wulfraem edited this page Aug 15, 2018 · 6 revisions

Table of Contents

Structure

The DBCP description is saved as a JSON file, which is stored is a distributed file system (IPFS). Files stored in the distributed file system can be retrieved via their hashes and this hash is stored at the smart contract. Further dependencies are resolved in the same manner. Description files for subcomponents are pulled from distributed file system as well and so on.

This description resembles a package.json known from NodeJS modules in its functionality.

The following information can be included in the description file:

  • basic information about the contract, for example:
    • name
    • description
    • version
  • apps for interacting with the contract
    Web pages build for interacting with the contract are referenced in the description, the physical files themselves are stored in a distributed file system and a reference to them is stored in the description.

References in the description can be stored in two ways:

  • distributed file system references:
    This is used when files are stored directly. Examples are configuration files, files used within an app and documents that belong to a contract directly.
  • module references:
    Module references are references to a description file on a module. These are resolved like an original description and allow nesting of modules, apps and module versioning.

DBCP descriptions can be stored at ENS names as well. ENS can be used to address smart contracts (which can by default only be addressed with their technical address) via a human readable DNS domain like syntax. Therefore it is possible to setup smart contracts and their ÐApps like websites.

DBCP based applications can be described as a bundle of the ENS address, where the DBCP description can be retrieved from, the smart contract that handles the logic and the ÐApps for interacting with it.

Information Flow

When having an ENS entry or a contract address, the DBCP description for that can be loaded. This provides enough information to interact with the contract:

  • a ÐAPP for end-users
  • contract address and ABI for developers to write applications / ÐAPPs on their own

DBCP information flow

Properties in Description

The current DBCP protocol definition spec is at version 1 (see property dbcpVersion).

The following snippet shows a shortened sample description, the full sample description can be found here.

{
  "public": {
    "name": "Cool Task with Abis",
    "author": "Some Company",
    "dapp": {
      "dependencies": {
        "angular-bc": "^1.0.0",
        "angular-core": "^1.0.0",
        "angular-libs": "^1.0.0"
      },
      "entrypoint": "task.js",
      "files": [
        "task.js",
        "task.css"
      ],
      "origin": "Qm...",
      "primaryColor": "#e87e23",
      "secondaryColor": "#fffaf5",
      "standalone": true,
      "type": "dapp"
    },
    "description": "Create todos and manage updates.",
    "dbcpVersion": 1,
    "i18n": {
      "description": {
        "de": "Erstelle Aufgaben oder zeige sie an",
        "en": "Create tasks or show them"
      },
      "name": {
        "de": "Task",
        "en": "Task"
      }
    },
    "imgSquare": "data:image/png;base64,...",
    "dataSchema": {
      "list_settable_by_member": {
        "$id": "list_settable_by_member_schema",
        "type": "object",
        "additionalProperties": false,
        "properties": {
          "foo": { "type": "string" },
          "bar": { "type": "integer" }
        }
      },
      "entry_settable_by_member": {
        "$id": "entry_settable_by_member_schema",
        "type": "integer",
      }
    },
    "abis": {
      "own": [
        "contract abi..."
      ]
    },
    "source": "Qm...",
    "version": "1.0.0",
    "versions": {
      "0.7.0": "Qmf...",
      "0.8.0": "Qmu...",
      "0.9.0": "Qmx...",
    },
  }
}

Depending on the visibility of the properties, these are placed under a different scope. These scopes are "public" (unencrypted, visible for everyone) and "private" (encrypted, visible for a limited scope of people).

Property Required? Type Description
name x string name of the contract
description x string short description of the contract
author x string author of the ÐAPP
version x string version information about the descripition itself
dbcpVersion x number used DBCP protocol definition version
versions object version history (including the version specific dbcp description hash)
abis object abis related to the contract or ÐApp
abis.own object[] if this DBCP description describes a contract, the abi of this contract
abis.related object abis of smart contracts related to this contract or ÐApp
source string reference to the source files of the smart contract(s)
dataSchema object json schema definition for data in the contract, written as ajv schemas
tags string[] tags for categorizing the contract
i18n object labels for displaying contract information (multilingual)
imgSquare string contract logo (square) e.g. for icons - can be Data URL or regular URL
imgWide string contract logo (wide) e.g. for sidebar - can be Data URL or regular URL
dapp object details about the used ÐApp, see section "ÐApp Definition" below
blockchain object blockchain reference, see section "Blockchain Reference" below
dfs object distributed file system reference, see section "Distributed File System Reference" below

ÐApp Definition

Contracts that use a ÐApp for interacting with it, need the "dapp" property, that supports the following elements:

Property Required? Type Description
entrypoint x string startup file for ÐApp
files x string[] included files (.css, .js, ...)
type x string library/dapp
origin x string hash reference where the ÐApp is stored in the distributed file system
primaryColor string color code for primary color
secondaryColor string color code for secondary color
standalone bool indicates whether this ÐApp runs in "full screen" without a run container
dependencies object dependencies of this ÐAPP

ÐAPP dependencies are similar to dependencies in npm packages and allow to specify their required version range, example:

"dependencies": {
  "angular-bc": "^1.0.0",
  "angular-core": "^1.0.0",
  "angular-libs": "^1.0.0",
  "bcc-bc": "^1.0.0"
}

Taking the version from the example, the ÐAPP will try to locate the latest minor version of the dependencies and load it from their respective ENS address. This example would use the latest feature adding or bug fixing versions but ignore possible breaking changes.

Applications build this way can be deployed once and used as long as desired, as they use a stable code base, that can be fixed if bugs occur.

Blockchain Reference

Contracts may be stored in side chains. Such contracts need the property "blockchain" in their DBCP description to point to that chain.

If omitted, the default blockchain is used

Property Required? Type Description
referenceType x string type of the reference, see below
referenceValue x string value describing the reference, see below
referenceType description example
ens blockchain reference is stored in an own ENS entry default.blockchainregistry.eth
url a link to an RPC endpoint ws://localhost:8546

Distributed File System Reference

Contract data may be stored in different distributed file systems. Such contracts need the property "dfs" in their DBCP description to point to that storage.

If omitted, the default DFS is used

Property Required? Type Description
referenceType x string type of the reference, see below
referenceValue x string value describing the reference, see below
referenceType description example
ens DFS reference is stored in an own ENS entry default.dfsregistry.eth
url a link to an DFS endpoint, like a IPFS server endpoint http://localhost:8080
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