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docs/developers/ddo-specification.md

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DDO /developers/ddo/ developers Specification of decentralized identifiers for assets in Ocean Protocol using the DDO standard.

DDO Specification

erDiagram
DDO
Metadata
Services
Compute
publisherTrustedAlgorithms
ConsumerParameters
AlgorithmMetadata
Container
DDO ||--|{Metadata : contains
DDO ||--|{Services : contains
Metadata ||--|{AlgorithmMetadata : contains
AlgorithmMetadata ||--|{Container : contains
Compute ||--|{ publisherTrustedAlgorithms : contains
Services ||--|{ Compute : contains
Services ||--|{ ConsumerParameters : contains
 
 

Required Attributes

A DDO in Ocean has these required attributes:

AttributeTypeDescription
@contextArray of stringContexts used for validation.
idstringComputed as sha256(address of ERC721 contract + chainId).
versionstringVersion information in SemVer notation referring to this DDO spec version, like 4.1.0.
chainIdnumberStores chainId of the network the DDO was published to.
nftAddressstringNFT contract linked to this asset
metadataMetadataStores an object describing the asset.
servicesServicesStores an array of services defining access to the asset.
credentialsCredentialsDescribes the credentials needed to access a dataset in addition to the services definition.
Full Enhanced DDO Example
{
  "@context": ["https://w3id.org/did/v1"],
  "id": "did:op:ACce67694eD2848dd683c651Dab7Af823b7dd123",
  "version": "4.1.0",
  "chainId": 1,
  "nftAddress": "0x123",
  "metadata": {
    "created": "2020-11-15T12:27:48Z",
    "updated": "2021-05-17T21:58:02Z",
    "description": "Sample description",
    "name": "Sample asset",
    "type": "dataset",
    "author": "OPF",
    "license": "https://market.oceanprotocol.com/terms"
  },
  "services": [
    {
      "id": "1",
      "type": "access",
      "files": "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",
      "name": "Download service",
      "description": "Download service",
      "datatokenAddress": "0x123",
      "serviceEndpoint": "https://myprovider.com",
      "timeout": 0,
      "consumerParameters": [
        {
          "name": "surname",
          "type": "text",
          "label": "Name",
          "required": true,
          "default": "NoName",
          "description": "Please fill your name"
        },
        {
          "name": "age",
          "type": "number",
          "label": "Age",
          "required": false,
          "default": 0,
          "description": "Please fill your age"
        }
      ]
    },
    {
      "id": "2",
      "type": "compute",
      "files": "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",
      "name": "Compute service",
      "description": "Compute service",
      "datatokenAddress": "0x124",
      "serviceEndpoint": "https://myprovider.com",
      "timeout": 3600,
      "compute": {
        "allowRawAlgorithm": false,
        "allowNetworkAccess": true,
        "publisherTrustedAlgorithmPublishers": ["0x234", "0x235"],
        "publisherTrustedAlgorithms": [
          {
            "did": "did:op:123",
            "filesChecksum": "100",
            "containerSectionChecksum": "200"
          },
          {
            "did": "did:op:124",
            "filesChecksum": "110",
            "containerSectionChecksum": "210"
          }
        ]
      }
    }
  ],
  "credentials": {
    "allow": [
      {
        "type": "address",
        "values": ["0x123", "0x456"]
      }
    ],
    "deny": [
      {
        "type": "address",
        "values": ["0x2222", "0x333"]
      }
    ]
  },

  "nft": {
    "address": "0x123",
    "name": "Ocean Protocol Asset v4",
    "symbol": "OCEAN-A-v4",
    "owner": "0x0000000",
    "state": 0,
    "created": "2000-10-31T01:30:00",
    "tokenURI": "xxx"
  },

  "datatokens": [
    {
      "address": "0x000000",
      "name": "Datatoken 1",
      "symbol": "DT-1",
      "serviceId": "1"
    },
    {
      "address": "0x000001",
      "name": "Datatoken 2",
      "symbol": "DT-2",
      "serviceId": "2"
    }
  ],

  "event": {
    "tx": "0x8d127de58509be5dfac600792ad24cc9164921571d168bff2f123c7f1cb4b11c",
    "block": 12831214,
    "from": "0xAcca11dbeD4F863Bb3bC2336D3CE5BAC52aa1f83",
    "contract": "0x1a4b70d8c9DcA47cD6D0Fb3c52BB8634CA1C0Fdf",
    "datetime": "2000-10-31T01:30:00"
  },

  "purgatory": {
    "state": false
  },

  "stats": {
    "orders": 4
  }
}

Metadata

This object holds information describing the actual asset.

