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000-833 kick Oriented Analysis and Design - fraction 1 (Analysis)

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000-833 exam Dumps Source : Object Oriented Analysis and Design - fraction 1 (Analysis)

Test Code : 000-833
Test cognomen : Object Oriented Analysis and Design - fraction 1 (Analysis)
Vendor cognomen : IBM
: 50 actual Questions

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IBM kick Oriented Analysis and

Object-Oriented analysis and Design | killexams.com actual Questions and Pass4sure dumps

This chapter is from the publication 

analysis emphasizes an investigation of the issue and requirements, in dwelling of a solution. as an example, if a brand novel on-line trading device is desired, how will it's used? What are its functions?

"evaluation" is a vast term, most useful qualified, as in necessities evaluation (an investigation of the requirements) or object-oriented analysis (an investigation of the domain objects).

Design emphasizes a conceptual solution (in application and hardware) that fulfills the necessities, in preference to its implementation. as an example, a description of a database schema and utility objects. Design concepts regularly exclude low-level or "obvious" details—obvious to the meant consumers. eventually, designs will besides exist carried out, and the implementation (similar to code) expresses the genuine and comprehensive realized design.

As with evaluation, the term is superior certified, as in object-oriented design or database design.

positive evaluation and design were summarized in the phrase Do the revise component (evaluation), and Do the component revise (design).


Object-Oriented evaluation And Design — Introduction (part 1) | killexams.com actual Questions and Pass4sure dumps

The thought Of Object-Orientation

Object-orientation is what’s known as a programming paradigm. It’s not a language itself but a set of concepts it really is supported by means of many languages.

in case you aren’t touchstone with the ideas of object-orientation, you may additionally hook a search for on the fable of Object-Oriented Programming.

If every slight thing they Do in these languages is object-oriented, it ability, we're oriented or focused around objects.

Now in an object-oriented language, this one mammoth program will as an alternative exist gash up apart into self contained objects, nearly dote having a yoke of mini-courses, each kick representing a special a fraction of the utility.

and each kick incorporates its own information and its own well-behaved judgment, and that they talk between themselves.

These objects aren’t random. They symbolize the manner you talk and feel about the vicissitude you are trying to remedy to your actual existence.

They characterize things dote personnel, photographs, monetary institution money owed, spaceships, asteroids, video segment, audio data, or something exists to your software.

Object-Oriented analysis And Design (OOAD)

It’s a structured formula for examining, designing a system by using applying the item-oriented ideas, and boost a group of graphical gadget models complete through the building lifestyles cycle of the application.

OOAD in the SDLC

The software lifestyles cycle is usually divided up into tiers going from abstract descriptions of the problem to designs then to code and trying out and finally to deployment.

The earliest stages of this process are analysis (requirements) and design.

The disagreement between evaluation and design is commonly described as “what Vs how”.

In analysis developers drudgery with users and locality experts to profile what the system is meant to do. Implementation details are presupposed to exist normally or absolutely disregarded at this phase.

The goal of the analysis fraction is to create a model of the system inspite of constraints reminiscent of usurp know-how. here's usually executed by means of expend circumstances and abstract definition of essentially the most crucial objects the expend of conceptual model.

The design fraction refines the evaluation model and applies the obligatory know-how and different implementation constrains.

It specializes in describing the objects, their attributes, habits, and interactions. The design model should acquire the entire details required in order that programmers can invoke the design in code.

They’re optimal performed in an iterative and incremental utility methodologies. So, the activities of OOAD and the developed models aren’t executed once, they are able to revisit and refine these steps constantly.

Object-Oriented evaluation

within the object-oriented analysis, we …

  • Elicit necessities: define what does the utility should do, and what’s the vicissitude the software making an attempt to pellucid up.
  • Specify requirements: relate the requirements, usually, using expend circumstances (and scenarios) or user experiences.
  • Conceptual mannequin: establish the captious objects, refine them, and define their relationships and conduct and draw them in an simple diagram.
  • We’re not going to cover the first two actions, just the final one. These are already explained in component in necessities Engineering.

    Object-Oriented Design

    The analysis angle identifies the objects, their relationship, and conduct the usage of the conceptual model (an abstract definition for the objects).

    while in design part, they relate these objects (with the aid of creating class diagram from conceptual diagram — always mapping conceptual mannequin to category diagram), their attributes, behavior, and interactions.

    in addition to applying the software design principles and patterns which could exist lined in later tutorials.

    The enter for object-oriented design is equipped through the output of object-oriented evaluation. however, analysis and design may happen in parallel, and the consequences of 1 activity will besides exist used by using the different.

    within the object-oriented design, we …

  • Describe the classes and their relationships the usage of classification diagram.
  • Describe the interplay between the objects the expend of sequence diagram.
  • observe application design ideas and design patterns.
  • a category diagram offers a visual illustration of the classes you want. And here is the dwelling you salvage to exist definitely inevitable about object-oriented principles dote inheritance and polymorphism.

    Describing the interactions between these objects allows you to improved recollect the responsibilities of the diverse objects, the behaviors they deserve to have.

    — different diagrams

    there are many different diagrams they will expend to model the system from distinctive perspectives; interactions between objects, constitution of the system, or the conduct of the gadget and the route it responds to hobbies.

    It’s complete the time about choosing the privilege diagram for the privilege want. build certain to understand which diagrams could exist advantageous when considering or discussing a condition that isn’t clear.

    equipment modeling and the distinct models they are able to expend will exist discussed subsequent.

    system Modeling

    gadget modeling is the procedure of developing models of the equipment, with every mannequin representing a different views of that equipment.

    probably the most essential point about a system mannequin is that it leaves out aspect; It’s an abstract representation of the system.

    The models are usually in accordance with graphical notation, which is almost always according to the notations within the Unified Modeling Language (UML). different models of the gadget dote mathematical model; a minute system description.

    models are used complete over the analysis process to back to elicit the necessities, privilege through the design manner to interpret the gadget to engineers, and after implementation to doc the device constitution and operation.

    different views

    We may enlarge a model to signify the gadget from different views.

