(6) ASP. NET core microservices micro-service----AOP Framework

AOPFramework Basics

Knowledge required to understand: AOP, Filter, Reflection (Attribute).

If you use Polly directly, you will create a mix of business-agnostic code in your business code. We encapsulate a simple framework that mimics the Hystrix in Spring cloud by using AOP (if you don't know about AOP, refer to the online material yourself).

You need to introduce an AOP that supports. NET core, and we use the AOP framework under. NET Core as Aspectcore (native, dynamic weave), or not support. NET core, or not support the interception of an MVC Filter on an async method.

Github:https://github.com/dotnetcore/aspectcore-framework

Install-package aspectcore.core-version 0.5.0

Here are just a few of our related uses:

1, write interceptors Custominterceptorattribute generally inherit from Abstractinterceptorattribute

 Public classcustominterceptorattribute:abstractinterceptorattribute{//executed in each intercepted method 　　  Public Async OverrideTask Invoke (aspectcontext context, aspectdelegate next) {
Try{Console.WriteLine ("before executing");
awaitNext (context);//execution of intercepted methods}Catch(Exception) {Console.WriteLine ("An exception occurred in the method being intercepted");
Throw; }finally{Console.WriteLine ("after execution"); }}}

2. Write classes that need to be intercepted by agents

Mark the Custominterceptorattribute on the method to be intercepted. The class needs to be a public class, and the method supports asynchronous methods if interception is a virtual method, because dynamic proxies are implemented dynamically to generate dynamic subclasses of the Proxied class.

class person{    [custominterceptor]              publicvoid Say (string  msg)    {         Console.WriteLine ("service calling ... "+msg);}    }

3. Create proxy objects through Aspectcore

Newusing (iproxygenerator proxygenerator = proxygeneratorbuilder.build ()) {    = Proxygenerator.createclassproxy<person>();    P.say ("rupeng.com");} Console.readkey ();

Note that the object that P points to is the object of the dynamic subclass of the person that the aspectcore generates, and the direct new person cannot be intercepted.

Study AOP Details

The meaning of the properties of the parameter Aspectcontext under the Invoke method in the Interceptor:

Implementation objects that are actually dynamically created by the person subclass.

Implementationmethod is the say method of the person sub-class

The parameter value of the Parameters method.

Proxy==implementation: Under current scenario

Proxymethod==implementationmethod: Under current scenario

ReturnValue return value

Servicemethod is the say method for person

Note: This article is the second edition of the. NET Core MicroServices second Edition and. NET core microservices that I see Yang Zhengko teacher.

(6) ASP. NET core microservices micro-service----AOP Framework