HTTP JSON API Service¶

The JSON API provides a significantly simpler way to interact with a ledger than the Ledger API by providing basic active contract set functionality:

creating contracts,
exercising choices on contracts,
querying the current active contract set, and
retrieving all known parties.

The goal of this API is to get your distributed ledger application up and running quickly, so we have deliberately excluded complicating concerns including, but not limited to:

inspecting transactions,
asynchronous submit/completion workflows,
temporal queries (e.g. active contracts as of a certain time), and

For these and other features, use the Ledger API instead. The HTTP JSON API service is a “proxy”, after a fashion, for that API; there is literally nothing that HTTP JSON API service can do that your own application cannot do via gRPC.

If you are using this API from JavaScript or TypeScript, we strongly recommend using the JavaScript bindings and code generator rather than invoking these endpoints directly. This will both simplify access to the endpoints described here and (with TypeScript) help to provide the correct JavaScript value format for each of your contracts, choice arguments, and choice results.

As suggested by those bindings, the primary target application for the HTTP JSON API service is a web application, where user actions translate to one or a few ledger operations. It is not intended for high-throughput, high-performance ledger automation; the Ledger API is better suited to such use cases.

We welcome feedback about the JSON API on our issue tracker, or on our forum.

Run the JSON API¶

Start a Daml Ledger¶

You can run the JSON API alongside any ledger exposing the gRPC Ledger API you want. If you don’t have an existing ledger, you can start an in-memory sandbox:

daml new my-project --template quickstart-java
cd my-project
daml build
daml sandbox --wall-clock-time --dar ./.daml/dist/quickstart-0.0.1.dar

Start the HTTP JSON API Service¶

Basic¶

The most basic way to start the JSON API is with the command:

daml json-api --config json-api-app.conf

where a corresponding minimal config file is

{
  server {
    address = "localhost"
    port = 7575
  }
  ledger-api {
    address = "localhost"
    port = 6865
  }
}

This will start the JSON API on port 7575 and connect it to a ledger running on localhost:6865.

Note

Your JSON API service should never be exposed to the internet. When running in production the JSON API should be behind a reverse proxy, such as via NGINX.

The full set of configurable options that can be specified via config file is listed below

{
  server {
    //IP address that HTTP JSON API service listens on. Defaults to 127.0.0.1.
    address = "127.0.0.1"
    //HTTP JSON API service port number. A port number of 0 will let the system pick an ephemeral port.
    port = 7575
  }
  ledger-api {
    address = "127.0.0.1"
    port = 6865
    tls {
        enabled = "true"
        // the certificate to be used by the server
        cert-chain-file = "cert-chain.crt"
        // private key of the server
        private-key-file = "pvt-key.pem"
        // trust collection, which means that all client certificates will be verified using the trusted
        // certificates in this store. if omitted, the JVM default trust store is used.
        trust-collection-file = "root-ca.crt"
    }
  }

  query-store {
    base-config {
      user = "postgres"
      password = "password"
      driver = "org.postgresql.Driver"
      url = "jdbc:postgresql://localhost:5432/test?&ssl=true"

      // prefix for table names to avoid collisions, empty by default
      table-prefix = "foo"

      // max pool size for the database connection pool
      pool-size = 12
      //specifies the min idle connections for database connection pool.
      min-idle = 4
      //specifies the idle timeout for the database connection pool.
      idle-timeout = 12s
      //specifies the connection timeout for database connection pool.
      connection-timeout = 90s
    }
    // option setting how the schema should be handled.
    // Valid options are start-only, create-only, create-if-needed-and-start and create-and-start
    start-mode = "start-only"
  }



  // Optional interval to poll for package updates. Examples: 500ms, 5s, 10min, 1h, 1d. Defaults to 5 seconds
  package-reload-interval = 5s
  //Optional max inbound message size in bytes. Defaults to 4194304.
  max-inbound-message-size = 4194304
  //Optional max inbound message size in bytes used for uploading and downloading package updates. Defaults to the `max-inbound-message-size` setting.
  package-max-inbound-message-size = 4194304
  //Optional max cache size in entries for storing surrogate template id mappings. Defaults to None
  max-template-id-cache-entries = 1000
  //health check timeout in seconds
  health-timeout-seconds = 5

  //Optional websocket configuration parameters
  websocket-config {
    //Maximum websocket session duration
    max-duration = 120m
    //Server-side heartbeat interval duration
    heartbeat-period = 5s
    //akka stream throttle-mode one of either `shaping` or `enforcing`
    mode = "shaping"
  }

  metrics {
    //Start a metrics reporter. Must be one of "console", "csv:///PATH", "graphite://HOST[:PORT][/METRIC_PREFIX]", or "prometheus://HOST[:PORT]".
    reporter = "console"
    //Set metric reporting interval , examples : 1s, 30s, 1m, 1h
    reporting-interval = 30s
  }

  // DEV MODE ONLY (not recommended for production)
  // Allow connections without a reverse proxy providing HTTPS.
  allow-insecure-tokens = false
  // Optional static content configuration string. Contains comma-separated key-value pairs, where:
  // prefix -- URL prefix,
  // directory -- local directory that will be mapped to the URL prefix.
  // Example: "prefix=static,directory=./static-content"
  static-content {
    prefix = "static"
    directory = "static-content-dir"
  }

  auth-config {
    target-scope = "scope-must-be-the-same-as-in-the-participant"
  }
}

Note

You can also start JSON API using CLI args (example below) however this is now deprecated

daml json-api --ledger-host localhost --ledger-port 6865 --http-port 7575

Standalone JAR¶

The daml json-api command is great during development since it is included with the SDK and integrates with daml start and other commands. Once you are ready to deploy your application, you can download the standalone JAR from Github releases. It is much smaller than the whole SDK and easier to deploy since it only requires a JVM but no other dependencies and no installation process. The JAR accepts exactly the same command line parameters as daml json-api, so to start the standalone JAR, you can use the following command:

java -jar http-json-2.0.0.jar --config json-api-app.conf

Replace the version number 2.0.0 by the version of the SDK you are using.

With Query Store¶

In production setups, you should configure the HTTP JSON API service to use a PostgreSQL backend as a Query Store. The in-memory backend will call the ledger to fetch the entire active contract set for the templates in your query every time so it is generally not recommended to rely on this in production. Note that the query store is a redundant copy of on-ledger data. It is safe to reinitialize the database at any time.

To enable the PostgreSQL backend you can add the query-store config block as described.

Access Tokens¶

Each request to the HTTP JSON API Service must come with an access token, regardless of whether the underlying ledger requires it or not. This also includes development setups using an unsecured sandbox. The HTTP JSON API Service does not hold on to the access token, which will be only used to fulfill the request it came along with. The same token will be used to issue the request to the Ledger API.

