EIP 1123: Revised Ethereum Smart Contract Packaging Standard

Simple Summary

A data format describing a smart contract software package.

Abstract

This EIP defines a data format for package manifest documents, representing a package of one or more smart contracts, optionally including source code and any/all deployed instances across multiple networks. Package manifests are minified JSON objects, to be distributed via content addressable storage networks, such as IPFS.

This document presents a natural language description of a formal specification for version 2 of this format.

Motivation

This standard aims to encourage the Ethereum development ecosystem towards software best practices around code reuse. By defining an open, community-driven package data format standard, this effort seeks to provide support for package management tools development by offering a general-purpose solution that has been designed with observed common practices in mind.

As version 2 of this specification, this standard seeks to address a number of areas of improvement found for the previous version (defined in EIP-190). This version:

• Generalizes storage URIs to represent any content addressable URI scheme, not only IPFS.

• Renames release lockfile to package manifest.

• Adds support for languages other than Solidity by generalizing the compiler information format.

• Redefines link references to be more flexible, to represent arbitrary gaps in bytecode (besides only addresses), in a more straightforward way.

• Forces format strictness, requiring that package manifests contain no extraneous whitespace, and sort object keys in alphabetical order, to prevent hash mismatches.

Specification

This document defines the specification for an EthPM package manifest. A package manifest provides metadata about a Package, and in most cases should provide sufficient information about the packaged contracts and its dependencies to do bytecode verification of its contracts.

Note

A hosted version of this specification is available via GitHub Pages. This EIP and the hosted HTML document were both autogenerated from the same documentation source.

Guiding Principles

This specification makes the following assumptions about the document lifecycle.

1. Package manifests are intended to be generated programatically by package management software as part of the release process.

2. Package manifests will be consumed by package managers during tasks like installing package dependencies or building and deploying new releases.

3. Package manifests will typically not be stored alongside the source, but rather by package registries or referenced by package registries and stored in something akin to IPFS.

Conventions

RFC2119

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in RFC 2119.

• https://www.ietf.org/rfc/rfc2119.txt

Prefixed vs Unprefixed

A prefixed hexadecimal value begins with 0x. Unprefixed values have no prefix. Unless otherwise specified, all hexadecimal values should be represented with the 0x prefix.

Document Format

The canonical format is a single JSON object. Packages must conform to the following serialization rules.

• The document must be tightly packed, meaning no linebreaks or extra whitespace.

• The keys in all objects must be sorted alphabetically.

• Duplicate keys in the same object are invalid.

• The document must use UTF-8 encoding.

• The document must not have a trailing newline.

Document Specification

The following fields are defined for the package. Custom fields may be included. Custom fields should be prefixed with x- to prevent name collisions with future versions of the specification.

EthPM Manifest Version: manifest_version

The manifest_version field defines the specification version that this document conforms to. Packages must include this field.

Package Name: package_name

The package_name field defines a human readable name for this package. Packages must include this field. Package names must begin with a lowercase letter and be comprised of only lowercase letters, numeric characters, and the dash character -. Package names must not exceed 214 characters in length.

Package Meta: meta

The meta field defines a location for metadata about the package which is not integral in nature for package installation, but may be important or convenient to have on-hand for other reasons. This field should be included in all Packages.

Version: version

The version field declares the version number of this release. This value must be included in all Packages. This value should conform to the semver version numbering specification.

Sources: sources

The sources field defines a source tree that should comprise the full source tree necessary to recompile the contracts contained in this release. Sources are declared in a key/value mapping.

Format

Keys must be relative filesystem paths beginning with a ./.

Paths must resolve to a path that is within the current working directory.

Values must conform to one of the following formats.

• Source string.

• Content Addressable URI.

When the value is a source string the key should be interpreted as a file path.

• If the resulting document is a directory the key should be interpreted as a directory path.

• If the resulting document is a file the key should be interpreted as a file path.

Contract Types: contract_types

The contract_types field holds the Contract Types which have been included in this release. Packages should only include contract types that can be found in the source files for this package. Packages should not include contract types from dependencies. Packages should not include abstract contracts in the contract types section of a release.

