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From alpinegizmo <...@git.apache.org>
Subject [GitHub] flink pull request #4041: [FLINK-6198] [cep] Update CEP documentation.
Date Fri, 02 Jun 2017 15:57:42 GMT
Github user alpinegizmo commented on a diff in the pull request:

    --- Diff: docs/dev/libs/cep.md ---
    @@ -98,48 +128,106 @@ val result: DataStream[Alert] = patternStream.select(createAlert(_))
    -Note that we use Java 8 lambdas in our Java code examples to make them more succinct.
     ## The Pattern API
    -The pattern API allows you to quickly define complex event patterns.
    -Each pattern consists of multiple stages or what we call states.
    -In order to go from one state to the next, the user can specify conditions.
    -These conditions can be the contiguity of events or a filter condition on an event.
    -Each pattern has to start with an initial state:
    -<div class="codetabs" markdown="1">
    -<div data-lang="java" markdown="1">
    -{% highlight java %}
    -Pattern<Event, ?> start = Pattern.<Event>begin("start");
    -{% endhighlight %}
    -<div data-lang="scala" markdown="1">
    -{% highlight scala %}
    -val start : Pattern[Event, _] = Pattern.begin("start")
    -{% endhighlight %}
    -Each state must have a unique name to identify the matched events later on.
    -Additionally, we can specify a filter condition for the event to be accepted as the start
event via the `where` method.
    -These filtering conditions can be either an `IterativeCondition` or a `SimpleCondition`.

    -**Iterative Conditions:** This type of conditions can iterate over the previously accepted
elements in the pattern and 
    -decide to accept a new element or not, based on some statistic over those elements. 
    -Below is the code for an iterative condition that accepts elements whose name start with
"foo" and for which, the sum 
    -of the prices of the previously accepted elements for a state named "middle", plus the
price of the current event, do 
    -not exceed the value of 5.0. Iterative condition can be very powerful, especially in
combination with quantifiers, e.g.
    -`oneToMany` or `zeroToMany`.
    +The pattern API allows you to quickly define complex pattern sequences that you want
to extract 
    +from your input stream.
    +Each such complex pattern sequence consists of multiple simple patterns, i.e. patterns
looking for 
    +individual events with the same properties. These simple patterns are called **states**.
A complex pattern 
    +can be seen as a graph of such states, where transition from one state to the next happens
based on user-specified
    --- End diff --
    ... where transitions from one state to the next occur ...

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