basic-redis-chat-demo-go

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basic-redis-chat-demo-go

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A Basic redis chat demo app written in Go language

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# Basic Redis Chat App Demo

A basic chat application built with Golang, Websocket and Redis.

# Overview video

Here's a short video that explains the project and how it uses Redis:

[![Watch the video on YouTube](https://github.com/redis-developer/basic-redis-chat-demo-go/raw/master/docs/YTThumbnail.png)](https://www.youtube.com/watch?v=miK7xDkDXF0)

## Technical Stacks

- Frontend - _React_, _Socket_
- Backend - _Go_, _Redis_ (go-redis/redis)

## How it works?

### Client Server

Communication build on websocket messages.

Client should handle messages from websocket with `onmessage(event)` event and processed it, where `event.data`
is stringify JSON.

Send request to server available with websocket `send(data)` function, where `data` is `JSON.stringify(Object)`.

Server receive and response stringify JSON object.

Usually for not atomic message sent with `type:"example"` server respond result will be with
same message type: `type:"example"`, for details see `Chat with websocket` block below.

Server not guarantee that responses is ordered as requests order.

As example:

Client requests

```
>>> Request A
>>> Request B
>>> Request C
```

May have responses in other order

```
<<< Response C
<<< Response A
<<< Response B
```

For complicated throws client should receive response for previous sent message before send next message.

As example in a pseudocode:

```
>>> Open websocket
<<< Waiting for message type ready
>>> Send message type signIn
<<< Waiting for message type authorized
>>> Send message type channelJoin
<<< Waiting for message type channelJoin
>>> Now send multiple message to websocket and multiple receive messages
```

### Registration

![How it works](https://raw.githubusercontent.com/redis-developer/basic-redis-chat-demo-go/master/docs/screenshot000.png)

#### User sign in

Send a message to websocket:

```
{
    type: "signIn",
    signIn: {
        username: "Username",
        password: "Password"
    }
}
```

Receive a message from websocket:

```
{
    type: "authorized",
    authorized: {
        userUUID: "123e4567-e89b-12d3-a456-426614174000",
        accessKey: "generated session access key"
    }
}
```

Send system message to all connected users on success:

```
{
    type: "sys",
    sys: {
        type: "signIn",
        signIn: {
            uuid: "123e4567-e89b-12d3-a456-426614174000",
            username: "Username"
        }
    }
}
```

##### Redis Commands

- Key for store user index by user UUID: `usersUUIDListIndex:<UserUUID>`
  - E.g `usersUUIDListIndex:123e4567-e89b-12d3-a456-426614174000`

###### How the data is stored:

User structure:

```
{
    UUID: "123e4567-e89b-12d3-a456-426614174000",
    Username: "User name",
    Password: "Password",
    AccessKey: "Access key",
    OnLine: true
}
```

- Add user to the end redis list, will return number of elements in success: `RPUSH users <JSON Stringify user structure>`. User index in the list is `<number of elements in list> - 1`

- E.g `RPUSH users "{\"UUID\":\"123e4567-e89b-12d3-a456-426614174000\",\"Username\":\"User name\",\"Password\":\"Password\",\"AccessKey\":\"Access key\",\"OnLine\":true}"`

- Save index for search user by Username:

- E.g `SET usersUsernameListIndex:123e4567-e89b-12d3-a456-426614174000 4` where 4 is **User Index**

- Save index for search user by UUID:

- E.g `SET usersUUIDListIndex:123e4567-e89b-12d3-a456-426614174000 4`

- On error, we should remove index for search by Username:

- E.g `DEL usersUsernameListIndex:123e4567-e89b-12d3-a456-426614174000`

- Set user online status, should expire after 60sec:
  - E.g `SETEX userStatus:123e4567-e89b-12d3-a456-426614174000 2021-04-06T12:53:10.436Z 60` where we pass the start date in the ISO string format.

