Micro Service Architecture
- 1. Cloud Native Computing -Webinar Series-
- 3. “Cloud native computing uses an open source software stack to deploy applications as microservices, packaging each part into its own container, and dynamically orchestrating those containers to optimize resource utilization. Cloud native technologies enable software developers to build great products faster” - Clod Native Computing Foundation What is Cloud Native Computing? ❖ Promotes Opensource ❖ Micro Services Architecture ❖ Containers and container orchestration tools ❖ Agility
- 4. “Cloud computing is shared pools of configurable computer system resources and higher-level services that can be rapidly provisioned with minimal management effort, often over the Internet. Cloud computing relies on sharing of resources to achieve coherence and economies of scale, similar to a public utility” - Wikipedia What is Cloud Computing? ❖ On demand computing over internet ❖ Minimal management effort ❖ Cost efficiency through economies of scale
- 5. “Serverless computing is a cloud-computing execution model in which the cloud provider acts as the server, dynamically managing the allocation of machine resources. Pricing is based on the actual amount of resources consumed by an application, rather than on pre-purchased units of capacity” “Application designs that incorporate third-party “Backend as a Service” (BaaS) services, and/or that include custom code run in managed, ephemeral containers on a “Functions as a Service” (FaaS) platform. ” What is Serverless Computing? AWS Lamda API Gateway S3 Dynamo DB RDS ❖ Reduced operational cost ❖ Reduced complexity ❖ Reduced engineering lead time
- 6. Part I - Micro Services Presented by Linjith K Kunnon 13th Jan 2019
- 7. Part I – Micro Services Overview Monolithic Architecture Service Oriented Architecture (SOA) Micro Service Architecture SOA Evolution Micro Service Architecture Pros & Cons Designing Micro Services Breaking the domain Micro Service Chassis Pattern Communication Style & API Design Event Driven Architecture Micro Service Architecture Variations Securing Micro Services JSON Web Token oAuth2 OpenID Connect Identity Servers Coordinating Micro Services Service Discovery API Gateway Fault Tolerance Monitoring Micro Services Log Aggregation Distributed Tracing Application Metrics Running Micro Services Containerization Configuration Management Continuous Delivery
- 8. Overview Monolithic Architecture Service Oriented Architecture (SOA) Micro Service Architecture SOA Evolution Micro Service Architecture Pros & Cons
- 9. Monolith Semi Mononlith Classic SOA Fine grained SOA (Micro Service) Function as a service (Serverless) “Microservices are a software development technique—a variant of the service- oriented architecture (SOA), an architectural style that structures an application as a collection of loosely coupled services. In a microservices architecture, services are fine- grained and the protocols are lightweight. The benefit of decomposing an application into different smaller services is that it improves modularity” -Wikipedia What are Micro Services?
- 10. Monolithic Architecture A monolithic application is self-contained, and independent. It is designed without modularity making it not possible to repair or replace parts of the application without requiring complete replacement. ❖ Less Operational Overhead. ❖ Architectural simplicity. ❖ Too large and complex to fully understand and make changes fast and correctly. ❖ The size of the application can slow down the start-up time. ❖ Redeploy the entire application on each update. ❖ Impact of a change is usually not very well understood which leads to do extensive manual testing. ❖ Continuous deployment is difficult. ❖ Difficult to scale when different modules have conflicting resource requirements. ❖ Less reliable. Bug in any module (e.g. memory leak) can potentially bring down the entire process. ❖ Barrier to adopt new technologies. User Interface Business Logic DB
- 11. Service Oriented Architecture Service D Service E Service F Service CService BService A UIUI Enterprise Service Bus DB User Interface Web ServiceWeb Service API Consumer A service-oriented architecture (SOA) is a style of software design where services are provided to the other components by application components, through a communication protocol over a network. ❖ Service Reusability ❖ Easy Maintenance ❖ Greater Reliability ❖ Platform Independence
- 12. Micro Service Architecture A microservice is a software development technique—a variant of the service-oriented architecture (SOA). An architecture style to build application as a collection of loosely coupled services The fallacies of distributed computing ❖ The network is reliable. ❖ Latency is zero. ❖ Bandwidth is infinite. ❖ The network is secure. ❖ Topology doesn't change. ❖ There is one administrator. ❖ Transport cost is zero. ❖ The network is homogeneous. Classic SOA Micro Service
- 13. Yet another buzzword? ❖ Service Oriented Architecture has been there for a while. Micro Service is fine grained SOA – a natural progression. ❖ Infrastructure revolution – containerization, elastic cloud & cloud native applications. ❖ Modern applications supports wide variety of digital devices like Mobile phones, PDA etc. Fine grained SOA is a mandate for building such systems. ❖ What really new about Micro Services are the tools and techniques. Played a vital role in transforming IT towards a DevOps-based culture. ❖ Emergence of public cloud and fully managed services. ❖ Business competency - Micro Service Architectural style helps deliver business capabilities faster and with greater confidence. ❖ Agile methodology based development.
