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What is a web app?

What is a web app?. Van Kelly Yeshiva University July 6, 2013 . Apps before the web. Timeshare Application Architecture. Terminal user interaction (text and block graphics). Mainframe data + programs. Standalone Apps with GUI. Netbeui or Netware over Ethernet or ARCnet. PC

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What is a web app?

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  1. What is a web app? Van Kelly Yeshiva University July 6, 2013

  2. Apps before the web

  3. Timeshare Application Architecture Terminal user interaction(text and block graphics) Mainframe data + programs

  4. Standalone Apps with GUI Netbeui or Netware over Ethernet or ARCnet PC all app functionality File Server

  5. Two-Tier Client-Server Applications ODBC/JDBC over Ethernet "Fat" Client presentation logic + business rules Server database

  6. Three-Tier Application Architecture Private Protocol over TCP Socket ODBC/JDBC "Thin" Client presentation logic Application Server business rules Data Server business data

  7. MVC Business Logic Model View Controller "Thin" Client presentation logic Application Server business rules Data Server business data M C V

  8. Three-Tier App Components • Disruptive economics = a vigorous market of "components" • Components = instantiable "templates" for software • super-encapsulated – "objects on steroids" • abstracted away locality – worked locally or remotely • configurable at compile-time or run-time • standardized deployment packages – plug & play • MS: "Lego for software" • Component examples • GUI widgets • spreadsheets, chart/graph generators • network services (e.g. FTP servers) • HTML/CSS rendering engine • app infrastructure (message queues) • all MS Office apps were also components • Needed language support (C++ bad, VB worked)

  9. Apps on the Web? How? • Browsers are unstable, slow • The Web was designed to serve pageddocuments/forms • Page refreshes take too long (>10 seconds) • The web has no "state" • HTML is not a rich UI language • JavaScript is just a toy for writing stuff like tic-tac-toe • Web UIs look nothing like "real" UIs • Web protocols have nothing like MVC • Web software is nothing like components

  10. Web App 1.0 HTTP Web Server Java applet TCP Socket JDBC Java Applet presentation logic Application Server business rules Data Server business data

  11. Canonical Example: Hangman

  12. Web App 1.5 Data Server business data *CGI HTTP Web Server presentation logic (PHP) JDBC Browser HTML + CSS + JS orFlash Application Server business rules

  13. Web App 1.9: "RESTful" Data Server business data mod_* HTTP Web Server proxy + caching JDBC Application Server presentation logic + business rules M C Browser HTML + CSS + JS V

  14. Web App 2.0: "AJAX" Data Server business data mod_* HTTP Web Server proxy + caching JDBC Browser HTML + CSS +JS presentation logic Application Server presentation logic + business rules M C V

  15. Web App 2.5: Single Page Apps (SPA) JSON HTTP Web Server app download + data proxy Data Server business data "Fat Client" in Browser HTML + CSS +JS presentation logic + business rules M C V

  16. Web Components (Web App 3.0?) • Current web "components" are just plug-ins for a specific server environment (e.g., WordPress) • Web Components promise universal component-like interfaces • Support only in Firefox and Chrome for now. • W3C Component Model: • HTML/JS templates • Decorators • Custom HTML Elements • Shadow DOM – a gory mess of new browser infrastructure to allow fine-grained encapsulation • HTML Imports

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