###### How the data is accessed:

- Read user by UUID from redis KV, on exist will return user index for users list in redis:

- E.g `GET usersUUIDListIndex:123e4567-e89b-12d3-a456-426614174000`

- Read user by username from redis KV, on exists will return user index for users list in redis:
  - E.g `GET usersUsernameListIndex:123e4567-e89b-12d3-a456-426614174000`

Key for store users in LList: `users`

- Read user from the start list by user index in list, will return json stringify on success:
  - E.g `lindex users 5` where **5** is index.

#### User sign up

New user registration, will append `signIn` on successful.

Send a message to websocket:

```
{
    type: "signUp",
    signUp: {
        username: "Username",
        password: "Password"
    }
}
```

Receive a message from websocket:

```
{
    type: "authorized",
    authorized: {
        userUUID: "123e4567-e89b-12d3-a456-426614174000",
        accessKey: "generated session access key"
    }
}
```

Each of authorized messages should contain authorized properties `userUUID` and `sessionUUID`, see details below.

Send system message to all connected users:

```
{
    type: "sys",
    sys: {
        type: "signIn",
        signIn: {
            uuid: "123e4567-e89b-12d3-a456-426614174000",
            username: "Username"
        }
    }
}
```

##### **Redis Commands**

Check the `Sign In` section for redis commands, it's the same

#### Logout user

This is atomic command without message body.

Send a message to websocket:

```
{
    type: "signOut",
    userUUID: "123e4567-e89b-12d3-a456-426614174000"
}
```

Receive a message from websocket:

```
{
    type: "signOut",
    signOut: {
        uuid: "123e4567-e89b-12d3-a456-426614174000"
    }
}
```

##### Redis Commands

##### How the data is stored:

On user exist and signed in, remove sign in data.

- Delete user access key:

- E.g `DEL access_key:123e4567-e89b-12d3-a456-426614174000`

- Set user offline:
  - E.g `DEL userStatus:123e4567-e89b-12d3-a456-426614174000`

##### How the data is accessed:

- Check if user exist. Read user index by UUID from redis list:

- E.g `GET usersUUIDListIndex:123e4567-e89b-12d3-a456-426614174000`

- Read user from redis list by an index:

- E.g `LINDEX users 4` where 4 is **User Index**

- Read user online status (it called in `UserGet` method):
  - E.g `GET userStatus:123e4567-e89b-12d3-a456-426614174000`

#### Get users

This is atomic operation, it not expected `users` block in request.

Send a message to websocket:

```
{
    userUUID: "123e4567-e89b-12d3-a456-426614174000",
    type: "users"
}
```

Receive a message from websocket:

```
{
    type: "users",
    users: {
        total: 0,
        received: 0,
        users: [
            {
                UUID: "123e4567-e89b-12d3-a456-426614174000",
                Username: "User name",
                OnLine: true
            }
        ]
    }
}
```

##### Redis Commands

- Read number of users:
  - E.g `LLEN users`
- Read all users:
  - E.g `LRANGE users 0 10` where **10** is number of users.

#### Code Example: Prepare User Data in Redis HashSet

```Go
func (r *Redis) UserCreate(username, password string) (*User, error) {
    log.Println("UserCreate", fmt.Sprintf("[%s|%s]", username, password))

if user, err := r.getUserFromListByUsername(username); err == nil {
        return user, nil
    }

user := &User{
        UUID:     uuid.NewString(),
        Username: username,
        Password: password,
    }

if err := r.addUser(user); err != nil {
        return nil, err
    }
    return user, nil
}
```

### Rooms

![How it works](https://raw.githubusercontent.com/redis-developer/basic-redis-chat-demo-go/master/docs/screenshot001.png)

After signIn/signUp client should send `channelJoin` for receive messages from specified channel.

With empty `channelJoin.recipientUUID` user will join to general channel.

For private channel set `channelJoin.recipientUUID` with valid `userUUID`.

Before channel join we should leave other channels if joined, user should have one joined channel.

