readme.txt

This a JavaBean application, which contains 4 beans. In this package, there are 4 files: cexchange

This package includes four Beans as required, two Customizers and four custom Events with its corresponding listeners. 


Beans: CurrencyExchange, QuoteProducer, Summarizer and Displayer.


Customizers: QuoteProducerCustomizer and SummaryChoiceCustomizer.


Custom Events: CurrencyEvent, QuoteEvent, ThresholdEvent and SummaryEvent. 


Custom Event Listeners: CurrencyEventListener, QuoteEventListener, ThresholdEventListener and SummaryEventListener.



Working Principle:


1.CurrencyExchange reads the currency data file into a vector(currencylist) regularly, which is controled by a timer; then, fires a CurrencyEvent that contains the vector(currencylist);


2.QuoteProducer receives the CurrencyEvent from CurrencyExchange and deal with the currency data; the QuoteProducerCustomizer helps users to choose their interested currency and set its threshold in QuoteProducer bean; once currency price reaching the threshold, this bean fires ThresholdEvent; aslo, it fires QuoteEvent once for each CurrencyEvent it received;


3.Summarizer receives CurrencyEvent from CurrencyExchange and QuoteEvent from QuoteProducer; then it calculate these data as user required (default type is average), such as for maximum, minimum and average, the SummaryChoiceCustomizer gives users a interface to do so; after that, it sends out a SummaryEvent to Displayer;


4.Displayer receives two customized events: QuoteEvent from QuoteProducer for displaying particular currency that user is interested, and SummaryEvent from Summarizer for showing the calculate result that has been done in last step.






User Instruction:
please read the screenshot for details.