Invoking FunctionGraph Event Function using API Calls¶

This section demonstrates how to call a FunctionGraph implemented in Node.js using API calls and AK/SK-based authentication.

For details on AK/SK-based authentication, see

AK/SK-based Authentication

in Identity and Access Management (IAM) API reference.

Prerequisites¶

For details on prerequisites, see: Prerequisites

Using AK/SK authentication for API calls¶

Using AK/SK authentication the requests have to be signed with the AK/SK (or for temporal credentials with SecurityAccessKey/SecurityKey/SecurityToken).

For request signing the otc-api-sign-sdk-nodejs can be used.

The SDK provides a method to sign the request with AK/SK or SecurityAccessKey/SecurityKey/SecurityToken.

Additional to the environment variables mentioned in the prerequisites, you also need to set the following environment variables for AK/SK authentication :

OTC_SDK_AK (Access Key with permission to invoke FunctionGraph)

OTC_SDK_SK (Secret Key corresponding to the Access Key)

Synchronous invocation using AK/SK¶

Following sample code demonstrates how to invoke a FunctionGraph event function synchronously using API calls with AK/SK authentication.

See Executing a Function Synchronously in FunctionGraph API reference for more details about synchronous invocation.

samples-doc/invoke-fg/src/invokeSync_AKSK.js¶

const https = require("https");
const { Signer, HttpRequest } = require("otc-api-sign-sdk-nodejs");
const path = require("path");

const region = process.env.OTC_SDK_REGION || "eu-de";

const fgEndpoint = `https://functiongraph.${region}.otc.t-systems.com`;
const projectId = process.env.OTC_SDK_PROJECT_ID;
const ak = process.env.OTC_SDK_AK;
const sk = process.env.OTC_SDK_SK;

const functionName = "nodejs-sample-invoke-function";
const functionVersion = "latest";
const functionApp = "default";

async function main() {
  const functionURN = `urn:fss:${region}:${projectId}:function:${functionApp}:${functionName}:${functionVersion}`;

  // Endpoint for synchronous invocation
  const invokeURI = `${fgEndpoint}/v2/${projectId}/fgs/functions/${functionURN}/invocations`;

  console.log("Invoke URI: ", invokeURI);

  // X-Cff-Log-Type:
  // "tail": 4KB logs will be returned
  // "": no logs will be returned
  const xCffLogType = "tail";

  // X-CFF-Request-Version:
  // "v0" response body in text format
  // "v1" response body in json format
  const xCffRequestVersion = "v1";

  // set body according to your function input
  const body = {
    key: "Hello T-Cloud Public World - SYNC",
  };

  // set request method
  const method = "POST";

  // set headers
  const headers = {
    "Content-Type": "application/json;charset=utf8",
    "Host": new URL(fgEndpoint).host,
    "X-Cff-Log-Type": xCffLogType,
    "X-CFF-Request-Version": xCffRequestVersion,
    "X-Project-Id": projectId,
  };

  // create HttpRequest instance
  const request = new HttpRequest(
    method,
    invokeURI,
    headers,
    JSON.stringify(body),
  );

  // create Signer instance and set AK/SK
  const signer = new Signer();
  signer.Key = ak;
  signer.Secret = sk;

  // sign the request
  const signedRequest = signer.Sign(request);

  // send the signed request
  const req = https.request(signedRequest, function (res) {
    res.setEncoding("utf8");

    let data = "";
    res.on("data", function (chunk) {
      data += chunk.toString();
    });

    res.on("end", function () {
      // output result
      console.log("Result: ", JSON.parse(data).result);

      // output logs
      console.log("Log: ", JSON.parse(data).log);
    });
  });

  req.on("error", function (e) {
    console.error("Error: ", e);
  });

  req.write(JSON.stringify(body));
  req.end();
}

main();

