Delivering Live Streaming with Azure Media Services

Overview

Microsoft Azure Media Services offers APIs that send requests to Media Services to start operations (for example: create, start, stop, or delete a channel). These operations are long-running.

The Media Services .NET SDK provides APIs that send the request and wait for the operation to complete (internally, the APIs are polling for operation progress at some intervals). For example, when you call channel.Start(), the method returns after the channel is started. You can also use the asynchronous version: await channel.StartAsync() (for information about Task-based Asynchronous Pattern, see TAP). APIs that send an operation request and then poll for the status until the operation is complete are called “polling methods”. These methods (especially the Async version) are recommended for rich client applications and/or stateful services.

There are scenarios where an application cannot wait for a long running http request and wants to poll for the operation progress manually. A typical example would be a browser interacting with a stateless web service: when the browser requests to create a channel, the web service initiates a long running operation and returns the operation ID to the browser. The browser could then ask the web service to get the operation status based on the ID. The Media Services .NET SDK provides APIs that are useful for this scenario. These APIs are called “non-polling methods”. The “non-polling methods” have the following naming pattern: SendOperationNameOperation (for example, SendCreateOperation). SendOperationNameOperation methods return the IOperation object; the returned object contains information that can be used to track the operation. The SendOperationNameOperationAsync methods return Task.

Currently, the following classes support non-polling methods: Channel, StreamingEndpoint, and Program.

To poll for the operation status, use the GetOperation method on the OperationBaseCollection class. Use the following intervals to check the operation status: for Channel and StreamingEndpoint operations, use 30 seconds; for Program operations, use 10 seconds.

Create and configure a Visual Studio project

Set up your development environment and populate the app.config file with connection information, as described in Media Services development with .NET.

Example

The following example defines a class called ChannelOperations. This class definition could be a starting point for your web service class definition. For simplicity, the following examples use the non-async versions of methods.

The example also shows how the client might use this class.

ChannelOperations class definition

using Microsoft.WindowsAzure.MediaServices.Client;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Net;

/// <summary> 
/// The ChannelOperations class only implements 
/// the Channel’s creation operation. 
/// </summary> 
public class ChannelOperations
{
    // Read values from the App.config file.
    private static readonly string _AADTenantDomain =
        ConfigurationManager.AppSettings["AMSAADTenantDomain"];
    private static readonly string _RESTAPIEndpoint =
        ConfigurationManager.AppSettings["AMSRESTAPIEndpoint"];
    private static readonly string _AMSClientId =
        ConfigurationManager.AppSettings["AMSClientId"];
    private static readonly string _AMSClientSecret =
        ConfigurationManager.AppSettings["AMSClientSecret"];

    // Field for service context.
    private static CloudMediaContext _context = null;

    public ChannelOperations()
    {
        AzureAdTokenCredentials tokenCredentials = 
            new AzureAdTokenCredentials(_AADTenantDomain,
                new AzureAdClientSymmetricKey(_AMSClientId, _AMSClientSecret),
                AzureEnvironments.AzureCloudEnvironment);

        var tokenProvider = new AzureAdTokenProvider(tokenCredentials);

        _context = new CloudMediaContext(new Uri(_RESTAPIEndpoint), tokenProvider);
    }

    /// <summary>  
    /// Initiates the creation of a new channel.  
    /// </summary>  
    /// <param name="channelName">Name to be given to the new channel</param>  
    /// <returns>  
    /// Operation Id for the long running operation being executed by Media Services. 
    /// Use this operation Id to poll for the channel creation status. 
    /// </returns> 
    public string StartChannelCreation(string channelName)
    {
        var operation = _context.Channels.SendCreateOperation(
            new ChannelCreationOptions
            {
                Name = channelName,
                Input = CreateChannelInput(),
                Preview = CreateChannelPreview(),
                Output = CreateChannelOutput()
            });

        return operation.Id;
    }

    /// <summary> 
    /// Checks if the operation has been completed. 
    /// If the operation succeeded, the created channel Id is returned in the out parameter.
    /// </summary> 
    /// <param name="operationId">The operation Id.</param> 
    /// <param name="channel">
    /// If the operation succeeded, 
    /// the created channel Id is returned in the out parameter.</param>
    /// <returns>Returns false if the operation is still in progress; otherwise, true.</returns> 
    public bool IsCompleted(string operationId, out string channelId)
    {
        IOperation operation = _context.Operations.GetOperation(operationId);
        bool completed = false;

        channelId = null;

        switch (operation.State)
        {
            case OperationState.Failed:
                // Handle the failure. 
                // For example, throw an exception. 
                // Use the following information in the exception: operationId, operation.ErrorMessage.
                break;
            case OperationState.Succeeded:
                completed = true;
                channelId = operation.TargetEntityId;
                break;
            case OperationState.InProgress:
                completed = false;
                break;
        }
        return completed;
    }

    private static ChannelInput CreateChannelInput()
    {
        return new ChannelInput
        {
            StreamingProtocol = StreamingProtocol.RTMP,
            AccessControl = new ChannelAccessControl
            {
                IPAllowList = new List<IPRange>
                    {
                        new IPRange
                        {
                            Name = "TestChannelInput001",
                            Address = IPAddress.Parse("0.0.0.0"),
                            SubnetPrefixLength = 0
                        }
                    }
            }
        };
    }

    private static ChannelPreview CreateChannelPreview()
    {
        return new ChannelPreview
        {
            AccessControl = new ChannelAccessControl
            {
                IPAllowList = new List<IPRange>
                    {
                        new IPRange
                        {
                            Name = "TestChannelPreview001",
                            Address = IPAddress.Parse("0.0.0.0"),
                            SubnetPrefixLength = 0
                        }
                    }
            }
        };
    }

    private static ChannelOutput CreateChannelOutput()
    {
        return new ChannelOutput
        {
            Hls = new ChannelOutputHls { FragmentsPerSegment = 1 }
        };
    }
}

The client code

ChannelOperations channelOperations = new ChannelOperations();
string opId = channelOperations.StartChannelCreation("MyChannel001");

string channelId = null;
bool isCompleted = false;

while (isCompleted == false)
{
    System.Threading.Thread.Sleep(TimeSpan.FromSeconds(30));
    isCompleted = channelOperations.IsCompleted(opId, out channelId);
}

// If we got here, we should have the newly created channel id.
Console.WriteLine(channelId);

Media Services learning paths

Read about the Azure Media Services learning paths:

Provide feedback

Use the User Voice forum to provide feedback and make suggestions on how to improve Azure Media Services. You also can go directly to one of the following categories: