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Web engineering

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Analysis of web based applications

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Web engineering

  1. 1. 1 Web Engineering A presentation by Athul Sai(P3MCA12012) Sreejith S(P3MCA12036)
  2. 2. 2 Web Applicat ions  WebApps encompass:  complete Web sites  Simple information Web sites  Complex e-Commerce of other sites with embedded functionality and data retrieval  Complex Web sites that are interoperable with other legacy software and systems  specialized functionality within Web sites  information processing applications that reside on the Internet or on an intranet or ExtraNet.
  3. 3. 3 WebApp At t ribut es—I  Network intensiveness. A WebApp resides on a network and must serve the needs of a diverse community of clients.  Concurrency. A large number of users may access the WebApp at one time; patterns of usage among end-users will vary greatly.  Unpredictable load. The number of users of the WebApp may vary by orders of magnitude from day to day.  Performance. If a WebApp user must wait too long (for access, for server-side processing, for client-side formatting and display), he or she may decide to go elsewhere.
  4. 4. 4 WebApp At t ribut es—I I  Availability. Although expectation of 100 percent availability is unreasonable, users of popular WebApps often demand access on a “24/7/365” basis.  Data driven. The primary function of many WebApps is to use hypermedia to present text, graphics, audio, and video content to the end-user.  Content sensitive. The quality and aesthetic nature of content remains an important determinant of the quality of a WebApp.  Continuous evolution. Unlike conventional application software that evolves over a series of planned, chronologically-spaced releases, Web applications evolve continuously.
  5. 5. 5 WebApp At t ribut es—I I I  Immediacy. WebApps often exhibit a time to market that can be a matter of a few days or weeks.  With modern tools, sophisticated Web pages can be produced in only a few hours.  Security. In order to protect sensitive content and provide secure modes of data transmission, strong security measures must be implemented throughout the infrastructure that supports a WebApp and within the application itself.  Aesthetics. When an application has been designed to market or sell products or ideas, aesthetics may have as much to do with success as technical design.
  6. 6. 6 WebApp Cat egories  informational—read-only content is provided with simple navigation and links  download—a user downloads information from the appropriate server  customizable—the user customizes content to specific needs  interaction—communication among a community of users occurs via chatroom, bulletin boards, or instant messaging  user input—forms-based input is the primary mechanism for communicating need  transaction-oriented—the user makes a request (e.g., places an order) that is fulfilled by the WebApp  service-oriented—the application provides a service to the user, e.g., assists the user in determining a mortgage payment  Portal—the application channels the user to other Web content or services outside the domain of the portal application  database access—the user queries a large database and extracts information  data warehousing—the user queries a collection of large databases and extracts information
  7. 7. WebE layers 7
  8. 8. 8 The WebE Process  Must accommodate:  Incremental delivery  Frequent changes  Short timeline  Therefore,  An incremental process model should be used in virtually all situations  An agile process model is appropriate in many situations
  9. 9. 9 The WebE Process sof t ware increment Release refact oring business analysis formulat ion it erat ion plan analysis model content iteration function configuration design model content architecture navigation interface coding component t est accept ance t est cust omer use cust omer evaluat ion
  10. 10. 10 The WebE Process Framework—I  Customer communication  Business analysis defines the business/organizational context for the WebApp.  Formulation is a requirements gathering activity involving all stakeholders. The intent is to describe the problem that the WebApp is to solve  Planning  The “plan” consists of a task definition and a timeline schedule for the time period (usually measured in weeks) projected for the development of the WebApp increment.
