Since the platform is built on revolutionary blockchain technology, we want to zoom in on some technical aspects. In this article, we’ll dive into a concept that is increasing in popularity: the token curated registry. We want to give you some insights into what this term means, and how we implemented it in DataBroker DAO.

There are a lot of great articles out there explaining the concept of a token curated registry (this one written by ConSensys’ Mike Goldin or this onecovering the Delphi approach to name a few). What they all describe, is the following:

  1. it lists something;
  2. stakeholders of the system determine the appearance/sorting index/…on the list

In practice, a certain amount of tokens (a stake) has to be locked-up to enlist something in the registry. The higher the stake, the higher the guarantee that what you put in the registry is of sound quality. Some TCRs put in place a voting system. A certain amount of users needs to vote that the (potential) listing is sound before it appears publicly in the registry.

Others opt for a challenging system, that allows users to mark a listing as bad.

The DataBroker DAO way

DataBroker DAO is built on the Ethereum network, powered by Solidity smart contracts.


For DataBroker DAO, we chose for the challenge approach. That way a sensor owners can add a new stream to the registry without having to waitfor the minimum amount of stakeholders to approve it. At the same time, users are still granted the opportunity to remove bad content from the registry.

Adding data

When a sensor owner wants to add new data to the marketplace, he will have to lock-up a certain amount in tokens (a stake) to be listed in the registry.If they want to, sensor owners can stake more DTX. This allows the listed streams/sets to appear more prominently in the listings (e.g., sorting, or additional badges in the interface). A higher listing improves the chances of the data being bought. At the same time increases the guarantees a buyer has that the data is of good quality and that it contains the advertised information.

Challenging data

A data buyer that is unhappy with the quality of data can challenge an entry in the registry by staking DTX tokens. The UI will mark this entry with a negative reputation score. In itself, it does not have any effect on selling of the data. Upon reaching a certain threshold of challenges, a DataBroker DAO administrator will check the data. Upon finding issues with the advertised data, its stake is distributed equally over all challengers and the DataBroker DAO platform wallet, and the entry is removed from the registry. If the data is deemed sound, the tokens that were staked by the challenger(s) get distributed to the data seller and the platform. This gives data sellers an incentive to maintain a good standing and to deliver data as advertised.

Data buyers are encouraged to report bad data to recoup the lost funds, and discouraged from reporting false challenges. The seller can reduce lost funds due to unfair bad reputation. The DataBroker DAO platform and its administrators are encouraged to handle these disputes quickly and efficiently and are rewarded for their time and effort.

Technical implementation

Since DataBroker DAO is an opensource project, the distributed API can be found on GitHub. For the scope of this article, we’ll zoom in on some parts of the Solidity smart contracts we wrote to power the DataBroker DAO token curated registry.

Enlisting data

The enlist method in the TokenCuratedRegistry.sol contract

We expect the amount of DTX tokens to be locked-up as stakeAmount , the price in DTX tokens as price and an IPFS-hash metadata for different extra properties we want to attribute to our listings.

After some checks and transfering the stake to the TCR contract to be locked up, we call a factory ListingFactory.sol that will create the actual listing for us.

We chose to create a separate listing contract to give us more flexibility later, because we want to add purchase subcontracts on these listing contracts. When the listing is created, we call another method on the TCR contract to actually add the listing to the TCR.

Raising a challenge

Check it out

You can check out our new discovery interface at

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