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Source vertex is responsible for reliable reading data from an unbounded source into Numaflow. Source vertex may require transformation or formatting of data prior to sending it to the output buffers. Source Vertex also does Watermark tracking and late data detection.

In Numaflow, we currently support the following sources

A user defined source is a custom source that a user can write using Numaflow SDK when the user needs to read data from a system that is not supported by the platform's built-in sources. User defined source also supports custom acknowledge management for exactly-once reading.