Adding Activities to Your Flow¶

Activities are the individual steps in a business process flow. They are the building blocks of the flow. We will use the following activities in our flow:

ExtractContentFromUrlAsync: Extracts the content from a URL
CreateTextReportAsync: Creates a text report from the content
SendEmailReportAsync: Sends the text report to the recipient

Temporal Workflows and Activities¶

Temporal workflows have an important constraint: they cannot perform I/O operations directly. This means you cannot make HTTP requests, read files, or perform any other external operations directly within a workflow. This restriction exists because workflows must be deterministic - they must produce the same sequence of commands when replayed, regardless of when they are executed.

Instead, all I/O operations must be performed through activities. Activities are the building blocks that handle all external interactions and I/O operations. They can:

Make HTTP requests
Read/write files
Send emails
Interact with databases
Perform any other external operations

This separation ensures that workflows remain deterministic while still allowing your application to interact with the outside world through activities.

Writing the Activity Code¶

Create a new file NewsActivities.cs and add the following code:

NewsActivities.cs >

using Temporalio.Activities;

interface INewsActivities
{
    [Activity]
    Task<string> ExtractContentFromUrlAsync(string url);
    [Activity]
    Task<string> CreateTextReportAsync(string content);
    [Activity]
    Task SendEmailReportAsync(string reportText, string recipientEmail = "recipient@example.com");
}

public class NewsActivities : INewsActivities
{


    public Task<string> ExtractContentFromUrlAsync(string url)
    {
        Console.WriteLine($"Extracting content from URL: {url}");
        // Dummy implementation - would actually call a service to extract content
        return Task.FromResult($"Extracted content from {url}");
    }

    public Task<string> CreateTextReportAsync(string content)
    {
        Console.WriteLine($"Creating text report from content: {content.Substring(0, Math.Min(50, content.Length))}");
        // Dummy implementation - would actually format the content into a report
        string reportText = $"NEWS REPORT\n\nDate: {DateTime.Now}\n\nCONTENT:\n{content}\n\nEND OF REPORT";
        Console.WriteLine("Text report created successfully");
        return Task.FromResult(reportText);
    }

    public Task SendEmailReportAsync(string reportText, string recipientEmail = "recipient@example.com")
    {
        Console.WriteLine($"Sending email with text report to {recipientEmail}");
        Console.WriteLine($"Report length: {reportText.Length} characters");
        // Dummy implementation - would actually send an email with the report text
        return Task.CompletedTask;
    }
}

Calling the Activities from the Flow¶

Use Temporal.io Workflow.ExecuteActivityAsync to call the above activities from the flow.

NewsReportFlow.cs >

using Microsoft.Extensions.Logging;
using Temporalio.Workflows;
using XiansAi.Flow;

[Workflow("News Report Flow")]
public class NewsReportFlow : FlowBase
{
    private readonly ActivityOptions _activityOptions = new()
    {
        ScheduleToCloseTimeout = TimeSpan.FromMinutes(5)
    };

    [WorkflowRun]
    public async Task<string> Run(string newsUrl, string recipientEmail)
    {
        Workflow.Logger.LogInformation("Starting News Report Flow for URL: {Url}", newsUrl);

        // Step 1: Extract content from the URL
        var content = await Workflow.ExecuteActivityAsync(
            (INewsActivities act) => act.ExtractContentFromUrlAsync(newsUrl), _activityOptions);

        Workflow.Logger.LogInformation("Content extracted successfully");

        // Step 2: Create a text report from the content
        var reportText = await Workflow.ExecuteActivityAsync(
            (INewsActivities act) => act.CreateTextReportAsync(content), _activityOptions);

        Workflow.Logger.LogInformation("Text report created successfully");

        // Step 3: Send an email with the text report
        await Workflow.ExecuteActivityAsync(
            (INewsActivities act) => act.SendEmailReportAsync(reportText, recipientEmail), _activityOptions);

        Workflow.Logger.LogInformation("Email sent successfully to: {RecipientEmail}", recipientEmail);

        return reportText;
    }
}

Adding the Activities to the Flow¶

Update Program.cs to include the activities:

Program.cs >

using XiansAi.Flow;
using DotNetEnv;

// Load the environment variables from the .env file
Env.Load();

// name your agent
var agent = new Agent("News Reader Agent");

var flow = agent.AddFlow<NewsReportFlow>();
flow.AddActivities<INewsActivities, NewsActivities>();

var bot = agent.AddBot<NewsReaderBot>();
bot.AddCapabilities(typeof(Capabilities));

await agent.RunAsync();

Running the Flow¶

Now you can run the flow again to see the activities in action.

dotnet run

Now on the portal, navigate to Agent Definitions and Activate a flow. Then observe the workflow getting executed under Agent Runs tab.