Deployments: deployments

The deployments field holds the information for the chains on which this release has Contract Instances as well as the Contract Types and other deployment details for those deployed contract instances. The set of chains defined by the *BIP122 URI <#bip122-uris>* keys for this object must be unique.

Format

Keys must be a valid BIP122 URI chain definition.

Values must be objects which conform to the following format.

• Keys must be valid Contract Instance Names.

• Values must be a valid Contract Instance Object.

Build Dependencies: build_dependencies

The build_dependencies field defines a key/value mapping of Ethereum Packages that this project depends on.

Definitions

Definitions for different objects used within the Package. All objects allow custom fields to be included. Custom fields should be prefixed with x- to prevent name collisions with future versions of the specification.

The Link Reference Object

A Link Reference object has the following key/value pairs. All link references are assumed to be associated with some corresponding Bytecode.

Offsets: offsets

The offsets field is an array of integers, corresponding to each of the start positions where the link reference appears in the bytecode. Locations are 0-indexed from the beginning of the bytes representation of the corresponding bytecode. This field is invalid if it references a position that is beyond the end of the bytecode.

Length: length

The length field is an integer which defines the length in bytes of the link reference. This field is invalid if the end of the defined link reference exceeds the end of the bytecode.

Name: name

The name field is a string which must be a valid Identifier. Any link references which should be linked with the same link value should be given the same name.

The Link Value Object

Describes a single Link Value.

A Link Value object is defined to have the following key/value pairs.

Offsets: offsets

The offsets field defines the locations within the corresponding bytecode where the value for this link value was written. These locations are 0-indexed from the beginning of the bytes representation of the corresponding bytecode.

Format

Array of integers, where each integer must conform to all of the following.

• greater than or equal to zero

• strictly less than the length of the unprefixed hexadecimal representation of the corresponding bytecode.

Type: type

The type field defines the value type for determining what is encoded when linking the corresponding bytecode.

Value: value

The value field defines the value which should be written when linking the corresponding bytecode.

Format

For static value literals (e.g. address), value must be a byte string

To reference the address of a Contract Instance from the current package the value should be the name of that contract instance.

• This value must be a valid contract instance name.

• The chain definition under which the contract instance that this link value belongs to must contain this value within its keys.

• This value may not reference the same contract instance that this link value belongs to.

To reference a contract instance from a Package from somewhere within the dependency tree the value is constructed as follows.

• Let [p1, p2, .. pn] define a path down the dependency tree.

• Each of p1, p2, pn must be valid package names.

• p1 must be present in keys of the build_dependencies for the current package.

• For every pn where n > 1, pn must be present in the keys of the build_dependencies of the package for pn-1.

• The value is represented by the string <p1>:<p2>:<...>:<pn>:<contract-instance> where all of <p1>, <p2>, <pn> are valid package names and <contract-instance> is a valid Contract Name.

• The <contract-instance> value must be a valid Contract Instance Name.

• Within the package of the dependency defined by <pn>, all of the following must be satisfiable:

  • There must be exactly one chain defined under the deployments key which matches the chain definition that this link value is nested under.

  • The <contract-instance> value must be present in the keys of the matching chain.

The Bytecode Object

A bytecode object has the following key/value pairs.

Bytecode: bytecode

The bytecode field is a string containing the 0x prefixed hexadecimal representation of the bytecode.

Link References: link_references

The link_references field defines the locations in the corresponding bytecode which require linking.

Format

This field is considered invalid if any of the Link References are invalid when applied to the corresponding bytecode field, or if any of the link references intersect.

Intersection is defined as two link references which overlap.

Link Dependencies: link_dependencies

The link_dependencies defines the Link Values that have been used to link the corresponding bytecode.

Format

Validation of this field includes the following:

• Two link value objects must not contain any of the same values for offsets.

• Each link value object must have a corresponding link reference object under the link_references field.

• The length of the resolved value must be equal to the length of the corresponding Link Reference.