To execute the sample code, run the following command in the terminal in folder samples-doc/invoke-fg:

node src/invokeSync_AKSK.js

# or use npm script:
npm run invokeSync_AKSK

samples-doc/invoke-fg/src/invokeSyncFetch_AKSK.js¶

const { Signer, HttpRequest } = require("otc-api-sign-sdk-nodejs");

const region = process.env.OTC_SDK_REGION || "eu-de";

const fgEndpoint = `https://functiongraph.${region}.otc.t-systems.com`;
const projectId = process.env.OTC_SDK_PROJECT_ID;
const ak = process.env.OTC_SDK_AK;
const sk = process.env.OTC_SDK_SK;

const functionName = "nodejs-sample-invoke-function";
const functionVersion = "latest";
const functionApp = "default";

async function main() {
  const functionURN = `urn:fss:${region}:${projectId}:function:${functionApp}:${functionName}:${functionVersion}`;

  // Endpoint for synchronous invocation
  const invokeURI = `${fgEndpoint}/v2/${projectId}/fgs/functions/${functionURN}/invocations`;

  console.log("Invoke URI: ", invokeURI);

  // X-Cff-Log-Type:
  // "tail": 4KB logs will be returned
  // "": no logs will be returned
  const xCffLogType = "tail";

  // X-CFF-Request-Version:
  // "v0" response body in text format
  // "v1" response body in json format
  const xCffRequestVersion = "v1";

  // set body according to your function input
  const body = {
    key: "Hello T-Cloud Public World - SYNC",
  };

  const bodyText = JSON.stringify(body);

  // set request method
  const method = "POST";

  // set headers
  const headers = {
    "Content-Type": "application/json;charset=utf8",
    "Host": new URL(fgEndpoint).host,
    "X-Cff-Log-Type": xCffLogType,
    "X-CFF-Request-Version": xCffRequestVersion,
    "X-Project-Id": projectId,
  };

  // create HttpRequest instance
  const request = new HttpRequest(method, invokeURI, headers, bodyText);

  // create Signer instance and set AK/SK
  const signer = new Signer();
  signer.Key = ak;
  signer.Secret = sk;

  // sign the request
  const signedRequest = signer.Sign(request);

  // send signed request with Node.js fetch
  try {
    const response = await fetch(invokeURI, {
      method: signedRequest.method,
      headers: signedRequest.headers,
      body: bodyText,
    });

    const data = await response.json();

    if (!response.ok) {
      console.error("Error: ", data);
      return;
    }

    // output result
    console.log("Result: ", data.result);

    // output logs
    console.log("Log: ", data.log);
  } catch (error) {
    console.error("Error: ", error);
  }
}

main();

To execute the sample code, run the following command in the terminal in folder samples-doc/invoke-fg:

node src/invokeSyncFetch_AKSK.js

# or use npm script:
npm run invokeSyncFetch_AKSK

In both cases, you should see an output similar to the following in the terminal:

Sample output of synchronous invocation using AK/SK¶

Result:  {"statusCode":200,"headers":{"Content-Type":"application/json"},"isBase64Encoded":false,"body":"{\"key\":\"Hello World\"}"}
Log:  2026-03-17T10:13:22Z Start invoke request '960d089c-c812-4fe7-9997-a72f773e4bcb', version: latest
2026-03-17T10:13:22Z 960d089c-c812-4fe7-9997-a72f773e4bcb INFO Function name: nodejs-sample-invoke-function
2026-03-17T10:13:22Z 960d089c-c812-4fe7-9997-a72f773e4bcb INFO Key value from event: Hello World
2026-03-17T10:13:22Z Finish invoke request '960d089c-c812-4fe7-9997-a72f773e4bcb', duration: 2.049ms, billing duration: 3ms, memory used: 36.535MB, billing memory: 128MB, cpu used: 0.300U, storage used: 0.039MB

Asynchronous invocation using AK/SK¶

Following sample code demonstrates how to invoke a FunctionGraph event function asynchronously using API calls with AK/SK authentication.

See Executing a Function Asynchronously in FunctionGraph API reference for more details about asynchronous invocation.

samples-doc/invoke-fg/src/invokeASync_AKSK.js¶

const https = require("https");
const { Signer, HttpRequest } = require("otc-api-sign-sdk-nodejs");
const path = require("path");

const region = process.env.OTC_SDK_REGION || "eu-de";

const fgEndpoint = `https://functiongraph.${region}.otc.t-systems.com`;
const projectId = process.env.OTC_SDK_PROJECT_ID;
const ak = process.env.OTC_SDK_AK;
const sk = process.env.OTC_SDK_SK;

const functionName = "nodejs-sample-invoke-function";
const functionVersion = "latest";
const functionApp = "default";

async function main() {
  const functionURN = `urn:fss:${region}:${projectId}:function:${functionApp}:${functionName}:${functionVersion}`;