The HTTP JSON API Service does not validate the token but may need to decode it to extract information that can be used to fill in request fields for party-specific request. How this happens depends partially on the token format you are using.

To connect to a Canton participant that uses target-scopes, the JSON API must also include target-scopes in its configuration as follows:

auth-config {
    target-scope = "scope-must-be-the-same-as-in-the-participant"
}

Party-specific Requests¶

Party-specific requests, i.e., command submissions and queries, are subject to additional restrictions. For command submissions the token must provide a proof that the bearer can act on behalf of at least one party (and possibly read on behalf of any number of parties). For queries the token must provide a proof that the bearer can either act and/or read of at least one party. This happens regardless of the used access token format. The following paragraphs provide guidance as to how different token formats are used by the HTTP JSON API in this regard.

Using User Tokens¶

If the underlying ledger supports user management (this includes Canton and the sandbox), you are recommended to use user tokens. For command submissions, the user of the bearer should have actAs rights for at least one party and readAs rights for any number of parties. Queries require the bearer’s user to have at least one actAs or readAs user right. The application id of the Ledger API request will be the user id.

Using Claim Tokens¶

These tokens can be used if the underlying ledger does not support user management. For command submissions, actAs must contain at least one party and readAs can contain any number of parties. Queries require at least one party in either actAs or readAs. The application id is mandatory.

Note

While the JSON API receives the token it doesn’t validate it itself. Upon receiving a token it will pass it, and all data contained within the request, on to the Ledger API’s AuthService which will then determine if the token is valid and authorized. However, the JSON API does decode the token to extract the ledger id, application id and party so it requires that you use a valid Daml ledger access token format.

For a ledger without authorization, e.g., the default configuration of Daml Sandbox, you can use https://jwt.io (or the JWT library of your choice) to generate your token. You can use an arbitrary secret here. The default “header” is fine. Under “Payload”, fill in:

{
  "https://daml.com/ledger-api": {
    "ledgerId": "sandbox",
    "applicationId": "foobar",
    "actAs": ["Alice"]
  }
}

The value of the ledgerId field has to match the ledgerId of your underlying Daml Ledger. For the Sandbox this corresponds to the participant id which by default is just sandbox.

Note

The value of applicationId will be used for commands submitted using that token.

The value for actAs is specified as a list and you provide it with the party that you want to use, such as in the example above which uses Alice for a party. actAs may include more than just one party as the JSON API supports multi-party submissions.

The party should reference an already allocated party.

Note

As mentioned above the JSON API does not validate tokens so if your ledger runs without authorization you can use an arbitrary secret.

Then the “Encoded” box should have your token, ready for passing to the service as described in the following sections.

Alternatively, here are two tokens you can use for testing:

{"https://daml.com/ledger-api": {"ledgerId": "sandbox", "applicationId": "HTTP-JSON-API-Gateway", "actAs": ["Alice"]}}:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJodHRwczovL2RhbWwuY29tL2xlZGdlci1hcGkiOnsibGVkZ2VySWQiOiJzYW5kYm94IiwiYXBwbGljYXRpb25JZCI6IkhUVFAtSlNPTi1BUEktR2F0ZXdheSIsImFjdEFzIjpbIkFsaWNlIl19fQ.FIjS4ao9yu1XYnv1ZL3t7ooPNIyQYAHY3pmzej4EMCM

{"https://daml.com/ledger-api": {"ledgerId": "sandbox", "applicationId": "HTTP-JSON-API-Gateway", "actAs": ["Bob"]}}:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJodHRwczovL2RhbWwuY29tL2xlZGdlci1hcGkiOnsibGVkZ2VySWQiOiJzYW5kYm94IiwiYXBwbGljYXRpb25JZCI6IkhUVFAtSlNPTi1BUEktR2F0ZXdheSIsImFjdEFzIjpbIkJvYiJdfX0.y6iwpnYt-ObtNo_FyLVxMtNTwpJF8uxzNfPELQUVKVg

Auth via HTTP¶

Set HTTP header Authorization: Bearer paste-jwt-here

Example:

Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJodHRwczovL2RhbWwuY29tL2xlZGdlci1hcGkiOnsibGVkZ2VySWQiOiJNeUxlZGdlciIsImFwcGxpY2F0aW9uSWQiOiJIVFRQLUpTT04tQVBJLUdhdGV3YXkiLCJhY3RBcyI6WyJBbGljZSJdfX0.34zzF_fbWv7p60r5s1kKzwndvGdsJDX-W4Xhm4oVdpk

Auth via WebSockets¶

WebSocket clients support a “subprotocols” argument (sometimes simply called “protocols”); this is usually in a list form but occasionally in comma-separated form. Check documentation for your WebSocket library of choice for details.

For HTTP JSON requests, you must pass two subprotocols:

daml.ws.auth
jwt.token.paste-jwt-here

Example:

jwt.token.eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJodHRwczovL2RhbWwuY29tL2xlZGdlci1hcGkiOnsibGVkZ2VySWQiOiJNeUxlZGdlciIsImFwcGxpY2F0aW9uSWQiOiJIVFRQLUpTT04tQVBJLUdhdGV3YXkiLCJhY3RBcyI6WyJBbGljZSJdfX0.34zzF_fbWv7p60r5s1kKzwndvGdsJDX-W4Xhm4oVdpk

HTTP Status Codes¶

The JSON API reports errors using standard HTTP status codes. It divides HTTP status codes into 3 groups indicating:

success (200)
failure due to a client-side problem (400, 401, 403, 404, 409, 429)
failure due to a server-side problem (500, 503)

The JSON API can return one of the following HTTP status codes:

200 - OK
400 - Bad Request (Client Error)
401 - Unauthorized, authentication required
403 - Forbidden, insufficient permissions
404 - Not Found
409 - Conflict, contract ID or key missing or duplicated
500 - Internal Server Error
503 - Service Unavailable, ledger server is not running yet or has been shut down
504 - Gateway Timeout, transaction failed to receive its completion within the predefined timeout

When the Ledger API returns an error code, the JSON API maps it to one of the above codes according to the official gRPC to HTTP code mapping.

