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Java Lunch ‘N Learn For QSI Talent Managers

Steinn  ‘Stan’  Jónsson,  March  24,  2014  

(Java  technologies  explained  to  non-­‐technical  audience)  

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Agenda

•  How  to  sell  QSI  to  developers?  •  Java  buzzwords  explained  in  layman  terms  

•  Q  &  A  

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How to sell QSI to Developers?

•  See  blog  post  at:  hMp://www.sjonsson.com/2013/08/7-­‐reasons-­‐to-­‐become-­‐soTware.html      

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Web  Purchase  -­‐  Example  used  to  explain  Java  buzzwords  

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EJB – Enterprise Java Beans

•  Leave  low-­‐level  details  to  others  

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EJB

Get  for  free:  •  Remotely  callable  •  Security  •  Transac]on  Management  •  Scalability  

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• What  are  the  benefits  of  EJBs?  (Enterprise  Java  Beans)  – Sample  answers:  • Allows  me  to  focus  on  business  logic  and  solving  business  problems  

• By  using  EJBs  I  need  to  worry  less  about:  – Remote  Access  – Security  – Scalability  – Transac]on  Management  

EJB – Possible Interview Question

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JMS – Java Message Service

•  Don’t  call.    Send  a  message.  

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JMS

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• What  are  some  benefit  of  JMS?    (Java  Message  Service)  – Sample  answers:  •  Improved  performance  by  making  calls  asynchronous  (via  JMS  Queues)  

• Allows  me  to  broadcast  messages  to  mul]ple  subscribers.    (Done  via  JMS  Topics.    Works  similar  to  email  mailing  lists)  

JMS – Possible Interview Question

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Hibernate

•  Take  the  easy  route  to  your  database  • Maps  “Java  speak”  to  “database  speak”  

SQL Maze

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• Why  to  people  use  Hibernate?  – Sample  answers:  • To  simplify  database  persistence  • For  produc]vity  reasons  -­‐  To  avoid  having  to  manually  write  SQL  queries  • For  performance  reasons  -­‐  To  take  advantage  of  caching  

• To  avoid  vendor  lock-­‐in  -­‐  Hibernate  is  database  independent    

Hibernate – Possible Interview Question

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The Spring Framework

•  Giant  toolbox  for  simplifying  Java  development  

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Spring – Most used for

•  Wire  the  applica]on  together  

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Spring – Wire the application together

BeMer  known  as  Dependency  Injec]on  

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• Why  do  people  use  the  Spring  Framework?  – Sample  answers:  • For  produc]vity  reasons  –  To  take  advantage  of  extensive  Spring  libraries  

• Helps  “wiring  applica]ons  together”  (make  more  loosely  coupled  applica]ons  via  dependency  injec]on)  • For  performance  reasons  (Spring  container  is  more  lightweight  than  JEE  container)      

Spring – Possible Interview Question

Business Value…Achieved

JUnit

•  Automate!    Don’t  have  a  human  do  a  robot’s  job!  

Unit  tests  automated.  Humans  can  focus  on  integra]on  tes]ng.  

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• Why  do  people  use  JUnit?  – Sample  answers:  •  It  is  the  de  facto  library  for  wri]ng  tests  in  Java  • To  write  unit  tests  (and  mul]ple  other  types  of  tests)    

• To  automate  tes]ng  of  their  code      

JUnit– Possible Interview Question

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Design Patterns

• Singleton  

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• What  is  a  Singleton?  – Sample  answer:  • Design  paMern  that  restricts  the  instan]a]on  of  a  class  to  one  object.  

• How  to  implement  Singleton?  – Sample  answers:  • Make  constructor  private.    Class  keeps  sta]c  reference  to  instance.    Typically  has  getInstance  method.  • Use  Spring  (Spring  beans  are  Singletons  by  default)  • Use  enum  (a  single-­‐element  enum  type)  

Design Patterns – Possible Interview Questions

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Q & A