Asset Processing Overview

Here you can find a short overview on how TON transfers work, what asset types can you find in TON (and what about will you read next) and how to interact with ton using your programming language, it's recommended to understand all information, discovered below, before going to the next pages.

Overview on messages and transactions

Embodying a fully asynchronous approach, TON Blockchain involves a few concepts which are uncommon to traditional blockchains. Particularly, each interaction of any actor with the blockchain consists of a graph of asynchronously transferred messages between smart contracts and/or the external world. Each transaction consists of one incoming message and up to 255 outgoing messages.

There are 3 types of messages, that are fully described here. To put it briefly:

• external message:
  • external in message (sometimes called just external message) is message that is sent from outside of the blockchain to a smart contract inside the blockchain.
  • external out message (usually called logs message) is sent from a blockchain entity to the outer world.
• internal message is sent from one blockchain entity to another, can carry some amount of digital assets and arbitrary portion of data.

The common path of any interaction starts with an external message sent to a wallet smart contract, which authenticates the message sender using public-key cryptography, takes charge of fee payment, and sends internal blockchain messages. That messages queue form directional acyclic graph, or a tree.

For example:

• Alice use e.g Tonkeeper to send an external message to her wallet.
• external message is the input message for wallet A v4 contract with empty source (a message from nowhere, such as Tonkeeper).
• outgoing message is the output message for wallet A v4 contract and input message for wallet B v4 contract with wallet A v4 source and wallet B v4 destination.

As a result there are 2 transactions with their set of input and output messages.

Each action, when contract take message as input (triggered by it), process it and generate or not generate outgoing messages as output, called transaction. Read more about transactions here.

That transactions can span a prolonged period of time. Technically, transactions with queues of messages are aggregated into blocks processed by validators. The asynchronous nature of the TON Blockchain does not allow to predict the hash and lt (logical time) of a transaction at the stage of sending a message.

The transaction accepted to the block is final and cannot be modified.

Transaction Confirmation

TON transactions are irreversible after just one confirmation. For the best user experience, it is suggested to avoid waiting on additional blocks once transactions are finalized on the TON Blockchain. Read more in the Catchain.pdf.

Smart contracts pay several types of fees for transactions (usually from the balance of an incoming message, behavior depends on message mode). Amount of fees depends on workchain configs with maximal fees on masterchain and substantially lower fees on basechain.

Digital asset types on TON

TON has three types of digital assets.

• Toncoin, the main token of the network. It is used for all basic operations on the blockchain, for example, paying gas fees or staking for validation.
• Contract assets, such as tokens and NFTs, which are analogous to the ERC-20/ERC-721 standards and are managed by arbitrary contracts and thus can require custom rules for processing. You can find more info on it's processing in process NFTs and process Jettons articles.
• Native token, which is special kind of assets that can be attached to any message on the network. But these asset is currently not in use since the functionality for issuing new native tokens is closed.

Interaction with TON blockchain

Basic operations on TON Blockchain can be carried out via TonLib. It is a shared library which can be compiled along with a TON node and expose APIs for interaction with the blockchain via so-called lite servers (servers for lite clients). TonLib follows a trustless approach by checking proofs for all incoming data; thus, there is no necessity for a trusted data provider. Methods available to TonLib are listed in the TL scheme. They can be used either as a shared library via wrappers.

Read next

After reading this article you can check:

1. Payments processing to get how to work with TON coins
2. Jetton processing to get how to work with jettons (sometime called tokens)
3. NFT processing to get how to work with NFT (that is the special type of jetton)