The Package Meta Object

The Package Meta object is defined to have the following key/value pairs.

Authors: authors

The authors field defines a list of human readable names for the authors of this package. Packages may include this field.

License: license

The license field declares the license under which this package is released. This value should conform to the SPDX format. Packages should include this field.

Description: description

The description field provides additional detail that may be relevant for the package. Packages may include this field.

Keywords: keywords

The keywords field provides relevant keywords related to this package.

Links: links

The links field provides URIs to relevant resources associated with this package. When possible, authors should use the following keys for the following common resources.

• website: Primary website for the package.

• documentation: Package Documentation

• repository: Location of the project source code.

The Contract Type Object

A Contract Type object is defined to have the following key/value pairs.

Contract Name: contract_name

The contract_name field defines the Contract Name for this Contract Type.

Deployment Bytecode: deployment_bytecode

The deployment_bytecode field defines the bytecode for this Contract Type.

Runtime Bytecode: runtime_bytecode

The runtime_bytecode field defines the unlinked 0x-prefixed runtime portion of Bytecode for this Contract Type.

ABI: abi

Natspec: natspec

Compiler: compiler

The Contract Instance Object

A Contract Instance Object represents a single deployed Contract Instance and is defined to have the following key/value pairs.

Contract Type: contract_type

The contract_type field defines the Contract Type for this Contract Instance. This can reference any of the contract types included in this Package or any of the contract types found in any of the package dependencies from the build_dependencies section of the Package Manifest.

Format

Values for this field must conform to one of the two formats herein.

To reference a contract type from this Package, use the format <contract-alias>.

• The <contract-alias> value must be a valid Contract Alias.

• The value must be present in the keys of the contract_types section of this Package.

To reference a contract type from a dependency, use the format <package-name>:<contract-alias>.

• The <package-name> value must be present in the keys of the build_dependencies of this Package.

• The <contract-alias> value must be be a valid Contract Alias.

• The resolved package for <package-name> must contain the <contract-alias> value in the keys of the contract_types section.

Address: address

The address field defines the Address of the Contract Instance.

Transaction: transaction

The transaction field defines the transaction hash in which this Contract Instance was created.

Block: block

The block field defines the block hash in which this the transaction which created this contract instance was mined.

Runtime Bytecode: runtime_bytecode

The runtime_bytecode field defines the runtime portion of bytecode for this Contract Instance. When present, the value from this field supersedes the runtime_bytecode from the Contract Type for this Contract Instance.

Every entry in the link_references for this bytecode must have a corresponding entry in the link_dependencies section.

Compiler: compiler

The compiler field defines the compiler information that was used during compilation of this Contract Instance. This field should be present in all Contract Types which include bytecode or runtime_bytecode.

The Compiler Information Object

The compiler field defines the compiler information that was used during compilation of this Contract Instance. This field should be present in all contract instances that locally declare runtime_bytecode.

A Compiler Information object is defined to have the following key/value pairs.

Name name

The name field defines which compiler was used in compilation.

Version: version

The version field defines the version of the compiler. The field should be OS agnostic (OS not included in the string) and take the form of either the stable version in semver format or if built on a nightly should be denoted in the form of <semver>-<commit-hash> ex: 0.4.8-commit.60cc1668.

Settings: settings

The settings field defines any settings or configuration that was used in compilation. For the "solc" compiler, this should conform to the Compiler Input and Output Description.

BIP122 URIs

BIP122 URIs are used to define a blockchain via a subset of the BIP-122 spec.

blockchain://<genesis_hash>/block/<latest confirmed block hash>

The <genesis hash> represents the blockhash of the first block on the chain, and <latest confirmed block hash> represents the hash of the latest block that’s been reliably confirmed (package managers should be free to choose their desired level of confirmations).

Rationale

The following use cases were considered during the creation of this specification.

Each use case builds incrementally on the previous one.

A full listing of Use Cases can be found on the hosted version of this specification.

Glossary

ABI

The JSON representation of the application binary interface. See the official specification for more information.