  • exterior, the dwelling you model the context or the atmosphere of the system.
  • interaction, where you mannequin the interplay between components of a device, or between a system and other programs.
  • Structural, where you model the organization of the system, or the structure of the data being processed by the system.
  • Behavioral, where you model the dynamic habits of the gadget and how it respond to routine.
  • Unified Modeling Language (UML)

    The unified modeling language become the average modeling language for object-oriented modeling. It has many diagrams, besides the fact that children, essentially the most diagrams which are conventional are:

  • Use case diagram: It suggests the interplay between a paraphernalia and it’s ambiance (clients or techniques) within a particular condition.
  • classification diagram: It suggests the diverse objects, their relationship, their behaviors, and attributes.
  • Sequence diagram: It indicates the interactions between the distinctive objects within the system, and between actors and the objects in a device.
  • State computing device diagram: It indicates how the system respond to exterior and inner events.
  • recreation diagram: It indicates the waddle of the statistics between the methods within the gadget.
  • that you could Do diagramming drudgery on paper or on a whiteboard, at the least within the initial degrees of a task. however there are some diagramming tools as a route to back you to attract these UML diagrams.


    record: IBM Outpaces opponents in utility construction application marketplace for Seventh Straight year | killexams.com actual Questions and Pass4sure dumps

    source: IBM

    June 13, 2008 08:00 ET

    ARMONK, ny--(Marketwire - June 13, 2008) - IBM (NYSE: IBM) nowadays introduced that analyst hard Gartner, Inc.* and market analysis enterprise Evans statistics Corp. acquire ranked IBM as the chief within the application building application market. These rankings advance just as IBM is projecting greater than 12,000 people will attend its 2008 IBM Rational application evolution Conferences in 13 international locations worldwide.

    Gartner named IBM the global market share leader in application evolution in accordance with complete utility salary in 2007 and Evans information Corp. survey respondents who were users of IBM Rational utility Developer ranked it the number 1 integrated Developer ambiance (IDE) for user satisfaction. this is the seventh consecutive 12 months that Gartner has ranked IBM the chief and 2nd consecutive 12 months that IBM Rational application Developer changed into chosen as the Developer's option usurp IDE by route of the 1,200 builders international taking fraction in the survey.

    in line with the independent Gartner record, IBM is the main market share vendor in total software earnings, with 37.eight percent market share -- superior market share than its three closest opponents combined. The worldwide application building application market grew greater than 10% percent in 2007 to very nearly $6.9 billion, in accordance with Gartner.

    IBM became besides mentioned for its typical leadership in accordance with total utility salary for 2007 across software construction market sub-categories, together with SCCM disbursed, kick Oriented analysis & Design and Java Platform ad tool. Telelogic, currently bought by route of IBM, had a 2007 marketshare of forty.6 % within the requirements Elicitation and management category in line with complete software earnings.

    "With the upward push of globally dispensed software evolution teams, consumers are searching for skilled providers to back them collaborate in an open and transparent manner," mentioned Dr. Daniel Sabbah, common supervisor, IBM Rational software. "We harmonize with the powerful response from the Evans information and Gartner experiences coincides with the remarks we've got bought from consumers about IBM's approach round advantageous application birth."

    IBM Kicks off the world's Most Attended Developer convention sequence

    This marketshare information coincides with IBM's announcement that over 12,000 members are anticipated to attend the 15 IBM Rational application construction Conferences deliberate around the globe. Following the event held last week in Orlando, FL, IBM will hook the parade on the highway to 17 cities including Sharm El Sheikh, Egypt; San Paulo, Brazil; Bangalore, India; Shanghai, China; Rome and Milan, Italy.

    For convention attendees using an iPhone, IBM is releasing a conference scheduler written in commercial enterprise technology Language (EGL) to enable iPhone clients to dynamically journey the IBM Rational utility building conference via an interface that they feel at ease with. using internet 2.0 and social engineering ideas, users can deliver remarks on and chat about sessions, navigate the convention looking for tracks and movements, and expend artistic expertise that suggests which talks the person should attend next in keeping with preferences.

    on the annual IBM Rational application building convention in Orlando, Florida, greater than 3,500 attendees realized about novel software and courses that aid valued clientele seriously change how they're birth application on a global scale. The announcement of recent products, services and company associate initiatives are designed to transform how IBM Rational utility can assist customers force superior price and performance from their globally allotted application investments.

    shoppers unable to attend the conference in the community can view the keynote presentations on IBM tv.

    IBM helps developers tarry aggressive in trendy quick-paced evolution ambiance. imaginative classes similar to IBM developerWorks, the premier technical useful resource for application developers, and IBM alphaWorks, IBM's rising applied sciences outlet, give an online group for the builders of today and day after today. developers who're unbiased utility vendors can hook competencies of income and marketing equipment, ability-building lessons and technical aid with the aid of becoming a member of the international IBM PartnerWorld software. IBM's tutorial Initiative and IBM Rational application building convention are examples of the continuing researching and neighborhood-constructing courses needed by students, educators and developers international.

    For greater suggestions, consult with http://www.ibm.com/software/rational.

    *"Market Share: utility building software, international, 2007" by route of Laurie Wurster, Teresa Jones and Asheesh Raina, may additionally 2008.


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    Object Oriented Analysis and Design - fraction 1 (Analysis)

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    Object-Oriented Analysis And Design — Introduction (Part 1) | killexams.com actual questions and Pass4sure dumps

    The Concept Of Object-Orientation

    Object-orientation is what’s referred to as a programming paradigm. It’s not a language itself but a set of concepts that is supported by many languages.

    If you aren’t chummy with the concepts of object-orientation, you may hook a search for at The fable of Object-Oriented Programming.

    If everything they Do in these languages is object-oriented, it means, they are oriented or focused around objects.

    Now in an object-oriented language, this one big program will instead exist split apart into self contained objects, almost dote having several mini-programs, each kick representing a different fraction of the application.

    And each kick contains its own data and its own logic, and they communicate between themselves.

    These objects aren’t random. They picture the route you talk and mediate about the problem you are trying to solve in your actual life.

    They picture things dote employees, images, bank accounts, spaceships, asteroids, video segment, audio files, or whatever exists in your program.

    Object-Oriented Analysis And Design (OOAD)

    It’s a structured manner for analyzing, designing a system by applying the object-orientated concepts, and develop a set of graphical system models during the evolution life cycle of the software.

    OOAD In The SDLC

    The software life cycle is typically divided up into stages going from abstract descriptions of the problem to designs then to code and testing and finally to deployment.

    The earliest stages of this process are analysis (requirements) and design.

    The distinction between analysis and design is often described as “what Vs how”.

