EventSourceMessage

Event names are of the format: on_[runnable_type]_(start|stream|end).

Runnable types are one of:

• llm - used by non chat models
• chat_model - used by chat models
• prompt -- e.g., ChatPromptTemplate
• tool -- LangChain tools
• chain - most Runnables are of this type

Further, the events are categorized as one of:

• start - when the runnable starts
• stream - when the runnable is streaming
• end - when the runnable ends

start, stream and end are associated with slightly different data payload.

Please see the documentation for EventData for more details.

An optional identifier for the document.

Ideally this should be unique across the document collection and formatted as a UUID, but this will not be enforced.

The reconnection interval (in milliseconds) to wait before retrying the connection