3/3/15 Announcement: Bug of the week (extra credit) Architectural - PDF document

3/3/15 Announcement: Bug of the week (extra credit) Architectural Patterns ❚ Each group can nominate a “ bug ” ❚ TA choose one to be “ bug of the week ” . Group gets extra credit. ❚ Bug due Sunday evening. Database-centric ❚ “ Bug ” can be any mistake; requirements, Model/View/Controller build, documentation. Best bugs will have Games “ lesson learned ” . CS361-10 2 1 More announcements Database-centric ❚ Final project hand in (Mon-Tue, March ❚ Relational database management system 9-10) ❙ Keep data safe ❙ Update the documentation to match the ❘ Crash recovery, human readable, adaptable current system (don’t simply copy-paste from ❙ Concurrency control HW2/HW3) ❘ Transactions - ACID (Atomicity, Consistency, Isolation, Durability) ❙ Integrate different applications ❙ Ad hoc querying CS361-10 3 CS361-10 4 Advantages of RDBMS Disadvantages of RDBMS ❚ Safety, concurrency, integration, queries ❚ Performance bottleneck ❚ Standard ❚ Object-relational impedance mismatch ❙ Compatible tools ❙ Must convert between tables and objects ❙ Expert developers ❙ Differing notions of identity ❚ Scalable (with cost) ❙ RDBMS do not support interfaces, inheritance, collections ❚ Tables not good for trees and graphs ❚ RDBMS work well for financial domain, not so well for the engineering fields CS361-10 5 CS361-10 6 1

3/3/15 RDBMS for integration New app … ❚ Reuse old tables ❚ Add new table ❚ Add column to old table App App App App ❚ Moving/deleting column is hard because old apps must be changed DBMS CS361-10 7 CS361-10 8 DB Administrator OO Domain Model ❚ Responsible for database design ❚ “ Domain model ” is a set of classes ❚ Ensure database is well-designed ❚ Applications talk to domain model. ❚ Ensure schema changes slowly ❚ Domain model talks to database. • Martin Fowler – • Patterns of Enterprise Application Architecture CS361-10 9 CS361-10 10 Alternatives to DBMS ❚ Persistence ❚ prevayler.org ❙ Flat files ❚ Keep all data in memory ❙ XML ❚ Store snapshot of data on disk, then log ❚ Concurrency every change to the data ❙ Prevayler-style in-memory database ❚ Change data using Command pattern ❚ Integration ❙ Log all commands ❙ SOA, message bus ❙ Lock all commands CS361-10 11 CS361-10 12 2

3/3/15 Prevayler trade-offs Model/View/Controller ❚ UI implementation pattern ❚ +Very fast ❚ Separate UI from application so UI can be ❚ +No object-relational impedance reused ❚ -Data must fit in memory ❚ Model - application data ❚ View - displays data ❚ -No query language ❚ Controller - maps user events into changes to the data CS361-10 13 CS361-10 14 Model/View/Controller Model/View/Controller ❚ In original MVC, ❙ View is a composite Model ❙ View is observer of Model ❙ Controller is strategy for handling input View Controller ❙ (active) Model pushes notifications to the list of registered viewers CS361-10 15 CS361-10 16 Design Principle: separate Model/View/Controller presentation from data ❚ In web systems, ❚ Make it easier to change presentation ❙ View is a template used to generate page ❙ from desktop, to web-based, to smartphone ❙ Controller is code used to handle “ post ” ❚ Make it easier to change data ❙ No “observer” relationship between the view ❚ Make presentation objects more reusable and the database (passive implementation) ❚ Allow people to specialize in data or in presentation CS361-10 17 CS361-10 18 3

3/3/15 Separating presentation from data MVC in games ❚ Hard to separate completely http://www.koonsolo.com/news/model- view-controller-for-games/ ❙ New feature requires change to data and to UI http://www.koonsolo.com/news/dewitters- gameloop/ ❚ Cross-functional teams - UI and data CS361-10 19 CS361-10 20 MVC in games MVC in games ❚ Real-time game consists of a game loop ❚ Put user input in a controller ❙ Get input ❚ Controller needs to query view to find ❙ Update game location of on-screen objects ❙ Display game ❚ Easier to test game code (i.e., the model) ❚ Make “ display game ” a separate object so automatically that game code is simpler CS361-10 21 CS361-10 22 MVC in games Architectural Patterns ❚ Determine how program is divided into modules ❚ Have advantages and disadvantages Controller ❚ Influence non-functional requirements / software quality Model ❚ Must be learned View CS361-10 23 CS361-10 24 4

3/3/15 Architectural Patterns Books Next time ❚ Career options in Software Engineering CS361-10 25 CS361-10 26 5