Send a message to websocket:

```
{
    userUUID: "123e4567-e89b-12d3-a456-426614174000",
    sessionUUID: "123e4567-e89b-12d3-a456-426614174000",
    type: "channelJoin",
    channelJoin: {
        recipientUUID: "123e4567-e89b-12d3-a456-426614174000",
    }
}
```

Receive a message from websocket

```
{
    type: "channelJoin",
    channelJoin: {
        recipientUUID: "123e4567-e89b-12d3-a456-426614174000",
        messages: [ // array of messages in channel in desc order
            {
                UUID: "123e4567-e89b-12d3-a456-426614174000", // message UUID
                SenderUUID: "123e4567-e89b-12d3-a456-426614174000",
                Sender: {
                    UUID: "123e4567-e89b-12d3-a456-426614174000", //user UUID
                    Username: "User name"
                },
                RecipientUUID: "123e4567-e89b-12d3-a456-426614174000",
                Recipient: {
                    UUID: "123e4567-e89b-12d3-a456-426614174000", //user UUID
                    Username: "User name"
                },
                Message: "Text message",
                CreatedAt: "Message send date"
            }
        ],
        users: [ // array of joined users
            {
                UUID: "123e4567-e89b-12d3-a456-426614174000", //user UUID
                Username: "Username",
                OnLine: true
            }
        ]
    }
}
```

Send system message to all connected users:

```
{
    type: "sys",
    SUUID: "123e4567-e89b-12d3-a456-426614174000",
    userUUID: "123e4567-e89b-12d3-a456-426614174000",
    user: {
        UUID: "123e4567-e89b-12d3-a456-426614174000",
        Username: "User name",
        OnLine: true
    },
    sys: {
        type: "channelJoin",
        channelJoin: {
            recipientUUID: "123e4567-e89b-12d3-a456-426614174000"
        }
    }
}
```

#### Join to channel (room)

After signIn/signUp client should send `channelJoin` for receive messages from specified channel.

With empty `channelJoin.recipientUUID` user will join to general channel.

For private channel set `channelJoin.recipientUUID` with valid `userUUID`.

Before channel join we should leave other channels if joined, user should have one joined channel.

Send a message to websocket:

Receive a message from websocket

Send system message to all connected users:

##### Redis Commands

Leave channel if joined before channel join, see redis flow in `Leave channel` section of this README.

#### How the data is stored:

- Save joined sender to channel `HSET channelUsers:<ChannelUUID> <SenderUUID> <Joined date as string>`:

- E.g `HSET channelUsers:123e4567-e89b-12d3-a456-426614174000 123e4567-e89b-12d3-a456-426634174000 2021-04-06T13:26:44.415Z`

- Save joined recipient for private channel `HSET channelUsers:<ChannelUUID> <RecipientUUID> <Joined date as string>`:

- E.g `HSET channelUsers:123e4567-e89b-12d3-a456-426614174000 123e4567-e89b-12d3-a456-426634174000 2021-04-06T13:26:44.415Z`

- Subcribe to channel `SUBSCRIBE <ChannelUUID>`:
  - E.g `SUBSCRIBE 123e4567-e89b-12d3-a456-426614174000`

#### How the data is accessed:

- Read user index by UUID:

- E.g `GET usersUUIDListIndex:123e4567-e89b-12d3-a456-426614174000`

- Read user list by user index:

- E.g `LINDEX users 5` where **5** is index

- Read channel UUID `GET channelSenderRecipient:<SenderUUID>:<RecipientUUID>`:

- E.g `GET channelSenderRecipient:123e4567-e89b-12d3-a456-426614174000:123e4567-e89b-12d3-a456-426614174022`

- Count message in a channel `LLEN channelMessages:<ChannelUUID>`:

- E.g `LLEN channelMessages:5`

- Read last 10 messages from a channel, if number of messages in a channel less than 10:

