap: design vs. implementation : doc must be maintained because it is the code. Add-on syndrome: refactoring. 4/21/2019 SOEN 343, © P.Chalin,
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Enterprise Application Layers
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Enterprise Application Layers
Presentation Domain Logic Data Source 4/21/2019 SOEN 343, © P.Chalin,
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Web EA Overhead 4/21/2019 SOEN 343, © P.Chalin,
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Layering (Larman) See Larman Sect 30.2 for examples of layer content.
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Exercise Set 4 Solution covered in class. SOEN 343, © P.Chalin,
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Code Sample: Class C public class C { private static int sc = 0;
private int c = 0; public void m() { ….println(“sc=” + sc++); ….println(“c=” + c++); } 4/21/2019 SOEN 343, © P.Chalin,
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Code Sample: Using C C c = new C(); c.m(); C c2 = new C(); c2.m();
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UML Class Diagrams: Visibility
public int a + a: int private int a - a: int protected int a # a: int /* package */ int a ~ a: int int a ~ a: int 4/21/2019 SOEN 343, © P.Chalin,
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[Encapsulation and Information Hiding]-----------------
![[Encapsulation and Information Hiding]](http://slideplayer.com/slide/16521043/96/images/13/%5BEncapsulation+and+Information+Hiding%5D.jpg "[Encapsulation and Information Hiding]")
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Access points at interface
Encapsulation A programming/design language mechanism. A packaging / scoping mechanism for names Names can refer to data, types, … Especially, a means of packaging data. Access points at interface 4/21/2019 SOEN 343, © P.Chalin,
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Information Hiding Design principle by which a module is assigned a “secret”. A module’s secret is usually A design decision. What type of design decisions might we want to hide from the clients of a module? 4/21/2019 SOEN 343, © P.Chalin,
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Information Hiding Often one hides, e.g.
Data representation. Choice of algorithm. Interface details / access mechanism of external entity (e.g. database, hardware) … Goal: particular design choice “invisible” to clients. Why would we want to do this? 4/21/2019 SOEN 343, © P.Chalin,
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Information Hiding Information Hiding may or may not be supported a the programming language level. 4/21/2019 SOEN 343, © P.Chalin,
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Servlet: HelloWeb public class HelloWebServlet extends HttpServlet {
protected void doGet( HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException ServletOutputStream out = response.getOutputStream(); out.println("Hello Web!"); } 4/21/2019 SOEN 343, © P.Chalin,
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Java Server Page Servlet: JSP Embed HTML inside code.
Embed code inside HTML. 4/21/2019 SOEN 343, © P.Chalin,
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HelloWeb.jsp <%@ page
contentType="text/html; charset=iso " language="java" ... %> <html> <body> Hello Web! </body> </html> 4/21/2019 SOEN 343, © P.Chalin,
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Hello.jsp page contentType="text/html; charset=iso " language="java" ... %> <html> <body> Hello <%= request.getParameter("name") %> </body> </html> 4/21/2019 SOEN 343, © P.Chalin,
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Java Server Page Implemented as a (special kind of) servlet.
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