坂本  篤司

坂本 篤司

1641253560

マイクロサービスサーキットブレーカーパターン (Microservice Circuit Breaker Pattern)

この記事では、サーキットブレーカーパターンと呼ばれるマイクロサービスアーキテクチャのクロスカッティングパターンの1つについて説明します。マイクロサービスアーキテクチャは、Kafkaなどの分散コンポーネントの一部を含む分散アーキテクチャであり、アーキテクチャは本質的に多言語である可能性があります。解決されている問題の種類に応じて、アーキテクチャにはいくつものサービスが存在する可能性があります。サービスが相互に通信するときは、すべてのサービスが生きている必要があることが重要です。

  1. サーキットブレーカーパターンとその重要性は何ですか?
  2. サーキットブレーカの状態。

サーキットブレーカ

サーキットブレーカは、短絡や過負荷の場合に電気回路を損傷から保護することを目的としたデバイスであり、機器を保護し、火災のリスクを防ぐために、欠陥が発生した場合に電気の流れを停止します。同様に、Circuit Breakerの設計パターンは、機能していない、または応答に時間がかかりすぎるサービスへの要求の送信を停止します。このパターンは、アーキテクチャをそのような悲惨なイベントから保護し、フォールトトレラントで復元力のあるシステムの構築に役立ちます。

サーキットブレーカパターン

サーキットブレーカーは、プロキシとして要求メカニズムと応答メカニズムの間に位置します。マイクロサービスで障害が発生したり、サーキットブレーカーが特定の期間トリップするのが遅くなったりすると、その期間中、特定のサービスへの要求はすぐに失敗します。期間が終了すると、Circuit Breakerはサービスへのいくつかの要求を許可し、サービスを監視下に置きます。サービスが正常に応答した場合、Circuit Breakerは以前と同じようにフローを再開し、サービスに障害が発生した場合、CircuitBreakerは残ります。問題が解決するまでトリップしました。

サーキットブレーカーパターンには3つの状態があります

  1. 閉まっている
  2. 開いた
  3. 半開き

閉まっている

CLOSED状態はハッピーパスシナリオであり、フローは正常に機能しており、マイクロサービスは稼働しています。この状態では、Circuitはサービスを介したリクエストを許可します。

サーキットブレーカパターン

開いた

サーキットブレーカーのタイムアウトがマイクロサービスの呼び出しで構成された値に達すると、マイクロサービスの速度が低下しているか、期待どおりに機能していないことを意味します。サーキットブレーカーがトリップしてOPEN状態になります。CircuitがOPEN状態の場合、着信要求はエラーとともに返され、マイクロサービス呼び出しは実行されません。この動作により、負荷がさらに軽減され、マイクロサービスが障害から回復できるようになります。

サーキットブレーカパターン

半開き

しばらくすると、CircuitはHALF-OPEN状態になります。HALF-OPEN状態では、Circuitは定期的にサービスに試行要求を行い、サービスが障害から回復したかどうかをテストします。それでもサービスコールがタイムアウトする場合、CircuitはOPEN状態のままです。コールが成功すると、CircuitはCLOSED状態に切り替わり、トラフィックは通常どおりに進みます。  

概要

これはマイクロサービスにとって非常に重要で有用なパターンであり、マイクロサービスアーキテクチャをフォールトトレラントにします。このパターンはタイムアウトと速度低下を効果的に処理し、マイクロサービスのタイムリーなリカバリに役立ちます。利用可能なさまざまなCircuitBreakerオープンソースライブラリがあり、広く使用されているもののいくつかは、Hystrix、Resilience4jです。

リンク:https//www.c-sharpcorner.com/article/microservice-circuit-breaker-pattern/

#microservice 

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マイクロサービスサーキットブレーカーパターン (Microservice Circuit Breaker Pattern)
Einar  Hintz

Einar Hintz

1599055326

Testing Microservices Applications

The shift towards microservices and modular applications makes testing more important and more challenging at the same time. You have to make sure that the microservices running in containers perform well and as intended, but you can no longer rely on conventional testing strategies to get the job done.

This is where new testing approaches are needed. Testing your microservices applications require the right approach, a suitable set of tools, and immense attention to details. This article will guide you through the process of testing your microservices and talk about the challenges you will have to overcome along the way. Let’s get started, shall we?

A Brave New World

Traditionally, testing a monolith application meant configuring a test environment and setting up all of the application components in a way that matched the production environment. It took time to set up the testing environment, and there were a lot of complexities around the process.

