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core	Blockstack naming service (BNS)	/:collection/:path.html

Choose a name

{:.no_toc}

This section explains how to choose and create a namespace, it contains the following sections:

TOC {:toc}

Intended uses for a namespace

The intention is that each application can create its own BNS namespace for its own purposes. Applications can use namespaces for things like:

Giving users a SSO system, where each user registers their public key under a username. Blockstack applications do this with names in the .id namespace, for example.
Providing a subscription service, where each name is a 3rd party that provides a service for users to subscribe to. For example, names in .podcast point to podcasts that users of the DotPodcast app can subscribe to.
Implementing software licenses, where each name corresponds to an access key. Unlike conventional access keys, access keys implemented as names can be sold and traded independently. The licensing fee (paid as a name registration) would be set by the developer and sent to a developer-controlled blockchain address.

Names within a namespace can serve any purpose the developer wants. The ability to collect registration fees for 1 year after creating the namespace not only gives developers the incentive to get users to participate in the app, but also gives them a way to measure economic activity.

Developers can query individual namespaces and look up names within them using the BNS API.

List all namespaces in existence (reference).

$ curl https://core.blockstack.org/v1/namespaces
[
  "id",
  "helloworld",
  "podcast"
]

List all names within a namespace (reference).

$ curl https://core.blockstack.org/v1/namespaces/id/names?page=0
[
  "0.id",
  "0000.id",
  "000000.id",
  "000001.id",
  "00000111111.id",
  "000002.id",
  "000007.id",
  "0011sro.id",
  "007_007.id",
  "00n3w5.id",
  "00r4zr.id",
  "00w1k1.id",
  "0101010.id",
  "01jack.id",
  "06nenglish.id",
  "08.id",
  "0cool_f.id",
  "0dadj1an.id",
  "0nelove.id",
  "0nename.id"
...
]

Each page returns a batch of 100 names.

Get the Cost to Register a Namespace (reference).

$ curl https://core.blockstack.org/v1/prices/namespaces/test
{
  "satoshis": 40000000
}

If you want to register a namespace, please see the [namespace creation section]({{ site.baseurl }}/core/naming/namespaces.html).

Getting the Current Consensus Hash (reference).

$ curl -sL https://core.blockstack.org/v1/blockchains/bitcoin/consensus
{
  "consensus_hash": "98adf31989bd937576aa190cc9f5fa3a"
}

A recent consensus hash is required to create a NAMESPACE_PREORDER transaction. The reference BNS clients do this automatically. See the [transaction format]({{ site.baseurl }}/core/wire-format.html) document for details on how the consensus hash is used to construct the transaction.

Create a namespace

There are four steps to creating a namespace:

Send a NAMESPACE_PREORDER transaction (live example). This is the first step. This registers the salted hash of the namespace with BNS nodes, and burns the requisite amount of cryptocurrency. In addition, it proves to the BNS nodes that user has honored the BNS consensus rules by including a recent consensus hash in the transaction (see the section on BNS forks for details).
Send a NAMESPACE_REVEAL transaction (live example). This is the second step. This reveals the salt and the namespace ID (pairing it with its NAMESPACE_PREORDER), it reveals how long names last in this namespace before they expire or must be renewed, and it sets a price function for the namespace that determines how cheap or expensive names its will be. The price function takes a name in this namespace as input, and outputs the amount of cryptocurrency the name will cost (i.e. by examining how long the name is, and whether or not it has any vowels or non-alphabet characters). The namespace creator has the option to collect name registration fees for the first year of the namespace's existence by setting a namespace creator address.
Seed the namespace with NAME_IMPORT transactions (live example). Once the namespace has been revealed, the user has the option to populate it with a set of names. Each imported name is given both an owner and some off-chain state. This step is optional---namespace creators are not required to import names.
Send a NAMESPACE_READY transaction (live example). This is the final step of the process. It launches the namespace, which makes it available to the public. Once a namespace is ready, anyone can register a name in it if they pay the appropriate amount of cryptocurrency (according to the price funtion revealed in step 2).

The reason for the NAMESPACE_PREORDER/NAMESPACE_REVEAL pairing is to prevent frontrunning. The BNS consensus rules require a NAMESPACE_REVEAL to be paired with a previous NAMESPACE_PREORDER sent within the past 24 hours. If it did not do this, then a malicious actor could watch the blockchain network and race a victim to claim a namespace.

Namespaces are created on a first-come first-serve basis. If two people try to create the same namespace, the one that successfully confirms both the NAMESPACE_PREORDER and NAMESPACE_REVEAL wins. The fee burned in the NAMESPACE_PREORDER is spent either way.

Once the user issues the NAMESPACE_PREORDER and NAMESPACE_REVEAL, they have 1 year before they must send the NAMESPACE_READY transaction. If they do not do this, then the namespace they created disappears (along with all the names they imported).

Developers wanting to create their own namespaces should read the [namespace creation section]({{ site.baseurl }}/core/naming/namespaces.html) document. It is highly recommended that developers request individual support before creating their own space, given the large amount of cryptocurrency at stake.

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