    In analysis developers drudgery with users and domain experts to define what the system is supposed to do. Implementation details are supposed to exist mostly or totally ignored at this phase.

    The goal of the analysis angle is to create a model of the system regardless of constraints such as usurp technology. This is typically done via expend cases and abstract definition of the most essential objects using conceptual model.

    The design angle refines the analysis model and applies the needed technology and other implementation constrains.

    It focuses on describing the objects, their attributes, behavior, and interactions. The design model should acquire complete the details required so that programmers can implement the design in code.

    They’re best conducted in an iterative and incremental software methodologies. So, the activities of OOAD and the developed models aren’t done once, they will revisit and refine these steps continually.

    Object-Oriented Analysis

    In the object-oriented analysis, we …

  • Elicit requirements: Define what does the software need to do, and what’s the problem the software trying to solve.
  • Specify requirements: relate the requirements, usually, using expend cases (and scenarios) or user stories.
  • Conceptual model: Identify the essential objects, refine them, and define their relationships and conduct and draw them in a simple diagram.
  • We’re not going to cover the first two activities, just the last one. These are already explained in detail in Requirements Engineering.

    Object-Oriented Design

    The analysis angle identifies the objects, their relationship, and conduct using the conceptual model (an abstract definition for the objects).

    While in design phase, they relate these objects (by creating class diagram from conceptual diagram — usually mapping conceptual model to class diagram), their attributes, behavior, and interactions.

    In addition to applying the software design principles and patterns which will exist covered in later tutorials.

    The input for object-oriented design is provided by the output of object-oriented analysis. But, analysis and design may occur in parallel, and the results of one activity can exist used by the other.

    In the object-oriented design, we …

  • Describe the classes and their relationships using class diagram.
  • Describe the interaction between the objects using sequence diagram.
  • Apply software design principles and design patterns.
  • A class diagram gives a visual representation of the classes you need. And here is where you salvage to exist really specific about object-oriented principles dote inheritance and polymorphism.

    Describing the interactions between those objects lets you better understand the responsibilities of the different objects, the behaviors they need to have.

    — Other diagrams

    There are many other diagrams they can expend to model the system from different perspectives; interactions between objects, structure of the system, or the conduct of the system and how it responds to events.

    It’s always about selecting the privilege diagram for the privilege need. You should realize which diagrams will exist useful when thinking about or discussing a situation that isn’t clear.

    System modeling and the different models they can expend will exist discussed next.

    System Modeling

    System modeling is the process of developing models of the system, with each model representing a different perspectives of that system.

    The most essential aspect about a system model is that it leaves out detail; It’s an abstract representation of the system.

    The models are usually based on graphical notation, which is almost always based on the notations in the Unified Modeling Language (UML). Other models of the system dote mathematical model; a minute system description.

    Models are used during the analysis process to back to elicit the requirements, during the design process to relate the system to engineers, and after implementation to document the system structure and operation.

    Different Perspectives

    We may develop a model to picture the system from different perspectives.

  • External, where you model the context or the environment of the system.
  • Interaction, where you model the interaction between components of a system, or between a system and other systems.
  • Structural, where you model the organization of the system, or the structure of the data being processed by the system.
  • Behavioral, where you model the dynamic conduct of the system and how it respond to events.
  • Unified Modeling Language (UML)

    The unified modeling language become the touchstone modeling language for object-oriented modeling. It has many diagrams, however, the most diagrams that are commonly used are:

  • Use case diagram: It shows the interaction between a system and it’s environment (users or systems) within a particular situation.
  • Class diagram: It shows the different objects, their relationship, their behaviors, and attributes.
  • Sequence diagram: It shows the interactions between the different objects in the system, and between actors and the objects in a system.
  • State machine diagram: It shows how the system respond to external and internal events.
  • Activity diagram: It shows the tide of the data between the processes in the system.
  • You can Do diagramming drudgery on paper or on a whiteboard, at least in the initial stages of a project. But there are some diagramming tools that will back you to draw these UML diagrams.


    MET CS 770 Object-Oriented Analysis & Design | killexams.com actual questions and Pass4sure dumps

    Last updated: November 13, 2002 Recent updates are often in red.

    Contacting Eric Braude changed if this is red Materials changed if this is red Forums changed if this is red Overview changed if this is red Grading changed if this is red Project Organization changed if this is red Homework and Due Dates changed if this is red        Phase 3 Required Background changed if this is red Learning Objectives changed if this is red Syllabus and Dates for Classes changed if this is red Overview

    A major engineering problem today is the predictable evolution of liable software-intensive systems. The object-oriented paradigm is an essential fraction of such development.

    Object-oriented methods can exist divided into languages, distribution, and analysis and design. There change in the language category, particularly Java and C#. Distribution includes the expend of vendor libraries of classes and besides distributed objects as specified by the kick Management Group etc.  Basic to the entire enterprise, however, are analysis and design, which has remained remarkable stable for years. Object-Oriented Analysis and Design includes the overall goals of the kick paradigm, the selection of classes, the relationships among them, and their utilization to implement systems.

    Required Background

    A lore of C++ or Java (MET CS 565) and software engineering methods (MET CS 673) are required.   It is preferable to acquire taken Design Patterns (MET CS 665).

    Materials and references

    The recommended textbook is “Applying UML and Patterns: An Introduction to Object-Oriented Analysis and Design, and the Unified Process ” by Larman (Prentice Hall) 2nd edition, Published July 2001, 627 pages, ISBN 0130925691.  This is the first time that this instructor has used this book, and it is not pellucid how much the book will exist used.

    The instructor will provide notes for complete classes.

    Other references:

  • The Unified Modeling Language User usher by Booch et al (Prentice Hall) ISBN0-201-57168-4
  • The Unified Modeling Language Reference Manual James Rumbaugh, Ivar Jacobson, Grady Booch Addison-Wesley Pub Co; ISBN: 020130998X
  • Design Patterns by Gamma et al
  • Object-Oriented Software Engineering by I Jacobson
  • Object-Oriented Analysis & Design by G. Booch
  • Modeling the world in data by S. Schlaer and S. Mellor
  • Modeling the world in states by S. Schlaer and S. Mellor
  • The Unified manner draft www.rational.com
  • Object-oriented Analysis by P. Coad and E. Yourdon
  • Object-oriented Design by P. Coad and E. Yourdon
  • Object-oriented Programming by P. Coad and A Nicola
  • Software Engineering: An Object-Oriented Perspective by Eric Braude
  • Learning Objectives

    Students will exist able to …

  • … anatomize problems from an kick perspective
  • … create OO designs which are ready for coding
  • … implement a pilot OO project
  • Grading

    The course will consist of homework and a project, weighted as follows:

    1.      Homework:                  30%

    2.      Project:                        70%

    There are three phases for the project, graded as follows:

  • phase 1 (problem statement):                            1/9
  • phase 2 (analysis):                                             2/9
  • phase 3 (design):                                               1/3
  • phase 4 (implementation and captious review): 1/3
  • Parts are evaluated equally unless otherwise stated.

