Class HttpDependency

Namespace

Cuemon.Net.Http

Assembly

Cuemon.Net.dll

Provides a way to monitor any changes occurred to one or more URI resources while notifying subscribing objects.

public class HttpDependency : Dependency, IDependency

Inheritance

object

Dependency

HttpDependency

Implements

IDependency

Inherited Members

Dependency.DependencyChanged

Dependency.BreakTieOnChanged

Dependency.UtcLastModified

Dependency.HasChanged

Dependency.SetUtcLastModified(DateTime)

Dependency.OnDependencyChangedRaised(DependencyEventArgs)

Dependency.Start()

Dependency.StartAsync()

Dependency.OnWatcherChanged(object, WatcherEventArgs)

Examples

HttpDependency wraps an HttpWatcher to monitor an HTTP resource for changes, detecting modifications via ETag and Last-Modified headers. This example creates a Lazy<HttpWatcher> that monitors https://example.com/api/status with HEAD requests at 30-second intervals, then constructs an HttpDependency from the factory and subscribes to the DependencyChanged event. Key steps include calling StartAsync to begin monitoring and handling the DependencyChanged event to react to changes. Console output prints the UTC timestamp when a resource change is detected.

using System;
using System.Net.Http;
using System.Threading.Tasks;
using Cuemon.Net.Http;

namespace MyApp.Net
{
    public class HttpDependencyExample
    {
        public async Task DemonstrateAsync()
        {
            // Create an HttpWatcher that monitors changes to a URI resource
            var watcherFactory = new Lazy<HttpWatcher>(() =>
            {
                var location = new Uri("https://example.com/api/status");
                return new HttpWatcher(location, o =>
                {
                    o.ReadResponseBody = false; // use HEAD requests (checks ETag/Last-Modified)
                    o.Period = TimeSpan.FromSeconds(30);
                });
            });

            // Create a dependency that wraps the watcher
            var dependency = new HttpDependency(watcherFactory);

            // Subscribe to change notifications
            dependency.DependencyChanged += (sender, args) =>
            {
                Console.WriteLine($"Resource changed at: {args.UtcLastModified}");
            };

            // Start monitoring
            await dependency.StartAsync();

            // The watcher will poll the URI every 30 seconds
            // and raise DependencyChanged when a change is detected

            Console.WriteLine("Monitoring started. Press any key to stop...");
            Console.ReadKey();
        }
    }
}

Constructors

HttpDependency(IEnumerable<Lazy<HttpWatcher>>, bool)

Initializes a new instance of the HttpDependency class.

public HttpDependency(IEnumerable<Lazy<HttpWatcher>> lazyFileWatchers, bool breakTieOnChanged = false)

Parameters

lazyFileWatchers IEnumerable<Lazy<HttpWatcher>>

The HttpWatcher sequence to associate with this dependency.

breakTieOnChanged bool

if set to true all HttpWatcher instances is disassociated with this dependency after first notification of changed.

Remarks

The sequence of HttpWatcher initializations is deferred until StartAsync() is invoked.

HttpDependency(Lazy<HttpWatcher>, bool)

Initializes a new instance of the HttpDependency class.

public HttpDependency(Lazy<HttpWatcher> lazyFileWatcher, bool breakTieOnChanged = false)

Parameters

lazyFileWatcher Lazy<HttpWatcher>

The HttpWatcher to associate with this dependency.

breakTieOnChanged bool

if set to true all HttpWatcher instances is disassociated with this dependency after first notification of changed.

Remarks

The HttpWatcher initialization is deferred until StartAsync() is invoked.

Exceptions

ArgumentNullException

lazyFileWatcher cannot be null.

See Also

Dependency