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Multi-channel DataWriters

In Connext DDS, producers publish data to a Topic, identified by a topic name; consumers subscribe to a Topic and optionally to specific content by means of a content-filter expression.

A Market Data Example:

A producer can publish data on the Topic "MarketData" which can be defined as a structured record containing fields that identify the exchange (e.g., "NYSE" or "NASDAQ"), the stock symbol (e.g., "APPL" or "JPM"), volume, bid and ask prices, etc.

Similarly, a consumer may want to subscribe to data on the "MarketData" Topic, but only if the exchange is "NYSE" or the symbol starts with the letter "M." Or the consumer may want all the data from the "NYSE" whose volume exceeds a certain threshold, or may want MarketData for a specific stock symbol, regardless of the exchange, and so on.

The middleware’s efficient implementation of content-filtering is critical for scenarios such as the above "Market Data" example, where there are large numbers of consumers, large volumes of data, or Topics that transmit information about many data-objects or subjects (e.g., individual stocks).

Traditionally, middleware products use four approaches to implement content filtering: Producer-based, Consumer-based, Server-based, and Network Switch-based.

RTI supports the producer-based, consumer-based and network-switch approaches to content filtering:

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