Federation

The Stellar federation protocol maps XDBChain addresses to more information about a given user. It’s a way for XDBChain client software to resolve email-like addresses such as name*yourdomain.com into account IDs like: GCCVPYFOHY7ZB7557JKENAX62LUAPLMGIWNZJAFV2MITK6T32V37KEJU. XDBChain addresses provide an easy way for users to share payment details by using a syntax that interoperates across different domains and providers.

XDBChain addresses

XDBChain addresses are divided into two parts separated by *, the username and the domain.

For example: joe*xdbchain.com:

• joe is the username,
• xdbchain.com is the domain.

The domain can be any valid RFC 1035 domain name. The username is limited to printable UTF-8 with whitespace and the following characters excluded: <*,> Although of course the domain administrator can place additional restrictions on usernames of its domain.

Note that the @ symbol is allowed in the username. This allows for using email addresses in the username of an address. For example: maria@gmail.com*xdbchain.com.

Supporting Federation

Step 1: Create a stellar.toml file

Create a file called stellar.toml and put it at https://YOUR_DOMAIN/.well-known/stellar.toml.

Step 2: Add federation_url

Add a FEDERATION_SERVER section to your stellar.toml file that tells other people the URL of your federation endpoint.

For example: FEDERATION_SERVER="https://api.yourdomain.com/federation"

Please note that your federation server must use https protocol.

Step 3: Implement federation url HTTP endpoint

The federation URL specified in your stellar.toml file should accept an HTTP GET request and issue responses of the form detailed below.

Federation Requests

You can use the federation endpoint to look up an account id if you have a XDBChain address. You can also do reverse federation and look up a XDBChain addresses from account ids or transaction ids. This is useful to see who has sent you a payment.

Federation requests are http GET requests with the following form:

?q=<string to look up>&type=<name,id,txid>

Supported types:

• name: Example: https://YOUR_FEDERATION_SERVER/federation?q=joe*xdbchain.com&type=name
• forward: Used for forwarding the payment on to a different network or different financial institution. The other parameters of the query will vary depending on what kind of institution is the ultimate destination of the payment and what you as the forwarding anchor supports. Your stellar.toml file should specify what parameters you expect in a forward federation request. If you are unable to forward or the other parameters in the request are incorrect you should return an error to this effect. Example request: https://YOUR_FEDERATION_SERVER/federation?type=forward&forward_type=bank_account&swift=BOPBPHMM&acct=2382376
• id: not supported by all federation servers Reverse federation will return the federation record of the XDBChain address associated with the given account ID. In some cases this is ambiguous. For instance if an anchor sends transactions on behalf of its users the account id will be of the anchor and the federation server won’t be able to resolve the particular user that sent the transaction. In cases like that you may need to use txid instead. Example: https://YOUR_FEDERATION_SERVER/federation?q=GD6WU64OEP5C4LRBH6NK3MHYIA2ADN6K6II6EXPNVUR3ERBXT4AN4ACD&type=id
• txid: not supported by all federation servers Will return the federation record of the sender of the transaction if known by the server. Example: https://YOUR_FEDERATION_SERVER/federation?q=c1b368c00e9852351361e07cc58c54277e7a6366580044ab152b8db9cd8ec52a &type=txid

Federation Response

The federation server should respond with an appropriate HTTP status code, headers and a JSON response.

You must enable CORS on the federation server so clients can send requests from other sites. The following HTTP header must be set for all federation server responses.

Access-Control-Allow-Origin: *

When a record has been found the response should return 200 OK http status code and the following JSON body:

{
  "xdbchain_address": <username*domain.tld>,
  "account_id": <account_id>,
  "memo_type": <"text", "id" , or "hash"> *optional*
  "memo": <memo to attach to any payment. if "hash" type then will be base64 encoded> *optional*
}

If a redirect is needed the federation server should return 3xx http status code and immediately redirect the user to the correct URL using the Location header.

When a record has not been found 404 Not Found http status code should be returned.

Every other http status code will be considered an error. The body should contain error details:

{
   "detail": "extra details provided by the federation server"
}

Looking up federation provider via a home domain entry

Accounts may optionally have a home domain specified. This allows an account to programmatically specify where is the main federation provider for that account.

Caching

You shouldn’t cache responses from federation servers. Some organizations may generate random IDs to protect their users’ privacy. Those IDs may change over time.