Book Image

Getting Started with Oracle Event Processing 11g

Book Image

Getting Started with Oracle Event Processing 11g

Overview of this book

Events are everywhere, events which can have positive or negative impacts on our lives and important business decisions. These events can impact a company's success, failure, and profitability. Technology now allows people from all walks of life to create Event Driven applications that will immediately and completely respond to the events that affect you and your business. So you are much more responsive to your customers, and competitive threats, and can take advantage of transient time sensitive situations. "Getting Started with Oracle Event Processing" will let you benefit from the skills and years of experience from the original pioneers who were the driving force behind this immensely flexible, complete, and award winning Event Stream Processing technology. It provides all of the information needed to rapidly deliver and understand Event Driven Architecture (EDA) Applications. These can then be executed on the comprehensive and powerful integral Java Event Server platform which utilizes the hardware and operating system.After an introduction into the benefits and uses of Event Stream Processing, this book uses tutorials and practical examples to teach you how to create valuable and rewarding Event Driven foundational applications. First you will learn how to solve Event Stream Processing problems, followed by the fundamentals of building an Oracle Event processing application in a step by step fashion. Exciting and unique topics are then covered: application construction, the powerful capabilities of the Oracle Event Processing language, CQL, monitoring and managing these applications, and the fascinating domain of real-time Geospatial Movement Analysis. Getting Started with Oracle Event Processing will provide a unique perspective on product creation, evolution and a solid understanding on how to effectively use the product.
Table of Contents (19 chapters)
Getting Started with Oracle Event Processing 11g
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

The structure and semantics of event processing


The structure of CQL queries is very similar to that of SQL. In fact, CQL is based on a subset of SQL99. Let's revisit the simple example from the beginning of the previous section:

SELECT p1 
FROM inputChannel

In this case, the FROM inputChannel clause informs the query that the input events arrive from the source called inputChannel, which happens to be the upstream channel to this CQL processor in the EPN. Further, the SELECT p1 clause states that the query is selecting only the event property p1 for output. The behavior of this query is best described with the following table:

Timet

Input event

Output event

0

{p1 = 1, p2 = "hi"}

{p1 = 1}

In other words, at time t = 0, we receive event {p1 = 1, p2 = "hi"} and output event {p1 = 1}. For the time being, ignore the time-related aspect of processing.

Here is a slightly more complicated case:

SELECT p2 
FROM inputChannel
WHERE p1 = 1

In this second query, we make use of a WHERE clause....