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Oracle® Fusion Middleware Getting Started Guide for Oracle Complex Event Processing
11g Release 1 (11.1.1.6.3)

Part Number E14476-10
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Glossary

Adapter

An element of the EPN that interfaces directly to an inbound event source. Adapters understand the inbound protocol, and are responsible for converting the event data into a normalized form that can be queried by a POJO. Adapters forward the normalized event data into a Stream.

Aggregate Function

Aggregate functions return a single aggregate result based on group of tuples, rather than on a single tuple.

See also Function and Single-Row Function.

CEP

Complex Event Processing.

Channel

A channel represents the physical conduit through which events flow between other types of components, such as between an Adapter and a Processor, and between a Processor and an Event Bean. A channel can model a Stream or Relation.

Condition

An Oracle CQL condition specifies a combination of one or more expressions and logical (Boolean) operators and returns a value of TRUE, FALSE, or UNKNOWN.

Constant value

A fixed data value. Synonymous with Literal.

CQL

Oracle Continuous Query Language. Supersedes EPL.

Data Feed

A synonym for Event Source.

Destination

An Oracle CQL destination identifies a consumer of query results such as the Enterprise Link BAM Adapter, JMS queue or topic, or file.

Deterministic Garbage Collection

Short, predictable pause times for memory heap garbage collection, which is the process of clearing dead objects from the heap, thus releasing that space for new objects.

DStream

A relation-to-stream operator that represents deleted tuples.

EDA

Event-Driven Architecture.

EPL

Oracle Event Processing Language. Superseded by CQL.

EPN

Oracle Event Processing Network. An EPN is the arbitrary interconnection of Adapter, Stream, POJO, and business logic POJOs used by Oracle CEP to process events.

Event Bean

A POJO to that contains the business logic executed when a notable event is detected. An event bean is an Event Sink.

Event Rule

A query, expressed in CQL or EPL, executed by a POJO to filter and aggregate events.

Event Sink

A component that consumes events, such as a Processor.

See also Event Source.

Event Source

A component that provides events, such as a sensor, wire service, or stock ticker.

See also Data Feed and Event Sink.

Expressions

An Oracle CQL expression is a combination of one or more values, operators, and Oracle CQL functions that evaluates to a value. An expression generally assumes the datatype of its components.

See also Condition and Function.

Format model

A character literal that describes the format of datetime or numeric data stored in a character string.

Function

Oracle CQL functions are similar to operators in that they manipulate data items and return a result. Functions differ from operators in the format of their arguments. This format enables them to operate on zero, one, two, or more arguments.

See also Condition, Aggregate Function, and Single-Row Function.

Incremental Processing

A user-defined aggregate function design pattern that improves scalability and performance by ensuring that the cost of (re)computation on arrival of new events will be proportional to the number of new events as opposed to the total number of events seen thus far.

If your user-defined aggregate function supports incremental processing, you specify the supports incremental processing clause in the register function statement to instruct the Oracle CEP Service Engine to supply only the new event data as opposed to performing a rescan over already processed event data.

IStream

A relation-to-stream operator that represents inserted tuples.

Join

A query that combines rows from two or more streams, views, or relations.

Latency

An expression of how much time it takes for data to get from one designated point to another.

Literal

A fixed data value. Synonymous with Constant value.

Monotonic

A sequence of values that are consistently increasing and never decreasing or consistently decreasing and never increasing. The sequence may contain multiple consecutive occurrences of the same value.

Now window

A special case of the time-based sliding window on a stream S that takes a time-interval T as a parameter and is specified by: S [Range T]. A Now window is defined as: S [Now] (short for S [Range 0]). When T = 0, the relation at time t consists of tuples obtained from elements of S with timestamp t.

See also Sliding window.

Operators

Oracle CQL operators manipulate data items and return a result. Syntactically, an operator appears before or after an operand or between two operands.

OSGi

A dynamic module system for Java that provides a service-oriented, component-based environment and standardized software lifecycle management. Oracle CEP applications are packaged and deployed as OSGi bundles. For more information, see http://www.osgi.org/.