If a client’s HTTP GET or POST request reaches an API endpoint, the corresponding response will always contain a JSON object with a status field, and either an errors or result field. It may also contain an optional warnings and/or an optional ledgerApiError :

{
    "status": <400 | 401 | 403 | 404 | 409 | 500 | 503 | 504>,
    "errors": <JSON array of strings>, | "result": <JSON object or array>,
    ["warnings": <JSON object> ],
    ["ledgerApiError": <JSON object> ]
}

Where:

status – a JSON number which matches the HTTP response status code returned in the HTTP header,
errors – a JSON array of strings, each string represents one error,
result – a JSON object or JSON array, representing one or many results,
warnings – an optional field with a JSON object, representing one or many warnings.
ledgerApiError – an optional field with a JSON object, representing detail of an error if it was originated from Ledger API.

See the following blog post for more details about error handling best practices: REST API Error Codes 101.

See The Ledger API error codes for more details about error codes from Ledger API.

Successful Response, HTTP Status: 200 OK¶

Content-Type: application/json
Content:

{
    "status": 200,
    "result": <JSON object>
}

Successful Response with a Warning, HTTP Status: 200 OK¶

Content-Type: application/json
Content:

{
    "status": 200,
    "result": <JSON object>,
    "warnings": <JSON object>
}

Failure, HTTP Status: 400 | 401 | 404 | 500¶

Content-Type: application/json
Content:

{
    "status": <400 | 401 | 404 | 500>,
    "errors": <JSON array of strings>,
    ["ledgerApiError": <JSON object> ]
}

Examples¶

Result with JSON Object without Warnings:

{"status": 200, "result": {...}}

Result with JSON Array and Warnings:

{"status": 200, "result": [...], "warnings": {"unknownTemplateIds": ["UnknownModule:UnknownEntity"]}}

Bad Request Error:

{"status": 400, "errors": ["JSON parser error: Unexpected character 'f' at input index 27 (line 1, position 28)"]}

Bad Request Error with Warnings:

{"status":400, "errors":["Cannot resolve any template ID from request"], "warnings":{"unknownTemplateIds":["XXX:YYY","AAA:BBB"]}}

Authentication Error:

{"status": 401, "errors": ["Authentication Required"]}

Not Found Error:

{"status": 404, "errors": ["HttpMethod(POST), uri: http://localhost:7575/v1/query1"]}

Internal Server Error:

{"status": 500, "errors": ["Cannot initialize Ledger API"]}

Create a New Contract¶

To create an Iou contract from the Quickstart guide:

template Iou
  with
    issuer : Party
    owner : Party
    currency : Text
    amount : Decimal
    observers : [Party]

HTTP Request¶

URL: /v1/create
Method: POST
Content-Type: application/json
Content:

{
  "templateId": "a3b788b4dc18dc060bfb82366ae6dc055b1e361d646d5cfdb1b729607e344336:Iou:IouTransfer",
  "payload": {
    "issuer": "Alice",
    "owner": "Alice",
    "currency": "USD",
    "amount": "999.99",
    "observers": []
  }
}

Where:

templateId is the contract template identifier which has the following two formats: #<package name>:<module>:<entity> or <package ID>:<module>:<entity>.

The package name format works with the smart contract upgrading feature so that contracts with different package IDs but the same package name can be used in a uniform manner.

Using the package ID format refers to a single package.

Previously JSON API had supported partially qualified template IDs, (i.e. simply <module>:<entity>) as an interactive convenience which fails if there is more than one package with matching template names. Since this format was not supported for production use and will not work with smart contract upgrades, it is now unavailable.
payload field contains contract fields as defined in the Daml template and formatted according to Daml-LF JSON Encoding.

HTTP Response¶

Content-Type: application/json
Content:

{
    "status": 200,
    "result": {
        "observers": [],
        "agreementText": "",
        "payload": {
            "observers": [],
            "issuer": "Alice",
            "amount": "999.99",
            "currency": "USD",
            "owner": "Alice"
        },
        "signatories": [
            "Alice"
        ],
        "contractId": "#124:0",
        "templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou",
        "completionOffset":"0000000000000084"
    }
}

Where:

status field matches the HTTP response status code returned in the HTTP header,
result field contains created contract details. Keep in mind that templateId in the JSON API response is always fully qualified (always contains package ID).

Create a Contract with a Command ID¶

When creating a new contract or exercising a choice you may specify an optional meta field. This allows you to control various extra settings used when submitting a command to the ledger. Each of these meta fields is optional.

Note

You cannot currently use commandIds anywhere else in the JSON API, but you can use it for observing the results of its commands outside the JSON API in logs or via the Ledger API’s Command Services

{
  "templateId": "a3b788b4dc18dc060bfb82366ae6dc055b1e361d646d5cfdb1b729607e344336:Iou:IouTransfer",
  "payload": {
    "observers": [],
    "issuer": "Alice",
    "amount": "999.99",
    "currency": "USD",
    "owner": "Alice"
  },
  "meta": {
    "commandId": "a unique ID",
    "actAs": ["Alice"],
    "readAs": ["PublicParty"],
    "deduplicationPeriod": {
      "durationInMillis": 10000,
      "type": "Duration"
    },
    "submissionId": "d2f941b1-ee5c-4634-9a51-1335ce6902fa"
  }
}

Where:

commandId – optional field, a unique string identifying the command.
actAs – a non-empty list of parties, overriding the set from the JWT user; must be a subset of the JWT user’s set.
readAs – a list of parties, overriding the set from the JWT user; must be a subset of the JWT user’s set.
submissionId – a string, used for deduplicating retried requests. If you do not set it, a random one will be chosen, effectively treating the request as unique and disabling deduplication.
deduplicationPeriod – either a Duration as above, which is how far back in time prior commands will be searched for this submission, or an Offset as follows, which is the earliest ledger offset after which to search for the submission.

"deduplicationPeriod": {
  "offset": "0000000000000083",
  "type": "Offset"
}

Exercise by Contract ID¶

The JSON command below, demonstrates how to exercise an Iou_Transfer choice on an Iou contract:

    choice Iou_Transfer : ContractId IouTransfer
      with
        newOwner : Party
      controller owner
      do create IouTransfer with iou = this; newOwner

HTTP Request¶

URL: /v1/exercise
Method: POST
Content-Type: application/json
Content:

{
    "templateId": "a3b788b4dc18dc060bfb82366ae6dc055b1e361d646d5cfdb1b729607e344336:Iou:IouTransfer",
    "choiceInterfaceId": "a3b788b4dc18dc060bfb82366ae6dc055b1e361d646d5cfdb1b729607e344336:Iou:IouTransferInterface",
    "contractId": "#124:0",
    "choice": "Iou_Transfer",
    "argument": {
        "newOwner": "Alice"
    }
}

Where:

templateId – contract template or interface identifier, same as in create request,
choiceInterfaceId – optional template or interface that defines the choice, same format as templateId,
contractId – contract identifier, the value from the create response,
choice – Daml contract choice, that is being exercised,
argument – contract choice argument(s).

templateId and choiceInterfaceId are treated as with exercise by key. However, because contractId is always unambiguous, you may alternatively simply specify the interface ID as the templateId argument, and ignore choiceInterfaceId entirely. This isn’t true of exercise-by-key or create-and-exercise, so we suggest treating this request as if this alternative isn’t available.

