brunodb3 / indexer

Index and query anchors, associations, and DID documents on LTO Network

Indexer

Index and query data from the LTO Network public chain.

Application

It can be launched via nmp start. It will run the index service, that will accept and process requests either through UI or using API calls. Server listens to port 80 or change the port number through the PORT env variable.

Expolore all API endpoint using the swagger interface.

Anchoring

Data, that can be anchored through UI, is either a text data, or a file.

Two operations are supported:

• verify, if text or file are already anchored
• perform anchoring

Through API these operations can be executed, using the following queries correspondingly:

• GET /hash/:hash This will check for hex encoded hashses.
• GET /hash/:hash/encoding/:encoding With allow encoding types being: base64, base58 and hex
• POST /hash

With the body contain the hash and optionally the encoding of the hash:

{ 
    "hash": {hash},
    "encoding": {hex} // Defaults to 'hex'
}

Both operations, in case if anchor exists/created, return a chainpoint, given in a format introduced by Chainpoint. Merkle tree is not used here for anchoring, so we ommit some chainpoint properties.

Example response:

{
    "chainpoint": {
        "@context": "https://w3id.org/chainpoint/v2",
        "type": "ChainpointSHA256v2",
        "targetHash": "6b51d431df5d7f141cbececcf79edf3dd861c3b4069f0b11661a3eefacbba918",
        "anchors": [
            {
                "type": "LTOAnchorTransaction",
                "sourceId": "DHAZrbPYDcqYnHb79jo5D6xReyUDtCvYUvXsx9DhP9NB"
            }
        ]
    }
}

where:

• targetHash is a sha256 data hash
• anchors[0].sourceId is a blockchain transactions id, where data is saved

If hash is not found in database on verification, the following response is returned:

{
  "chainpoint": null
}

Associations

It's possibible to index and query associations.

• GET /associations/:address

{
  "children": [
    "did:lto:3Jmh1EcLL2GieVAYeyF42D4cBxjAFVUJMpR",
    "did:lto:3JsYP8QYvkiC5x2nPzUkVYEfQVwXnogXaGP"
  ],
  "parents": [
    "did:lto:3JuijVBB7NCwCz2Ae5HhCDsqCXzeBLRTyeL"
  ]
}

TODO: query associations as DID URLs

DID documents

By default the service will index the public keys of all addresses that have done a transaction on LTO Network. These addresses are available as DID document.

• GET /did/:url

The url parameter is either the LTO Network DID url (eg lto:did:3JuijVBB7NCwCz2Ae5HhCDsqCXzeBLRTyeL) or just the wallet address (eg 3JuijVBB7NCwCz2Ae5HhCDsqCXzeBLRTyeL).

The response is a DID document with an authentication section.

{
  "@context": "https://www.w3.org/ns/did/v1",
  "id": "did:lto:3JuijVBB7NCwCz2Ae5HhCDsqCXzeBLRTyeL",
  "verificationMethod": [
    {
      "id": "did:lto:3JuijVBB7NCwCz2Ae5HhCDsqCXzeBLRTyeL#key",
      "type": "Ed25519VerificationKey2018",
      "controller": "did:lto:3JuijVBB7NCwCz2Ae5HhCDsqCXzeBLRTyeL",
      "publicKeyBase58": "AVXUh6yvPG8XYqjbUgvKeEJQDQM7DggboFjtGKS8ETRG"
    }
  ],
  "authentication": [
    "did:lto:3JuijVBB7NCwCz2Ae5HhCDsqCXzeBLRTyeL#key"
  ],
  "assertionMethod": [
    "did:lto:3JuijVBB7NCwCz2Ae5HhCDsqCXzeBLRTyeL#key"
  ]
}

Transactions

The public node will only store the latest transactions of each account. Use the indexer to store all transactions.

• GET /transactions/addresses/:address

The response is an array of transactions.

Transaction statistics

The indexer will also keep track of the total number of transactions per day for each transaction type.

• GET /transactions/stats/:type/:from/:to

The from and to parameters are either a timestamp (in ms since epoch) or a date string as year-month-day.

[
  { "period": "2021-03-01 00:00:00", "count": 56847 },
  { "period": "2021-03-02 00:00:00", "count": 103698 },
  { "period": "2021-03-03 00:00:00", "count": 33329 }
]

Errors

In case if an error occured during processing, the object with a single error property is returned, that can be either a string or an object.

Example:

{
  "error": "State check failed. Reason: negative balance: 3Mr6yz6hp7cDKBaNzKuMFU6Nh2UjfpdvtHa, old: 3, new: -99997"
}

When using API and performing save operation call, it does not auto-perform verify operation, so you should perform it manually.

Verification is performed not on blockchain, but on anchors, uploaded from blockchain to database.

Configuration

You can run container with predefined environment variables:

env variable	description
LTO_API_KEY	ApiKey used in communication with the public node
LOG_LEVEL	Node logging level, available values: OFF, ERROR, WARN, INFO, DEBUG
PORT	Port number the service should use
LTO_NODE_URL	URL of the LTO public node