Hello, this page is about the Raven.NET framework which is an implementation of the observer pattern with several extensions that can be used for a variety of benefits. The name is not accidental and is intended, more precisely described as the last paragraph of this page. If you have suggestions for development, please contact us or create an issue and mark it with correct label.
To make use of Raven.NET library and its most important features you need to install Core nuget package, you can do this with dotnet command like this:
dotnet add package Raven.NET.Core
or via nuget package manager console:
Install-Package Raven.NET.Core
(feel free to checkout Analytics package as well)
To check newest updates and additional information please check direct link: https://www.nuget.org/packages/Raven.NET.Core
To use Raven.NET first step is to register necesary dependencies in service collection, its possible to do this manually (it will be described in details in docs) but there is already extension method prepared for this that you should call in your ConfigureServices method. Example with IHostedService below.
var host = Host.CreateDefaultBuilder()
.ConfigureServices((_, services) =>
{
services.ConfigureRaven(configuration);
}).Build();
Then to make use of the most simple observer you should inject IRavenWatcher interface. With this you can create new watchers by using Create method. It needs 2 parameters, when first is name of watcher (needs to be unique) and the second is the callback where we will get updates. Additionally it can have the third parameter which is options, if not provided it will load options from appsettings and if those do not exist then it will use the default configuration. Example of usage is shown below:
var watcher1 = _ravenWatcher1.Create("Raven1", PhoneUpdated, (options) => { options.AutoDestroy = true; });
After our watcher is created then we can tell him to watch a certain object.
watcher1.Watch(testPhone2).Watch(testPhone3);
With this code after we will make changes to watched objects and notify observers about it, we get a message in our callback
testPhone2.Price = 420;
testPhone2.TryNotify();
And we get in our console logged:
In addition we have an implementation for watcher that allows you to watch all objects of a given type automatically and checks for updates, this may be really useful when you don't have strict control over objects in your system (you want to check for updates in lots of objects that you get form database, or load any other different way to your application). The implementation looks similar but has some core differences. And for this case, you need to inject IRavenTypeWatcher
Creation looks similar, the difference is that you need to provide type as a generic parameter and an additionally key that is unique for objects of this type.
_ravenTypeWatcher.Create<Car>("RavenTypeWatcherExample", nameof(Console.Car.Id), Callback);
That is basically it, and now when you will have new object with same id, it will be considered as update (if its different)
var Car = new Car(1231, "Qudi", "Q2", 40000);
var Car2 = new Car(1231, "Qudi", "Q2", 43000);
Feel free to check out more detailed documentation, as good start we propose taking look on the introduction page
Some time ago I watched a series in which a raven was an animal that was used for observation. It starred at the target carefully as if it wanted to see all the details and potential clues. For those interested, there were also vampires and werewolves in the series (probably many of you already guess what the series is about). I recently remembered this and read a bit about it, even found out that ravens are considered animals that can be tracked by military and governmental organizations. Hence the idea to name the library whose core will be based on the observer pattern as Raven. An additional advantage of this approach is an easy understanding of the context and purpose, I would like this library to be able to describe what it does, and this approach is also evident in the interfaces and approaches to using the framework. I believe that by basing the elements of logic that are visible in the code on elements that are visible in the natural environment, the principles of operation should be easier to understand
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