Namespace com.ibm.streamsx.topology.topic

# Namespace `com.ibm.streamsx.topology.topic`

Toolkits > com.ibm.streamsx.topology 1.15.9 > com.ibm.streamsx.topology.topic

Topic based publish-subscribe model supporting a microservice architecture style for Streams applications.

Publish-subscribe Overview
  Applications can publish streams to a topic name which can then be subscribed to by other applications (or even the same application).

Relationship to Export & Import
  Publish-subscribe is a simplification of IBM Streams `Export` and `Import`.

## Operators

- Buffered: Connect subscriber to publisher using a buffer.
- Direct: Directly connect subscriber to publisher.
- FilteredSubscribe: Filtered subscribe to a topic.
- Publish: Publish a stream to a topic.
- Subscribe: Subscribe to topics using a topic filter.

## Functions

- addUDPSubscription(rstring): Take a subscription and modify it to account for parallel regions in the publisher or subscriber.
- andFilter(rstring, rstring): Return a string representation of `cond1 && cond2`.
- checkTopicFilter(rstring): Check a topic filter is valid.
- checkTopicName(rstring): Check a topic name is valid.
- equalsFilter(rstring, float64): Return a string representation of `name == value` for a `float64` attribute.
- equalsFilter(rstring, int64): Return a string representation of `name == value` for a `int64` attribute.
- equalsFilter(rstring, rstring): Return a string representation of `name == value` for a `rstring` attribute.
- getTopicSubscription(rstring): Get the subscription that matches a topic for topic based subscription.
- getTopicSubscription(rstring, boolean): Get the subscription that matches a topic for topic based subscription with explicit matching for the publisher allowing filters.
- inFilter(rstring, list<rstring>): Return a string representation of filter `name in values` for a `rstring` attribute.
- orFilter(rstring, rstring): Return a string representation of `cond1 || cond2`.
- setSubscribeFilter(rstring): Set filter for input port zero.
- setSubscribeSubscription(rstring): Set a subscription expression adding in UDP channel based matching if the subscriber is in a parallel region.