Testing also requires the application to run in full. It is not possible to test monolith apps on a per-component basis, mainly because there is usually a base code that ties everything together, and the app is designed to run as a complete app to work properly.

Microservices running in containers offer one particular advantage: universal compatibility. You don’t have to match the testing environment with the deployment architecture exactly, and you can get away with testing individual components rather than the full app in some situations.

Of course, you will have to embrace the new cloud-native approach across the pipeline. Rather than creating critical dependencies between microservices, you need to treat each one as a semi-independent module.

The only monolith or centralized portion of the application is the database, but this too is an easy challenge to overcome. As long as you have a persistent database running on your test environment, you can perform tests at any time.

Keep in mind that there are additional things to focus on when testing microservices.

  • Microservices rely on network communications to talk to each other, so network reliability and requirements must be part of the testing.
  • Automation and infrastructure elements are now added as codes, and you have to make sure that they also run properly when microservices are pushed through the pipeline
  • While containerization is universal, you still have to pay attention to specific dependencies and create a testing strategy that allows for those dependencies to be included

Test containers are the method of choice for many developers. Unlike monolith apps, which lets you use stubs and mocks for testing, microservices need to be tested in test containers. Many CI/CD pipelines actually integrate production microservices as part of the testing process.

Contract Testing as an Approach

As mentioned before, there are many ways to test microservices effectively, but the one approach that developers now use reliably is contract testing. Loosely coupled microservices can be tested in an effective and efficient way using contract testing, mainly because this testing approach focuses on contracts; in other words, it focuses on how components or microservices communicate with each other.

Syntax and semantics construct how components communicate with each other. By defining syntax and semantics in a standardized way and testing microservices based on their ability to generate the right message formats and meet behavioral expectations, you can rest assured knowing that the microservices will behave as intended when deployed.

#testing #software testing #test automation #microservice architecture #microservice #test #software test automation #microservice best practices #microservice deployment #microservice components

Ida  Nader

Ida Nader

1598179680

What Is Circuit Breaker and How to implement It With .NET Core?

What is Circuit Breaker?

circuit breaker is an automatically operated electricalswitch designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit. Its basic function is to interrupt current flow after a fault is detected. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. — Wikipedia.

But, wait….!

This is a Software Programming topic, and why I’m bring something related to Electrical Technology into this topic?

Because the way we apply Circuit Breaker Pattern in Software Programming is very similar. And I just want to bring something that you are familiar with in order to make the topic easier to understand.

Back to the definition of Circuit Breaker in Software Programming…

Circuit Breaker pattern is used to detect failures and encapsulates the logic of preventing a failure from constantly recurring, during maintenance, temporary external system failure or unexpected system difficulties. —Wikipedia

Bear in mind that, It’s not available to prevent the broken service, but not to make it worse than it was. While other design patterns are born for making our solution easy to maintain, maximize reusability, better performance… then Circuit Breaker is the one for “when sh*t happens”.

image source: me.me

Why Circuit Breaker?

Back to several years ago — the time I started digging and applying Microservices architecture (MSA), MSA was something very new with not only me but also other developers. Nowadays, you can easily find technical articles, sample projects and case studies about MSA as it’s becoming very popular. There is a fact which can’t be denied that MSA brings so many advantages and benefits, it also makes our solution brittle because a request from user will need to call multiple micro-services. It replaces the in-memory calls of a Monolithic architecture with remote calls across the network, which works well when all services are up and running. But when one or more services are unavailable, slow network connection or timeout… it results in a cascading failure across the application.

And, Circuit Breaker is here to help us can build a fault-tolerant and resilient system that can survive gracefully when key services are either unavailable or have high latency. Circuit Breaker pattern enables an application to detect whether the fault has been resolved. If the problem appears to have been fixed, the application can try to invoke the operation.

Circuit Breaker States

Image for post

Photo by Blake Weyland on Unsplash

Although the name “Circuit Breaker” is mimicked from Electrical Technology, in software programming, Circuit Breaker can do much more than turning on/off the electricity (tripping).

  • Both of them can detect when there is a problem and automatically turn on. But while Circuit Breaker in software programming can turn off automatically, then Circuit Breaker in Electrical Technology couldn’t.
  • Besides having fully opened and fully closed state, Circuit Breaker in software programming can have an intermediate state, called “Half-open” where an application can operate at degraded functionalities.