HTTP Response¶

Content-Type: application/json
Content:

{
    "status": 200,
    "result": {
        "exerciseResult": "#201:1",
        "events": [
            {
                "archived": {
                    "contractId": "#124:0",
                    "templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"
                }
            },
            {
                "created": {
                    "observers": [],
                    "agreementText": "",
                    "payload": {
                        "iou": {
                            "observers": [],
                            "issuer": "Alice",
                            "amount": "999.99",
                            "currency": "USD",
                            "owner": "Alice"
                        },
                        "newOwner": "Alice"
                    },
                    "signatories": [
                        "Alice"
                    ],
                    "contractId": "#201:1",
                    "templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:IouTransfer"
                }
            }
        ],
        "completionOffset":"0000000000000083"
    }
}

Where:

status field matches the HTTP response status code returned in the HTTP header,
result field contains contract choice execution details:
- exerciseResult field contains the return value of the exercised contract choice.
- events contains an array of contracts that were archived and created as part of the choice execution. The array may contain: zero or many {"archived": {...}} and zero or many {"created": {...}} elements. The order of the contracts is the same as on the ledger.
- completionOffset is the ledger offset of the transaction containing the exercise’s ledger changes.

Exercise by Contract Key¶

The JSON command below, demonstrates how to exercise the Archive choice on the Account contract with a (Party, Text) contract key defined like this:

template Account with
    owner : Party
    number : Text
    status : AccountStatus
  where
    signatory owner
    key (owner, number) : (Party, Text)
    maintainer key._1

HTTP Request¶

URL: /v1/exercise
Method: POST
Content-Type: application/json
Content:

{
    "templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Account:Account",
    "key": {
        "_1": "Alice",
        "_2": "abc123"
    },
    "choiceInterfaceId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Account:AccountInterface",
    "choice": "Archive",
    "argument": {}
}

Where:

templateId – contract template identifier, same as in create request,
key – contract key, formatted according to the Daml-LF JSON Encoding,
choiceInterfaceId – optional template or interface that defines the choice, same format as templateId,
choice – Daml contract choice, that is being exercised,
argument – contract choice argument(s), empty, because Archive does not take any.

key is always searched in relation to the templateId. The choice, on the other hand, is searched according to choiceInterfaceId; if choiceInterfaceId is not specified, templateId is its default. We recommend always specifying choiceInterfaceId when invoking an interface choice; however, if the set of Daml-LF packages on the participant only contains one choice with a given name associated with templateId, that choice will be exercised, regardless of where it is defined. If a template and one or more of the interfaces it implements declares a choice, and choiceInterfaceId is not used, the one directly defined on the choice will be exercised. If choice selection is still ambiguous given these rules, the endpoint will fail as if the choice isn’t defined.

HTTP Response¶

Formatted similar to Exercise by Contract ID response.

Create and Exercise in the Same Transaction¶

This command allows creating a contract and exercising a choice on the newly created contract in the same transaction.

HTTP Request¶

URL: /v1/create-and-exercise
Method: POST
Content-Type: application/json
Content:

{
  "templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou",
  "payload": {
    "observers": [],
    "issuer": "Alice",
    "amount": "999.99",
    "currency": "USD",
    "owner": "Alice"
  },
  "choiceInterfaceId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:IouInterface",
  "choice": "Iou_Transfer",
  "argument": {
    "newOwner": "Bob"
  }
}

Where:

templateId – the initial contract template identifier, in the same format as in the create request,
payload – the initial contract fields as defined in the Daml template and formatted according to Daml-LF JSON Encoding,
choiceInterfaceId – optional template or interface that defines the choice, same format as templateId,
choice – Daml contract choice, that is being exercised,
argument – contract choice argument(s).

templateId and choiceInterfaceId are treated as with exercise by key, with the exception that it is payload, not key, strictly interpreted according to templateId.

HTTP Response¶

Please note that the response below is for a consuming choice, so it contains:

created and archived events for the initial contract ("contractId": "#1:0"), which was created and archived right away when a consuming choice was exercised on it,
a created event for the contract that is the result of exercising the choice ("contractId": "#1:2").
Content-Type: application/json
Content:

{
  "result": {
    "exerciseResult": "#1:2",
    "events": [
      {
        "created": {
          "observers": [],
          "agreementText": "",
          "payload": {
            "observers": [],
            "issuer": "Alice",
            "amount": "999.99",
            "currency": "USD",
            "owner": "Alice"
          },
          "signatories": [
            "Alice"
          ],
          "contractId": "#1:0",
          "templateId": "a3b788b4dc18dc060bfb82366ae6dc055b1e361d646d5cfdb1b729607e344336:Iou:Iou"
        }
      },
      {
        "archived": {
          "contractId": "#1:0",
          "templateId": "a3b788b4dc18dc060bfb82366ae6dc055b1e361d646d5cfdb1b729607e344336:Iou:Iou"
        }
      },
      {
        "created": {
          "observers": [
            "Bob"
          ],
          "agreementText": "",
          "payload": {
            "iou": {
              "observers": [],
              "issuer": "Alice",
              "amount": "999.99",
              "currency": "USD",
              "owner": "Alice"
            },
            "newOwner": "Bob"
          },
          "signatories": [
            "Alice"
          ],
          "contractId": "#1:2",
          "templateId": "a3b788b4dc18dc060bfb82366ae6dc055b1e361d646d5cfdb1b729607e344336:Iou:IouTransfer"
        }
      }
    ]
  },
  "status": 200
}

Fetch Contract by Contract ID¶

HTTP Request¶

URL: /v1/fetch
Method: POST
Content-Type: application/json
Content:

application/json body:

{
  "contractId": "#201:1",
  "templateId": "a3b788b4dc18dc060bfb82366ae6dc055b1e361d646d5cfdb1b729607e344336:Iou:IouTransfer"
}

readers may be passed as with Query. templateId is optional, but you are strongly advised to always pass it explicitly to minimize the data read from the Ledger API to answer the query. It can be either a template ID or an interface ID.

