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Thursday, November 21, 2024

Integrating xAPI with EJS Simulations: A Step-by-Step Guide

 first draft

Integrating xAPI with EJS Simulations: A Step-by-Step Guide

If you're an EJS (Easy JavaScript Simulations) user looking to enhance your simulations with xAPI (Experience API) capabilities, you've come to the right place. This guide will walk you through the process of integrating xAPI into your EJS simulations using a totalScore variable. We'll provide detailed instructions and code snippets to make the integration seamless.

What is xAPI?

xAPI is a specification that allows learning content and learning systems to communicate with each other about learner actions. It enables the collection of data about a wide range of experiences a learner has (both online and offline). By integrating xAPI into your EJS simulations, you can track user interactions, scores, and more.

Prerequisites

  • Basic Knowledge of EJS: Familiarity with creating and editing EJS simulations.
  • Understanding of JavaScript: Basic knowledge to modify and insert code.
  • xAPI Endpoint and Credentials: Access to an LRS (Learning Record Store) endpoint, along with authentication details.

Overview

We'll modify your EJS simulation to:

  1. Include the xAPI Wrapper library. sample file sample-html5corrected.zip
  2. Extract necessary parameters from the URL.
  3. Initialize the totalScore variable.
  4. Send the totalScore to the LRS whenever it changes.

Step-by-Step Integration

1. Include the xAPI Wrapper Library

First, you need to include the xAPI Wrapper library in your EJS simulation. This library simplifies sending xAPI statements to an LRS.

Action:

  • Download the xapiwrapper.min.js file from the official repository.
  • Place it in the same directory as your EJS simulation or host it on your server.

Insert the following script tag in your HTML file (usually in the <head> section):

html
<script src="xapiwrapper.min.js"></script>

2. Extract Parameters from the URL

We'll use URL parameters to pass the endpoint, authentication, actor, and activity ID to the simulation.

Add the following function to your EJS source code:

javascript
function getParameters() {
  var urlParams = new URLSearchParams(window.location.search);
  var endpoint = urlParams.get('endpoint') + "/";
  var auth = urlParams.get('auth');
  var actorObject = JSON.parse(urlParams.get('actor'));
  var actor = actorObject ? actorObject.id : null;
  var activity_id = urlParams.get('activityId');

  // Configure the xAPI Wrapper
  var conf = {
    "endpoint": endpoint,
    "auth": `Basic ${auth}`,
    "withCredentials": true
  };
  ADL.XAPIWrapper.changeConfig(conf);

  return {
    actor,
    activity_id
  };
}

Explanation:

  • Endpoint: The LRS endpoint where xAPI statements will be sent.
  • Auth: The Base64-encoded authentication string.
  • Actor: The user's identifier.
  • Activity ID: The unique identifier for the simulation activity.

3. Initialize the totalScore Variable

Ensure that your simulation has a totalScore variable that keeps track of the user's score.

Action:

  • Declare var totalScore = 0; at the beginning of your script if it's not already defined.
javascript
var totalScore = 0;

4. Send the totalScore to the LRS

We'll create a function that sends the current totalScore to the LRS whenever it changes.

Add the following function to your EJS source code:

javascript
function sendTotalScore() {
  try {
    var parameters = getParameters();
    var stateval = {
      score: totalScore
    };
    ADL.XAPIWrapper.sendState(
      parameters.activity_id,
      parameters.actor,
      null,
      stateval
    );
    console.log("Score Submitted: " + totalScore);
  } catch (err) {
    console.error("An error has occurred!", err);
  }
}

Explanation:

  • sendState(): Sends the state document (in this case, the totalScore) to the LRS.
  • Parameters:
    • Activity ID: From parameters.activity_id.
    • Actor: From parameters.actor.
    • Registration: null (optional, can be used if you have a registration ID).
    • State Data: An object containing the score.

5. Update totalScore and Trigger Data Sending

Whenever the totalScore changes within your simulation, ensure that sendTotalScore() is called.

Action:

  • Identify where totalScore is modified in your simulation.
  • After each modification, add a call to sendTotalScore().

Example:

javascript
function increaseScore(points) {
  totalScore += points;
  sendTotalScore();
}

function decreaseScore(points) {
  totalScore -= points;
  sendTotalScore();
}

6. Modify the Simulation's HTML (Optional)

If you have interactive elements like buttons to adjust the score, ensure they call the appropriate functions.

Example HTML:

html
<button onclick="increaseScore(5)">+5</button>
<button onclick="decreaseScore(5)">-5</button>

7. Testing the Integration

Before deploying, test the integration to ensure data is being sent correctly.

Steps:

  1. Run the Simulation with URL Parameters:

    Append the necessary parameters to your simulation's URL:

    swift
    your_simulation.html?endpoint=YOUR_LRS_ENDPOINT&auth=BASE64_ENCODED_AUTH&actor=YOUR_ACTOR_JSON&activityId=YOUR_ACTIVITY_ID

    Example:

    perl
    your_simulation.html?endpoint=https://lrs.example.com/xapi/&auth=QWxhZGRpbjpPcGVuU2VzYW1l&actor={"id":"mailto:user@example.com"}&activityId=http://example.com/activities/simulation

  2. Interact with the Simulation:

    Perform actions that modify the totalScore.

