flashcache.package.html Maven / Gradle / Ivy
This package contains a simple NASDAQ stock quote application using
the GemFire JCache API and the NASDAQ FlashQuote web site.
The Quote class is a command-line application that uses a cache Region to
look up stock market quotes. The Region has a QuoteLoader cache loader
associated with it that is used to load missing quotes into the cache.
If the requested stock quote is in shared memory, the Region merely
returns it. If not, the QuoteLoader is asked to provide the quote.
QuoteLoader first performs a netSearch operation to see if there are
any other GemFire caches holding the requested stock. If there aren't,
QuoteLoader performs a query against quotes.nasdaq.com (so you need to
be able to access that web site to run this demo) and caches the result.
Cached quotes expire after twenty seconds.
This example can be run interactively as follows: Start the GemFire
shared memory manager on one or more computers and configure the
systems to listen on the same port.
Run java flashcache.Quote SUNW to get a NASDAQ quote
for Sun Microsystems. Run java flashcache.Quote ORCL AMZN
to get quotes for Oracle and Amazon. In each case you'll see the
QuoteLoader look for the value in peer systems, using netSearch
and then go to quotes.nasdaq.com to get an up to date quote.
If you've started other peer GemFire systems, you can go to those
computers and perform the same queries and see, if you're fast enough
to beat the expiration period, that the value is fetched from the first
system.
Here's some sample output
$ java flashcache.Quote
Enter symbol: AMZN
AMZN: last sale=19.8 net change=+0.8 volume=10,389,53
Enter next symbol: ORCL
(QuoteLoader netSearching for ORCL)
(QuoteLoader querying nasdaq for ORCL)
ORCL: last sale=9.5 net change=+0.4 volume=51,675,88
This example shows Amazon being found in the cache, but Oracle wasn't.
QuoteLoader queried quotes.nasdaq.com to find the current information on
Oracle.