- E.g `LRANGE channelMessages:123e4567-e89b-12d3-a456-426614174000 0, 10`

- Read last 10 messages from a channel, if number of messages in a channel more than 10 `<Offset>` is `<Number of messages>-1`: `LRANGE channelMessages:<ChannelUUID> <Offset>, -1`

- E.g `LRANGE channelMessages:123e4567-e89b-12d3-a456-426614174000 10, -1`

- Read channel users:
  - E.g `HGETALL channelUsers:123e4567-e89b-12d3-a456-426614174000`

#### Leave channel

Send a message to websocket:

```
{
    SUUID: "123e4567-e89b-12d3-a456-426614174000",
    type: "channelLeave",
    userUUID: "123e4567-e89b-12d3-a456-426614174000",
    channelLeave: {
        recipientUUID: "123e4567-e89b-12d3-a456-426614174000"
    }
}
```

Receive a message from websocket, all connected users will receive it:

##### Redis Commands

###### How the data is stored:

If channel UUID not found for sender or recipient, we should crate it for both.

Generate `channelUUID`.

- Set channel UUID for sender `SET channelSenderRecipient:<SenderUUID>:<RecipientUUID> <ChannelUUID>`:

- E.g `SET channelSenderRecipient:123e4567-e89b-12d3-a456-426614174000:123e4567-e89b-12d3-a456-426614174000 123e4567-e89b-12d3-a456-426614174000`

- Set channel UUID for recipient: `SET channelSenderRecipient:<RecipientUUID>:<SenderUUID> <ChannelUUID>`
  - E.g `SET channelSenderRecipient:123e4567-e89b-12d3-a456-426614174000:123e4567-e89b-12d3-a456-426614174000 123e4567-e89b-12d3-a456-426614174000`

###### How the data is accessed:

Get channel UUID, will return `public` on empty `recipientUUID`.

Key for private channels, first UUID is a sender(userUUID), second is recipient(userUUID):

```
channelSenderRecipient:123e4567-e89b-12d3-a456-426614174000:123e4567-e89b-12d3-a456-426614174000
```

Key for public channels:

```
channelSenderRecipient:123e4567-e89b-12d3-a456-426614174000:public
```

- Read channel UUID:
  - E.g `GET channelSenderRecipient:123e4567-e89b-12d3-a456-426614174000:public`

#### Code Example: Join Room

```Go
func (r *Redis) ChannelJoin(senderUUID, recipientUUID string) (*ChannelPubSub, string, error) {

channelUUID, err := r.getChannelUUID(senderUUID, recipientUUID)
	if err != nil {
		return nil, "", err
	}

err = r.channelJoin(channelUUID, senderUUID, recipientUUID)
	if err != nil {
		return nil, "", err
	}
	pubSub := r.client.Subscribe(channelUUID)
	channel := r.addChannelPubSub(channelUUID, pubSub)
	return channel, channelUUID, nil
}
```

### Messages

Send a message to websocket:

```
{
    userUUID: "123e4567-e89b-12d3-a456-426614174000",
    type: "channelMessage",
    channelMessage: {
        recipientUUID: "123e4567-e89b-12d3-a456-426614174000",
        message: "Message text"
    }
}
```

Receive a message from websocket, all joined users received it too:

```
{
    type: "channelMessage",
    channelMessage: {
        SenderUUID: "123e4567-e89b-12d3-a456-426614174000",
        Sender: {
            UUID: "123e4567-e89b-12d3-a456-426614174000",
            Username: "User name",
            OnLine: true,
        },
        RecipientUUID: "123e4567-e89b-12d3-a456-426614174000",
        Recipient: {
            UUID: "123e4567-e89b-12d3-a456-426614174000",
            Username: "User name",
            OnLine: true,
        },
        Message: "Text message",
        CreatedAt: "0000-00-00T00:00:00.000000000Z"
    }
}
```

#### **Redis Commands**

#### How the data is stored:

- Publish a message to redis PubSub: `PUBLISH <ChannelUUID> <Message json as string>`