  11. 11. 11 The WebE Process Framework—I I  Modeling  Analysis model—establishes a basis for design  Content Analysis.  Interaction Analysis.  Functional Analysis.  Configuration Analysis.  Design model—represents key WebApp elements  Content design  Aesthetic design  Architectural design  Interface design  Navigation design  Component design
  12. 12. 12 The WebE Process Framework—I I I  Construction  WebE tools and technology are applied to construct the WebApp that has been modeled  Testing of all design elements  Delivery and Evaluation (Deployment)  configure for its operational environment  deliver to end-users, and  Evaluation feedback is presented to the WebE team  the increment is modified as required (the beginning of the next incremental cycle)
  13. 13. 13 WebE—Best Pract ices  Take the time to understand the business needs and product objectives, even if the details of the WebApp are vague.  Describe how users will interact with the WebApp using a scenario-based approach  Develop a project plan, even it its very brief.  Spend some time modeling what it is that you’re going to build.  Review the models for consistency and quality.  Use tools and technology that enable you to construct the system with as many reusable components as possible.  Don’t rely on early users to debug the WebApp—design comprehensive tests and execute them before releasing the system.
  14. 14. 14 Analysis Modeling f or WebApps
  15. 15. 15 Analysis  Content Analysis. The full spectrum of content to be provided by the WebApp is identified, including text, graphics and images, video, and audio data. Data modeling can be used to identify and describe each of the data objects.  Interaction Analysis. The manner in which the user interacts with the WebApp is described in detail. Use-cases can be developed to provide detailed descriptions of this interaction.  Functional Analysis. The usage scenarios (use-cases) created as part of interaction analysis define the operations that will be applied to WebApp content and imply other processing functions. All operations and functions are described in detail.  Configuration Analysis. The environment and infrastructure in which the WebApp resides are described in detail.
  16. 16. 16 When Do We Perf orm Analysis?  In some WebE situations, analysis and design merge. However, an explicit analysis activity occurs when …  the WebApp to be built is large and/or complex  the number of stakeholders is large  the number of Web engineers and other contributors is large  the goals and objectives (determined during formulation) for the WebApp will effect the business’ bottom line  the success of the WebApp will have a strong bearing on the success of the business
  17. 17. 17 The User Hierarchy SafeHomeAssured.com user Figure 18.1 User hierarchy for SafeHomeAssured.com guest regist ered user cust omer service st aff exist ing cust omernew cust omer
  18. 18. 18 Use-Case Diagram Figure 18.2 Use-case diagram f or new-cust omer new customer log-in to SafeHomeAssured.com customize SafeHome describe home layout select SafeHome components save configuration purchase conf iguration view shopping cart provide purchase data recall saved configuration peruse descriptive content complete SafeHome order customization functionality e-commerce functionality <<inc lude>> <<inc lude>> <<inc lude>> <<inc lude>> <<inc lude>> <<inc lude>>
  19. 19. 19 The Cont ent Model  Content objects are extracted from use-cases  examine the scenario description for direct and indirect references to content  Attributes of each content object are identified  The relationships among content objects and/or the hierarchy of content maintained by a WebApp  Relationships—entity-relationship diagram or UML  Hierarchy—data tree or UML
  20. 20. 20 Dat a Tree Figure 1 8 .3 Dat a t ree for aSafeHom e com ponent component part Number part Name part Type description price MarketingDescript ion Phot ograph TechDescript ion Schemat ic Video WholesalePrice Ret ailPrice
  21. 21. 21 Analysis Classes  Analysis classes are derived by examining each use-case  A grammatical parse is used to identify candidate classes  A UML class diagram is developed for each analysis class
  22. 22. 22 Analysis Class Example Figure 18.4 Analysis classes for use-case: select SafeHomecomponents BillOfMat erials ident ifier priceTot al addEnt ry( ) delet eEnt ry( ) edit Ent ry( ) name( ) save( ) comput ePrice( ) Product Component part Number part Name part Type descript ion price creat eNewIt em( ) get Descript ion( ) get TechSpec BoMIt em quant it y price addt oList( ) delet efromList( ) Sensor Camera Cont rolPanel Soft Feat ure 1 * 1 *
  23. 23. 23 The I nt eract ion Model  Composed of four elements:  use-cases  sequence diagrams  state diagrams  a user interface prototype  Each of these is an important UML notation