  3. Check the LRS:

    Log in to your LRS and verify that the state documents are being received.

8. Handling Authentication Securely

For security, avoid exposing the authentication details in the URL in a production environment.

Recommendation:

  • Use server-side code to inject the auth parameter securely.
  • Consider implementing OAuth or another secure authentication method.

9. Advanced: Customize xAPI Statements

If you wish to send more detailed xAPI statements, you can customize them further.

Example of Sending an xAPI Statement:

javascript
function sendScoreStatement() {
  var parameters = getParameters();
  var statement = {
    "actor": {
      "mbox": parameters.actor
    },
    "verb": {
      "id": "http://adlnet.gov/expapi/verbs/scored",
      "display": { "en-US": "scored" }
    },
    "object": {
      "id": parameters.activity_id,
      "definition": {
        "name": { "en-US": "EJS Simulation" },
        "description": { "en-US": "An interactive EJS simulation." }
      },
      "objectType": "Activity"
    },
    "result": {
      "score": {
        "raw": totalScore
      }
    }
  };

  ADL.XAPIWrapper.sendStatement(statement, function(err, resp) {
    if (err) {
      console.error("Error sending statement:", err);
    } else {
      console.log("Statement sent:", resp);
    }
  });
}

Action:

  • Replace sendTotalScore() calls with sendScoreStatement() if you prefer sending statements over state documents.

Full Code Example

Here's how your EJS source code might look after integration:

javascript
<script src="xapiwrapper.min.js"></script>
<script>
  var totalScore = 0;

  function getParameters() {
    var urlParams = new URLSearchParams(window.location.search);
    var endpoint = urlParams.get('endpoint') + "/";
    var auth = urlParams.get('auth');
    var actorObject = JSON.parse(urlParams.get('actor'));
    var actor = actorObject ? actorObject.id : null;
    var activity_id = urlParams.get('activityId');

    var conf = {
      "endpoint": endpoint,
      "auth": `Basic ${auth}`,
      "withCredentials": true
    };
    ADL.XAPIWrapper.changeConfig(conf);

    return {
      actor,
      activity_id
    };
  }

  function sendTotalScore() {
    try {
      var parameters = getParameters();
      var stateval = {
        score: totalScore
      };
      ADL.XAPIWrapper.sendState(
        parameters.activity_id,
        parameters.actor,
        null,
        stateval
      );
      console.log("Score Submitted: " + totalScore);
    } catch (err) {
      console.error("An error has occurred!", err);
    }
  }

  function increaseScore(points) {
    totalScore += points;
    sendTotalScore();
  }

  function decreaseScore(points) {
    totalScore -= points;
    sendTotalScore();
  }
</script>

Conclusion

By following this guide, you can integrate xAPI into your EJS simulations, allowing you to track and store user interactions and scores in an LRS. This enhances the learning experience by enabling data-driven insights and personalized feedback.

Remember:

  • Always test your integration thoroughly.
  • Secure your authentication details.
  • Explore xAPI's capabilities to enrich your simulations further.

References:

Happy simulating!


Analysis of the code

The provided code is a simple web application designed to interact with the SLS (let's assume SLS stands for "Sample Learning System" or similar) by sending user interaction data to it. The key purpose of this application is to capture user inputs (like score adjustments) and send this data to SLS's new interactive response item type using the xAPI (Experience API) standard.

Here's a detailed explanation of how the code works to send data to SLS's new interactive response item type:

Overview

  • HTML Structure (index.html): The HTML file sets up the web page with buttons that the user can click to adjust a score value. It also includes sections to display developer info, cookies, and results.

  • JavaScript Logic (index.js): This script handles the logic of capturing user interactions, updating the score, and sending the data to SLS using the xAPIWrapper library.

  • xAPIWrapper Library (xapiwrapper.min.js): This is a JavaScript library that simplifies interactions with Learning Record Stores (LRS) using the xAPI standard.

Step-by-Step Explanation

1. Loading Necessary Scripts

html
<script src="xapiwrapper.min.js"></script>
<script src="index.js" defer></script>
  • xAPIWrapper Library: Provides functions to send xAPI statements to an LRS.
  • Custom Script (index.js): Contains the logic to handle user interactions and data submission.

