# HTTP read task > Poll a web API and record values from its JSON responses in channels. An HTTP read task polls a web API at a fixed rate and records values from each JSON response in channels. Before you start, [connect an HTTP server](https://docs.synnaxlabs.com/reference/hardware/http/connect-server). ## Endpoints and fields An endpoint is one request. A field is one value in its JSON response, found by a [JSON pointer](https://datatracker.ietf.org/doc/html/rfc6901) such as `/temperature`, and recorded in one channel. * **Numbers** -> recorded as they are. * **Booleans** -> recorded as 1 and 0. * **Strings** -> converted with the **Enum mapping**, else read as a number. A string channel records the text. The **Source** of an endpoint sets its timestamps: * **Poll time** -> the time halfway through the request. * **Response value** -> a time in the response, at a **Pointer**, in a **Format**: ISO 8601, or Unix time in seconds, milliseconds, microseconds, or nanoseconds. ## Create an HTTP read task [Enterprise](https://docs.synnaxlabs.com/reference/get-started/editions "Needs Synnax Enterprise") **Console** 1. In the devices toolbar, right-click the server and select **Create read task**. 2. Set **Rate**, the number of requests per second to each endpoint. 3. Click **Add endpoint**, then set **Method** and **Path**, such as `/api/data`. 4. Click **Add field** on the endpoint, then set **Pointer** and **Data type**. 5. Click (**Start**). The Console creates a channel for each field and an index channel for each endpoint, named from the server, path, and pointer. To choose a name, set **Channel** before you start. [](https://synnax.nyc3.cdn.digitaloceanspaces.com/docs/hardware/http/read-task/cb0f7b2f5524-dark.mp4#t=0.001) **Python** Python does not create channels. Create one index channel for each endpoint first. ```python import synnax as sy from synnax import http server = client.devices.retrieve(name="Weather station") time = client.channels.create( name="weather_time", is_index=True, data_type=sy.DataType.TIMESTAMP ) temperature = client.channels.create( name="weather_temperature", index=time.key, data_type=sy.DataType.FLOAT64 ) task = http.ReadTask( name="Weather station read", device=server.key, rate=1, endpoints=[ http.ReadEndpoint( method="GET", path="/api/data", fields=[ http.ReadField(pointer="/temperature", channel=temperature.key) ], ) ], ) client.tasks.configure(task) task.start() ``` **TypeScript** TypeScript does not create channels. Create one index channel for each endpoint first. ```typescript import { http } from "@synnaxlabs/client"; const [server] = await client.devices.retrieve({ where: { name: { eq: "Weather station" } }, }); const time = await client.channels.create({ name: "weather_time", isIndex: true, dataType: "timestamp", }); const temperature = await client.channels.create({ name: "weather_temperature", index: time.key, dataType: "float64", }); const task = await client.tasks.create({ name: "Weather station read", rack: server.rack, type: "http_read", config: http.readConfigZ.parse({ device: server.key, rate: 1, endpoints: [ { method: "GET", path: "/api/data", fields: [{ pointer: "/temperature", channel: temperature.key }], }, ], }), }); await task.start(); ``` ## Task options | Console label | Python field | Default | Notes | | ------------- | ---------------------- | ------- | ------------------------------------------------------------------------------------ | | Rate | `rate` | 1 Hz | Requests per second to each endpoint. One sample for each field. | | Data saving | `data_saving_disabled` | On | See [data saving](https://docs.synnaxlabs.com/reference/hardware/tasks#data-saving). | | Auto start | `auto_start` | Off | Starts the task each time the Driver starts. | An invalid field skips every field that shares its endpoint and index channel. Turn on **NaN fill** (`nan_fill_enabled`) to write `NaN` for an invalid float field instead. It still sends a warning. Invalid non-float fields always skip the group. The task has no [stream rate](https://docs.synnaxlabs.com/reference/hardware/tasks#read-tasks). Each response goes to the Core at once. ## Endpoint and field reference Each setting shows its Console label, then its Python field. An endpoint has these settings: | Setting | Default | Notes | | ------------------------------- | ------- | --------------------------------------------------------------- | | Method `method` | `GET` | `GET` or `POST` in the Console. Code accepts any method. | | Path `path` | | Added to the base address of the server. | | Query parameters `query_params` | None | A list of `{parameter, value}`. | | Headers `headers` | None | A list of `{name, value}`. | | Body `body` | Empty | Sent only with methods that take a body, as `application/json`. | A field has these settings: | Setting | Default | Notes | | -------------------------- | --------- | ----------------------------------------------- | | Pointer `pointer` | | The JSON pointer to the value. | | Data type `data_type` | `float64` | Used only when the Console creates the channel. | | Channel `channel` | | The channel that records the value. | | Enum mapping `enum_values` | None | Maps text labels in the response to numbers. | | Optional `optional` | Off | A missing value is normal for this field. | | Fill value `fill_value` | None | Written when an optional value is missing. | Turn on **Optional** for a value that can be missing as a normal state of the device, such as a sensor that is off. A value is missing when its pointer is absent, or when it is `null` or an empty string. On a string channel, an empty string is a real value. The task then writes the **Fill value** with no warning, so the other fields on its index channel keep writing. With no fill value, it writes `NaN`, so a non-float channel needs one. An index channel cannot be optional. A wrong pointer on an optional field also sends no warning. Other invalid values still warn. If a request fails, the task skips the field, so an outage does not look like a real reading. ## Troubleshooting * [index channel ... is referenced by fields on different endpoints](https://docs.synnaxlabs.com/reference/hardware/http/read-task#index-channel-is-referenced-by-fields-on-different-endpoints) * Cause Two endpoints record into channels that share one index channel. * Fix Give each endpoint its own index channel. * [Field ... not found in response from ...](https://docs.synnaxlabs.com/reference/hardware/http/read-task#field-not-found-in-response-from) * Cause The response has no value at the pointer. * Fix Check the pointer against a response from the server. Pointers start with `/` and are case sensitive. * [Falling behind poll rate](https://docs.synnaxlabs.com/reference/hardware/http/read-task#falling-behind-poll-rate) * Cause The requests take longer than one period. * Fix Lower **Rate**, or increase **Concurrent requests** on the [server](https://docs.synnaxlabs.com/reference/hardware/http/connect-server#connection-options). * [The task stopped while the server was down.](https://docs.synnaxlabs.com/reference/hardware/http/read-task#the-task-stopped-while-the-server-was-down) * Cause The task tries again for a long time, then stops. * Fix Start the task again when the server is back. For other problems, see [Troubleshoot hardware](https://docs.synnaxlabs.com/reference/hardware/troubleshooting).