    Late homework is not accepted unless there is a understanding why it was impossible for you. If there is such an impossibility, the drudgery will exist graded on a pass/fail basis.

    Project Organization

    You will exist required to submit an analyzed, designed and implemented project according to the deadlines shown in the schedule. minute requirements will follow.

    With the instructor’s permission, it may exist possible to substitute complete or fraction of the project with an investigation of tools for OOA&D such as Rational Rose or Together.  This will require a minute evaluation and an investigation of how these tools are being used extensively in a particular company.

    Teams two are permitted, and will exist evaluated at a higher standard. complete members must know complete parts.

    You will exist required to give a presentation on at least two of the phases in your project.

    Syllabus:

    This syllabus is theme to about 15% modification.

    The order of topics will exist driven by the notes, which the instructor will hand out, not by the textbook. The textbook will serve as background and reference.

    Wk. Date Topic Text

    chapters

    Project

    Times are approximate.  contemplate “date homework due” section for final dates

    1 9/3
  • Review Syllabus
  • Review Software evolution Process
  • Notes 0-1 Phase 1 assigned 2 9/10
  • Introduction, Overview, and Goals of Design
  • UML as required
  • Extreme programming and refactoring
  • Notes 1-3 3 9/17
  • Requirements I: expend Cases
  • Notes 13 fraction 1 Presentations;

    Assign angle 2

    4 9/24
  • Requirements II: Sequence Diagrams
  • Notes 13 fraction 2 Phase 1 due; 5 10/1
  • Requirements III:  Completing Domain Classes
  • Writing minute Requirements
  • Review Student Designs
  • Notes 13 fraction 3

    Larman 10

    6 10/8 Notes 14 fraction 1 Assign angle 3 7 10/22 To exist determined Presentations; angle 2 due; 8 10/29
  • Review Design Patterns as required
  • Discussion of Tools
  • Review Student Designs
  • Notes 4-6 9 11/5
  • Frameworks
  • Review Student Designs
  • Presentations on architectures 10 11/12
  • Design Topics
  • Review Student Designs
  • Notes 14 fraction 2 Assign angle 4

    Phase 3 due

    11 11/19 Presentations on minute designs 12 11/26
  • Detailed Design
  • Review Student Designs
  • Presentations 13 12/3
  • Implementing OO designs
  • Shlaer-Mellor
  • Presentation of results (1 of 2) 14 12/10
  • Presentations on Finished Applications
  • Phase 4 due Presentation of results (2 of 2)
  • Notes are from Software Design (Braude, to exist published by Wiley in March 2002)
  • ** Applying UML and Patterns: … (Larman)
  • Dates Homework is due

    Num-ber Name Due date Project angle 1 9/24 1 “Design Issues” 9/17 1 3.4 (Pass Fail) 9/17 Project angle 2: (10/2/2002

    )

    1.Attach first a copy of your angle 1.  Respond specifically to whatever comments I may acquire made on your angle 1.   You can write these directly on the copy.

    2.

    Show the sequence diagrams for at least the two expend cases you acquire introduced.  Key them to the expend case steps, which you should number.3.List requirements by “domain class” paragraphs, including

    — The testable functionality that the application will definitely accomplish

    –What you would dote to acquire the application accomplish if time permits

    Criterion: a. Requirements clearly written. (A = very pellucid description of application’s goals; no detail omitted)

    4.Provide a class diagram for your project consisting of complete of the domain classes as well as the domain packages that you will use.

    Criteria:

    b. Clarity and completeness Sufficiency of key classes for committed requirements and expend cases (A = very pellucid class meanings; no domain class missing no other domain classes required)

    g. Economy (A = no redundancy at complete in the class model)

    Here are some typical improvements.

    Most elbowroom for improvement

    1.      build your domain names specific to your application; e.g., PetStoreTransaction, FootballGame, FootballTeam rather than Transaction or Game or Team.

    2.      expend the “entities” section correctly.  This applies when there are specific entities that the application is required to have. It does not comprise entities that will exist created at runtime that you can’t specify entirely at requirements time.

    3.      Many internal classes acquire corresponding GUI classes.  For example, PetStoreAccount entities may salvage their data from a PetStoreAccountGUI entity.  Specify the latter in its own category rather than under PetStoreAccount.

    4.      In your requirements, distinguish between the initiator and the burden of functionality.

    For example, under “Courses” a functionality might exist “12.1.5 The application shall exist able to parade the catalog description of each course in the following format …”  (Corresponds to class Course).  Under the “Course GUI” paragraph an event might exist “When the parade course button is pressed, the functionality described in section 12.1.5 is initated.”  Under the “Student GUI” paragraph an event might exist “When the interpret course button is pressed, the functionality described in section 12.1.5 is initated.” Etc.

    Do not order “12.1.5 When the parade course button is pressed on the Course GUI, the application can parade the catalog description of each course in the following format …”  Otherwise you will acquire a maintenance nightmare and a penniless mapping to the design and implementation.

    5.

    Room for improvement

    1. Most

    2.

    3.

    4.

    5.

    6.

    7.

    objects are not sensitive to events unless they are GUI objects.  Buttons are examples.  Many objects acquire functionality that may exist invoked as a result of an event on an

    other object.  For example, a customer’s information may exist displayed when the button is clicked.  But “display” is a office of Customer: Any one of clients can invoke it, some event-sensitive and others not.  The kick with (direct) event reaction is the button, not the customer.

    2. In your requirements document, don’t order “The customer shall comprise a cognomen …” (which is odd English).  Instead: “The application shall maintain the cognomen of customers ….”

    3. Distinguish between objects and kick aggregates.  For example, you could acquire a “Customers” requirements paragraph with functionality such as “App shall exist able to dispatch a customer profile to the central database.”  This will correspond to a class Customer.  You could besides acquire a “Customer List”  paragraph with functionality such as “It shall exist possible to add novel customers …”  This will correspond to a class such as CustomerList.

