Create Background-Workers.md

docs/en/Background-Workers.md

@@ -0,0 +1,83 @@
+# Background Workers
+
+## Introduction
+
+Background workers are used to execute some tasks in the background. You may need background workers for several reasons.
+
+### Create a Background Worker
+
+A background worker is a class that derives from the `AsyncPeriodicBackgroundWorkerBase` or `PeriodicBackgroundWorkerBase` class. Both base classes are derived from `ISingletonDependency`.
+
+### Status Checker
+This example is used to simple check remote application status. Just suppose that, we want to check and store some web applications are running or not? 
+
+````csharp
+public class AppStatusService : ITransientDependency
+{
+    .
+    .
+    public void CheckAppStatus()
+    {
+        var ping = new System.Net.NetworkInformation.Ping();
+
+        var result = ping.Send("www.google.com");
+
+        // save the result
+    }
+    .
+    .
+}
+````
+
+Then create a background worker class that derived from the `PeriodicBackgroundWorkerBase`:
+
+````csharp
+.
+.
+using Volo.Abp.BackgroundWorkers;
+
+namespace Volo.Www.Application
+{
+    public class AppStatusCheckingWorker : PeriodicBackgroundWorkerBase
+    {
+        private readonly IAppStatusService _appStatusService;
+
+        public AppStatusCheckingWorker(
+            AbpTimer timer,
+            IServiceScopeFactory scopeFactory, 
+            IAppStatusService appStatusService)
+            : base(timer, scopeFactory)
+        {
+            _appStatusService = appStatusService;
+            Timer.Period = 10_000; // 10 secs
+        }
+
+        protected override void DoWork(PeriodicBackgroundWorkerContext workerContext)
+        {
+            _appStatusService.CheckAppStatus();
+        }
+    }
+}
+````
+
+This worker will call DoWorkAsync() method every 10 seconds while the application is running.
+
+### Configuration
+
+Add your BackgroundWorker at `OnApplicationInitialization` in your [module class](Module-Development-Basics.md). The example below initialize the background worker to your module:
+
+````csharp
+using Volo.Abp.BackgroundWorkers;
+
+public class MyModule : AbpModule
+{
+    public override void OnApplicationInitialization(ApplicationInitializationContext context)
+        {
+            context.ServiceProvider
+                .GetRequiredService<IBackgroundWorkerManager>()
+                .Add(
+                    context.ServiceProvider.GetRequiredService<AppStatusCheckingWorker>()
+                );
+        }
+}
+````