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Lecture 37: Proxy Pattern

Computer Science 313 – Advanced Economic Topics. Lecture 37: Proxy Pattern. Is This a Check or Money?. Currency issued by Bank of the United States Once we figure that out: how much was it worth?. Silver Standard Is Best. While now illegal, how much was this worth?.

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Lecture 37: Proxy Pattern

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  1. Computer Science 313 – Advanced Economic Topics Lecture 37:Proxy Pattern

  2. Is This a Check or Money? • Currency issued by Bank of the United States • Once we figure that out: how much was it worth?

  3. Silver Standard Is Best • While now illegal, how much was this worth?

  4. Silver Standard Is Best • While now illegal, how much was this worth? • WHY?

  5. Other Currency Standard • What was value of these denominations? • Notes on gold standard used by banks in late 30s

  6. Other Currency Standard • What was value of these denominations? • Federal reserve note from early 30s

  7. How Much Is This Worth?

  8. How Much Is This Worth? • When ordering online, pay $0.0259 per check • Under $0.01 of pen ink used on the check • At cheapest, check worth little over 3.5 cents • $0.15/check for really fancy ones I found • Would need to supply your name & address • Bank name & account number needed for this too

  9. Generous Offer • Following offer open to all students in class: I will trade $0.16 for your next signed paycheck • My offer is VERY serious with contract ready • Probably not high quality, expensive type of check • Without additional value, you will end up richer

  10. Why Not?

  11. Why Not?

  12. Patterns In Real-Life • Usually worth more than their components • They are both implementations of proxy pattern • Checks are remote proxies, but in the real-world • See working of virtual proxy with old U.S. currency • Consider definition of the word "Proxy" Ally or friend whom you give power to work as if they were you; Agent; Substitute

  13. Remote Proxy in Action • Signed check is deposited into your account • Client sees bank give them cash, but more needed • To get cash, bankmust follow several steps • Image of useless paper made at local bank branch • Bank then has image sent to local clearinghouse • Request routed to source bank for approval • Other bank has check amount deducted from account • Approval sent to clearinghouse as electronic transfer • Clearinghouse has result sent back to your bank

  14. Remote Proxy Example Clearing- house Other Bank Your Bank You

  15. Remote Proxy Example Clearing- house Other Bank Your Bank You

  16. Remote Proxy Picture

  17. Virtual Proxy • Silver & gold standard currency virtual proxies • Bills still (nearly) worthless paper & ink creation • Fed reserve banks kept vaults of gold and silver • Trade for bill for gold/silver at any of these banks • This is simpler proxy, no 3rd party needed! Vault You Bank

  18. For Next Class • Lab updated soon with Final info • Will run office hours during time scheduled for exam • Last design pattern reading continues for Monday

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