- 14. Micro Service Architecture Benefits Agility Fine-grained Scaling Technology Independence Parallel Development Better Fault Isolation Easier to Refactor Easy to Understand Faster Developer Onboarding
- 15. Micro Service Architecture Challenges Operational Complexity Performance Hit Due to Network Latency Increased Configuration Management Unsafe Communication Medium Harder to Troubleshoot Architectural Complexity Higher Costs Duplication of Developer Effort
- 16. Designing Micro Services Breaking the domain Micro Service Chassis Pattern Communication Style & API Design Event Driven Architecture Micro Service Architecture Variations
- 17. Domain Driven Design (DDD) is about designing software based on models of the underlying domain. A model acts as a Ubiquitous Language to help communication between software developers and domain experts. Breaking the domain using DDD ❖ Ubiquitous Language – A common language between developers and the business. ❖ Bounded Context – The setting in which a word or statement appears that determines its meaning. ❖ Domain Entity – A domain object means something to the business, defined primarily by its identity. ❖ Value Object – Defined primarily by its attributes and is immutable. ❖ Aggregate Root – A group of entities and value objects that needs to be consistent while persisting. ❖ Core Subdomain - The core domain is so critical and fundamental to the business that it gives you a competitive advantage and is a foundational concept behind the business. ❖ Supporting Subdomain - Help perform ancillary or supporting functions related directly to what the business does. In these cases, high-quality code and perfectly designed structure are not necessary. ❖ Generic Subdomain - In general, these types of pieces can be purchased from a vendor and then wrapped in such a way to communicate with the rest of the enterprise as necessary (Anti-corruption layer)
- 18. Breaking the domain using DDD ❖ Always decompose to Bounded Contexts ❖ Don’t go further, unless you have to ❖ Buy/adopt generic subdomains ❖ Core subdomain – don’t rush ❖ Evaluate consistency requirements ❖ Evaluate reasons for change ❖ Don’t expect the ideal model. Expect many iterations. ❖ Do not over engineer. Courtesy: Martin Fowler
- 19. Micro Service Chassis Pattern When you start the development of an application you often spend a significant amount of time putting in place the mechanisms to handle cross-cutting concerns. Examples of cross-cutting concern includes ❖ Externalized configuration ❖ Logging ❖ Health checks ❖ Distributed tracing ❖ Boilerplate code for integrations with message broker, db etc. Microservice Template Web DTO Service Domain REST Client Repository Microservice Template Interface REST Endpoint Implementation REST Interface REST Client Microservice Template Web Domain
- 20. API design is important in a microservices architecture - all data exchange between services happens either through messages or API calls. ❖ An API is a contract between a service and clients or consumers of that service. If an API changes, there is a risk of breaking clients that depend on the API. ❖ REST over HTTP using JSON is a common choice for API interface. ❖ Consider using an Interface definition language (IDL) for designing API contracts. Latest standard is Open API. ❖ APIs should not leak internal implementation. It should change only when new functionality is added. ❖ Consider using the Backends for Frontends pattern to create separate backends for each client. ❖ For operations with side effects, consider making them idempotent and implementing them as PUT methods. ❖ Return proper http status codes. ❖ Consistent error handling. Create custom envelop for communicating errors. API Design
- 21. Communication Style ❖ Synchronous protocol. HTTP is a synchronous protocol. The client sends a request and waits for a response from the service. Client code can only continue its task when it receives the HTTP server response. Usually follow REST architectural style. Micro Service A Micro Service B Sync Request Sync Response Micro Service C ❖ Asynchronous protocol. Protocol like AMQP use asynchronous messages. The client code or message sender usually does not wait for a response. Follows Smart endpoints and dumb pipes pattern. Micro Service A Micro Service B Micro Service C Sync Request Sync Response Queue Queue Service E Service H Service A Service F Service G Service B Service C Service D
- 22. ❖ Event Notification ❖ Event Carried State Transfer ❖ Event Sourcing ❖ CQRS – Command Query Responsibility Segregation Event Driven Architecture Micro Service A Micro Service B Micro Service C Sync Request Sync Response Queue Order.created Order.created Order.created User Interface Read Model Write Model Validation Commands Domain Logic Data Persistance Queries (Generate DTOs) Domain Model (Shopping cart aggregate) Command Handler User Interface Item a removed Item c added Item a added ... Event Store Query Event CQRS Pattern Event Sourcing Pattern Event Notification Availability over consistency
