Director - Integration Architecture, WSO2

Microservices for Enterprises

Kasun Indrasiri

Pre-Microservices era SOA/ESB with APIs

Consumers

ESB

System

Service 1 Service 2 Service 3 Service 4 Service 5

API Management

Application server

• The foundation of MSA is about developing a single application as a suite of fine-grained and independent services running in its own process, developed and deployed independently.

Microservice Architecture

Evolution of Microservices Microservices

Web Portal Mobile Apps Store Admin Web Storefrons Promotion Mgmt

API Management

Product Details Shopping Cart Order Mgt Payment Proc. Payment Proc. Customer Mgt.

Account Mgt Order Tracking Financial Mgt Fraud Detection Tax Mgt Inventory Mgt Allocation-Release

Self-Service Giftcards Promotions Pricing Subscription Credit service CRM Mgt Shipping

Data Warehouse Finance System Shipping Inventory Payment Gateway Cloud ServicesE.g. Salesforce, Paypal etc

• Common Misconceptions – Lines of Code, Team size, 'Micro' is a bit misleading term

• Single Responsibility Principle(SRP)– Having a limited and a focused business requirement.

• Scope– Find the service boundaries and align them with the business

capabilities (aka DDD)• Miniservices

– “A miniservice is a coarse-grained, independently deployable and independently scalable application component.”

– “Innovation Insight for Miniservices”

Designing Microservices : Size, scope and capabilities

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• In Monolithic architecture: – Function calls or language-level method calls– SOA/web services : SOAP and WS* with HTTP, JMS etc. – Web services with several dozens of operations and complex

message schemas • In Microservices architecture:

– Simple and lightweight messaging mechanism.

Messaging in Microservices

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• REST– HTTP 1.x – OpenAPI/Swagger – JSON

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Messaging in MicroservicesSynchronous Messaging

• gRPC - https://grpc.io/ – IDL, Protobuf– HTTP2 – Internal service calls

• Other RPC styles : Avro, Thrift

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Messaging in MicroservicesSynchronous Messaging

• Propagating changes across multiple microservices– Single-receiver message-based communication– Multiple-receivers message-based communication

• AMQP, Kafka, MQTT

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Messaging in MicroservicesAsynchronous Messaging

Source : https://docs.microsoft.com/en-us/dotnet/standard/microservices-architecture/architect-microservice-container-applications/communication-in-microservice-architecture

• Asynchronous microservice integration -> enforces microservices autonomy

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Messaging in MicroservicesSynchronous vs Asynchronous Messaging

Source : https://docs.microsoft.com/en-us/dotnet/standard/microservices-architecture/architect-microservice-container-applications/communication-in-microservice-architecture

• Not all microservices are similar– Business logic heavy, while some contain a lot of

interservice calls– Synchronous vs async communication– Too fine-grained to be exposed as a business functionality– Some services are exposed as APIs

Do all Microservices similar?

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Technologies for Building Composite/Integration Microservices

• General Purpose Languages/Frameworks - Java, Node.js, Groovy, e.g. SpringBoot, Dropwizard

• Bulky traditional ESB architecture -> Not fully compatible with MSA principles

Technologies for Building Composite/Integration Microservices

• General Purpose Languages/Frameworks - Java, Node.js, Groovy, e.g. SpringBoot, Dropwizard

• Bulky traditional ESB architecture -> Not fully compatible with MSA principles

Technologies for Building Composite/Integration Microservices Ballerina - ballerinalang.org

Organizing Microservices Microservice Types with Different Granularities

Consumer 1

API Service 1 API Service 2 API Service 3 API Service 4

ConsumersConsumer 2 Consumer 3

Service 6 Service 7 Service 8 Service 9

Service 1 Service 2 Service 3 Service 4 Service 5 Proprietary & Legacy

Systems

Web API / SaaS

API Services/Edge Services

Composite Service/Integration Services

Core Services/Atomic Services

Organizing Microservices Microservice Types with Different Granularities

Consumer 1

API Service P API Service Q API Service R API Service S

ConsumersConsumer 2 Consumer 3

μ Service A μ Service B

μ Service F

μ Service G

Proprietary & Legacy

Systems

Web API / SaaS

API Services/Edge Services

Composite Service/Integration Services

Core Services/Atomic Services

μ Service I

μ Service H

μ Service J

μ Service E

μ Service C

μ Service D

Microservices Security Microservice security with OAuth2 and OpenID Connect.

17Refer : https://medium.facilelogin.com/securing-microservices-with-oauth-2-0-jwt-and-xacml-d03770a9a838

• Ability to deploy/un-deploy independently of other microservices.• Must be able to scale at each microservices level. • Building and deploying microservices quickly. • Failure in one microservice must not affect any of the other services.• Docker and Kubernetes.

Microservices Deployment

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• Isolate the legacy and modern systems by placing an anti-corruption layer between them.

• Translates communications between the two systems, allowing the legacy system to remain unchanged while the modern application can avoid compromising its design and technological approach.

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Bridging Microservices and Monolithic systemsAnti-Corruption Layer pattern

Source: https://docs.microsoft.com/en-us/azure/architecture/patterns/anti-corruption-layer

• Incrementally replace specific pieces of functionality with new applications and services.

• Create a façade that intercepts requests going to the backend legacy system.

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Bridging Microservices and Monolithic systemsStrangler Pattern

Source: https://docs.microsoft.com/en-us/azure/architecture/patterns/strangler

Data Management

Database per service

• Keep each microservice’s persistent data private to that service and accessible only via its API.

• Create composite services to retrieve data from multiple microservices.

• Eventual consistency between microservices through event-driven communication and a publish-and-subscribe system.

Governance

Decentralized Governance

• Decentralized governance of Service Design, Deployment and Execution– Give the teams the freedom to develop software

components using different stacks – Define some ‘global standards’ that apply to the

methodology behind the software

Governance

Service Registry

• Central component which supports: – APIs to publish service

information (service endpoints, contract, message models, available service versions)

– APIs to query/discover service information.

– Pull and push models to retrieve service information

– Service ownership/consumerssource : https://www.nirmata.com/2014/08/13/getting-started-with-microservices-using-netflix-oss-docker/

Governance

Service Dependencies

• Managing/tracking and tracking dependencies and associations between services

• Derive service dependencies and associations automatically, ability to monitor/visualize them.

• Netflix Vizceral : https://github.com/Netflix/vizceral

Governance

Runtime Policy Enforcements and IAM

• Throttling, Caching, Security, Identity management • Centrally applied at API Gateway level

Governance in Microservices

Service Observability

• Metrics• Monitoring• Distributed logging• Distributed tracing.• Visualization

• “The most complex challenge in realizing microservice architecture is not building the services themselves, but the communication between services.”

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Service MeshWhy Service Mesh?

Service Mesh

Why Service Mesh?

• With MSA, business logic + network communication logic are dispersed across independent services

Consumers

Microservice X Microservice Y Microservice Z

Microservice P Microservice Q Microservice R Microservice S

JAVA Node.js Python

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Service MeshInter-service communication

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Service MeshWhat is a ‘Service Mesh’?

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Service Mesh in Action

• Istio : https://istio.io/ • Linkerd: https://linkerd.io/

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Service MeshImplementations

• Use a pragmatic approach for adopting microservices architecture for enterprises.

• Select the appropriate patterns and technologies based on your business requirements.

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Conclusion

• https://medium.com/microservices-in-practice • https://docs.microsoft.com/en-us/dotnet/standard/microservices-a

rchitecture

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References

wso2.com

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