  // Endpoint for asynchronous invocation
  const invokeURI = `${fgEndpoint}/v2/${projectId}/fgs/functions/${functionURN}/invocations-async`;

  console.log("Invoke URI: ", invokeURI);

  // set body according to your function input
  const body = {
    key: "Hello T-Cloud Public World - ASYNC ",
  };

  // set request method
  const method = "POST";

  // set headers
  const headers = {
    "Content-Type": "application/json;charset=utf8",
    Host: new URL(fgEndpoint).host,
    "X-Project-Id": projectId,
  };

  // create HttpRequest instance
  const request = new HttpRequest(
    method,
    invokeURI,
    headers,
    JSON.stringify(body),
  );

  // create Signer instance and set AK/SK
  const signer = new Signer();
  signer.Key = ak;
  signer.Secret = sk;

  // sign the request
  const signedRequest = signer.Sign(request);

  // send the signed request
  const req = https.request(signedRequest, function (res) {
    res.setEncoding("utf8");

    let data = "";
    res.on("data", function (chunk) {
      data += chunk.toString();
    });

    res.on("end", function () {
      // output response
      console.log("Response: ", data);
    });
  });

  req.on("error", function (e) {
    console.error("Error: ", e);
  });

  req.write(JSON.stringify(body));
  req.end();
}

main();

To execute the sample code, run the following command in the terminal in folder samples-doc/invoke-fg:

node src/invokeASync_AKSK.js

# or use npm script:
npm run invokeASync_AKSK

samples-doc/invoke-fg/src/invokeASyncFetch_AKSK.js¶

const { Signer, HttpRequest } = require("otc-api-sign-sdk-nodejs");

const region = process.env.OTC_SDK_REGION || "eu-de";

const fgEndpoint = `https://functiongraph.${region}.otc.t-systems.com`;
const projectId = process.env.OTC_SDK_PROJECT_ID;
const ak = process.env.OTC_SDK_AK;
const sk = process.env.OTC_SDK_SK;

const functionName = "nodejs-sample-invoke-function";
const functionVersion = "latest";
const functionApp = "default";

async function main() {
  const functionURN = `urn:fss:${region}:${projectId}:function:${functionApp}:${functionName}:${functionVersion}`;

  // Endpoint for asynchronous invocation
  const invokeURI = `${fgEndpoint}/v2/${projectId}/fgs/functions/${functionURN}/invocations-async`;

  console.log("Invoke URI: ", invokeURI);

  // set body according to your function input
  const body = {
    key: "Hello T-Cloud Public World - ASYNC ",
  };

  const bodyText = JSON.stringify(body);

  // set request method
  const method = "POST";

  // set headers
  const headers = {
    "Content-Type": "application/json;charset=utf8",
    Host: new URL(fgEndpoint).host,
    "X-Project-Id": projectId,
  };

  // create HttpRequest instance
  const request = new HttpRequest(method, invokeURI, headers, bodyText);

  // create Signer instance and set AK/SK
  const signer = new Signer();
  signer.Key = ak;
  signer.Secret = sk;

  // sign the request
  const signedRequest = signer.Sign(request);

  // send signed request with Node.js fetch
  try {
    const response = await fetch(invokeURI, {
      method: signedRequest.method,
      headers: signedRequest.headers,
      body: bodyText,
    });

    const data = await response.text();

    if (!response.ok) {
      console.error("Error: ", data);
      return;
    }

    // output response
    console.log("Response: ", data);
  } catch (error) {
    console.error("Error: ", error);
  }
}

main();

To execute the sample code, run the following command in the terminal in folder samples-doc/invoke-fg:

node src/invokeASyncFetch_AKSK.js

# or use npm script:
npm run invokeASyncFetch_AKSK

In both cases, you should see an output similar to the following in the terminal:

Sample output of asynchronous invocation using AK/SK¶

Response:  {"request_id": "3d1a4f5a-b4e2-4429-80c8-3d82d2fe8791"}

last updated: 2026-05-07 12:49:22 UTC - commit: b33b3f65aa4809f3bbb42c38e0f31e3067f81d22