> ## Documentation Index
> Fetch the complete documentation index at: https://cosmos-docs-cosmjs-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Transaction Encoding

> When orchestrating an interchain account transaction, which comprises multiple sdk.Msg objects represented as Any types, the transactions must be encoded as bytes within InterchainAccountPacketData.

When orchestrating an interchain account transaction, which comprises multiple `sdk.Msg` objects represented as `Any` types, the transactions must be encoded as bytes within [`InterchainAccountPacketData`](https://github.com/cosmos/ibc-go/blob/v7.2.0/proto/ibc/applications/interchain_accounts/v1/packet.proto#L21-L26).

```protobuf theme={"system"}
/ InterchainAccountPacketData is comprised of a raw transaction, type of transaction and optional memo field.
message InterchainAccountPacketData {
  Type   type = 1;
  bytes  data = 2;
  string memo = 3;
}
```

The `data` field must be encoded as a [`CosmosTx`](https://github.com/cosmos/ibc-go/blob/v7.2.0/proto/ibc/applications/interchain_accounts/v1/packet.proto#L28-L31).

```protobuf theme={"system"}
/ CosmosTx contains a list of sdk.Msg's. It should be used when sending transactions to an SDK host chain.
message CosmosTx {
  repeated google.protobuf.Any messages = 1;
}
```

The encoding method for `CosmosTx` is determined during the channel handshake process. If the channel version [metadata's `encoding` field](https://github.com/cosmos/ibc-go/blob/v7.2.0/proto/ibc/applications/interchain_accounts/v1/metadata.proto#L22) is marked as `proto3`, then `CosmosTx` undergoes protobuf encoding. Conversely, if the field is set to `proto3json`, then [proto3 json](https://protobuf.dev/programming-guides/proto3/#json) encoding takes place, which generates a JSON representation of the protobuf message.

## Protobuf Encoding

Protobuf encoding serves as the standard encoding process for `CosmosTx`. This occurs if the channel handshake initiates with an empty channel version metadata or if the `encoding` field explicitly denotes `proto3`. In Golang, the protobuf encoding procedure utilizes the `proto.Marshal` function. Every protobuf autogenerated Golang type comes equipped with a `Marshal` method that can be employed to encode the message.

## (Protobuf) JSON Encoding

The proto3 JSON encoding presents an alternative encoding technique for `CosmosTx`. It is selected if the channel handshake begins with the channel version metadata `encoding` field labeled as `proto3json`. In Golang, the Proto3 canonical encoding in JSON is implemented by the `"github.com/cosmos/gogoproto/jsonpb"` package. Within Cosmos SDK, the `ProtoCodec` structure implements the `JSONCodec` interface, leveraging the `jsonpb` package. This method generates a JSON format as follows:

```json expandable theme={"system"}
{
  "messages": [
    {
      "@type": "/cosmos.bank.v1beta1.MsgSend",
      "from_address": "cosmos1...",
      "to_address": "cosmos1...",
      "amount": [
        {
          "denom": "uatom",
          "amount": "1000000"
        }
      ]
    }
  ]
}
```

Here, the `"messages"` array is populated with transactions. Each transaction is represented as a JSON object with the `@type` field denoting the transaction type and the remaining fields representing the transaction's attributes.