<a id="ksqldb-rest-api-reference"></a>

# HTTP API Reference for ksqlDB for Confluent Platform

This reference lists the HTTP API endpoints for ksqlDB running on Confluent Platform.

- [Execute a statement (/ksql endpoint)](ksql-endpoint.md#ksqldb-rest-api-ksql-endpoint)
- [Run a query (/query endpoint)](query-endpoint.md#ksqldb-rest-api-query-endpoint)
- [Run push and pull queries (/query-stream endpoint)](streaming-endpoint.md#ksqldb-rest-api-query-stream-endpoint)
- [Terminate a cluster (/ksql/terminate endpoint)](terminate-endpoint.md#ksqldb-rest-api-terminate-endpoint)
- [Introspect query status (/status endpoint)](status-endpoint.md#ksqldb-rest-api-status-endpoint)
- [Introspect server status (/info endpoint)](info-endpoint.md#ksqldb-rest-api-info-endpoint)
- [Introspect cluster status (/clusterStatus endpoint)](cluster-status-endpoint.md#ksqldb-rest-api-cluster-status-endpoint)
- [Get the validity of a property (/is_valid_property)](is-valid-property-endpoint.md#ksqldb-rest-api-is-valid-property-endpoint)

## REST endpoint

The default HTTP API endpoint is `http://0.0.0.0:8088/`.

Change the server configuration that controls the HTTP API endpoint by
setting the `listeners` parameter in the ksqlDB server config file.
For more info, see
[listeners](../../reference/server-configuration.md#ksqldb-reference-server-configuration-listeners). To
configure the endpoint to use HTTPS, see
[Configuring Listener for SSL encryption](../../operate-and-deploy/installation/security.md#ksqldb-installation-security-configure-listener-for-ssl-encryption).

## Content types

The ksqlDB HTTP API uses content types for requests and responses to
indicate the serialization format of the data and the API version.

Your request should specify this serialization format and version in the
`Accept` header, for example:

```none
Accept: application/vnd.ksql.v1+json
```

The less specific `application/json` content type is also permitted.
However, this is only for compatibility and ease of use, and you should
use the versioned value where possible. `application/json` maps to the
latest versioned content type, meaning the response may change after
upgrading the server to a later version.

The server also supports content negotiation, so you may include
multiple, weighted preferences:

```none
Accept: application/vnd.ksql.v1+json; q=0.9, application/json; q=0.5
```

For example, content negotiation is useful when a new version of the API
is preferred, but you are not sure if it is available yet.

Here’s an example request that returns the results from the
`LIST STREAMS` command:

```bash
curl -X "POST" "http://localhost:8088/ksql" \
     -H "Accept: application/vnd.ksql.v1+json" \
     -d $'{
  "ksql": "LIST STREAMS;",
  "streamsProperties": {}
}'
```

Here’s an example request that retrieves streaming data from
`TEST_STREAM`:

```bash
curl -X "POST" "http://localhost:8088/query" \
     -H "Accept: application/vnd.ksql.v1+json" \
     -d $'{
  "ksql": "SELECT * FROM TEST_STREAM EMIT CHANGES;",
  "streamsProperties": {}
}'
```

A `PROTOBUF` content type where the rows are serialized in the
`PROTOBUF` format is also supported for querying the `/query` and
`/query-stream` endpoints. You can specify this serialization format
in the `Accept` header:

```none
Accept: application/vnd.ksql.v1+protobuf
```

The following example shows a curl command that issues a Pull query on a
table called `CURRENTLOCATION` with the `PROTOBUF` content type:

```bash
curl -X "POST" "http://localhost:8088/query" \
     -H "Accept: application/vnd.ksql.v1+protobuf" \
     -d $'{
  "ksql": "SELECT * FROM CURRENTLOCATION;",
  "streamsProperties": {}
}'
```

Response:

```json
[{"header":{"queryId":"query_1655152127973","schema":"`PROFILEID` STRING KEY, `LA` DOUBLE, `LO` DOUBLE","protoSchema":"syntax = \"proto3\";\n\nmessage ConnectDefault1 {\n  string PROFILEID = 1;\n  double LA = 2;\n  double LO = 3;\n}\n"}},
{"row":{"protobufBytes":"CggxOGY0ZWE4NhF90LNZ9bFCQBmASL99HYRewA=="}},
{"row":{"protobufBytes":"Cgg0YTdjN2I0MRFAE2HD07NCQBnM7snDQoVewA=="}},
{"row":{"protobufBytes":"Cgg0YWI1Y2JhZBGKsOHplbJCQBmMSuoENIVewA=="}},
{"row":{"protobufBytes":"Cgg0ZGRhZDAwMBHNO07RkeRCQBk9m1Wfq5lewA=="}},
{"row":{"protobufBytes":"Cgg4YjZlYWU1ORFtxf6ye7JCQBmMSuoENIVewA=="}},
{"row":{"protobufBytes":"CghjMjMwOWVlYxGUh4Va0+RCQBn0/dR46ZpewA=="}}]
```

The `protoSchema` field in the `header` corresponds to the content
of a `.proto` file that the proto compiler uses at build time. Use the
`protoSchema` field to deserialize the `protobufBytes` into
`PROTOBUF` messages.

Provide the `--basic` and `--user` options if basic HTTPS
authentication is enabled on the cluster, as shown in the following
command.

`bash hl_lines="3" curl -X "POST" "https://localhost:8088/ksql" \      -H "Accept: application/vnd.ksql.v1+json" \      --basic --user "<API key>:<secret>" \      -d $'{   "ksql": "LIST STREAMS;",   "streamsProperties": {} }'`

## Errors

All API endpoints use a standard error message format for any requests
that return an HTTP status indicating an error (any 4xx or 5xx
statuses):

```http
HTTP/1.1 <Error Status>
Content-Type: application/json

{
    "error_code": <Error code>
    "message": <Error Message>
}
```

Some endpoints may include additional fields that provide more context
for handling the error.