Eventhandler Toolbox

Eventhandler toolbox

Installation

To add the toolbox to a project, you add the package to the project.json :

"dependencies": {
    "Digipolis.Toolbox.Eventhandler":  "1.0.1"
 }

In Visual Studio you can also use the NuGet Package Manager to do this.

Configuration in Startup.ConfigureServices

The Event toolbox is registered in the ConfigureServices method of the Startup class.

There are 2 ways to configure the Event toolbox :

using a json config file
using code

Json config file

The path to the Json config file has to be given as argument to the AddEventHandler method :

  services.AddEventHandler(opt => opt.FileName = ConfigPath + "/eventhandlerconfig.json");

The Event toolbox will read the given section of the json file with the following structure :

{
  "EventHandler": {
    "Version": "1",
     "MessageVersion": "1",
     "AppId": "666",
     "AppName": "SampleApi",
     "InstanceId": "123",
     "InstanceName": "MySampleInstance",
     "EventEndpointUrl": "https://myendpoint.com",
     "EventEndpointNamespace": "EventNamespace",
     "EventEndpointApikey": "6546-6544-6464-6654",
     "EventEndpointOwnerkey": "dgpls",
     "HideEventHandlerErrors": true
   }
}

Code

You can also call the AddEventHandler method, passing in the needed options directly :

services.AddDataAccess<MyEntityContext>(opt => opt.Version = 1, (...) );

Registering service

public static IServiceCollection AddBusinessServices(this IServiceCollection services)
		{
            // Register your business services here, e.g. services.AddTransient<IMyService, MyService>();
            services.AddTransient<IEventHandler, EventHandler>();
           return services;
		}

Events

This toolbox was made to be able to send events from ASP.NET Core applications. This allows the developers to send out events in a quick and uniform way.

The event message has the following structure :

Header
Timestamp	2012-01-01T12:00:00Z	Timestamp of the event.
Version	1	Version of the event handler.
Correlation
CorrelationId	8e82e349-b430-4c7b-a86a-b8b6133382e9	Unique id of the request.
Application
ApplicationId	b02ea486-506a-47e4-b136-cd658eb8f805	Unique id of the application that initiated the request.
ApplicationName	MyUserInterface	Display-name of the application that initiated the request.
Instance
InstanceId	24213d47-1c26-46d5-a0d1-52d9c3913935	Unique id of the instance of the application that initiated the request.
InstanceName	MyUserInterface-instance3	Display-name of the instance of the application that initiated the request.
Source
Application
ApplicationId	1df240eb-7d0e-42c0-9bb3-f22ad30fd353	Unique id of the application that publishes the event.
ApplicationName	myApp	Display-name of the application that publishes the event.
Instance
InstanceId	e75ab07e-e96c-462c-962c-393ecfdc5726	Unique id of the instance of the application that publishes the event.
InstanceName	myApp-instance1	Display-name of the instance of the application that publishes the event.
Component
ComponentId	9da00df0-6bb3-4b22-be90-3f3bc70329ad	Unique id of the component in the application that publishes the event.
ComponentName	Invoicer	Display-name of the components in the application that publishes the event.
Host
IPAddress	126.35.45.2	IP adress of the server where the event is being published.
ProcessId	15984	Process id from where the event is being sent.
ThreadId	6875	Thread id from where the event is being sent.
Body
EventVersion	1	Version of the event (can be used by parsers).
User
UserName	theuser	User that sends the event.
IPAddress	168.237.25.91	IP adress of that user.
Event
Type	invoice:created	Type of the event.
Content	{"id":45987}	Content of the event (can be empty if the event type speaks for itself).
Format	json	Format of the content (can be used by parsers).

The Header contains the metadata, the Body the real message.

The display-friendly names are a tool for the subscribers of the events. Id’s alone are usually not very user-friendly. By using the display-friendly names subscribes can get the name right away.

The version fields can be used when logic needs to be executed on the messages (eg by parsers or (de)serializers). Between versions the structure or content could have changed.

Methods

The toolbox offers methods to send out events in a user-friendly manner. The metadata fields are filled in by the toolbox.

(Refer to the samples project to see a working demo)

Publish(topic, eventtype, [principal], componentId, componentname, optional eventFormat)
```
  The toolbox will serialize the datatype to JSON and send it as content.
```
PublishString(topic, eventtype, string, componentId, componentname, optional eventFormat)

The toolbox will convert the string to a json with 1 field and send it as content.
PublishJson(topic, eventtype, json-string, componentId, componentname, optional eventFormat)

The toolbox will pass the json-string literally as content.

For event types the following format is recommended : entity:operation (eg person:changed, invoice:created, payment:recieved)

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