- E.g `PUBLISH 123e4567-e89b-12d3-a456-426614174000 {\"UUID\":\"123e4567-e89b-12d3-a456-426614174000\",\"SenderUUID\":\"123e4567-e89b-12d3-a456-426614174000\",\"RecipientUUID\":\"123e4567-e89b-12d3-a456-426614174000\",\"Message\":\"Text message\",\"CreatedAt\":\"0000-00-00T00:00:00.000000000Z\"}`

- Save message in the end of redis list: `RPUSH channelMessages.<ChannelUUID> <Message json as string>`
  - E.g `RPUSH channelMessages.123e4567-e89b-12d3-a456-426614174000 {\"UUID\":\"123e4567-e89b-12d3-a456-426614174000\",\"SenderUUID\":\"123e4567-e89b-12d3-a456-426614174000\",\"RecipientUUID\":\"123e4567-e89b-12d3-a456-426614174000\",\"Message\":\"Text message\",\"CreatedAt\":\"0000-00-00T00:00:00.000000000Z\"}`

Message structure:

```
{
    UUID: "123e4567-e89b-12d3-a456-426614174000", // message UUID
    SenderUUID: "123e4567-e89b-12d3-a456-426614174000", // user UUID
    RecipientUUID: "123e4567-e89b-12d3-a456-426614174000", // user UUID, or empty for public channel
    Message: "Text message",
    CreatedAt: "0000-00-00T00:00:00.000000000Z"
}
```

#### How the data is accessed:

Read channel UUID. See **Redis Commands** in `Channel leave`.

#### Code Example: Send Message

```Go
func channelSessionsSendMessage(skipUserUUID, channelUUID string, write Write, message *Message) {
	channelSessionsSync.RLock()
	defer channelSessionsSync.RUnlock()
	for _, data := range channelSessionsJoins[channelUUID] {
		if skipUserUUID != "" && skipUserUUID == data.userUUID {
			continue
		}
		if err := write(data.conn, ws.OpText, message); err != nil {
			log.Println(err)
		}
	}
}
```

### Session handling

On first connect to websocket client receive `ready` message:

```
{
    type: "ready",
    ready: {
        sessionUUID: "123e4567-e89b-12d3-a456-426614174000"
    }
}
```

#### Redis Commands

##### How the data is stored:

- Key for store user session UUID: `userSession:123e4567-e89b-12d3-a456-426614174000`

- E.g `SETEX userSession.123e4567-e89b-12d3-a456-426614174000 0000-00-00T00:00:00.000000000Z 3600`

- Remove user session:

- E.g `DEL userSession.123e4567-e89b-12d3-a456-426614174000`

##### How the data is accessed:

- Read user session created time:

- E.g `GET userSession.123e4567-e89b-12d3-a456-426614174000`

#### Code example: Managing session

```Go
func (r *Redis) getKeyUserSession(userSessionUUID string) string {
	return fmt.Sprintf("%s.%s", keyUserSession, userSessionUUID)
}

func (r *Redis) AddConnection(userSessionUUID string) error {
	key := r.getKeyUserSession(userSessionUUID)
	return r.client.Set(key, time.Now().String(), time.Hour).Err()
}

func (r *Redis) DelConnection(userSessionUUID string) error {
	key := r.getKeyUserSession(userSessionUUID)
	return r.client.Del(key).Err()
}
```

## How to run it locally?

The client utilizes **Create React App** template, to run it with the development instance of backend, specify the proxy parameter in **package.json**:

```
  "proxy": "http://localhost:5555",
```

#### Run frontend

```sh
cd client
yarn install
yarn start
```

#### Run backend

#### Set the next environment variables (.env.example):

```
SERVER_ADDRESS=:5555
CLIENT_LOCATION=/api/public
REDIS_HOST=chat-redis
REDIS_ADDRESS=:6379
REDIS_PASSWORD=
```

```sh
go run
```

## Try it out

#### Deploy to Heroku

#### Deploy to Google Cloud

basic-redis-chat-demo-go

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