    4. Don’t fritter words. In particular, give a sentence or two under each paragraph that adds value.

    NOT:

    1.4 Customers

    This section describes the requirements for customers.

    BUT

    1.4 Customers

    The application shall track the customers of the video store as follows. …

    1.

    10/22 3 Clown problem 10/9/02

    Draw a class model for an application for drawing human figures.  The picture shown is a typical product of the application.  The figures are always neck-upward; mouths are always lines, necks always rectangles, etc. – the shapes that issue in the figure.  Assume that the traffic will never change — but they want to exist able to easily upgrade the shop’s capability within these constraints (e.g., draw necks with various colors, novel kinds of rim lines).  The class model should build device drawing convenient (e.g., allowing the retrieval of previously constructed device parts). interpret attributes or operations whenever they clarify your solution.  comprise useful abstractions (but to extend the current business).

    There is no requirement to hook into account the GUI for the application (icons, menu’s etc.)

    Here is a scenario:

    The user … pulls onto the monitor “abeLincolnFace14” (which excludes the ears and neck)

    … adds “ear123” on the left by dragging to its vicinity and releasing

    The application places ear123 in a revise position

    The user invokes the “complete with suitable parts” command.

    The application

    … completes the device with a neck and hat that it considers most suitable.

    … creates an ear on the right, complete with matching position, interior texture and color, and styles of rim lines

    Criteria: a. completeness relative to requirements (A = enough classes for requirements, including usurp generalizations)

    b. economy of classes (A = no more than necessary for requirements)

    10/29 4 14.1 – 14.6 11/5 see more below see below

    Project angle 3: Due 11/12

    1.  Attach a copy of your angle 2 as graded by me, with specific responses to whatever comments I may acquire made on your angle 2.

    2. Provide a class diagram for your project, showing inheritance and aggregation.  interpret key methods, key dependencies, and inheritance and aggregation.   expend your packages and Facades to avoid a sole overwhelming figure.

    3. interpret at least one additional model that completes your design.

    Criteria:

    a. Clarity of the model (A = very pellucid class meanings; very pellucid organization; no unnecessary details)

    b. Adequacy of class model for effecting the requirements.  (A= minute enough to clearly allow an implementation that satisfies the requirements.)

    g. Completeness **** of models to specify the entire design. (A=right models selected; clearly no gaps in description)

    Most elbowroom for improvement

    1. If you expend a data tide diagram, argue the data types that flow.

    2. If you expend a data tide diagram, argue the functionality at each processing node.

    3. In the interest of clarity, interpret the relationships among the packages.  You can employ <<uses>> relationships.  Omit the classes from such a figure.

    Room for improvement

    1. In this course they did not give acceptation to solid lines with arrows.  interpret what you influence by them, or don’t expend them.

    2. exist specific about associations: Do you influence two-way aggregations?

    3. You acquire introduced a class whose cognomen does not argue a pellucid purpose and which is not a domain class.  interpret it’s purpose.

    A slight elbowroom for improvement

    1. …..

    Project angle 4:     Due 12/10

    Section 1 Attach Phases 2 and 3. Response to my comments on angle 3. ( not graded, but required)

    Section 2 interpret representative input and output.

    Section 3 interpret the application of complete of the steps covered in the notes — interpret if they did not apply.

    (criterion: a. Clarity and completeness — A = complete apposite steps thoroughly implemented where applicable and explained where not)

    Section 4 Provide a complete class diagram and other usurp model(s), building on the models you submitted for angle 3.

    (criterion: b. clarity and completeness — A = very clearly chosen and arranged models)

    Section 5 Account of the degree to which you accomplished your requirements as given in angle 2.  gratify refer to them by number (e.g., 11.3.5).

    (criterion: g. degree of accomplishment.  A = excellent functional capabilities for a graduate course)

    Section 6. Source code.

    (d. criterion: clarity — A = extremely pellucid layout & code; each fraction easily traceable to the corresponding design element)

    Please …

    note that your class diagrams and code must exist consistent;

    indicate complete differences with prior design decisions;

    indicate complete sections using numbered tabs (e.g., Post-it notes)

    Forums — past and present

    Fall 2001

    Fall 2002 email to the group is: 770F02@yahoogroups.com


    Object-oriented design patterns in the kernel, fraction 2 | killexams.com actual questions and Pass4sure dumps

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    June 7, 2011

    This article was contributed by Neil Brown

    In the first fraction of this analysis they looked at how the polymorphic side of object-oriented programming was implemented in the Linux kernel using regular C constructs. In particular they examined manner dispatch, looked at the different forms that vtables could take, and the circumstances where divide vtables were eschewed in preference for storing office pointers directly in objects. In this conclusion they will explore a second essential aspect of object-oriented programming - inheritance, and in particular data inheritance.

    Data inheritance

    Inheritance is a core concept of object-oriented programming, though it comes in many forms, whether prototype inheritance, mixin inheritance, subtype inheritance, interface inheritance etc., some of which overlap. The figure that is of interest when exploring the Linux kernel is most dote subtype inheritance, where a concrete or "final" kind inherits some data fields from a "virtual" parent type. They will convoke this "data inheritance" to emphasize the fact that it is the data rather than the conduct that is being inherited.

    Put another way, a number of different implementations of a particular interface share, and separately extend, a common data structure. They can exist said to inherit from that data structure. There are three different approaches to this sharing and extending that can exist create in the Linux kernel, and complete can exist seen by exploring the struct inode structure and its history, though they are widely used elsewhere.

    Extension through unions

    The first approach, which is probably the most obvious but besides the least flexible, is to declare a union as one component of the common structure and, for each implementation, to declare an entry in that union with extra fields that the particular implementation needs. This approach was introduced to struct inode in Linux-0.97.2 (August 1992) when

    union { struct minix_inode_info minix_i; struct ext_inode_info ext_i; struct msdos_inode_info msdos_i; } u;

    was added to struct inode. Each of these structures remained barren until 0.97.5 when i_data was moved from struct inode to struct ext_inode_info. Over the years several more "inode_info" fields were added for different filesystems, peaking at 28 different "inode_info" structures in 2.4.14.2 when ext3 was added.

