CIS 644 Thus. Oct. 28, 1999 W10B

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CIS 644 Thus. Oct. 28, 1999 W10B
misc. questions thread, Runable
communication patterns
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Exam1 covers class scenario
models open book lt 1.5 hours Tues
Nov 2. on campus in class off campus
sent email 430pm C.T.
email or fax it back

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administrative gt corrections to GRADES file
are being made will be reposted later. gt
CIS web server was killed this week
temporarily moved some scripts may not
work CIS644 local pages should be OK now.
gt I keep up with urgent email rest may
wait for a while (will post patterns lists
later)
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?? are GRADES 4 digits SSN number? ... they
are KSU student ID number. ?? send back
off-campus homework no just class
discussion ?? post my answer no posted
TAs answer
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?? 1.5 hours for exam on-campus ... up to 90
minutes off-campus honor system
will draw some diagrams FAX is OK
asap if you want to use Rose or other
tool, great dont count that as part of exam
time.
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review questions "class variables" , "class
markers" (page 21) c getList( list)
there are times with class methods are
required Coads use of class methods for
collections is optional not my
preference
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my preference
theAirports LOOP
getAirport( anAirport) --gt

anAirport
getInfo( )
-----------------------gt ENDLOOP
translates loop anAirport
theAirports.getAirport( i )
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??is this related to aggregation vs
composition ?? no I see A vs C as
who owns the items who is responsible for
keeping refs UML what are the items "part
of"
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?? c new(passenger aReservation)
converts to Java as aReservation
new Reservation(passenger)

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?? Airports
c
remove( anAirport) --gt could translate as
class Airports Airport items
void remove( integer i) items i null

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?? getValues( values) indicates
a loop calls to multiple objects from
the collection
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threads use comments threads are used in
CIS625 distributed Processing CIS725
Computer Networks
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I use Solaris threads Posix threads. I use the
ACE framework (thread details are hidden
within) at Motorola
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at Sprint ...Every application is
multi-threaded ... created our own thread
classes in C ( inconsistencies with the
standard class) e.g. credit card validation
(C) allows concurrent requests vendor
communication (C) allows concurrent
requests orders system (Java) ..
Enterprise Java Beans framework (hidden
multi-threads )
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.. some Java threads. .. more with multi-tasking
in real-time OS (OS-9, iRMX, Unison, VersaDos)
using C these OS's have features such as
mailboxes, signals, shared memory for
intertask communication semaphores to control
access
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we use concurrency ...in modeling aircraft
systems for real-time
simulation --------------------------------------
--------------- threads (multiple processes)
are becoming more common in systems we are
developing
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?? was there only one thread in the Video
Store?? Chap 1 yes real no need to
define the "system" arch. assume one processor,
many agents in PD should be multiple Agent
tasks, each with own UI
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continuing into Chaps 4 5 Coad "this is
easy" -( UML objects passive vs
active active
process vs thread ADA object vs task
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Java Runable interface
defines run() but is not per se
active object Thread implements Runable
and is active object Runable object can be
executed "in" (with ??) its own thread. pass
object to Thread(Obj) . or, Runable object can
make its own thread, as Sensor version p. 194
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or .. Thread can execute several different
runable objects (invoke their run() ) in
sequence , of course.
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threads can have priorities but current JVMs
do not guarentee exact mapping of priorities !!
Lea recommends HI for system critical
threads LO for background threads Coad
mapping p. 192 -(
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visual representation of active objects at
Java level, only Thread is really
active, at design (abstract) level,
Runable objects can be "active" -( Coad does
not show bold boxes __
__ Ada /__ / for Task vs __
for obj.
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skim Chap 4, 5 for overview several different
forms for communication passive (polling)
timer active (source notifies its
listeners) message vs notification of
course, at Java level, notification
implemented as message
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End