Contract Not Found HTTP Response¶

Content-Type: application/json
Content:

{
    "status": 200,
    "result": null
}

Contract Found HTTP Response¶

Content-Type: application/json
Content:

{
    "status": 200,
    "result": {
        "observers": [],
        "agreementText": "",
        "payload": {
            "iou": {
                "observers": [],
                "issuer": "Alice",
                "amount": "999.99",
                "currency": "USD",
                "owner": "Alice"
            },
            "newOwner": "Alice"
        },
        "signatories": [
            "Alice"
        ],
        "contractId": "#201:1",
        "templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:IouTransfer"
    }
}

Fetch Contract by Key¶

Show the currently active contract that matches a given key.

The websocket endpoint /v1/stream/fetch can be used to search multiple keys in the same request, or in place of iteratively invoking this endpoint to respond to changes on the ledger.

HTTP Request¶

URL: /v1/fetch
Method: POST
Content-Type: application/json
Content:

{
    "templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Account:Account",
    "key": {
        "_1": "Alice",
        "_2": "abc123"
    }
}

readers may be passed as with Query.

Contract Not Found HTTP Response¶

Content-Type: application/json
Content:

{
    "status": 200,
    "result": null
}

Contract Found HTTP Response¶

Content-Type: application/json
Content:

{
    "status": 200,
    "result": {
        "observers": [],
        "agreementText": "",
        "payload": {
            "owner": "Alice",
            "number": "abc123",
            "status": {
                "tag": "Enabled",
                "value": "2020-01-01T00:00:01Z"
            }
        },
        "signatories": [
            "Alice"
        ],
        "key": {
            "_1": "Alice",
            "_2": "abc123"
        },
        "contractId": "#697:0",
        "templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Account:Account"
    }
}

Get All Active Contracts¶

List all currently active contracts for all known templates.

Note

Retrieved contracts do not get persisted into a query store database. Query store is a search index and can be used to optimize search latency. See Start HTTP service for information on how to start JSON API service with a query store enabled.

Note

You can only query active contracts with the /v1/query endpoint. Archived contracts (those that were archived or consumed during an exercise operation) will not be shown in the results.

HTTP Request¶

URL: /v1/query
Method: GET
Content: <EMPTY>

HTTP Response¶

The response is the same as for the POST method below.

Get All Active Contracts Matching a Given Query¶

List currently active contracts that match a given query.

The websocket endpoint /v1/stream/query can be used in place of iteratively invoking this endpoint to respond to changes on the ledger.

HTTP Request¶

URL: /v1/query
Method: POST
Content-Type: application/json
Content:

{
    "templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"],
    "query": {"amount": 999.99},
    "readers": ["Alice"]
}

Where:

templateIds – either an array of contract template identifiers in the same format as in the create request. It can also be an array containing a single interface identifier to search through. Mixing of template ID’s and interface ID’s, or specifying more than one interface ID is not allowed.
query: search criteria to apply to the specified templateIds, formatted according to the Query Language.
readers: optional non-empty list of parties to query as; must be a subset of the actAs and readAs parties in the JWT.

Empty HTTP Response¶

Content-Type: application/json
Content:

{
    "status": 200,
    "result": []
}

Nonempty HTTP Response¶

Content-Type: application/json
Content:

{
    "result": [
        {
            "observers": [],
            "agreementText": "",
            "payload": {
                "observers": [],
                "issuer": "Alice",
                "amount": "999.99",
                "currency": "USD",
                "owner": "Alice"
            },
            "signatories": [
                "Alice"
            ],
            "contractId": "#52:0",
            "templateId": "b10d22d6c2f2fae41b353315cf893ed66996ecb0abe4424ea6a81576918f658a:Iou:Iou"
        }
    ],
    "status": 200
}

Where

result contains an array of contracts, each contract formatted according to Daml-LF JSON Encoding,
status matches the HTTP status code returned in the HTTP header.

Nonempty HTTP Response With Unknown Template IDs Warning¶

Content-Type: application/json
Content:

{
    "warnings": {
        "unknownTemplateIds": ["UnknownModule:UnknownEntity"]
    },
    "result": [
        {
            "observers": [],
            "agreementText": "",
            "payload": {
                "observers": [],
                "issuer": "Alice",
                "amount": "999.99",
                "currency": "USD",
                "owner": "Alice"
            },
            "signatories": [
                "Alice"
            ],
            "contractId": "#52:0",
            "templateId": "b10d22d6c2f2fae41b353315cf893ed66996ecb0abe4424ea6a81576918f658a:Iou:Iou"
        }
    ],
    "status": 200
}

Fetch Parties by Identifiers¶

URL: /v1/parties
Method: POST
Content-Type: application/json
Content:

["Alice", "Bob", "Dave"]

If an empty JSON array is passed: [], this endpoint returns BadRequest(400) error:

{
  "status": 400,
  "errors": [
    "JsonReaderError. Cannot read JSON: <[]>. Cause: spray.json.DeserializationException: must be a list with at least 1 element"
  ]
}

HTTP Response¶

Content-Type: application/json
Content:

{
  "status": 200,
  "result": [
    {
      "identifier": "Alice",
      "displayName": "Alice & Co. LLC",
      "isLocal": true
    },
    {
      "identifier": "Bob",
      "displayName": "Bob & Co. LLC",
      "isLocal": true
    },
    {
      "identifier": "Dave",
      "isLocal": true
    }
  ]
}

Please note that the order of the party objects in the response is not guaranteed to match the order of the passed party identifiers.

Where

identifier – a stable unique identifier of a Daml party,
displayName – optional human readable name associated with the party. Might not be unique,
isLocal – true if party is hosted by the backing participant.

Response With Unknown Parties Warning¶

Content-Type: application/json
Content:

{
  "result": [
    {
      "identifier": "Alice",
      "displayName": "Alice & Co. LLC",
      "isLocal": true
    }
  ],
  "warnings": {
    "unknownParties": ["Erin"]
  },
  "status": 200
}

The result might be an empty JSON array if none of the requested parties is known.

Fetch All Known Parties¶

URL: /v1/parties
Method: GET
Content: <EMPTY>

HTTP Response¶

The response is the same as for the POST method above.

Allocate a New Party¶

This endpoint is a JSON API proxy for the Ledger API’s AllocatePartyRequest. For more information about party management, please refer to Provisioning Identifiers part of the Ledger API documentation.

HTTP Request¶

URL: /v1/parties/allocate
Method: POST
Content-Type: application/json
Content:

{
  "identifierHint": "Carol",
  "displayName": "Carol & Co. LLC"
}

Please refer to AllocateParty documentation for information about the meaning of the fields.

All fields in the request are optional, this means that an empty JSON object is a valid request to allocate a new party:

{}

HTTP Response¶

{
  "result": {
    "identifier": "Carol",
    "displayName": "Carol & Co. LLC",
    "isLocal": true
  },
  "status": 200
}

Create a New User¶

This endpoint exposes the Ledger API’s CreateUser RPC.

