Project Product. Thanks to Nilesh Bansal for material in these slides

Transcription

1 Project Product Thanks to Nilesh Bansal for material in these slides 1

2 REAL WORLD 2

3 Core Difference Project You define the problem statement 3

4 Core Difference Project You define the problem statement You are the primary user INPUT DATE: 03 / 06 /

5 Core Difference Project You define the problem statement You are the primary user OJen technically challenging and novel 5

6 Core Difference Project You define the problem statement You are the primary user OJen technically challenging and novel Product Solving someone else s problem Someone else is using the product OJen simple solu:ons to complex problems 6

7 Overview Usability Security Reliability Performance 7

8 USABILITY 8

9 Usability Most important, but oien overlooked Very difficult task 9

10 Usability Most important, but oien overlooked Very difficult task Silently observe user Make common easy, and uncommon possible 10

11 Google Search 11

12 Google Search Make common easy, uncommon possible 12

13 Google Search Make common easy, uncommon possible 13

14 Reasonable Defaults Customizable interface But 90% users do not customize They use what system provides by default 14

15 Features vs Solu:ons People are inherently lazy They do not want to use your product But people have real life problems And they want the easiest way to solve the problem If a feature is not easy to use, it does not exist 15

16 Google+ 16

17 Facebook always had lists 17

18 Affordance: Knobs are for turning A quality of an object that allows an individual to perform an aczon 18

19 BuVons for pressing 19

20 Is This Really Necessary? 20

21 Affordance 21

22 Affordance 22

23 Affordance 23

24 Typography and Content Display More important informa:on in bigger font Progressively move down Use bold / yellow backgrounds to highlight 24

25 Layout Toronto Weather 25

26 Layout Toronto Weather 26

27 Typography / Text Name: Marshall Mathers User Id: eminem LocaZon: Detroit Bio: I am not afraid Url: h]p://twi]er.com/eminem Picture: 27

28 Typography / Text Name: Marshall Mathers User Id: eminem LocaZon: Detroit Bio: I am not afraid Url: h]p://twi]er.com/eminem Picture: 28

29 Consistency Consistent terminology Login or Sign In? Pick one. Do not mix Logout and Sign Out. Different terminology User Se`ngs Account Se`ngs User Preferences Account SeZngs 29

30 Example: Delete / Undo Confirma:on boxes are intrusive 30

31 Example: Delete / Undo Provide an Undo op:on 31

32 Aesthe:cs Beauty mavers. Direct correla:on to sales Clients will buy a sleeker looking sojware over one with more features 32

33 Please, do not design like this 33

34 SECURITY 34

35 ALWAYS think about security Sony Playsta:on Network Personal data of 77 million users stolen Lots of bad guys out there IBM monitors 150,000 security events per second Mostly automated, exploit common flaws Want to use your server as a bot Anonymous, LulzSec and others 35

36 XSS: Cross Site Scrip:ng AVacker injects a script into web page Contents of index.php: <input value= <? echo $_GET[ name ] > /> Request: index.php?name= /><script Escape HTML from all dynamic content before displaying Java has StringEscapeUZls.escapeHtml( ) 36

37 SQL Injec:on SELECT login_id, full_name FROM table WHERE = 'x' AND 1=(SELECT COUNT(*) FROM table);'; Always escape strings Use PreparedStatement (in Java) 37

38 Other Security Issues Always store passwords using one- way encryp:on Can not be decrypted Check for user privileges Specially when including or redireczng to other files Keep base system secure Stop unnecessary services Update regularly for security patches Use firewalls 38

39 RELIABILITY 39

40 Up:me Near- 100% availability is important System is always operazonal No data loss Backups and disaster recovery Remember Failures are correlated Human errors are common cause 40

41 Redundancy Hot Failover AutomaZc switch from failed to available system Hardware Redundancy RAID 10 mirror all data Two network switches, two Ethernet cards, two power supplies, two HBA (host bus adapter) controllers etc.. Redundant Infrastructure 41

42 Simplified Infrastructure Example Apache HTTPD Use of virtual IP to make sure the user is always directed to the server that is available. Apache acts as front- end proxy to redirect the request to backend Tomcat. ApplicaZon Server Tomcat is commonly used Java app server. Most code runs on this machine. Apache HTTPD Load Balancer and Proxy Pass module are used to provide failover and redundancy. Databases Master Slave replicated database servers. ApplicaZon server maintains the sate of each server to provide reliability. All writes must happen on master. 42

43 Monitoring Open Source CacZ Nagios Custom Internal System Check module Paid Hosted Site 24x7 43

44 PERFORMANCE 44

45 Performance and Scalability Don't op:mize un:l you need to Make code readable Use Profiler (for Java, Netbeans is great and free) Common tricks Cache Pre- compute Sample Parallelize Using mulz- core To different machines 45

46 Scalability, Consistency, Reliability You can only easily have two of the three Consistency: among mulzple replica of data Reliability: conznuous operazonal Scalability: growing with increase in number of users reliability consistency scalability 46

47 Caching and Pre- compu:ng User queries are correlated Caching is most common opzmizazon Must be willing to sacrifice some consistency Fully or par:ally pre- compute Every night, create useful stazszcs (e.g., a stazszcal histogram of word frequencies in search services) Sample Approximate results are fine 47

48 CPU Op:miza:ons Mul:- thread Java has package to manage Executors Pay a]enzon to thread safety Use op:mized collec:ons CERN Colt, GNU Trove to save memory Use a Profiler 48

49 Code Quality vs Performance KISS Keep It Simple Stupid KIWI Kill It With Iron Upgrade your hardware (more disks, more memory, etc.) 49

50 CONCLUSION 50

51 Ques:ons? 51