const timeseries = await client.timeseries.retrieve([
  { id: 123 },
  { externalId: 'abc' }
]);

res = client.time_series.retrieve(id=1)

res = client.time_series.retrieve(external_id="1")
res = client.time_series.retrieve_multiple(ids=[1, 2, 3])

res = client.time_series.retrieve_multiple(external_ids=["abc", "def"])

List<Item> byExternalIds = List.of(Item.newBuilder().setExternalId("10").build()); 
List<TimeseriesMetadata> retrievedAssets = client.timeseries().retrieve(byExternalIds);// by list of items 
List<TimeseriesMetadata> retrievedAssets = client.timeseries().retrieve("10", "20");// by varargs of String 

List<Item> byInternalIds = List.of(Item.newBuilder().setId(10).build()); 
List<TimeseriesMetadata> retrievedAssets = client.timeseries().retrieve(byInternalIds);// by list of items 
List<TimeseriesMetadata> retrievedAssets = client.timeseries().retrieve(10, 20);// by varargs of Long

curl --request POST \
  --url https://{cluster}.cognitedata.com/api/v1/projects/{project}/timeseries/byids \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "items": [
    {
      "id": 4503599627370496
    }
  ],
  "ignoreUnknownIds": false
}
'

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://{cluster}.cognitedata.com/api/v1/projects/{project}/timeseries/byids",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'items' => [
        [
                'id' => 4503599627370496
        ]
    ],
    'ignoreUnknownIds' => false
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://{cluster}.cognitedata.com/api/v1/projects/{project}/timeseries/byids"

	payload := strings.NewReader("{\n  \"items\": [\n    {\n      \"id\": 4503599627370496\n    }\n  ],\n  \"ignoreUnknownIds\": false\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

require 'uri'
require 'net/http'

url = URI("https://{cluster}.cognitedata.com/api/v1/projects/{project}/timeseries/byids")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"items\": [\n    {\n      \"id\": 4503599627370496\n    }\n  ],\n  \"ignoreUnknownIds\": false\n}"

response = http.request(request)
puts response.read_body

{
  "items": [
    {
      "id": 4503599627370496,
      "isString": true,
      "type": "<string>",
      "isStep": true,
      "createdTime": 1730204346000,
      "lastUpdatedTime": 1730204346000,
      "externalId": "<string>",
      "instanceId": {
        "space": "<string>",
        "externalId": "<string>"
      },
      "name": "<string>",
      "metadata": {},
      "unit": "<string>",
      "unitExternalId": "<string>",
      "assetId": 4503599627370496,
      "description": "<string>",
      "securityCategories": [
        123
      ],
      "dataSetId": 4503599627370496
    }
  ]
}

{
  "error": {
    "code": 400,
    "message": "<string>",
    "missing": [
      {
        "id": 4503599627370496
      }
    ]
  }
}

{
  "error": {
    "code": 422,
    "message": "<string>",
    "duplicated": [
      {
        "id": 4503599627370496
      }
    ]
  }
}