HTTP Request¶

URL: /v1/user/create
Method: POST
Content-Type: application/json
Content:

{
  "userId": "carol",
  "primaryParty": "Carol",
  "rights": [
    {
      "type": "CanActAs",
      "party": "Carol"
    },
    {
      "type": "CanReadAs",
      "party": "Alice"
    },
    {
      "type": "CanReadAs",
      "party": "Bob"
    },
    {
      "type": "ParticipantAdmin"
    }
  ]
}

Please refer to CreateUser RPC documentation for information about the meaning of the fields.

Only the userId fields in the request is required, this means that an JSON object containing only it is a valid request to create a new user.

HTTP Response¶

{
  "result": {},
  "status": 200
}

Get Authenticated User Information¶

This endpoint exposes the Ledger API’s GetUser RPC.

The user ID will always be filled out with the user specified via the currently used user token.

HTTP Request¶

URL: /v1/user
Method: GET

HTTP Response¶

{
  "result": {
    "userId": "carol",
    "primaryParty": "Carol"
  },
  "status": 200
}

Get Specific User Information¶

This endpoint exposes the Ledger API’s GetUser RPC.

HTTP Request¶

URL: /v1/user
Method: POST
Content-Type: application/json
Content:

{
  "userId": "carol"
}

Please refer to GetUser RPC documentation for information about the meaning of the fields.

HTTP Response¶

{
  "result": {
    "userId": "carol",
    "primaryParty": "Carol"
  },
  "status": 200
}

Delete Specific User¶

This endpoint exposes the Ledger API’s DeleteUser RPC.

HTTP Request¶

URL: /v1/user/delete
Method: POST
Content-Type: application/json
Content:

{
  "userId": "carol"
}

Please refer to DeleteUser RPC documentation for information about the meaning of the fields.

HTTP Response¶

{
  "result": {},
  "status": 200
}

List Users¶

This endpoint exposes the Ledger API’s ListUsers RPC.

HTTP Request¶

URL: /v1/users
Method: GET

HTTP Response¶

{
  "result": [
    {
        "userId": "carol",
        "primaryParty": "Carol"
    },
    {
        "userId": "bob",
        "primaryParty": "Bob"
    }
  ],
  "status": 200
}

Grant User Rights¶

This endpoint exposes the Ledger API’s GrantUserRights RPC.

HTTP Request¶

URL: /v1/user/rights/grant
Method: POST
Content-Type: application/json
Content:

{
  "userId": "carol",
  "rights": [
    {
      "type": "CanActAs",
      "party": "Carol"
    },
    {
      "type": "CanReadAs",
      "party": "Alice"
    },
    {
      "type": "CanReadAs",
      "party": "Bob"
    },
    {
      "type": "ParticipantAdmin"
    }
  ]
}

Please refer to GrantUserRights RPC documentation for information about the meaning of the fields.

HTTP Response¶

{
  "result": [
    {
      "type": "CanActAs",
      "party": "Carol"
    },
    {
      "type": "CanReadAs",
      "party": "Alice"
    },
    {
      "type": "CanReadAs",
      "party": "Bob"
    },
    {
      "type": "ParticipantAdmin"
    }
  ],
  "status": 200
}

Returns the rights that were newly granted.

Revoke User Rights¶

This endpoint exposes the Ledger API’s RevokeUserRights RPC.

HTTP Request¶

URL: /v1/user/rights/revoke
Method: POST
Content-Type: application/json
Content:

{
  "userId": "carol",
  "rights": [
    {
      "type": "CanActAs",
      "party": "Carol"
    },
    {
      "type": "CanReadAs",
      "party": "Alice"
    },
    {
      "type": "CanReadAs",
      "party": "Bob"
    },
    {
      "type": "ParticipantAdmin"
    }
  ]
}

Please refer to RevokeUserRights RPC documentation for information about the meaning of the fields.

HTTP Response¶

{
  "result": [
    {
      "type": "CanActAs",
      "party": "Carol"
    },
    {
      "type": "CanReadAs",
      "party": "Alice"
    },
    {
      "type": "CanReadAs",
      "party": "Bob"
    },
    {
      "type": "ParticipantAdmin"
    }
  ],
  "status": 200
}

Returns the rights that were actually granted.

List Authenticated User Rights¶

This endpoint exposes the Ledger API’s ListUserRights RPC.

The user ID will always be filled out with the user specified via the currently used user token.

HTTP Request¶

URL: /v1/user/rights
Method: GET

HTTP Response¶

{
  "result": [
    {
      "type": "CanActAs",
      "party": "Carol"
    },
    {
      "type": "CanReadAs",
      "party": "Alice"
    },
    {
      "type": "CanReadAs",
      "party": "Bob"
    },
    {
      "type": "ParticipantAdmin"
    }
  ],
  "status": 200
}

List Specific User Rights¶

This endpoint exposes the Ledger API’s ListUserRights RPC.

HTTP Request¶

URL: /v1/user/rights
Method: POST
Content-Type: application/json
Content:

{
  "userId": "carol"
}

Please refer to ListUserRights RPC documentation for information about the meaning of the fields.

HTTP Response¶

{
  "result": [
    {
      "type": "CanActAs",
      "party": "Carol"
    },
    {
      "type": "CanReadAs",
      "party": "Alice"
    },
    {
      "type": "CanReadAs",
      "party": "Bob"
    },
    {
      "type": "ParticipantAdmin"
    }
  ],
  "status": 200
}

List All DALF Packages¶

HTTP Request¶

URL: /v1/packages
Method: GET
Content: <EMPTY>

HTTP Response¶

{
  "result": [
    "c1f1f00558799eec139fb4f4c76f95fb52fa1837a5dd29600baa1c8ed1bdccfd",
    "733e38d36a2759688a4b2c4cec69d48e7b55ecc8dedc8067b815926c917a182a",
    "bfcd37bd6b84768e86e432f5f6c33e25d9e7724a9d42e33875ff74f6348e733f",
    "40f452260bef3f29dede136108fc08a88d5a5250310281067087da6f0baddff7",
    "8a7806365bbd98d88b4c13832ebfa305f6abaeaf32cfa2b7dd25c4fa489b79fb"
  ],
  "status": 200
}

Where result is the JSON array containing the package IDs of all loaded DALFs.

Download a DALF Package¶

HTTP Request¶

URL: /v1/packages/<package ID>
Method: GET
Content: <EMPTY>

Note that the desired package ID is specified in the URL.