    This approach to data inheritance is simple and straightforward, but is besides degree clumsy. There are two obvious problems. Firstly, every novel filesystem implementation needs to add an extra domain to the union "u". With 3 fields this may not look dote a problem, with 28 it was well past "ugly". Requiring every filesystem to update this one structure is a barrier to adding filesystems that is unnecessary. Secondly, every inode allocated will exist the selfsame size and will exist big enough to store the data for any filesystem. So a filesystem that wants lots of space in its "inode_info" structure will impose that space cost on every other filesystem.

    The first of these issues is not an impenetrable barrier as they will contemplate shortly. The second is a actual problem and the universal ugliness of the design encouraged change. Early in the 2.5 evolution sequence this change began; it was completed by 2.5.7 when there were no "inode_info" structures left in union u (though the union itself remained until 2.6.19).

    Embedded structures

    The change that happened to inodes in early 2.5 was effectively an inversion. The change which removed ext3_i from struct inode.u besides added a struct inode, called vfs_inode, to struct ext3_inode_info. So instead of the private structure being embedded in the common data structure, the common data structure is now embedded in the private one. This neatly avoids the two problems with unions; now each filesystem needs to only usurp recollection to store its own structure without any need to know anything about what other filesystems might need. Of course nothing ever comes for free and this change brought with it other issues that needed to exist solved, but the solutions were not costly.

    The first vicissitude is the fact that when the common filesystem code - the VFS layer - calls into a specific filesystem it passes a pointer to the common data structure, the struct inode. Using this pointer, the filesystem needs to find a pointer to its own private data structure. An obvious approach is to always dwelling the struct inode at the top of the private inode structure and simply cast a pointer to one into a pointer to the other. While this can work, it lacks any semblance of kind safety and makes it harder to disarrange fields in the inode to salvage optimal performance - as some kernel developers are wont to do.

    The solution was to expend the list_entry() macro to execute the necessary pointer arithmetic, subtracting from the address of the struct inode its offset in the private data structure and then casting this appropriately. The macro for this was called list_entry() simply because the "list.h lists" implementation was the first to expend this pattern of data structure embedding. The list_entry() macro did exactly what was needed and so it was used despite the odd name. This rehearse lasted until 2.5.28 when a novel container_of() macro was added which implemented the selfsame functionality as list_entry(), though with slightly more kind safety and a more meaningful name. With container_of() it is a simple matter to map from an embedded data structure to the structure in which it is embedded.

    The second vicissitude was that the filesystem had to exist liable for allocating the inode - it could no longer exist allocated by common code as the common code did not acquire enough information to usurp the revise amount of space. This simply involved adding alloc_inode() and destroy_inode() methods to the super_operations structure and calling them as appropriate.

    Void pointers

    As renowned earlier, the union pattern was not an impenetrable barrier to adding novel filesystems independently. This is because the union u had one more domain that was not an "inode_info" structure. A generic pointer domain called generic_ip was added in Linux-1.0.5, but it was not used until 1.3.7. Any file system that does not own a structure in struct inode itself could define and usurp a divide structure and link it to the inode through u.generic_ip. This approach addressed both of the problems with unions as no changes are needed to shared declarations and each filesystem only uses the space that it needs. However it again introduced novel problems of its own.

    Using generic_ip, each filesystem required two allocations for each inode instead of one and this could lead to more wastage depending on how the structure size was rounded up for allocation; it besides required writing more error-handling code. besides there was recollection used for the generic_ip pointer and often for a back pointer from the private structure to the common struct inode. Both of these are wasted space compared with the union approach or the embedding approach.

    Worse than this though, an extra recollection dereference was needed to access the private structure from the common structure; such dereferences are best avoided. Filesystem code will often need to access both the common and the private structures. This either requires lots of extra recollection dereferences, or it requires holding the address of the private structure in a register which increases register pressure. It was largely these concerns that stopped struct inode from ever migrating to broad expend of the generic_ip pointer. It was certainly used, but not by the major, high-performance filesystems.

    Though this pattern has problems it is still in wide use. struct super_block has an s_fs_info pointer which serves the selfsame purpose as u.generic_ip (which has since been renamed to i_private when the u union was finally removed - why it was not completely removed is left as an exercise for the reader). This is the only route to store filesystem-private data in a super_block. A simple search in the Linux comprise files shows quite a collection of fields which are void pointers named "private" or something similar. Many of these are examples of the pattern of extending a data kind by using a pointer to a private extension, and most of these could exist converted to using the embedded-structure pattern.

    Beyond inodes

    While inodes serve as an efficacious vehicle to interpose these three patterns they Do not parade the plenary scope of any of them so it is useful to search for further afield and contemplate what else they can learn.

    A survey of the expend of unions elsewhere in the kernel shows that they are widely used though in very different circumstances than in struct inode. The particular aspect of inodes that is missing elsewhere is that a wide orbit of different modules (different filesystems) each wanted to extend an inode in different ways. In most places where unions are used there are a wee fixed number of subtypes of the basis kind and there is slight expectation of more being added. A simple example of this is struct nfs_fattr which stores file impute information decoded out of an NFS reply. The details of these attributes are slightly different for NFSv2 and NFSv3 so there are effectively two subtypes of this structure with the disagreement encoded in a union. As NFSv4 uses the selfsame information as NFSv3 this is very unlikely to ever exist extended further.

    A very common pattern in other uses of unions in Linux is for encoding messages that are passed around, typically between the kernel and user-space. struct siginfo is used to convey extra information with a signal delivery. Each signal kind has a different kind of ancillary information, so struct siginfo has a union to encode six different subtypes. union inputArgs appears to exist the largest current union with 22 different subtypes. It is used by the "coda" network file system to pass requests between the kernel module and a user-space daemon which handles the network communication.

    It is not pellucid whether these examples should exist considered as the selfsame pattern as the original struct inode. Do they really picture different subtypes of a basis type, or is it just one kind with internal variants? The Eiffel object-oriented programming language does not back variant types at complete except through subtype inheritance so there is clearly a school of thought that would want to deal complete usages of union as a figure of subtyping. Many other languages, such as C++, provide both inheritance and unions allowing the programmer to build a choice. So the retort is not clear.

    For their purposes it doesn't really matter what they convoke it as long as they know where to expend each pattern. The examples in the kernel fairly clearly interpret that when complete of the variants are understood by a sole module, then a union is a very usurp mechanism for variants structures, whether you want to refer to them as using data inheritance or not. When different subtypes are managed by different modules, or at least widely divide pieces of code, then one of the other mechanisms is preferred. The expend of unions for this case has almost completely disappeared with only struct cycx_device remaining as an example of a deprecated pattern.

