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https://issues.apache.org/jira/browse/S4-5?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13207961#comment-13207961
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Leo Neumeyer commented on S4-5:
-------------------------------
I just committed the first version of the S4 Embedded Domain-Specific Language
to the S4-5 branch. I ended up using Diezel to implement it. Eric, the author,
was very responsive fixing the few bugs I found. The advantage of using Diezel
is that it is almost impossible to code by hand and it makes it easy to modify
and extend the grammar in the future. I created a Gradle build script that uses
the Diezel Maven plugin to generate the EDSL Java source code. Here is the
grammar I committed:
{code:title=S4 EDSL Grammar|borderStyle=solid}
(pe , type , prop* , (fireOn , afterInterval? , afterNumEvents?)? , (timer,
withPeriod)? , (cache, size , expires? )? , asSingleton? , (emit, onField?,
(withKey|withKeyFinder)?, to+ )* )+ , build
{code}
and this is the counter app:
{code:title=Counter App using the S4 EDSL|borderStyle=solid}
protected void onInit() {
pe("Print").type(PrintPE.class).asSingleton().
pe("User
Count").type(CounterPE.class).fireOn(Event.class).afterInterval(100,
TimeUnit.MILLISECONDS)
.emit(CountEvent.class).withKeyFinder(new
CountKeyFinder()).to("Print").
pe("Gender
Count").type(CounterPE.class).fireOn(Event.class).afterInterval(100,
TimeUnit.MILLISECONDS)
.emit(CountEvent.class).withKeyFinder(new
CountKeyFinder()).to("Print").
pe("Age
Count").type(CounterPE.class).fireOn(Event.class).afterInterval(100,
TimeUnit.MILLISECONDS)
.emit(CountEvent.class).withKeyFinder(new
CountKeyFinder()).to("Print").
pe("Generate User
Event").type(GenerateUserEventPE.class).timer().withPeriod(1,
TimeUnit.MILLISECONDS)
.asSingleton().
emit(UserEvent.class).withKeyFinder(new
UserIDKeyFinder()).to("User Count").
emit(UserEvent.class).withKey("gender").to("Gender Count").
emit(UserEvent.class).withKeyFinder(new AgeKeyFinder()).to("Age
Count").
build();
}
{code}
We can iterate a bit on the names of the tokens.
For more details look at:
* The [Diezel Project|http://code.google.com/p/diezel]
* New subproject s4-edsl
* Test case in s4-edsl
* The Counter example in the s4-example subproject package
org.apache.s4.edsl.counter
> Prototype app builder
> ---------------------
>
> Key: S4-5
> URL: https://issues.apache.org/jira/browse/S4-5
> Project: Apache S4
> Issue Type: New Feature
> Affects Versions: 0.5
> Reporter: Leo Neumeyer
> Priority: Minor
> Fix For: 0.5
>
> Attachments: s4-fluent.pdf
>
>
> Extend Guice AbstractModule to create a simple application builder layer. The
> idea is to evaluate if we can use Guice to do all the wiring including PEs
> and Streams and Apps.
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