#polly #software-architecture #design-patterns #circuit-breaker #microservices

Fredy  Larson

Fredy Larson

1598759220

Microservices Adoption Using Different Patterns

Microservice is an architectural style that made up of smaller (micro) applications that communicate with each other, through open protocols like HTTP. Microservices have a much simpler and direct communication mechanism. Microservices typically deployed Docker platforms in the cloud environment will get maximum benefit.

Microservices architecture’s main aim is to break down the applications into smaller applications for maintainability and address the particular functionality. Microservices are scalable, and the maintainability of the application was as typical in monolithic applications. Below are some of the benefits of microservices architecture

  • Time to market for new functionality
  • Seamless integrations
  • Adoption of new technologies
  • Resource (Hardware) utilization effectively
  • Security
  • API based functions for reuse effectively

In monolithic apps, all the functionalities are part of a single application and deployed as a single war/ear file. Earlier days, most of the applications are building by using the MVC design pattern. Microservice architectures create applications that remain maintainable in the long run since the applications are can modify and deploy without impacting other services leads to flexibility. Development and deployment efforts are increasing, and testing should perform for each component or Service in Microservice applications

The biggest challenge is deciding how to partition the exiting system into Microservices. Some strategies have to adapt to decouple the Microservices from existing Monolithic applications. Below are some of the patterns uses in the different domains while decoupling the applications. The patterns are widely used in all domains

  • Decompose by Business Capability
  • Decompose by Sub Domain
  • API Gateway
  • Aggregator
  • Circuit Breaker
  • Distribute Tracing
  • Log Aggregator

#microservices #api gateway #circuit breaker #microservices adoption #aggregator #monolithic apps

Samanta  Moore

Samanta Moore

1623835440

Builder Design Pattern

What is Builder Design Pattern ? Why we should care about it ?

Starting from **Creational Design Pattern, **so wikipedia says “creational design pattern are design pattern that deals with object creation mechanism, trying to create objects in manner that is suitable to the situation”.

The basic form of object creations could result in design problems and result in complex design problems, so to overcome this problem Creational Design Pattern somehow allows you to create the object.

Builder is one of the** Creational Design Pattern**.

When to consider the Builder Design Pattern ?

Builder is useful when you need to do lot of things to build an Object. Let’s imagine DOM (Document Object Model), so if we need to create the DOM, We could have to do lot of things, appending plenty of nodes and attaching attributes to them. We could also imagine about the huge XML Object creation where we will have to do lot of work to create the Object. A Factory is used basically when we could create the entire object in one shot.

As **Joshua Bloch (**He led the Design of the many library Java Collections Framework and many more) – “Builder Pattern is good choice when designing the class whose constructor or static factories would have more than handful of parameters

#java #builder #builder pattern #creational design pattern #design pattern #factory pattern #java design pattern

Tia  Gottlieb

Tia Gottlieb

1597438200

What Is a Microservice Architecture? Why Is It Important Now?

We have been building software applications for many years using various tools, technologies, architectural patterns and best practices. It is evident that many software applications become large complex monolith over a period for various reasons. A monolith software application is like a large ball of spaghetti with criss-cross dependencies among its constituent modules. It becomes more complex to develop, deploy and maintain monoliths, constraining the agility and competitive advantages of development teams. Also, let us not undermine the challenge of clearing any sort of technical debt monoliths accumulate, as changing part of monolith code may have cascading impact of destabilizing a working software in production.

Over the years, architectural patterns such as Service Oriented Architecture (SOA) and Microservices have emerged as alternatives to Monoliths.

SOA was arguably the first architectural pattern aimed at solving the typical monolith issues by breaking down a large complex software application to sub-systems or “services”. All these services communicate over a common enterprise service bus (ESB). However, these sub-systems or services are actually mid-sized monoliths, as they share the same database. Also, more and more service-aware logic gets added to ESB and it becomes the single point of failure.

Microservice as an architectural pattern has gathered steam due to large scale adoption by companies like Amazon, Netflix, SoundCloud, Spotify etc. It breaks downs a large software application to a number of loosely coupled microservices. Each microservice is responsible for doing specific discrete tasks, can have its own database and can communicate with other microservices through Application Programming Interfaces (APIs) to solve a large complex business problem. Each microservice can be developed, deployed and maintained independently as long as it operates without breaching a well-defined set of APIs called contract to communicate with other microservices.

#microservice architecture #microservice #scaling #thought leadership #microservices build #microservice