# Messenger

## Variables

### Message

```solidity
struct Message {
    bytes32 txUniqueIdentification;
    bytes32 crossType;
    bytes32 srcAnchor;
    bytes bnExtraFeed;
    bytes32 dstAnchor;
    bytes payload;
}
```

A properly defined struct to pack essential cross-chain information.

#### Params

<table><thead><tr><th width="269.3333333333333">Name</th><th width="103">Type</th><th>Description</th></tr></thead><tbody><tr><td><code>txUniqueIdentification</code></td><td>bytes32</td><td>A globally unique identifier for each cross-chain message</td></tr><tr><td><code>crossType</code></td><td>bytes32</td><td>Indicate the type of a cross-chain message</td></tr><tr><td><code>srcAnchor</code></td><td>bytes32</td><td>The address of the source chain Anchor in bytes32</td></tr><tr><td><code>bnExtraFeed</code></td><td>bytes</td><td>Additional data that depends on the <code>crossType</code></td></tr><tr><td><code>dstAnchor</code></td><td>bytes32</td><td>The address of the destination chain Anchor in bytes32</td></tr><tr><td><code>payload</code></td><td>bytes</td><td>Application-level data that will be forwarded to the destination consumer contract</td></tr></tbody></table>

### MessageStatus

```solidity
enum MessageStatus {
    DELIVERED,
    FAILED
}
```

Returns `DELIVERED` when the cross-chain message has been successfully delivered to the destination. Otherwise, `FAILED` is signalled, along with an event `MessageCached` emitted.&#x20;

## Events

### MessageSent

```solidity
event MessageSent(Message message);
```

Emits on the source chain with essential cross-chain information packed in a `Message` struct.

### MessageReceived

```solidity
event MessageReceived(
    bytes32 txUniqueIdentification,
    bytes32 crossType,
    bytes32 srcAnchor,
    bytes32 dstAnchor,
    MessageStatus status
);
```

Emits on the destination chain where the `MessageStatus` can be either `DELIVERED` or `FAILED`.

### MessageCached

```solidity
event MessageCached(bytes reason, bytes payload)
```

Emits when the destination transaction reverted for some reason. A bridge builder should define the error logic in their application-level contracts.&#x20;

It can be combined with the corresponding `MessageReceived` event to recover the original message and identify the reverting reason.

## Functions

### sendToBool

```solidity
function sendToBool(
    address payable refundAddress,
    bytes32 crossType,
    bytes memory valueFeed,
    uint32 dstChainId,
    bytes32 dstAnchor,
    bytes calldata payload
) external payable onlyRegisteredAnchor returns (bytes32 txUniqueIdentification)
```

Called by registered Anchors to forward cross-chain messages to BOOLNetwork.

#### Params

<table><thead><tr><th width="183.33333333333331">Name</th><th width="175">Type</th><th>Description</th></tr></thead><tbody><tr><td><code>refundAddress</code></td><td>address payable</td><td>The address to receive the rest of the pre-paid transaction fee</td></tr><tr><td><code>crossType</code></td><td>bytes32</td><td>Indicate the type of a cross-chain message</td></tr><tr><td><code>valueFeed</code></td><td>bytes</td><td>Additional data that depends on the <code>crossType</code></td></tr><tr><td><code>dstChainId</code></td><td>uint32</td><td>ID of the destination chain</td></tr><tr><td><code>dstAnchor</code></td><td>bytes32</td><td>The address of the destination chain Anchor in bytes32</td></tr><tr><td><code>payload</code></td><td>bytes</td><td>Application-level data that will be forwarded to the destination consumer contract</td></tr></tbody></table>

#### Return  Values

<table><thead><tr><th width="269.3333333333333">Name</th><th width="102">Type</th><th>Description</th></tr></thead><tbody><tr><td><code>txUniqueIdentification</code></td><td>bytes32</td><td>A globally unique identifier for each cross-chain message</td></tr></tbody></table>

### receiveFromBool

```solidity
function receiveFromBool(
    Message memory message, 
    bytes calldata signature
)external payable returns (MessageStatus status)
```

Receives cross-chain messages from BOOLNetwork.

#### Params

<table><thead><tr><th width="201">Name</th><th width="112.33333333333331">Type</th><th>Description</th></tr></thead><tbody><tr><td><code>message</code></td><td>Message</td><td>A Message struct consists of all the essential cross-chain information</td></tr><tr><td><code>signature</code></td><td>bytes</td><td>Signature from a committee which is used to verify the validity of a cross-chain message</td></tr></tbody></table>

#### Return Values

<table><thead><tr><th width="130.33333333333331">Name</th><th width="156">Type</th><th>Description</th></tr></thead><tbody><tr><td><code>status</code></td><td>MessageStatus</td><td>An identifier to present the final status of a cross-chain message</td></tr></tbody></table>