Querying Task Status and Output

Fetching task status from the API

Once a task, either one from the Code Editor or a repository Task, has been accepted, you can use its TaskID to query the status of the task from the API by making a GET request to /tasks/{taskID}. The Signaloid Cloud Compute Engine returns the Task status in the Status field of the response object. You should continue to poll the API until the task status is in a terminal state; i.e., either Completed, Cancelled, or Stopped.

TypeScript

The code snippet below shows how to fetch the status of the task from the API using the axios library.

  interface TaskAPIResponse {
    data: {
      Status: string;
      // Add other properties here
    };
  }

  let taskID = taskPostResponse.data.TaskID;
  let taskStatus = taskPostResponse.data.Status;
  let retryCount = 0;
  let retryDelay = 2000;
  let taskStdout: string;
  const maxRetryDelay = 30000;

  console.log("Waiting for the task to finish...");
  await getTaskStatus(taskID);

  // Helper functions for fetching task status with backoff
  async function getTaskStatus(taskID: string) {
    try {
      // get task data from API
      const response = await signaloidClient.get(`/tasks/${taskID}`);
      taskAPIResponseHandler(response);
    } catch (error) {
      console.log("Error:", error);
    }
  }

  async function taskAPIResponseHandler(response: TaskAPIResponse) {
    if ("Status" in response.data) {
      taskStatus = response.data.Status;
      console.log(`...task status : ${taskStatus}`);
    } else {
      throw new Error("Task status not found in response");
    }

    if (["Completed", "Cancelled", "Stopped"].includes(taskStatus)) {
      // task is in a terminal state
      console.log(`Task in terminal state : ${taskStatus}. Can fetch task outputs.`);
      await getTaskOutputs(taskID); // `getTaskOutputs` is defined below.
    } else {
      // task is not in a terminal state. retry with delay
      retryCount += 1;
      retryDelay = Math.min(Math.pow(2, retryCount) * 1000, maxRetryDelay);
      console.log(`Task still active : ${taskStatus}. Waiting for ${retryDelay}ms and retying...`);
      setTimeout(() => {
        getTaskStatus(taskID);
      }, retryDelay);
    }
  }

cURL

The code snippet below shows how to fetch the status of the task from the API using curl.

# The following calls to the Signaloid API check whether your task has completed its execution.
# Delay for consequtive calls to the API.
delayForAPIPolling=2

# The following call to the Signaloid API gets back the Task status.
# The call queries the `tasks` endpoint using the Task ID. The output
# is redirected to the `jq` utility to retrieve the `Status` field.
taskStatus=$(curl -s --request GET --location https://api.signaloid.io/tasks/$TaskID \
	--header "Authorization: $signaloidAPIKey" \
	| jq -r '.Status')

while [ "$taskStatus" != "Completed" ] && [ "$taskStatus" != "Cancelled" ] && [ "$taskStatus" != "Stopped" ];
do
	echo "Specified task is still in progress. Waiting."
	sleep $delayForAPIPolling
	# The following call to the Signaloid API gets back the Task status.
	taskStatus=$(curl -s --request GET --location https://api.signaloid.io/tasks/$TaskID \
		--header "Authorization: $signaloidAPIKey" \
		| jq -r '.Status')
done

echo "Task "$TaskID" completed with status: \""$taskStatus"\""

Retrieving task outputs from the API

Once the task is in a terminal state, you can retrieve the outputs of the task from the API by making a GET request to /tasks/{taskID}/outputs.

TypeScript

The code snippet below shows an implementation of the getTaskOutputs placeholder function referred to in the previous step that will fetch the outputs of the task from the API using the axios library.

  // Helper function for fetching task output
  async function getTaskOutputs(taskID: string) {
    console.log("Fetching task outputs...");
    try {
      // get task data from API
      const taskOutputsResponse = await signaloidClient.get(`/tasks/${taskID}/outputs?sanitized=false`);
      if (taskOutputsResponse.data.Stdout) {
        const outputStream = await axios.get(taskOutputsResponse.data.Stdout);
        taskStdout = outputStream.data;
        console.log(`Task Stdout: \n${taskStdout}`);
      }
    } catch (error) {
      console.log("Error:", error);
    }
  }

cURL

The code snippet below shows how to get the standard output (stdout) of the task from the API using curl.

# Use this API endpoint to get the Task output using a TaskID
taskOutputsEndpointResponse=$(curl --request GET \
	--location 'https://api.signaloid.io/tasks/'$TaskID'/outputs?sanitized=false' \
	--header "Authorization: $signaloidAPIKey")

# The tasks outputs endpoint contains multiple fields. You can use the following to get the field corresponding to `stdout`
taskStdout=$(echo $taskOutputsEndpointResponse | jq -r '.Stdout')
if [ "$taskStdout" == "null" ];
then
	errorMessage=$(echo $taskOutputsEndpointResponse | jq -r '.error')
	echo "Task outputs endpoint returned error message: \""$errorMessage"\""
	exit 1
else
	# Use curl to download and print the Task output
	curl "$taskStdout"
fi

TypeScript

The code snippet below shows how to get the first compressed chunk of standard output (stdout) of the task from the API using the axios library.

