WebSocket API

If a client is not available for your programming language yet, your app can interact directly with the Endb WebSocket API. Any WebSocket client can be used but in the examples below we'll use websocat to demonstrate the API without writing any code. Connect to Endb with:

websocat ws://localhost:3803/sql

You can send SQL statements to endb over WebSockets with JSON-RPC 2.0.

{"jsonrpc": "2.0", "id": 1, "method": "sql", "params": {"q": "INSERT INTO users (name) VALUES (?);", "p": [["Tsehay"], ["Iniku"]], "m": true}}
{"jsonrpc": "2.0", "id": 2, "method": "sql", "params": {"q": "SELECT * FROM users;", "p": [], "m": false}}

NOTE: To send the method calls above, paste them into a websocat session one-at-a-time and press <enter>. Further examples will assume JSON-RPC strings are sent in an existing websocat session.

JSON-RPC Request Object

Following the JSON-RPC 2.0 spec, a SQL statement or query to the Endb WebSocket API requires these components:

  • id - a string or integer identifier used to correlate requests to responses
  • method - always the string "sql"
  • params - request params are sent as JSON-RPC by-name request parameters, as listed below

JSON-RPC Request Parameters

  • q - (q)uery: a SQL query, optionally parameterized
  • p - (p)arameters: named or positional SQL parameters
  • m - (m)any parameter lists: bulk parameters, used for bulk insert/update

JSON-RPC Response Object

A response from the Endb WebSocket API will include these components:

  • id - the id provided in the request object, so it can be correlated
  • result - the response, encoded as JSON-LD, as in this example:
{"jsonrpc":"2.0", "id":111, "result":{"@context":{"xsd":"http://www.w3.org/2001/XMLSchema#","@vocab":"http://endb.io/"},"@graph":[{"name":"Hing","price":2.99}]}}

If your query is invalid or causes an internal error, you will receive an error instead, which includes:

  • id - the id of the request object, if one was provided (otherwise null)
  • error - a code and message, as returned by Endb
{"jsonrpc":"2.0", "id":222, "error":{"code":-32603,"message":"Error: Unknown table: users\n   ╭─[<unknown>:1:15]\n   │\n 1 │ SELECT * FROM users;\n   │               ──┬──  \n   │                 ╰──── Unknown table\n───╯\n"}}

WebSocket Basic Authentication

Endb supports HTTP Basic Authentication, as defined by RFC 7235, on top of RFC 6455. This is because the WebSocket Protocol RFC (6455) does not define authentication mechanisms itself.

Pass --username and --password arguments to the endb binary to force basic authentication for HTTP connections. (See Operation for more details, including environment variables which can be passed to Docker images.)

./target/endb --username zig --password zag

Then, use Basic Auth headers to connect to Endb:

websocat -H='Authorization: Basic' ws://zig:zag@localhost:3803/sql

Rather than Authorization: Basic, the Sec-WebSocket-Protocol header may be used. It is offered because web browsers do not support the Basic Auth header over WebSockets.


SQL parameters to a WebSocket request are always JSON-LD. A JSON-LD scalar always has the form: {"@type": "xsd:TYPE", "@value": "DATA"}. JSON-LD types are listed under the Data Types table.

For example, if a strongly-typed DateTime is required, it can be submitted like so:

{"jsonrpc": "2.0", "id": 11, "method": "sql", "params": {"q": "INSERT INTO users (name, date) VALUES (?, ?);", "p": ["dosha", {"@value": "2024-01-29T18:18:30.129159", "@type": "xsd:dateTime"}], "m": false}}

Named Parameters

Named SQL parameters substitute parameter placeholders with the form :param by the parameter key with the corresponding name. Named parameters are represented as a JSON object.

{"jsonrpc": "2.0", "id": 111, "method": "sql", "params": {"q": "INSERT INTO products {name: :name, price: :price};", "p": {"name": "Hing", "price": 2.99}, "m": false}}
{"jsonrpc": "2.0", "id": 112, "method": "sql", "params": {"q": "INSERT INTO events {start: :start};", "p": {"start": {"@type": "xsd:dateTime", "@value": "2021-04-09T20:00:00Z"}}, "m": false}}

Positional Parameters

Positional SQL parameters substitute parameter placeholders with the form ? by the parameter values, in the order they appear. Positional parameters are respresented as a JSON array.

{"jsonrpc": "2.0", "id": 211, "method": "sql", "params": {"q": "SELECT * FROM products WHERE name = ? AND price > ?;", "p": ["Hing", 2.00], "m": false}}
{"jsonrpc": "2.0", "id": 213, "method": "sql", "params": {"q": "INSERT INTO events {start: ?};", "p": [{"@type": "xsd:dateTime", "@value": "2021-04-09T20:00:00Z"}], "m": false}}

Bulk Parameters

Bulk operations are possible by setting the m flag to true. Bulk operations are available to both named and positional parameters. The list of parameters supplied in bulk must be nested in an array.

{"jsonrpc": "2.0", "id": 311, "method": "sql", "params": {"q": "INSERT INTO users {name: :name};", "p": [{"name": "Sungwon"}, {"name": "Olga"}], "m": true}}
{"jsonrpc": "2.0", "id": 312, "method": "sql", "params": {"q": "INSERT INTO sauces {name: ?, color: ?};", "p": [["Sriracha", "#FE6F5E"], ["Gochujang", "#FF8066"]], "m": true}}


Unlike the HTTP API, the WebSocket API is stateful and thus capable of explicit transactions. See the Transactions documentation for further details on SQL syntax.

{"jsonrpc": "2.0", "id": 411, "method": "sql", "params": {"q": "BEGIN TRANSACTION;", "p": [], "m": false}}
{"jsonrpc": "2.0", "id": 412, "method": "sql", "params": {"q": "INSERT INTO delete_me {name: 'Roll Me Back'};", "p": [], "m": false}}
{"jsonrpc": "2.0", "id": 413, "method": "sql", "params": {"q": "ROLLBACK;", "p": [], "m": false}}
{"jsonrpc": "2.0", "id": 414, "method": "sql", "params": {"q": "SELECT * FROM delete_me;", "p": [], "m": false}}