    Problems with void pointers

    Void pointers are not quite so simple to classify. It would probably exist just to order that void pointers are the modern equivalent of "goto" statements. They can exist very useful but they can besides lead to very convoluted designs. A particular problem is that when you search for at a void pointer, dote looking at a goto, you don't really know what it is pointing at. A void pointer called private is even worse - it is dote a "goto destination" command - almost purposeless without reading lots of context.

    Examining complete the different uses that void pointers can exist achieve to would exist well beyond the scope of this article. Instead they will restrict their attention to just one novel usage which relates to data inheritance and illustrates how the untamed nature of void pointers makes it hard to recognize their expend in data inheritance. The example they will expend to interpret this usage is struct seq_file used by the seq_file library which makes it simple to synthesize simple text files dote some of those in /proc. The "seq" fraction of seq_file simply indicates that the file contains a sequence of lines corresponding to a sequence of items of information in the kernel, so /proc/mounts is a seq_file which walks through the mount table reporting each mount on a sole line.

    When seq_open() is used to create a novel seq_file it allocates a struct seq_file and assigns it to the private_data domain of the struct file which is being opened. This is a straightforward example of void pointer based data inheritance where the struct file is the basis kind and the struct seq_file is a simple extension to that type. It is a structure that never exists by itself but is always the private_data for some file. struct seq_file itself has a private domain which is a void pointer and it can exist used by clients of seq_file to add extra status to the file. For example md_seq_open() allocates a struct mdstat_info structure and attaches it via this private field, using it to meet md's internal needs. Again, this is simple data inheritance following the described pattern.

    However the private domain of struct seq_file is used by svc_pool_stats_open() in a subtly but importantly different way. In this case the extra data needed is just a sole pointer. So rather than allocating a local data structure to refer to from the private field, svc_pool_stats_open simply stores that pointer directly in the private domain itself. This certainly seems dote a sensible optimization - performing an allocation to store a sole pointer would exist a fritter - but it highlights exactly the source of confusion that was suggested earlier: that when you search for at a void pointer you don't really know what is it pointing at, or why.

    To build it a bit clearer what is happening here, it is helpful to imagine "void *private" as being dote a union of every different possible pointer type. If the value that needs to exist stored is a pointer, it can exist stored in this union following the "unions for data inheritance" pattern. If the value is not a sole pointer, then it gets stored in allocated space following the "void pointers for data inheritance" pattern. Thus when they contemplate a void pointer being used it may not exist obvious whether it is being used to point to an extension structure for data inheritance, or being used as an extension for data inheritance (or being used as something else altogether).

    To highlight this issue from a slightly different perspective it is instructive to examine struct v4l2_subdev which represents a sub-device in a video4linux device, such as a sensor or camera controller within a webcam. According to the (rather helpful) documentation it is expected that this structure will normally exist embedded in a larger structure which contains extra state. However this structure still has not just one but two void pointers, both with names suggesting that they are for private expend by subtypes:

    /* pointer to private data */ void *dev_priv; void *host_priv;

    It is common that a v4l sub-device (a sensor, usually) will exist realized by, for example, an I2C device (much as a bury device which stores your filesystem might exist realized by an ATA or SCSI device). To allow for this common occurrence, struct v4l2_subdev provides a void pointer (dev_priv), so that the driver itself doesn't need to define a more specific pointer in the larger structure which struct v4l2_subdev would exist embedded in. host_priv is intended to point back to a "parent" device such as a controller which acquires video data from the sensor. Of the three drivers which expend this field, one appears to follow that end while the other two expend it to point to an allocated extension structure. So both of these pointers are intended to exist used following the "unions for data inheritance" pattern, where a void pointer is playing the role of a union of many other pointer types, but they are not always used that way.

    It is not immediately pellucid that defining this void pointer in case it is useful is actually a valuable service to provide given that the device driver could easily enough define its own (type safe) pointer in its extension structure. What is pellucid is that an apparently "private" void pointer can exist intended for various qualitatively different uses and, as they acquire seen in two different circumstances, they may not exist used exactly as expected.

    In short, recognizing the "data inheritance through void pointers" pattern is not easy. A fairly abysmal examination of the code is needed to determine the exact purpose and usage of void pointers.

    A diversion into struct page

    Before they leave unions and void pointers behind a search for at struct page may exist interesting. This structure uses both of these patterns, though they are hidden degree due to historical baggage. This example is particularly instructive because it is one case where struct embedding simply is not an option.

    In Linux recollection is divided into pages, and these pages are achieve to a variety of different uses. Some are in the "page cache" used to store the contents of files. Some are "anonymous pages" holding data used by applications. Some are used as "slabs" and divided into pieces to retort kmalloc() requests. Others are simply fraction of a multi-page allocation or maybe are on a free list waiting to exist used. Each of these different expend cases could exist seen as a subtype of the universal class of "page", and in most cases need some dedicated fields in struct page, such as a struct address_space pointer and index when used in the page cache, or struct kmem_cache and freelist pointers when used as a slab.

    Each page always has the selfsame struct page describing it, so if the efficacious kind of the page is to change - as it must as the demands for different uses of recollection change over time - the kind of the struct page must change within the lifetime of that structure. While many kind systems are designed assuming that the kind of an kick is immutable, they find here that the kernel has a very actual need for kind mutability. Both unions and void pointers allow types to change and as noted, struct page uses both.

    At the first even of subtyping there are only a wee number of different subtypes as listed above; these are complete known to the core recollection management code, so a union would exist ideal here. Unfortunately struct page has three unions with fields for some subtypes spread over complete three, thus hiding the actual structure somewhat.

    When the primary subtype in expend has the page being used in the page cache, the particular address_space that it belongs to may want to extend the data structure further. For this purpose there is a private domain that can exist used. However it is not a void pointer but is an unsigned long. Many places in the kernel assume an unsigned long and a void * are the selfsame size and this is one of them. Most users of this domain actually store a pointer here and acquire to cast it back and forth. The "buffer_head" library provides macros attach_page_buffers and page_buffers to set and salvage this field.

    So while struct page is not the most elegant example, it is an informative example of a case where unions and void pointers are the only option for providing data inheritance.

