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Synthetic OO Design Concepts & Reuse Lecture 8: Modeling & documenting collaborations

Synthetic OO Design Concepts & Reuse Lecture 8: Modeling & documenting collaborations. Topics: Synthesis of multiple collaborations Documenting collaborations with abstract roles A “model” of reuse in role-based designs. New concepts.

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Synthetic OO Design Concepts & Reuse Lecture 8: Modeling & documenting collaborations

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  1. Synthetic OO Design Concepts & ReuseLecture 8: Modeling & documenting collaborations Topics: Synthesis of multiple collaborations Documenting collaborations with abstract roles A “model” of reuse in role-based designs CSE 335: Software Design

  2. New concepts Collaboration:Contextual relationship among instances that interact to implement a desired functionality • pattern of message exchange among those instances to achieve some goal • protocol Role:that subset of an object’s characteristics needed to fulfill its responsibilities in a collaboration • alternatively, a “slot” that can be filled by objects that wish to participate in the collaboration • such objects are said to “play” the role Observe: Both definitions refer to instances Goals: • Design reusable collaborations • Compose applications by synthesizing collaborations CSE 335: Software Design

  3. Example Suppose we want to design a graphical browser that allows users to view and print documents Two collaborations here: • A viewPort that displays lines of text, which it receives by collaborating with a docMgr; and • A printButton that sends messages to docMgr to cause it to print. Observe: • docMgr object is involved in both collaborations • It plays a different role in each CSE 335: Software Design

  4. #ifndef VIEWPORT_H #define VIEWPORT_H #include <FL/Fl_Multiline #include “ViewPortModel.h class ViewPort : public public: ViewPort( int x, int y, unsigned numberOfLines Print Graphical depiction of example app Note:The unseen document manager is serving lines from file “ViewPort.h” CSE 335: Software Design

  5. Motivation: Explaining a design Modern OO systems comprise lots of collaborations To understand such systems, requires visualizing: • the inter-connection of these objects (i.e., structure) • the dynamic interactions among these objects (i.e., behavior) Problem: How can we visualize these phenomena in a useful way? CSE 335: Software Design

  6. Sequence diagrams Illustrate one instance of one collaboration among multiple objects Feature: • Use of spatial position to reflect time dimension • Use of vertical bars to denote object “activity” • Graphic denotation of returns from operations Note: Because it depicts only one instance, a single sequence diagram rarely sufficient to fully document a collaboration CSE 335: Software Design

  7. Example sequence diagram sd clickPrint print : Button docMgr : MyDocManager userEvent() buttonPressed(“Print”) printDocument() CSE 335: Software Design

  8. Example sequence diagram (continued) sd clickPrint print : Button docMgr : MyDocManager userEvent() buttonPressed(“Print”) printDocument() activations CSE 335: Software Design

  9. Example sequence diagram (continued) sd clickPrint print : Button docMgr : MyDocManager userEvent() buttonPressed(“Print”) printDocument() messages CSE 335: Software Design

  10. Example sequence diagram (continued) sd clickPrint print : Button docMgr : MyDocManager userEvent() buttonPressed(“Print”) printDocument() return messages CSE 335: Software Design

  11. New concept: Role Defn: A “slot” that can be filled by many different object (or link) instances Example: The ButtonListener “object” in a design that uses buttons • Not really any such thing as a ButtonListener “object” • But lots of objects can be “plugged into” that slot. Design tip: Identification of roles enables the design of reusable collaborations CSE 335: Software Design

  12. Reusable interaction, defined using a role sd clickButton : Button listener : ButtonListener userEvent() buttonPressed(…) CSE 335: Software Design

  13. Instance of an abstract class? sd clickButton : Button listener : ButtonListener userEvent() buttonPressed(…) Notice: OK to depict what appears to be an “instance” of an abstract class in this situation CSE 335: Software Design

  14. listeners Collaboration diagram Button–ButtonListener button : Button listener : ButtonListener [0..*] Example of a collaboration diagram. CSE 335: Software Design

  15. Collaboration diagram Button–ButtonListener role name type role name type multiplicity listeners button : Button listener : ButtonListener [0..*] connector role role Example of a collaboration diagram. CSE 335: Software Design

  16. Collaboration + seq diagrams A reusable collaboration is specified using: • One collaboration diagram that names all of the roles and connectors and specifies any relevant multiplicities • Multiple sequence diagrams, each depicting a “key” behavior among the objects that and links that play roles in the collaboration Such documentation much more useful than “header” comments in the code  CSE 335: Software Design

