DDO Specification

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

DDO Schema - High Level

The below diagram shows the high-level DDO schema depicting the content of each data structure and the relations between them.

Please note that some data structures apply only on certain types of services or assets.

Required Attributes

A DDO in Ocean has these required attributes:

Attribute	Type	Description
@context	Array of string	Contexts used for validation.
id	string	Computed as sha256(address of ERC721 contract + chainId).
version	string	Version information in SemVer notation referring to this DDO spec version, like 4.1.0.
chainId	number	Stores the chainId of the network the DDO was published to.
nftAddress	string	NFT contract linked to this asset
metadata	Metadata	Stores an object describing the asset.
services	Services	Stores an array of services defining access to the asset.
credentials	Credentials	Describes 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",
    "symbol": "OCEAN-A",
    "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.

Attribute	Type	Description
created	ISO date/time string	Contains the date of the creation of the dataset content in ISO 8601 format preferably with timezone designators, e.g. 2000-10-31T01:30:00Z.
updated	ISO date/time string	Contains 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*	string	Details of what the resource is. For a dataset, this attribute explains what the data represents and what it can be used for.
copyrightHolder	string	The party holding the legal copyright. Empty by default.
name*	string	Descriptive name or title of the asset.
type*	string	Asset type. Includes "dataset" (e.g. csv file), "algorithm" (e.g. Python script). Each type needs a different subset of metadata attributes.
author*	string	Name of the entity generating this data (e.g. Tfl, Disney Corp, etc.).
license*	string	Short 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".
links	Array of string	Mapping of URL strings for data samples, or links to find out more information. Links may be to either a URL or another asset.
contentLanguage	string	The language of the content. Use one of the language codes from the IETF BCP 47 standard
tags	Array of string	Array of keywords or tags used to describe this content. Empty by default.
categories	Array of string	Array of categories associated to the asset. Note: recommended to use tags instead of this.
additionalInformation	Object	Stores additional information, this is customizable by publisher
algorithm**	Algorithm Metadata	Information 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.

Attribute	Type	Description
id*	string	Unique ID
type*	string	Type of service access, compute, wss etc.
name	string	Service friendly name
description	string	Service description
datatokenAddress*	string	Datatoken
serviceEndpoint*	string	Provider URL (schema + host)
files*	Files	Encrypted file.
timeout*	number	Describing how long the service can be used after consumption is initiated. A timeout of 0 represents no time limit. Expressed in seconds.
compute**	Compute	If service is of type compute, holds information about the compute-related privacy settings & resources.
consumerParameters	Consumer Parameters	An object the defines required consumer input before consuming the asset
additionalInformation	Object	Stores 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:

State	Description	Discoverable in Ocean Market	Ordering allowed	Listed under profile
0	Active	Yes	Yes	Yes
1	End-of-life	Yes	No	No
2	Deprecated (by another asset)	No	No	No
3	Revoked by publisher	No	No	No
4	Ordering is temporary disabled	Yes	No	Yes
5	Asset unlisted.	No	Yes	Yes

States details:

1. Active: Assets in the "Active" state are fully functional and available for discovery in Ocean Market, and other components. Users can search for, view, and interact with these assets. Ordering is allowed, which means users can place orders to purchase or access the asset's services.

2. End-of-life: Assets in the "End-of-life" state remain discoverable but cannot be ordered. This state indicates that the assets are usually deprecated or outdated, and they are no longer actively promoted or maintained.

3. Deprecated (by another asset): This state indicates that another asset has deprecated the current asset. Deprecated assets are not discoverable, and ordering is not allowed. Similar to the "End-of-life" state, deprecated assets are not listed under the owner's profile.

4. Revoked by publisher: When an asset is revoked by its publisher, it means that the publisher has explicitly revoked access or ownership rights to the asset. Revoked assets are not discoverable, and ordering is not allowed.

5. Ordering is temporarily disabled: Assets in this state are still discoverable, but ordering functionality is temporarily disabled. Users can view the asset and gather information, but they cannot place orders at that moment. However, these assets are still listed under the owner's profile.

6. Asset unlisted: Assets in the "Asset unlisted" state are not discoverable. However, users can still place orders for these assets, making them accessible. Unlisted assets are listed under the owner's profile, allowing users to view and access them.

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.

Attribute	Type	Description
address	string	Contract address of the deployed ERC721 NFT contract.
name	string	Name of NFT set in contract.
symbol	string	Symbol of NFT set in contract.
owner	string	ETH account address of the NFT owner.
state	number	State of the asset reflecting the NFT contract value. See State
created	ISO date/time string	Contains the date of NFT creation.
tokenURI	string	tokenURI

NFT Object Example

{
  "nft": {
    "address": "0x000000",
    "name": "Ocean Protocol Asset",
    "symbol": "OCEAN-A",
    "owner": "0x0000000",
    "state": 0,
    "created": "2000-10-31T01:30:00Z"
  }
}

Datatokens

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

Attribute	Type	Description
address	string	Contract address of the deployed ERC20 contract.
name	string	Name of NFT set in contract.
symbol	string	Symbol of NFT set in contract.
serviceId	string	ID 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.

Attribute	Type	Description
state	boolean	If true, asset is in purgatory.
reason	string	If asset is in purgatory, contains the reason for being there as defined in list-purgatory.

Purgatory Example

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

}

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

Statistics

The stats section contains different statistics fields.

Attribute	Type	Description
orders	number	How 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.

DDO Schema - Detailed

The below diagram shows the detailed DDO schema depicting the content of each data structure and the relations between them.

Please note that some data structures apply only on certain types of services or assets.