Partitioned window

A partitioned sliding window on a stream S takes a positive integer number of tuples N and a subset {A1,... Ak} of the stream's attributes as parameters and is specified by: S[Partition By A1 ... Ak Rows N] or, optionally, S[Partition By A1 ... Ak Rows N Range T].

See also Sliding window.

POJO

A Plain Old Java Object. A Java class that is not required to implement a third-party interface or extend a third-party class. In Oracle CEP, you can express your business logic using POJOs.

Processor

An element of the EPN that consumes normalized event data from a stream, processes it using queries (expressed in CQL or EPL), and may generate new events to an output stream.

Query

A query is an operation that retrieves data from one or more streams or views. In this reference, a top-level SELECT statement is called a query.

Real-time

A level of computer responsiveness that a user senses as sufficiently immediate or that enables the computer to keep up with some external process (for example, to present visualizations of the weather as it constantly changes).

Relation

A relation is time-varying bag of tuples. Here "time" refers to an instant in the time domain. At every instant of time, a relation is a bounded set. It can also be represented as a sequence of timestamped tuples that includes insertions, deletions, and updates to capture the changing state of the relation. The updates are required to arrive at the system in the order of increasing timestamps. Like streams, relations have a fixed schema to which all tuples conform.

RStream

A relation-to-stream operator that maintains the entire current state of its input relation and outputs all of the tuples as insertions at each time step.

Single-Row Function

Single-row functions return a single result row for every row of a queried stream or view.

See also Function and Aggregate Function.

Sliding window

A stream-to-relation operator based on the window specification derived from SQL99.

See also: Now window, Partitioned window, Unbounded window, tuple-based, and Unbounded window, time-based.

Source

An Oracle CQL source identifies a producer of data that a Oracle CQL query operates on such as the Enterprise Link BAM Adapter, JMS queue or topic, or file.

Spring Framework

A light-weight, open source application framework for Java. Oracle CEP server uses the Spring Framework to host Oracle CEP applications. For more information, see http://www.springframework.org/.

Stream

A stream is a sequence of timestamped tuples. There could be more than one tuple with the same timestamp. The tuples of an input stream are required to arrive at the system in the order of increasing timestamps. A stream has an associated schema consisting of a set of named attributes, and all tuples of the stream conform to the schema.

A stream is a bag (or multi-set) of tuple-timestamp pairs, which can be represented as a sequence of timestamped tuple "insertions".

In Oracle CEP, a stream is modeled as a channel component.

See also Tuple and Channel.

Throughput

An Oracle CQL source identifies a producer of data that a Oracle CQL query operates on such as the Enterprise Link BAM Adapter, JMS queue or topic, or file.

Tuple

The term "tuple of a stream" denotes the ordered list of data (excluding timestamp data) portion of a stream element (the s of <s,t>). For example, a stock ticker data stream might appear like this where each stream element is made up of <timestamp value>, <stock symbol>, and <stock price>:

...
<timestampN>    NVDA,4
<timestampN+1>  ORCL,62
<timestampN+2>  PCAR,38
<timestampN+3>  SPOT,53
<timestampN+4>  PDCO,44
<timestampN+5>  PTEN,50
...

In the stream element <timestampN+1>  ORCL,62, the tuple is ORCL,62.

See also Stream.

Unbounded window, time-based

A special case of the time-based sliding window on a stream S that takes a time-interval T as a parameter and is specified by: S [Range T]. An Unbounded window is defined as: S [Range Unbounded] (short for S [Range infinity]). When T = infinity, the relation at time t consists of tuples obtained from all elements of S up to t.

See also Sliding window.

Unbounded window, tuple-based

A special case of the tuple-based sliding window on a stream S that takes a number of tuples N as a parameter and is specified by: S [Rows N]. An Unbounded window is defined as: S [Rows Unbounded] (short for S [Rows infinity] and equivalent to S [Range Unbounded]). When T = infinity, the relation at time t consists of tuples obtained from all elements of S up to t.

See also Sliding window.

View

An Oracle CQL view represents an alternative selection on a stream or relation. In Oracle CQL, you use a view instead of a subquery.