The document discusses a general extension system for event processing languages. It presents two scenarios that demonstrate how to blend the Continuous Query Language (CQL) with other languages like Java and Oracle Spatial. The proposed architecture includes a type registry and language extensions that allow CQL to interface with other languages while remaining agnostic to language specifics. This achieves extensibility while keeping CQL highly descriptive.

1. <Insert Picture Here>
A General Extension System for Event Processing Languages
Alexandre Alves - Oracle CEP
Monday, July 11, 2011

2. Agenda DEBS2011
• Scenario 1
• String manipulation (programming-in-the-small)
• Blending CQL and Java
• Architecture
• Scenario 2 Text
• Geo-fence (extensibility)
• Blending CQL and Spatial
• Architecture
• Q/A
Monday, July 11, 2011

3. Scenario 1: DEBS2011
Programming-in-the-small
• Correlate security price changes to real-time event
news.
Text
Monday, July 11, 2011

4. Scenario 1: DEBS2011
Programming-in-the-small
Oracle CQL
Processor
SELECT *
FROM Text
news [RANGE 1 HOUR],
stock_tick [RANGE 1 HOUR]
WHERE /* join-criteria */
Monday, July 11, 2011

5. Scenario 1: DEBS2011
Programming-in-the-small
• Problem: the NEWS feed is a unstructured (String),
hence not trivial to identify its event properties
• For example, a naive join criteria is to look for a stock’s
symbol
• The problem of parsing a String can be solved using
Regular Expressions. Text
• Regular Expressions and other programming-in-the-
small tasks have long been solved by general
purpose programming languages
• Can we leverage this within an event processing
language (e.g. CQL)?
Monday, July 11, 2011

6. Java Regular Expressions DEBS2011
• Let’s look at a simple solution to the problem using
Java:
Matcher matcher =
Text
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher
(message);
if (matcher.find()) {
Matches three letter
symbol = message.substring(matcher.start() + 1, symbols, separated by
leading and trailing
matcher.end() - 1)); white-spaces
}
Monday, July 11, 2011

7. Blending CQL with Java DEBS2011
CREATE VIEW filtered_news(message, matcher) AS
SELECT
message,
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher(message) as
matcher
FROM news [RANGE 1 HOUR] Text
SELECT
location, item_description, message
FROM filtered_news, stock_tick[RANGE 1 HOUR]
WHERE
matcher.find() = true AND
filtered_news.message.substring(matcher.start() + 1,
matcher.end() - 1) = stock_tick.symbol
Monday, July 11, 2011

8. Blending CQL with Java DEBS2011
CQL char conversion
to Java String
CREATE VIEW filtered_news(message, matcher) AS
SELECT
message,
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher(message) as matcher
FROM news [RANGE 1 HOUR]
Text
SELECT
location, item_description, message Method invocation
FROM filtered_news, stock_tick[RANGE 1 HOUR]
WHERE
matcher.find() = true AND Static method
filtered_news.message.substring(matcher.start() + 1, invocation
matcher.end() - 1) = stock_tick.symbol
Monday, July 11, 2011

9. Blending CQL with Java DEBS2011
‘matcher’ is a Java
Object, and treated as
CREATE VIEW filtered_news(message, matcher) AS
a complex type by
SELECT CQL
message,
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher(message) as matcher
FROM news [RANGE 1 HOUR]
Text
SELECT Overload of CQL ‘+’
location, item_description, message operator to handle
FROM filtered_news, stock_tick[RANGE 1 HOUR] Java Integer
WHERE
matcher.find() = true AND Overload of CQL
filtered_news.message.substring(matcher.start() + 1, equality to handle
matcher.end() - 1) = stock_tick.symbol Java String
Monday, July 11, 2011

10. Architecture DEBS2011
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher(message)
(message)
• Is this symbol:
• Text
A stream attribute (e.g. message)?
• A stream alias (e.g. FROM S1 as A)
• A CQL function (e.g. SELECT myfunc())
• The l-value of complex type (e.g. myObj.myMethod())
• A constructor
• A (static) method
• A class name
Monday, July 11, 2011

11. Architecture DEBS2011
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher(message)
(message)
• To be able to semantically compile symbols, we need
to have type information.Text
• However, CQL is not aware of Java, nor should it be.
• There is a need of a generic type-system, and an
extension model for providers to plug-in their own
languages
Monday, July 11, 2011

12. Architecture DEBS2011
CQL Parser
Semantic Type
Analyzer Registry
Text
Code
Generator Java
Type-System
Code
Executor
Monday, July 11, 2011

13. Architecture DEBS2011
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher(message)
(message)
ComplexType
“Pattern”
Text
Type fields
Registry
methods
Java
Type-System
Monday, July 11, 2011

14. Architecture DEBS2011
ComplexType
fields
“Pattern” Type
Registry
methods
Text
Java
Type-System
CQL deals with a ‘complex type’ abstraction, and
does not know of its ‘Java Language’ binding.
Monday, July 11, 2011

15. Architecture DEBS2011
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher(message)
(message)
Pattern
ComplexType
fields Text
Find a “compile” method and its return type
methods
Monday, July 11, 2011

16. Architecture DEBS2011
Pattern.compile("[.,; ][A-Z][A-Z][A-Z][.,; ]").matcher(message)
Pattern Matcher
ComplexType ComplexType Text
fields fields Store ‘matcher’ as
methods methods a stream/view attribute
Monday, July 11, 2011

17. Architecture DEBS2011
Extensible Language
stream 1 * attribute Type
<<is-of>>
‘matcher’ is an attribute of the view
of type ‘java.util.regex.Matcher’ ComplexType
Text <<metadata binding>>
Extension Java Language
CREATE VIEW filtered_news(message, matcher)
Java Class
Monday, July 11, 2011

18. Extensibility DEBS2011
Extensible Language
stream 1 * attribute Type
<<is-of>>
ComplexType
Text <<metadata binding>>
How do we know which Extension Java Language
‘language extension’ to use?
How to provide new Java Class
extensions?
Monday, July 11, 2011

19. Scenario 2: DEBS2011
Spatial Integration
• Targeted marketing for a mobile subscriber
• CEP application checks if the location of the subscriber is
within the distance of a registered shop
Text
Text
Oracle Spatial
Shop
id: CHAR
geometry: SDO_GEOMETRY
Monday, July 11, 2011

20. Blending CQL with Spatial DEBS2011
CREATE VIEW CustomerLocation-Stream(point, custId) AS
SELECT createPoint@spatial(lng, lat) as point, custId
FROM Location-Stream
point is a spatial type
SELECT loc.custId, shop.id Text
FROM
CustomerLocation-Stream[NOW] AS loc, Shop as shop
WHERE
contain@spatial(shop.geometry, loc.point, 2.0d) ‘spatial’ link points to
Oracle Spatial
‘extension’, where
‘contain’ function
resides
Monday, July 11, 2011

21. Architecture DEBS2011
CQL
CQL link specifies language
extension, which are plugged
into the system as a CQL
cartridge
Text <<link>>
CQL Cartridge
Cartridge
contain@spatial(shop.geometry, loc.point, 2.0d)
Monday, July 11, 2011

22. Conclusion DEBS2011
• Blending of CQL with other languages allow for the
creation of feature-rich CEP applications while still
being highly descriptive
• Example:
• String manipulation using Java
Text
• Geo-fencing using Oracle Spatial
• Generic frameworks allows for the dynamic plugin of
extensions (cartridges)
Monday, July 11, 2011