AttributeTypeDescription
createdISO date/time stringContains the date of the creation of the dataset content in ISO 8601 format preferably with timezone designators, e.g. 2000-10-31T01:30:00Z.
updatedISO date/time stringContains the date of last update of the dataset content in ISO 8601 format preferably with timezone designators, e.g. 2000-10-31T01:30:00Z.
description*stringDetails of what the resource is. For a dataset, this attribute explains what the data represents and what it can be used for.
copyrightHolderstringThe party holding the legal copyright. Empty by default.
name*stringDescriptive name or title of the asset.
type*stringAsset type. Includes "dataset" (e.g. csv file), "algorithm" (e.g. Python script). Each type needs a different subset of metadata attributes.
author*stringName of the entity generating this data (e.g. Tfl, Disney Corp, etc.).
license*stringShort name referencing the license of the asset (e.g. Public Domain, CC-0, CC-BY, No License Specified, etc. ). If it's not specified, the following value will be added: "No License Specified".
linksArray of stringMapping of URL strings for data samples, or links to find out more information. Links may be to either a URL or another asset.
contentLanguagestringThe language of the content. Use one of the language codes from the IETF BCP 47 standard
tagsArray of stringArray of keywords or tags used to describe this content. Empty by default.
categoriesArray of stringArray of categories associated to the asset. Note: recommended to use tags instead of this.
additionalInformationObjectStores additional information, this is customizable by publisher
algorithm**Algorithm MetadataInformation about asset of type algorithm

* Required

** Required for algorithms only

Metadata Example
{
  "metadata": {
    "created": "2020-11-15T12:27:48Z",
    "updated": "2021-05-17T21:58:02Z",
    "description": "Sample description",
    "name": "Sample asset",
    "type": "dataset",
    "author": "OPF",
    "license": "https://market.oceanprotocol.com/terms"
  }
}

Services

Services define the access for an asset, and each service is represented by its respective datatoken.

An asset should have at least one service to be actually accessible, and can have as many services which make sense for a specific use case.

AttributeTypeDescription
id*stringUnique ID
type*stringType of service access, compute, wss etc.
namestringService friendly name
descriptionstringService description
datatokenAddress*stringDatatoken
serviceEndpoint*stringProvider URL (schema + host)
files*FilesEncrypted file.
timeout*numberDescribing how long the service can be used after consumption is initiated. A timeout of 0 represents no time limit. Expressed in seconds.
compute**ComputeIf service is of type compute, holds information about the compute-related privacy settings & resources.
consumerParametersConsumer ParametersAn object the defines required consumer input before consuming the asset
additionalInformationObjectStores additional information, this is customizable by publisher

* Required

** Required for compute assets only

Files

The files field is returned as a string which holds the encrypted file URLs.

Files Example
{
  "files": "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"
}

Credentials

By default, a consumer can access a resource if they have 1 datatoken. Credentials allow the publisher to optionally specify more fine-grained permissions.

Consider a medical data use case, where only a credentialed EU researcher can legally access a given dataset. Ocean supports this as follows: a consumer can only access the resource if they have 1 datatoken and one of the specified "allow" credentials.

This is like going to an R-rated movie, where you can only get in if you show both your movie ticket (datatoken) and some identification showing you're old enough (credential).

Only credentials that can be proven are supported. This includes Ethereum public addresses, and in the future W3C Verifiable Credentials and more.

Ocean also supports "deny" credentials: if a consumer has any of these credentials, they can not access the resource.

Here's an example object with both "allow" and "deny" entries:

Credentials Example
{
  "credentials": {
    "allow": [
      {
        "type": "address",
        "values": ["0x123", "0x456"]
      }
    ],
    "deny": [
      {
        "type": "address",
        "values": ["0x2222", "0x333"]
      }
    ]
  }
}

DDO Checksum

In order to ensure the integrity of the DDO, a checksum is computed for each DDO:

const checksum = sha256(JSON.stringify(ddo));

The checksum hash is used when publishing/updating metadata using the setMetaData function in the ERC721 contract, and is stored in the event generated by the ERC721 contract.