HTTP Response, status: 200 OK¶

Transfer-Encoding: chunked
Content-Type: application/octet-stream
Content: <DALF bytes>

The content (body) of the HTTP response contains raw DALF package bytes, without any encoding. Note that the package ID specified in the URL is actually the SHA-256 hash of the downloaded DALF package and can be used to validate the integrity of the downloaded content.

HTTP Response With Error, Any Status Different from 200 OK¶

Any status different from 200 OK will be in the format specified below.

Content-Type: application/json
Content:

{
    "errors": [
        "io.grpc.StatusRuntimeException: NOT_FOUND"
    ],
    "status": 500
}

Upload a DAR File¶

HTTP Request¶

URL: /v1/packages
Method: POST
Content-Type: application/octet-stream
Content: <DAR bytes>

The content (body) of the HTTP request contains raw DAR file bytes, without any encoding.

HTTP Response, Status: 200 OK¶

Content-Type: application/json
Content:

{
    "result": 1,
    "status": 200
}

HTTP Response With Error¶

Content-Type: application/json
Content:

{
    "errors": [
        "io.grpc.StatusRuntimeException: INVALID_ARGUMENT: Invalid argument: Invalid DAR: package-upload, content: [}]"
    ],
    "status": 500
}

Metering Report¶

For a description of participant metering, the parameters, and the report format see the Participant Metering.

URL: /v1/metering-report
Method: POST
Content-Type: application/json
Content:

{
  "from": "2022-01-01",
  "to": "2022-02-01",
  "application": "some-application"
}

HTTP Response¶

Content-Type: application/json
Content:

{
  "status": 200,
  "result": {
    "participant": "some-participant",
    "request": {
      "from": "2022-01-01T00:00:00Z",
      "to": "2022-02-01T00:00:00Z"
    },
    "final": true,
    "applications": [
      {
        "application": "some-application",
        "events": 42
      }
    ]
  }
}

Streaming API¶

Two subprotocols must be passed with every request, as described in Auth via WebSockets.

JavaScript/Node.js example demonstrating how to establish Streaming API connection:

const wsProtocol = "daml.ws.auth";
const tokenPrefix = "jwt.token.";
const jwt =
  "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJodHRwczovL2RhbWwuY29tL2xlZGdlci1hcGkiOnsibGVkZ2VySWQiOiJNeUxlZGdlciIsImFwcGxpY2F0aW9uSWQiOiJIVFRQLUpTT04tQVBJLUdhdGV3YXkiLCJhY3RBcyI6WyJBbGljZSJdfX0.34zzF_fbWv7p60r5s1kKzwndvGdsJDX-W4Xhm4oVdp";
const subprotocols = [`${tokenPrefix}${jwt}`, wsProtocol];

const ws = new WebSocket("ws://localhost:7575/v1/stream/query", subprotocols);

ws.addEventListener("open", function open() {
  ws.send(JSON.stringify({templateIds: ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"]}));
});

ws.addEventListener("message", function incoming(data) {
  console.log(data);
});

Please note that Streaming API does not allow multiple requests over the same WebSocket connection. The server returns an error and disconnects if second request received over the same WebSocket connection.

Error and Warning Reporting¶

Errors and warnings reported as part of the regular on-message flow: ws.addEventListener("message", ...).

Streaming API error messages formatted the same way as synchronous API errors.

Streaming API reports only one type of warnings – unknown template IDs, which is formatted as:

{"warnings":{"unknownTemplateIds":<JSON Array of template ID strings>>}}

Error and Warning Examples¶

{"warnings": {"unknownTemplateIds": ["UnknownModule:UnknownEntity"]}}

{
  "errors":["JsonReaderError. Cannot read JSON: <{\"templateIds\":[]}>. Cause: spray.json.DeserializationException: search requires at least one item in 'templateIds'"],
  "status":400
}

{
  "errors":["Multiple requests over the same WebSocket connection are not allowed."],
  "status":400
}

{
  "errors":["Could not resolve any template ID from request."],
  "status":400
}

Contracts Query Stream¶

URL: /v1/stream/query
Scheme: ws
Protocol: WebSocket

List currently active contracts that match a given query, with continuous updates.

Simpler use-cases that do not require continuous updates should use the simpler /v1/query endpoint instead.

application/json body must be sent first, formatted according to the Query Language:

{"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"]}

Multiple queries may be specified in an array, for overlapping or different sets of template IDs.:

[
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"], "query": {"amount": {"%lte": 50}}},
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:OtherIou:OtherIou"], "query": {"amount": {"%gt": 50}}},
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"]}
]

Only one interface ID can be provided in templateIds. An interface ID can be used in all queries:

[
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Ifc:Ifc"], "query": {"amount": {"%lte": 50}}},
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Ifc:Ifc"], "query": {"amount": {"%gt": 50}}},
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Ifc:Ifc"]}
]

Mixing of template ID’s and interface ID’s or specifying more than one interface ID across queries is not allowed. BadRequest(400) error will be returned.:

[
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"], "query": {"amount": {"%lte": 50}}},
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Ifc:Ifc"], "query": {"amount": {"%gt": 50}}},
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Ifc:Ifc"]}
]

Queries have two ways to specify an offset.

An offset, a string supplied by an earlier query output message, may optionally be specified alongside each query itself:

[
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"], "query": {"amount": {"%lte": 50}}},
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"], "query": {"amount": {"%gt": 50}}},
    {"templateIds": ["11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Iou:Iou"], "offset": "5609"}
]

If specified, the stream will include only contract creations and archivals after the response body that included that offset. Queries with no offset will begin with all active contracts for that query, as usual.

If an offset is specified before the queries, as a separate body, it will be used as a default offset for all queries that do not include an offset themselves:

{"offset": "4307"}

For example, if this message preceded the above 3-query example, it would be as if "4307" had been specified for the first two queries, while "5609" would be used for the third query.

If any offset has been pruned, the websocket will immediately fail with code 1011 and message internal error.

The output is a series of JSON documents, each payload formatted according to Daml-LF JSON Encoding:

{
    "events": [{
        "created": {
            "observers": [],
            "agreementText": "",
            "payload": {
                "observers": [],
                "issuer": "Alice",
                "amount": "999.99",
                "currency": "USD",
                "owner": "Alice"
            },
            "signatories": ["Alice"],
            "contractId": "#1:0",
            "templateId": "eb3b150383a979d6765b8570a17dd24ae8d8b63418ee5fd20df20ad2a1c13976:Iou:Iou"
        },
        "matchedQueries": [1, 2]
    }]
}

where matchedQueries indicates the 0-based indices into the request list of queries that matched this contract.

