RFC-0010/CodeStructure

Tari Code Structure and Organization

status: draft

Maintainer(s): Cayle Sharrock

Licence

The 3-Clause BSD Licence.

Copyright 2018 The Tari Development Community

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  1. Redistributions of this document must retain the above copyright notice, this list of conditions and the following disclaimer.
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Language

The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY" and "OPTIONAL" in this document are to be interpreted as described in BCP 14 (covering RFC2119 and RFC8174) when, and only when, they appear in all capitals, as shown here.

Disclaimer

This document and its content are intended for information purposes only and may be subject to change or update without notice.

This document may include preliminary concepts that may or may not be in the process of being developed by the Tari community. The release of this document is intended solely for review and discussion by the community of the technological merits of the potential system outlined herein.

Goals

The aim of this Request for Comment (RFC) is to describe and explain the Tari codebase layout.

Related Requests for Comment

None.

Description

The code follows a Domain-driven Design (DDD) layout, with top-level directories falling into infrastructure, domain and application layers.

Infrastructure Layer

The infrastructure layer provides a set of crates that have general infrastructural utility. The rest of the Tari codebase can make use of these crates to obtain persistence, communication and cryptographic services. The infrastructure layer doesn't know anything about blockchains, transactions or digital assets.

We recommend that code in this layer generalizes infrastructure services behind abstraction layers as much as is reasonable, so that specific implementations can be swapped out with relative ease.

Domain Layer

The domain layer houses the Tari "business logic". All protocol-related concepts and procedures are defined and implemented here.

This means that any and all terms defined in the Glossary will have a software implementation here, and only here. They can be used in the application layer, but must be implemented in the domain layer.

The domain layer can make use of crates in the infrastructure layer to achieve its goals.

Application Layer

In the application layer, applications build on top of the domain layer to produce the executable software that is deployed as part of the Tari network.

As an example, the following base layer applications may be developed as part of the Tari protocol release:

  • A standalone miner (tari_miner)
  • A pool miner (tari_pool_miner)
  • A Command Line Interface (CLI) wallet for the Tari cryptocurrency (cli_wallet)
  • A base node executable (tari_basenode)
  • A REST Application Programming Interface (API) server for the base node

Code Layout

The top-level source code directories in this repository reflect the respective DDD layers; except that there are two domain layer directories, corresponding to the two network layers that make up the Tari network.

  1. The infrastructure directory contains application-layer code and is not Tari-specific. It holds the following crates:

    • comms - the networking and messaging subsystem;
    • crypto - all cryptographic services, including a Curve25519 implementation;
    • storage - data persistence services, including a Lightning Memory-mapped Database (LMDB) persistence implementation;
    • merklemountainrange - an independent implementation of a Merkle Mountain Range;
    • derive - a crate to contain derive(...) macros.
  2. base_layer is a domain-layer directory and contains:

    • blockchain - the Tari consensus code;
    • core - common classes and traits, such as Transactions and Blocks;
    • mempool - the unconfirmed transaction pool implementation;
    • mining - the merged-mining modules;
    • p2p - the block and transaction propagation module;
    • api - interfaces for clients and wallets to interact with the base layer components.
  3. digital_assets_layer is a domain-layer directory. It contains code related to the management of native Tari digital assets. Its substructure is to be determined.

  4. applications contains crates for all the application-layer executables that form part of the Tari codebase.