    The details of structure embedding

    Where structure embedding can exist used, and where the list of possible subtypes is not known in advance, it seems to exist increasingly the preferred choice. To gain a plenary understanding of it they will again need to explore a slight bit further than inodes and contrast data inheritance with other uses of structure embedding.

    There are essentially three uses for structure embedding - three reasons for including a structure within another structure. Sometimes there is nothing particularly challenging going on. Data items are collected together into structures and structures within structures simply to highlight the closeness of the relationships between the different items. In this case the address of the embedded structure is rarely taken, and it is never mapped back to the containing structure using container_of().

    The second expend is the data inheritance embedding that they acquire already discussed. The third is dote it but importantly different. This third expend is typified by struct list_head and other structs used as an embedded anchor when creating abstract data types.

    The expend of an embedded anchor dote struct list_head can exist seen as a style of inheritance as the structure containing it "is-a" member of a list by virtue of inheriting from struct list_head. However it is not a strict subtype as a sole kick can acquire several struct list_heads embedded - struct inode has six (if they comprise the similar hlist_node). So it is probably best to mediate of this sort of embedding more dote a "mixin" style of inheritance. The struct list_head provides a service - that of being included in a list - that can exist mixed-in to other objects, an arbitrary number of times.

    A key aspect of data inheritance structure embedding that differentiates it from each of the other two is the actuality of a reference counter in the inner-most structure. This is an observation that is tied directly to the fact that the Linux kernel uses reference counting as the primary means of lifetime management and so would not exist shared by systems that used, for example, garbage collection to manage lifetimes.

    In Linux, every kick with an independent actuality will acquire a reference counter, sometimes a simple atomic_t or even an int, though often a more explicit struct kref. When an kick is created using several levels of inheritance the reference counter could exist buried quite deeply. For example a struct usb_device embeds a struct device which embeds struct kobject which has a struct kref. So usb_device (which might in revolve exist embedded in a structure for some specific device) does acquire a reference counter, but it is contained several levels down in the nest of structure embedding. This contrasts quite nicely with a list_head and similar structures. These acquire no reference counter, acquire no independent actuality and simply provide a service to other data structures.

    Though it seems obvious when achieve this way, it is useful to recollect that a sole kick cannot acquire two reference counters - at least not two lifetime reference counters (It is fine to acquire two counters dote s_active and s_count in struct super_block which matter different things). This means that multiple inheritance in the "data inheritance" style is not possible. The only figure of multiple inheritance that can drudgery is the mixin style used by list_head as mentioned above.

    It besides means that, when designing a data structure, it is essential to mediate about lifetime issues and whether this data structure should acquire its own reference counter or whether it should depend on something else for its lifetime management. That is, whether it is an kick in its own right, or simply a service provided to other objects. These issues are not really novel and apply equally to void pointer inheritance. However an essential disagreement with void pointers is that it is relatively simple to change your intelligence later and switch an extension structure to exist a fully independent object. Structure embedding requires the discipline of thinking clearly about the problem up front and making the privilege conclusion early - a discipline that is worth encouraging.

    The other key telltale for data inheritance structure embedding is the set of rules for allocating and initializing novel instances of a structure, as has already been hinted at. When union or void pointer inheritance is used the main structure is usually allocated and initialized by common code (the mid-layer) and then a device specific open() or create() office is called which can optionally usurp and initialize any extension object. By contrast when structure embedding is used the structure needs to exist allocated by the lowest even device driver which then initializes its own fields and calls in to common code to initialize the common fields.

    Continuing the struct inode example from above which has an alloc_inode() manner in the super_block to request allocation, they find that initialization is provided for with inode_init_once() and inode_init_always() back functions. The first of these is used when the previous expend of a piece of recollection is unknown, the second is enough by itself when they know that the recollection was previously used for some other inode. They contemplate this selfsame pattern of an initializer office divide from allocation in kobject_init(), kref_init(), and device_initialize().

    So apart from the obvious embedding of structures, the pattern of "data inheritance through structure embedding" can exist recognized by the presence of a reference counter in the innermost structure, by the delegation of structure allocation to the final user of the structure, and by the provision of initializing functions which initialize a previously allocated structure.

    Conclusion

    In exploring the expend of manner dispatch (last week) and data inheritance (this week) in the Linux kernel they find that while some patterns look to dominate they are by no means universal. While almost complete data inheritance could exist implemented using structure embedding, unions provide actual value in a few specific cases. Similarly while simple vtables are common, mixin vtables are very essential and the competence to delegate methods to a related kick can exist valuable.

    We besides find that there are patterns in expend with slight to recommend them. Using void pointers for inheritance may acquire an initial simplicity, but causes longer term wastage, can antecedent confusion, and could nearly always exist replaced by embedded inheritance. Using NULL pointers to argue default conduct is similarly a penniless altenative - when the default is essential there are better ways to provide for it.

    But maybe the most valuable lesson is that the Linux kernel is not only a useful program to run, it is besides a useful document to study. Such study can find elegant practical solutions to actual problems, and some less elegant solutions. The willing student can pursue the former to back ameliorate their mind, and pursue the latter to back ameliorate the kernel itself. With that in mind, the following exercises might exist of interest to some.

    Exercises
  • As inodes now expend structure embedding for inheritance, void pointers should not exist necessary. Examine the consequences and wisdom of removing "i_private" from "struct inode".

  • Rearrange the three unions in struct page to just one union so that the enumeration of different subtypes is more explicit.

  • As was renowned in the text, struct seq_file can exist extended both through "void pointer" and a limited figure of "union" data inheritance. interpret how seq_open_private() allows this structure to besides exist extended through "embedded structure" data inheritance and give an example by converting one usage in the kernel from "void pointer" to "embedded structure". reckon submitting a patch if this appears to exist an improvement. Contrast this implementation of embedded structure inheritance with the mechanism used for inodes.

  • Though subtyping is widely used in the kernel, it is not uncommon for a kick to contain fields that not complete users are interested in. This can argue that more fine grained subtyping is possible. As very many completely different things can exist represented by a "file descriptor", it is likely that struct file could exist a candidate for further subtyping.

    Identify the smallest set of fields that could serve as a generic struct file and explore the implications of embedding that in different structures to implement regular files, socket files, event files, and other file types. Exploring more universal expend of the proposed open() manner for inodes might back here.

  • Identify an "object-oriented" language which has an kick model that would meet complete the needs of the Linux kernel as identified in these two articles.

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