# Introduction

#### Memory Templates

1. **User Parameters**: Store text, numbers, time (in seconds).
2. **User Tags**: Add tags for push notifications.
3. **Bot Parameters**: Fixed parameters similar to environment variables, typically used for resource keys.
4. **Single Session Storage**: Store text, numbers, time (in seconds), lists. Each chat session lasts 30 minutes and extends if the conversation continues, expiring 30 minutes after the conversation ends.

#### Scene

Scene allow for multiple conversation threads, useful for different scenes in Messenger or web-embedded scenarios.

#### Domain Invocation

Domains must be connected to the bot and published in production to be invoked. Error codes include:

* `10001`: Domain may have been deleted or not found.
* `10002`: Domain has been closed.
* `11000`: Unknown error occurred.

#### Resource Invocation

Direct HTTP calls are supported with a maximum connection time of 5 seconds. Avoid using this for connections that may time out.

#### Process Nodes

Graphical process design includes five node types:

1. **Resource Node**: For invoking resources.
2. **Reply Node**: For user responses.
3. **Scene Node**: (Discussed in the next chapter)
4. **Variable Node**: Write parameters into user parameters, tags, or single session storage.
5. **Invoke Node**: For invoking any service (discussed in the next chapter).

#### Publishing

Supports multiple versions with two branches per bot: dev (development) and prod (production).