Definitions

Terminology related to data streams and messages.

• Field
  A field holds a single piece of data, such as a salary,a person's last name, or a timestamp.
• Message / Row
  A message(also called a "row", a "tuple", or an "event") is very similar to a row of data in a database table. A row is a group of fields that all have data about the same thing.
• Row Timestamp
  In a Sybase CEP Engine, each row contains a "row timestamp" that is used to help ensure that rows are processed in order.
• Schema
  Every row in a stream has the same structure, or "schema". The schema comprises the column names, the column data types, and the order in which the columns appear.
• Tuple Descriptor
  A "Tuple Descriptor" stores information about the schema of a stream and information about the schema of the rows in the stream. Adapters written using certain Sybase CEP SDKs use a Tuple Descriptor to help the adapter work properly with the stream.
• Data Stream
  A data stream carries rows from one place to another, for example, from one query to a subsequent query, or from an adapter to the server.
• Stream URI
  Each stream has a unique URI, which serves as anaddressthat enables software to connect to that stream. For example, when an adapter connects to a stream, the adapter needs to know the stream's URI.
• Publishing and Subscribing
  Messages are written to a stream and then read from that stream.
• Windows
  A window is a stored group of rows that has a retention policy, such as "KEEP 10 MINUTES" or "KEEP 50 ROWS".
• User-Defined Functions
  Write your own functions and call them from CCL; these functions are called User-Defined Functions (UDFs). As with built-in functions, you can pass in values from the current row, and you get back a return value from the function.
• Expiring Messages
  When rows are deleted from a window, some queries may need to be re-evaluated.
• Bundles
  In some cases, a particular event can cause multiple output rows, and those rows can be grouped into a bundle. A bundle is a set of two or more data messages that are conceptually part of the same operation and are thus grouped together.
• SDK
  A Software Development Kit (SDK) is a set of software that helps you write other software, such as input and output adapters and User-Defined Functions.