Every events block following the end of contracts that existed when the request started includes an offset. The stream is guaranteed to send an offset immediately at the beginning of this “live” data, which may or may not contain any events; if it does not contain events and no events were emitted before, it may be null if there was no transaction on the ledger or a string representing the current ledger end; otherwise, it will be a string. For example, you might use it to turn off an initial “loading” indicator:

{
    "events": [],
    "offset": "2"
}

Note

Events in the following “live” data may include events that precede this offset if an earlier per-query offset was specified.

This has been done with the intent of allowing to use per-query offset s to efficiently use a single connection to multiplex various requests. To give an example of how this would work, let’s say that there are two contract templates, A and B . Your application first queries for A s without specifying an offset. Then some client-side interaction requires the application to do the same for B s. The application can save the latest observed offset for the previous query, which let’s say is 42, and issue a new request that queries for all B s without specifying an offset and all A s from 42. While this happens on the client, a few more A s and B s are created and the new request is issued once the latest offset is 47. The response to this will contain a message with all active B s, followed by the message reporting the offset 47, followed by a stream of live updates that contains new A s starting from 42 and new B s starting from 47 .

To keep the stream alive, you’ll occasionally see messages like this, which can be safely ignored if you do not need to capture the last seen ledger offset:

{"events":[],"offset":"5609"}

where offset is the last seen ledger offset.

After submitting an Iou_Split exercise, which creates two contracts and archives the one above, the same stream will eventually produce:

{
    "events": [{
        "archived": {
            "contractId": "#1:0",
            "templateId": "eb3b150383a979d6765b8570a17dd24ae8d8b63418ee5fd20df20ad2a1c13976:Iou:Iou"
        }
    }, {
        "created": {
            "observers": [],
            "agreementText": "",
            "payload": {
                "observers": [],
                "issuer": "Alice",
                "amount": "42.42",
                "currency": "USD",
                "owner": "Alice"
            },
            "signatories": ["Alice"],
            "contractId": "#2:1",
            "templateId": "eb3b150383a979d6765b8570a17dd24ae8d8b63418ee5fd20df20ad2a1c13976:Iou:Iou"
        },
        "matchedQueries": [0, 2]
    }, {
        "created": {
            "observers": [],
            "agreementText": "",
            "payload": {
                "observers": [],
                "issuer": "Alice",
                "amount": "957.57",
                "currency": "USD",
                "owner": "Alice"
            },
            "signatories": ["Alice"],
            "contractId": "#2:2",
            "templateId": "eb3b150383a979d6765b8570a17dd24ae8d8b63418ee5fd20df20ad2a1c13976:Iou:Iou"
        },
        "matchedQueries": [1, 2]
    }],
    "offset": "3"
}

If any template IDs are found not to resolve, the first element of the stream will report them:

{"warnings": {"unknownTemplateIds": ["UnknownModule:UnknownEntity"]}}

and the stream will continue, provided that at least one template ID resolved properly.

Aside from "created" and "archived" elements, "error" elements may appear, which contain a string describing the error. The stream will continue in these cases, rather than terminating.

Some notes on behavior:

Each result array means “this is what would have changed if you just polled /v1/query iteratively.” In particular, just as polling search can “miss” contracts (as a create and archive can be paired between polls), such contracts may or may not appear in any result object.
No archived ever contains a contract ID occurring within a created in the same array. So, for example, supposing you are keeping an internal map of active contracts keyed by contract ID, you can apply the created first or the archived first, forwards, backwards, or in random order, and be guaranteed to get the same results.
Within a given array, if an archived and created refer to contracts with the same template ID and contract key, the archived is guaranteed to occur before the created.
Except in cases of #3, within a single response array, the order of created and archived is undefined and does not imply that any element occurred “before” or “after” any other one.
You will almost certainly receive contract IDs in archived that you never received a created for. These are contracts that query filtered out, but for which the server no longer is aware of that. You can safely ignore these. However, such “phantom archives” are guaranteed to represent an actual archival on the ledger, so if you are keeping a more global dataset outside the context of this specific search, you can use that archival information as you wish.

Fetch by Key Contracts Stream¶

URL: /v1/stream/fetch
Scheme: ws
Protocol: WebSocket

List currently active contracts that match one of the given {templateId, key} pairs, with continuous updates.

Simpler use-cases that search for only a single key and do not require continuous updates should use the simpler /v1/fetch endpoint instead.

application/json body must be sent first, formatted according to the following rule:

[
    {"templateId": "<template ID 1>", "key": <key 1>},
    {"templateId": "<template ID 2>", "key": <key 2>},
    ...
    {"templateId": "<template ID N>", "key": <key N>}
]

Where:

templateId – contract template identifier, same as in create request,
key – contract key, formatted according to the Daml-LF JSON Encoding,

Example:

[
    {"templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Account:Account", "key": {"_1": "Alice", "_2": "abc123"}},
    {"templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Account:Account", "key": {"_1": "Alice", "_2": "def345"}}
]

The output stream has the same format as the output from the Contracts Query Stream. We further guarantee that for every archived event appearing on the stream there has been a matching created event earlier in the stream, except in the case of missing contractIdAtOffset fields in the case described below.

You may supply optional offset s for the stream, exactly as with query streams. However, you should supply with each {templateId, key} pair a contractIdAtOffset, which is the contract ID currently associated with that pair at the point of the given offset, or null if no contract ID was associated with the pair at that offset. For example, with the above keys, if you had one "abc123" contract but no "def345" contract, you might specify:

[
    {"templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Account:Account", "key": {"_1": "Alice", "_2": "abc123"},
     "contractIdAtOffset": "#1:0"},
    {"templateId": "11c8f3ace75868d28136adc5cfc1de265a9ee5ad73fe8f2db97510e3631096a2:Account:Account", "key": {"_1": "Alice", "_2": "def345"},
     "contractIdAtOffset": null}
]

If every contractIdAtOffset is specified, as is so in the example above, you will not receive any archived events for contracts created before the offset unless those contracts are identified in a contractIdAtOffset. By contrast, if any contractIdAtOffset is missing, archived event filtering will be disabled, and you will receive “phantom archives” as with query streams.

Healthcheck Endpoints¶

The HTTP JSON API provides two healthcheck endpoints for integration with schedulers like Kubernetes.

Liveness Check¶

URL: /livez
Method: GET

A status code of 200 indicates a successful liveness check.

This is an unauthenticated endpoint intended to be used as a liveness probe.

Readiness Check¶

URL: /readyz
Method: GET

A status code of 200 indicates a successful readiness check.

This is an unauthenticated endpoint intended to be used as a readiness probe. It validates both the ledger connection as well as the database connection.