lecture 37: proxy pattern
DESCRIPTION
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?. - PowerPoint PPT PresentationTRANSCRIPT
LECTURE 37:PROXY PATTERN
Computer Science 313 – Advanced Economic Topics
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?
Silver Standard Is Best
While now illegal, how much was this worth? WHY?
Other Currency Standard
What was value of these denominations? Notes on gold standard used by banks in
late 30s
Other Currency Standard
What was value of these denominations? Federal reserve note from early 30s
How Much Is This Worth?
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
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
Why Not?
Why Not?
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
Remote Proxy in Action
Signed check is deposited into your account Client sees bank give them cash, but more
needed To get cash, bank must 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
Remote Proxy Example
YouYourBank
Clearing-house
OtherBank
Remote Proxy Example
YouYourBank
Clearing-house
OtherBank
Remote Proxy Picture
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!You Ban
kVault
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