  17. Another useful collaboration Viewport–ViewPortModel CSE 335: Software Design

  18. #ifndef VIEWPORT_H #define VIEWPORT_H #include <FL/Fl_Multiline #include “ViewPortModel.h class ViewPort : public public: ViewPort( int x, int y, unsigned numberOfLines Print Recall the running example... Note:The unseen document manager is serving lines from file “ViewPort.h” CSE 335: Software Design

  19. Exercise Draw a sequence diagram that depicts the interaction between a viewport object (vp) and a DocumentManager object (docMgr) when vp is resized CSE 335: Software Design

  20. Example: Class DocManager class DocManager { public: … void printDocument() const; unsigned docSize() const; const string& docLine( unsigned ) const; void insertLine( unsigned, const string& ); void appendLine( const string& ); void deleteLine( unsigned ); }; CSE 335: Software Design

  21. Example: Sequence diagram sd resizeView vp : ViewPort docMgr : MyDocManager resize() update() docSize() retrieve( 0, .... ) docLine(0,...) docSize() retrieve( 1, .... ) docLine(1,...) docSize() retrieve( n-1, .... ) docLine(n-1,...) CSE 335: Software Design

  22. Question Consider the interaction between the document manager and a viewport that displays its contents. Are there any opportunities for role abstraction in this interaction? CSE 335: Software Design

  23. When vp collaborates with a docMgr... sd resizeView vp : ViewPort docMgr : MyDocManager resize() update() docSize() retrieve( 0, .... ) docLine(0,...) docSize() retrieve( 1, .... ) docLine(1,...) docSize() retrieve( n-1, .... ) docLine(n-1,...) CSE 335: Software Design

  24. More general (reusable) interaction using the abstract role “model” sd refreshView : ViewPort model : ViewPortModel update() retrieve(n) * CSE 335: Software Design

  25. model Collaboration diagram ViewPort–ViewPortModel vp : ViewPort vpm : ViewPortModel Example of a collaboration diagram. CSE 335: Software Design

  26. Reusable class ViewPort class ViewPort : public Fl_Multiline_Output { public: ViewPort( int x, int y, int w, int h ); unsigned capacity() const; void setModel( ViewPortModel* ); protected: ViewPortModel* model; void resize(int, int, int, int); void update(); }; Question:Why is this method protected, rather than public? CSE 335: Software Design

  27. ViewportModel interface class ViewPortModel { public: virtual bool retrieve( unsigned lineNumber, string& line ) const =0; }; CSE 335: Software Design

  28. Example: ViewPort::Update method void ViewPort::update() { if (!model) return; string contents, str; const string endofline("\n"); for (int i=0; i < upperBound; i++) { if( model->retrieve(i, str) ) { contents += str; contents += endofline; } } value(contents.c_str()); } CSE 335: Software Design

  29. Example: Synthesis of multiple roles class MyDocManager : public DocManager, public ButtonListener, public ViewPortModel { public: void buttonPressed( const string& s ) { if(s == “print”) DocManager::printDocument(); } bool retrieve( unsigned lineNo, string& line ) const { bool retVal = (lineNo < DocManager::docSize()); if (retVal) line = DocManager::docLine(lineNo); return retVal; } }; CSE 335: Software Design

  30. Configuration code int main(void) { ContainerWindow myContainer(500,150); MyDocManager docMgr(...); Button printButton(200, 80, “Print"); ViewPort viewPort(0,0, 350, 120); printButton.addListener(&docMgr); viewPort.setModel(&docMgr); myContainer.end(); myContainer.show(); return Fl::run(); } CSE 335: Software Design

  31. Terminology Collaboration: Contextual relationship among instances that interact to implement a desired functionality Collaboration diagram: A diagram describing the structural relationship among the roles in a collaboration Collaboration role: A “slot” for an object or link within a collaboration. It specifies the kind of object or link that may appear in an instance of the collaboration. CSE 335: Software Design

  32. ScrollBar collaboration sd moveHandle : ScrollBar listener : ValuatorListener userEvent() announceNewValue(n) CSE 335: Software Design

  33. Exercise Integrate a scrollbar object into our viewport–docManager collaboration. Draw a sequence diagram to illustrate what happens when the user drags the slider handle to a new position. CSE 335: Software Design

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