  24. 24. 24 Sequence Diagram Figure 18.5 Sequence diagram for use-case:select SafeHomecomponents new cust omer :Room :FloorPlan desc ribes room * plac es room in f loor plan :Product Component selec t s produc t c om ponent * :Billof Mat erials add t o BoM FloorPlan Reposit ory sav e f loor plan c onf igurat ion sav e bill of m at erials BoM Reposit ory
  25. 25. 25 St at e Diagram Figure 1 8 .6 Part ial st at e diagram for ne w c ust ome rinteract ion n e w cu st o m e r Validating user system status=“input ready” displaymsg = “enteruserid” displaymsg =“enterpswd” entry/ log-in requested do: run user validation exit/set user access switch select “log-in” userid validated password validated Selecting user action system status=“link ready” display: navigation choices” entry/ validated user do: link as required exit/user action selected select other functions select customization functionality select e-commerce (purchase) functionality Customizing system status=“input ready” display: basic instructions entry/validated user do: process user selection exit/ customization terminated select descriptive content room being defined Defining room system status=“input ready” display: roomdef. window entry/ roomdef.selected do: run room queries do: store room variables exit/room completed select descriptive content Building floor plan system status=“input ready” display: floor plan window entry/ floor plan selected do: insert room in place do: store floor plan variables exit/room insertion completed select descriptive content select enter room in floor plan Saving floor plan system status=“input ready” display: storage indicator entry/ floor plan save selected do: store floor plan exit/save completed select save floor plan room insertion completed next selection customization complete all rooms defined
  26. 26. 26 The Funct ional Model  The functional model addresses two processing elements of the WebApp  user observable functionality that is delivered by the WebApp to end-users  the operations contained within analysis classes that implement behaviors associated with the class.  An activity diagram can be used to represent processing flow
  27. 27. 27 Act ivit y Diagram Figure 1 8 .7 Act ivit y diagram f or c omput e Pr i c e( ) ope r a t i on init ialize t ot alCost invoke calcShippingCost get price and quant it y components remain onBoMList invoke det ermineDiscount discount < = 0 discount>0 t ot alCost= t ot alCost - discount t axTot al= t ot alCost x t axrat e no components remain onBoMList lineCost = price x quant it y add lineCost t o t ot alCost priceTot al = t ot alCost + t axTot al + shippingCost ret urns: shippingCost ret urns: discount
  28. 28. 28 The Conf igurat ion Model  Server-side  Server hardware and operating system environment must be specified  Interoperability considerations on the server-side must be considered  Appropriate interfaces, communication protocols and related collaborative information must be specified  Client-side  Browser configuration issues must be identified  Testing requirements should be defined
  29. 29. 29 Relat ionship-Navigat ion Analysis  Relationship-navigation analysis (RNA) identifies relationships among the elements uncovered as part of the creation of the analysis model  Steps:  Stakeholder analysis—identifies the various user categories and establishes an appropriate stakeholder hierarchy  Element analysis—identifies the content objects and functional elements that are of interest to end users  Relationship analysis—describes the relationships that exist among the WebApp elements  Navigation analysis—examines how users might access individual elements or groups of elements  Evaluation analysis—considers pragmatic issues (e.g., cost/benefit) associated with implementing the relationships defined earlier
  30. 30. 30 Navigat ion Analysis-I  Should certain elements be easier to reach (require fewer navigation steps) than others? What is the priority for presentation?  Should certain elements be emphasized to force users to navigate in their direction?  How should navigation errors be handled?  Should navigation to related groups of elements be given priority over navigation to a specific element.  Should navigation be accomplished via links, via search-based access, or by some other means?  Should certain elements be presented to users based on the context of previous navigation actions?  Should a navigation log be maintained for users?
  31. 31. 31 Navigat ion Analysis-I I  Should a full navigation map or menu (as opposed to a single “back” link or directed pointer) be available at every point in a user’s interaction?  Should navigation design be driven by the most commonly expected user behaviors or by the perceived importance of the defined WebApp elements?  Can a user “store” his previous navigation through the WebApp to expedite future usage?  For which user category should optimal navigation be designed?  How should links external to the WebApp be handled? overlaying the existing browser window? as a new browser window? as a separate frame?
  32. 32. THANKYOU  32