CCL Project Basics
ESP projects are written in CCL, an SQL-like language which specifies a
data flow (by defining streams, windows, operations, and connections), and provides the
capability to incorporate functions written in other languages, such as SPLASH, to handle
more complex computational work.
- Events
A business event is a message that contains information about an actual business event that occurred. Many business systems produce streams of such events as things happen.
- Operation Codes
The operation code (opcode) of an event record specifies the action to perform on the underlying store of a window for that event.
- Streams
Streams subscribe to incoming events and process the event data according to the rules you specify (which can be thought of as a "continuous query") to publish output events. Because they are stateless, they cannot retain data.
- Windows
A window is a stateful element that can be named or unnamed, and retains rows based on a defined retention policy.
- Delta Streams
Delta streams are stateless elements that can understand all opcodes.
- Comparing Streams, Windows, and Delta Streams
Streams, windows, and delta streams offer different characteristics and features, but also share common designation, visibility, and column parameters.
- Input/Output/Local
You can designate streams, windows, and delta streams as input, output, or local.
- Implicit Columns
All streams, windows, and delta streams use three implicit columns called ROWID, ROWTIME, and BIGROWTIME.
- Schemas
A schema defines the structure of data rows in a stream or window.
- Stores
Set store defaults, or choose a log store or memory store to specify how data from a window is saved.
- CCL Continuous Queries
Build a continuous query using clauses and operators to specify its function. This section provides reference for queries, query clauses, and operators.
- Adapters
Adapters connect the Event Stream Processor to the external world.
- Order of Elements
Determine the order of CCL project elements based on clause and statement syntax definitions and limitations.
Created August 28, 2012. Send feedback on this help topic to Sybase Technical Publications:
pubs@sybase.com