On Wed, Feb 2, 2011 at 11:15 AM, clwham...@gmail.com
<clwham...@gmail.com> wrote:
> I am doing some prototyping with the event processing framework Esper
> (http://esper.codehaus.org/) and I'm running up against my ignorance
> of clojure/java interop. I would like to create a java bean in clojure
> that is visible to the Esper runtime; I found some sample Java code
> that I clojurized as follows:
>
> (ns cepdemo.core
> (:import [com.espertech.esper.client
> Configuration UpdateListener
> EPServiceProviderManager EPRuntime]))
>
> (defrecord Tick [symbol price timestamp])
...
> The error I get is:
> Property named 'symbol' is not valid in any stream [select * from
> StockTick(symbol='AAPL').win:length(2) having avg(price) > 6.0]
>
> from which I conclude that defrecord may not be the way to create a
> java bean. Do I need to use gen-class?
I'd try first to make Tick bean-ish with
(definterface ITick
(getSymbol [this])
(setSymbol [this y])
(getPrice [this])
(setPrice [this y])
(getTimeStamp [this])
(setTimeStamp [this y]))
(defrecord Tick [symbol price timestamp]
ITick
(getSymbol [this] symbol)
(setSymbol [this] (throw (UnsupportedOperationException.)))
(getPrice [this] price)
(setPrice [this] (throw (UnsupportedOperationException.)))
(getTimeStamp [this] timestamp)
(setTimeStamp [this] (throw (UnsupportedOperationException.)))
Tell the external tool that the bean properties are Symbol, Price, and
TimeStamp (rather than symbol, price, and timestamp) and unless it
tries to mutate your Ticks it ought to work.
Of course, you might also consider making a defbean macro that wraps
defrecord and automates the above. :)
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