Address

A public identifier for an account on a particular chain

Bytecode

The set of EVM instructions as produced by a compiler. Unless otherwise specified this should be assumed to be hexadecimal encoded, representing a whole number of bytes, and prefixed with 0x.

Bytecode can either be linked or unlinked. (see Linking)

Chain Definition

This definition originates from BIP122 URI.

A URI in the format blockchain://<chain_id>/block/<block_hash>

• chain_id is the unprefixed hexadecimal representation of the genesis hash for the chain.

• block_hash is the unprefixed hexadecimal representation of the hash of a block on the chain.

A chain is considered to match a chain definition if the the genesis block hash matches the chain_id and the block defined by block_hash can be found on that chain. It is possible for multiple chains to match a single URI, in which case all chains are considered valid matches

Content Addressable URI

Any URI which contains a cryptographic hash which can be used to verify the integrity of the content found at the URI.

The URI format is defined in RFC3986

It is recommended that tools support IPFS and Swarm.

Contract Alias

This is a name used to reference a specific Contract Type. Contract aliases must be unique within a single Package.

The contract alias must use one of the following naming schemes:

• <contract-name>

• <contract-name>[<identifier>]

The <contract-name> portion must be the same as the Contract Name for this contract type.

The [<identifier>] portion must match the regular expression \[[-a-zA-Z0-9]{1,256}].

Contract Instance

A contract instance a specific deployed version of a Contract Type.

All contract instances have an Address on some specific chain.

Contract Instance Name

A name which refers to a specific Contract Instance on a specific chain from the deployments of a single Package. This name must be unique across all other contract instances for the given chain. The name must conform to the regular expression [a-zA-Z][a-zA-Z0-9_]{0,255}

In cases where there is a single deployed instance of a given Contract Type, package managers should use the Contract Alias for that contract type for this name.

In cases where there are multiple deployed instances of a given contract type, package managers should use a name which provides some added semantic information as to help differentiate the two deployed instances in a meaningful way.

Contract Name

The name found in the source code that defines a specific Contract Type. These names must conform to the regular expression [a-zA-Z][-a-zA-Z0-9_]{0,255}.

There can be multiple contracts with the same contract name in a projects source files.

Contract Type

Refers to a specific contract in the package source. This term can be used to refer to an abstract contract, a normal contract, or a library. Two contracts are of the same contract type if they have the same bytecode.

Example:

contract Wallet {
    ...
}

A deployed instance of the Wallet contract would be of of type Wallet.

Identifier

Refers generally to a named entity in the Package.

A string matching the regular expression [a-zA-Z][-_a-zA-Z0-9]{0,255}

Link Reference

A location within a contract’s bytecode which needs to be linked. A link reference has the following properties.

Link Value

A link value is the value which can be inserted in place of a Link Reference

Linking

The act of replacing Link References with Link Values within some Bytecode.

Package

Distribution of an application’s source or compiled bytecode along with metadata related to authorship, license, versioning, et al.

For brevity, the term Package is often used metonymously to mean Package Manifest.

Package Manifest

A machine-readable description of a package (See Specification for information about the format for package manifests.)

Prefixed

Bytecode string with leading 0x.

Unprefixed

Not Prefixed.

Backwards Compatibility

This specification supports backwards compatibility by use of the manifest_version property. This specification corresponds to version 2 as the value for that field.

Implementations

This submission aims to coincide with development efforts towards widespread implementation in commonly-used development tools.

The following tools are known to have begun or are nearing completion of a supporting implementation.

• Truffle

• Populus

• Embark

Full support in implementation may require Further Work, specified below.

Further Work

This EIP addresses only the data format for package descriptions. Excluded from the scope of this specification are:

• Package registry interface definition

• Tooling integration, or how packages are stored on disk.

These efforts should be considered separate, warranting future dependent EIP submssions.

Acknowledgements

The authors of this document would like to thank the original authors of EIP-190, ETHPrize for their funding support, all community contributors, and the Ethereum community at large.

Copyright

Copyright and related rights waived via CC0.