2. Capturing URL Parameters

javascript
function getParameters() {
  var urlParams = new URLSearchParams(window.location.search);
  var endpoint = urlParams.get('endpoint') + "/";
  var auth = urlParams.get('auth');
  var actorObject = JSON.parse(urlParams.get('actor')); // JSON decoded
  var actor = actorObject ? actorObject.id : null;
  var activity_id = urlParams.get('activityId');

  // Displaying developer info on the page
  document.querySelector("#cookieId").innerText = "Cookie: " + auth;
  document.querySelector("#questionId").innerText = "QuestionId: " + activity_id;
  document.querySelector("#userId").innerText = "UserId: " + actor;

  // Configuring the xAPI Wrapper
  var conf = {
    "endpoint": endpoint,
    "auth": `Basic ${auth}`,
    "withCredentials": true
  };
  ADL.XAPIWrapper.changeConfig(conf);

  return { actor, activity_id };
}
  • Purpose: Extracts necessary parameters from the URL to configure the xAPI wrapper and identify the user and activity.
  • Parameters Captured:
    • Endpoint: The LRS endpoint where data will be sent.
    • Auth: Authentication token for secure communication.
    • Actor: Represents the user interacting with the application.
    • Activity ID: Identifies the specific activity or question in SLS.

3. Initializing and Updating the Score

javascript
var totalScore = 0;
  • Purpose: Initializes a variable to keep track of the user's total score.

4. Handling User Interactions

html
<button onclick="sendState(5)">+5</button>
<!-- Other buttons with different values -->
<button onclick="sendState('randomText')">randomText</button>
  • Purpose: When a user clicks a button, it calls the sendState function with a specific value (positive or negative numbers, or 'randomText').

5. Updating the Score and Sending Data

javascript
function sendState(answer){
  if (totalScore === 'randomText'){
    totalScore = 0;
  }
  if(answer === 'randomText'){
    totalScore = 'randomText';
  } else {
    totalScore = totalScore + answer;
  }

  try {
    var parameters = getParameters();
    var stateval = {
      score: totalScore
    };
    ADL.XAPIWrapper.sendState(
      "http://adlnet.gov/expapi/activities/question/" + parameters.activity_id,
      {"mbox":"mailto:tom@example.com"},
      parameters.actor,
      null,
      stateval
    );
    document.querySelector("#result").innerText = "Score Submitted: " + totalScore;
  } catch (err) {
    console.error("An error has occurred!", err);
    document.querySelector("#result").innerText = "Error has occurred: " + err;
  }
}

  • Updating the Score:

    • If totalScore is 'randomText', reset it to 0.
    • If answer is 'randomText', set totalScore to 'randomText'.
    • Otherwise, adjust totalScore by adding the answer value.

  • Sending Data to SLS:

    • Retrieve Parameters: Calls getParameters() to get the latest configuration.
    • Prepare State Data: Creates an object stateval containing the current score.
    • Send State Data:
      • Uses ADL.XAPIWrapper.sendState() to send the state data to the LRS.
      • Parameters:
        • Activity ID: Constructs a URL identifying the activity/question.
        • Agent: Represents the user (hardcoded here as "mailto:tom@example.com" for demonstration purposes).
        • Registration: Uses the actor from the URL parameters.
        • State ID: null (could be used to specify a particular state document).
        • State Data: The stateval object containing the score.

  • Updating the UI:

    • On success, displays "Score Submitted: " along with the current totalScore.
    • On error, logs the error and displays an error message on the page.

6. Configuring the xAPI Wrapper

javascript
var conf = {
  "endpoint": endpoint,
  "auth": `Basic ${auth}`,
  "withCredentials": true
};
ADL.XAPIWrapper.changeConfig(conf);
  • Purpose: Sets up the xAPI wrapper with the endpoint and authentication details so that it can communicate with the LRS securely.

How It Integrates with SLS's New Interactive Response Item Type

  • Interactivity: The application provides interactive elements (buttons) that simulate user responses or score adjustments.

  • Data Capture: Each interaction updates the totalScore and prepares it to be sent as part of the state data.

  • xAPI Communication: By using the xAPI standard and the sendState function, the application sends the user's state (current score) to the SLS's LRS.

  • Activity Identification: The activity_id ensures that the data is associated with the correct activity or question within SLS.

  • User Identification: The actor parameter links the state data to the specific user, enabling SLS to track individual user responses.

Important Considerations

  • Authentication and Security: The auth parameter should be securely handled. In a production environment, it should not be exposed in the URL or client-side scripts.

  • Agent Representation: The agent is currently hardcoded as {"mbox":"mailto:tom@example.com"}. In a real-world scenario, this should dynamically represent the actual user's email or unique identifier.

  • Error Handling: The code includes basic error handling to catch and display errors that may occur during the data submission process.

  • Extensibility: The application can be extended to handle more complex interactions or additional data types as required by SLS's new interactive response item type.

Summary

  • The application captures user interactions through button clicks.
  • It updates a totalScore based on these interactions.
  • It sends the updated score to SLS using the xAPI standard via the sendState function.
  • The xAPI wrapper handles the communication with the LRS at the specified endpoint.
  • The use of URL parameters allows dynamic configuration and integration with SLS.

By following this flow, the application effectively sends data to SLS's new interactive response item type, allowing SLS to record and process user responses in a standardized format.

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