> For the complete documentation index, see [llms.txt](https://docs.contextual.io/documentation-and-resources/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.contextual.io/documentation-and-resources/patterns/solution-architecture/event-i-o.md).

# Events, Messages, Queues

Events are passed within Contextual in 3 ways:

* Send To Agent Nodes - These are nodes within your Contextual flow that will send the message payload (msg.payload) along to another Agent.
* Triggers - These are configured on Object Types and pass a new (post insert), updated (post-update) or deleted (post-delete) record along to the designated Agent for processing.
* Actions - These can be manually run or triggered via API. To run an Action manually you configure the Action on the Object Type and then execute it in the overflow menu for the record itself.

Note that the format of a Trigger payload for a Record is slightly different than that for an Action. On a Trigger the record be passed as an event as msg.payload. On an Action it will be under an instance property, so msg.event.instance.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://docs.contextual.io/documentation-and-resources/patterns/solution-architecture/event-i-o.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.