  import pako from "pako";
  // Helper function for fetching task output
  async function getTaskOutputsChunks(taskID: string) {
    console.log("Fetching task outputs...");
    try {
      // get task data from API
      const taskOutputsResponse = await signaloidClient.get(`/tasks/${taskID}/outputs`);
      if (taskOutputsResponse.data.StdoutChunks.length) {
        const response = await axios.get(taskOutputsResponse.data.StdoutChunks.stdoutChunks[0], {
          responseType: "arraybuffer", // Ensure you're fetching the data as a binary array buffer
        });
        const decompressed = pako.inflate(new Uint8Array(response.data)); // Decompress to get Uint8Array
        const decompressedStdOutChunk = new TextDecoder("utf-8").decode(decompressed);
        console.log(`Task Stdout First Chunk: \n${decompressedStdOutChunk}`);
      }
    } catch (error) {
      console.log("Error :>> ", error);
    }
  }

The task outputs response will have the following shape:

{
  "data": {
    "Stdout": "...",
    "Stderr": "...",
    "Build": "...",
    "StdoutChunks": "..."
  },
  "status": 200,
  "statusText": "Ok"
}

Each key of the data key in this object will be a URL to the file containing the output of the task from corresponding output stream. The Build stream contains the build output of the application. The Stdout and Stderr streams will not be available for tasks that failed to build.

Output of an uncertainty-tracking (UT) C0 or C0 Pro core

For each floating-point variable that you print in the stdout or stderr of your application, the Signaloid Cloud Compute Engine also prints the distributional information of the variable in the form of the Uncertainty Hexadecimal (“Ux”) data format. You can instruct the Signaloid Cloud Compute Engine to avoid printing the Ux data format by using the particle %P modifier when printing floating-point values. You can feed the Ux data format in other Signaloid Cloud Compute Engine endpoints, e.g., for sampling or plotting the associated distributional information.

For example, the file containing the output of the Stdout stream should contain text similar to the following:

Alloy strength (σc)     = 6.5E+02Ux0400000000000010004086182D94915B0500000040405417BDA0AC9B250188F2CF171EF8E0405B6757D802080F01AA44F4C3CE568040605E6EDBDD0AA702040E39582CDA604062549EC48E6D54020049C5A87763C040640CD2FABF29F1022269E95ECAD3204065A2D65BCAA361022F84B7CF914A00406727AAD835034E022C821EA01770804068ABA18A9EE5DC0233ECFFBF89D480406A1A71BCBA96AA021309E840103300406B7F731CA16D9D023008CD59709980406CEA500FE458BE0216D7D76EA0CD60406E4625AE7BBFB2020894010FDC81C0406FAE24D94A8ED3022E84F454DD4DC0407091C94C35C8CD021F4E4D67909B6040714ADA1EC604E7020934E1AD5155C04072073BE9D7C24002380BAD55143FA04072C877D44122360219C4964B2DEDC040738B6D24BC0CB3023624DCF65BCEE0407468DAE5A46FD102348E828B9D4040407539A19D9F821B022AA3BD78F283204076167CFC01CEE8021EAFD30F8D4F804076FEEB22272855022FD02B048E12004077F8D99DA024F4021FBFEDEFCF39E0407911F818FF1163024B9A05B43447E0407A44B81557DD0B020AC5B8BAED2980407B8E07EC978C0101FD737CB6050FB0407D0E31FBF77D3601C9D92AB5DDC9C0407EE3846D4850FB01B43118EE7BDFA040807F8E3216120901A47793B2ACECE04081B8804AECCFDC01C654E526CDF2404082F417B2B6626101E413F66F2E0BE040840D1DBA88D35701CEBE2AB6CD70C0408523C73B05C890021438342616F4C04086298D67225EC6020013D66E8E76C040871E9A2AA378710230A511292A23804087F9B09002581701D759C8D68904604088C7B205CAB0AB021E0FB3C15CA2804089965E2291CDE7021DA9F67BE6FF20408A698B9837CD60024A1C4F46724F80408B36CFF7F80044020D42C0D2B48740408BF982A4EA135402177F700F0C7260408CB56FF95BF061020DC70452029680408D7F1051A80FE2024B9180F3388240408E4C026194A08602254479374CCCE0408F11E4C8CC147E0233CFEF28534EA0408FE9FE2B2171910259E3427835FB0040905B657856A26A01FFD69C48900AE04090C529DBCEB142023ECCA96C147E40409131C144D49BCE01F9712FECEDF4E040919F70F107944E022F3F8EEA118040409217F42CBAA75902099DCD5C4478804092925B872D66D202148613EE120C60409321859F3242A901CDABBE98092FD04093B3D8892B772B01C170077C3F2280409447C6AFCE86FE01B05B17344BD5E04094E93148DE8CB301DE50DA37D36D0040959763034D4D0E01C5164F700D8CA040965B0C13AC387B01FD2C401BCDB7E04097247B8B31A85E01A2730BD05949004097FDF4B706DFC001E33E60D12A90D04098F3FDDF43582D01BA699075EEE5D0409A0E41FFBE591C01CABF57DA2AF080409B90AD8877191901BC28A982C0B7C0409E41771B832D090117EFFC3F286460 MPa

(Note that Axios will automatically parse the text to get "un-escape" special characters in the output.)

Output of a C0 or C0 Pro Reference core

For each floating-point variable that you print in the stdout or stderr of your application, the Signaloid Cloud Compute Engine also prints a ValueID field which is a reference to the distributional data. You can feed this ValueID in other Signaloid Cloud Compute Engine endpoints, e.g., for sampling or plotting the associated distributional information.

For example, the file containing the output of the Stdout stream should contain text similar to the following:

Alloy strength (σc)     = 4.5E+02<ValueID>val_80e5b9ed7a2a530eb1d15bc32ef5b337</ValueID> MPa

(Note that Axios will automatically parse the text to get "un-escape" special characters in the output.)