MetadataCreated and MetadataUpdated smart contract events
event MetadataCreated(
  address indexed createdBy,
  uint8 state,
  string decryptorUrl,
  bytes flags,
  bytes data,
  bytes metaDataHash,
  uint256 timestamp,
  uint256 blockNumber
);

event MetadataUpdated(
  address indexed updatedBy,
  uint8 state,
  string decryptorUrl,
  bytes flags,
  bytes data,
  bytes metaDataHash,
  uint256 timestamp,
  uint256 blockNumber
);

Aquarius should always verify the checksum after data is decrypted via a Provider API call.

State

Each asset has a state, which is held by the NFT contract. The possible states are:

StateDescriptionDiscoverable in Ocean MarketOrdering allowedListed under profile
0ActiveYesYesYes
1End-of-lifeNoNoNo
2Deprecated (by another asset)NoNoNo
3Revoked by publisherNoNoNo
4Ordering is temporary disabledYesNoYes
5Asset unlisted.NoYesYes

Aquarius Enhanced DDO Response

The following fields are added by Aquarius in its DDO response for convenience reasons, where an asset returned by Aquarius inherits the DDO fields stored on-chain.

These additional fields are never stored on-chain, and are never taken into consideration when hashing the DDO.

NFT

The nft object contains information about the ERC721 NFT contract which represents the intellectual property of the publisher.

AttributeTypeDescription
addressstringContract address of the deployed ERC721 NFT contract.
namestringName of NFT set in contract.
symbolstringSymbol of NFT set in contract.
ownerstringETH account address of the NFT owner.
statenumberState of the asset reflecting the NFT contract value. See State
createdISO date/time stringContains the date of NFT creation.
tokenURIstringtokenURI
NFT Object Example
{
  "nft": {
    "address": "0x000000",
    "name": "Ocean Protocol Asset v4",
    "symbol": "OCEAN-A-v4",
    "owner": "0x0000000",
    "state": 0,
    "created": "2000-10-31T01:30:00Z"
  }
}

Datatokens

The datatokens array contains information about the ERC20 datatokens attached to asset services.

AttributeTypeDescription
addressstringContract address of the deployed ERC20 contract.
namestringName of NFT set in contract.
symbolstringSymbol of NFT set in contract.
serviceIdstringID of the service the datatoken is attached to.
Datatokens Array Example
{
  "datatokens": [
    {
      "address": "0x000000",
      "name": "Datatoken 1",
      "symbol": "DT-1",
      "serviceId": "1"
    },
    {
      "address": "0x000001",
      "name": "Datatoken 2",
      "symbol": "DT-2",
      "serviceId": "2"
    }
  ]
}

Event

The event section contains information about the last transaction that created or updated the DDO.

Event Example
{
  "event": {
    "tx": "0x8d127de58509be5dfac600792ad24cc9164921571d168bff2f123c7f1cb4b11c",
    "block": 12831214,
    "from": "0xAcca11dbeD4F863Bb3bC2336D3CE5BAC52aa1f83",
    "contract": "0x1a4b70d8c9DcA47cD6D0Fb3c52BB8634CA1C0Fdf",
    "datetime": "2000-10-31T01:30:00"
  }
}

Purgatory

Contains information about an asset's purgatory status defined in list-purgatory. Marketplace interfaces are encouraged to prevent certain user actions like adding liquidity on assets in purgatory.

AttributeTypeDescription
statebooleanIf true, asset is in purgatory.
reasonstringIf asset is in purgatory, contains the reason for being there as defined in list-purgatory.
Purgatory Example

```json { "purgatory": { "state": true, "reason": "Copyright violation" } } ```

{
  "purgatory": {
    "state": false
  }
}

Statistics

The stats section contains different statistics fields.

AttributeTypeDescription
ordersnumberHow often an asset was ordered, meaning how often it was either downloaded or used as part of a compute job.
Statistics Example
{
  "stats": {
    "orders": 4
  }
}

Compute to data

For algorithms and datasets that are used for compute to data, there are additional fields and objects within the DDO structure that you need to consider. These include:

  • compute attributes.
  • publisherTrustedAlgorithms
  • consumerParameters

Details for each of these are explained on the Compute Options page.