- 23. Shared Database & Database Per Service Micro Service A DB Micro Service B Micro Service C Micro Service D API Gateway Micro Service A DB Micro Service B Micro Service C Micro Service D DB DB API Gateway ❖ Data needs to be encapsulated with the business logic that operates on the data. ❖ Data access only via a published service interface. ❖ No direct database access is allowed from outside the service. ❖ No data sharing among the service ❖ Enables polyglot persistence ❖ Business transactions may need to query data that is owned by multiple services. ❖ Aggregating data that is owned by multiple services. ❖ A single database is much simpler to operate. ❖ Creates development time & run time coupling ❖ Widely Considered as anti-pattern. Shared Database Database per service
- 24. ❖ Domain services and business process are not directly exposed to internet facing users. ❖ Web & Mobile applications talks to Digital Experience APIs ❖ Data transformation specific to user experience. ❖ Domain API abstraction Layered Micro Services & API Composition Domain APIs Domain APIs Domain APIsDomain APIs Domain APIs Domain APIs Domain APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs Digital Experience APIs User Experience Layer (Portal) Digital Experience API Domain APIs & Business Process Data Assets ❖ Simple way to query data in a micro service architecture ❖ Restrict direct access to database. ❖ Aggregate data in higher order micro service. ❖ Prepare for possible performance issue due to network latency. Micro Service A Higher Order Micro Service Micro Service B Aggregator Consumer Request Response
- 26. Semi Monolith vs Micro Service API Gateway Discovery Server UI Server Serves Static Assets Micro Services InfrastructureServices Monitoring Api Health Dashboard Performance Monitoring Log Aggregation & Analysis Container Dashboard Configuration Server Messaging Middleware Identity Server External Systems Distributed Cache Data Stores Web ServiceUI Server Serves Static Assets DB Semi-Monolith Micro Services
- 27. Semi-Monolith VPC NAT gateway VPC NAT gateway Public Subnet-10.0.1.0/24 Public Subnet - 10.0.0.0/24 Private Subnet-10.0.2.0/24 Private Subnet-10.0.3.0/24 sgDataLayersgPublic sgWebLayer vpc-demo:us-east-1 -10.0.0.0/16 us-east-1a us-east-1b us-east-1a-public us-east-1b-public us-east-1a-private us-east-1b-private Web Server Web Server DB-MasterAmazon S3
- 28. Micro Service VPC NAT gateway VPC NAT gateway Public Subnet-10.0.1.0/24 Public Subnet - 10.0.0.0/24 Private Subnet-10.0.2.0/24 Private Subnet-10.0.3.0/24 sgDataLayersgPublic sgWebLayer vpc-demo:us-east-1 -10.0.0.0/16 us-east-1a us-east-1b us-east-1a-public us-east-1b-public us-east-1a-private us-east-1b-private DB-MasterDB-MasterDB-MasterDB-MasterDB-MasterAmazon S3
- 29. Micro service instances changes dynamically and they have dynamically assigned network locations. Service discovery mechanism address this issue. ❖ service provider registers itself with service registry when it enters and deregister itself when it leaves the system ❖ service consumer gets the location of a provider from registry, and then talks to the provider ❖ service registry maintains the latest location of providers Service Discovery Service B Service C Service A Service Registry Registry Client Registry Client Registry Client Registry Aware HTTP Client Service B Service C Service Registry Registry Client Registry Client HTTP Client Service A Registry Client Load Balancer Client side service discovery Server side service discovery
- 30. API Gateway Service C Service A Service B Service E Service D External API Consumers API Gateway An API gateway sits between clients and micro services. It acts as a reverse proxy, routing requests from clients to services. ❖ Single URL and consistent interface. ❖ Reduces the coupling between client and backend. ❖ Act as aggregator. ❖ Exposes client-friendly protocol such as HTTP or WebSocket. ❖ SSL termination ❖ Authentication ❖ IP whitelisting ❖ Client rate limiting (throttling) ❖ Logging and monitoring ❖ Response caching
- 31. Fault Tolerance ❖ The Circuit Breaker pattern can prevent an application from repeatedly trying to execute an operation that's likely to fail. It allows services to recover and limit cascading failures across multiple systems. Failure threshold reached Operation Success Delay (timeout) Operation Failed Open Half Open Closed❖ Closed state - Allowed to make remote calls when in closed state. This state implies that the service is up and running. If the number of error responses from the needed service passes a certain threshold limit, the circuit is tripped. ❖ Open state – Remote calls are not made in this state. Circuit breaker triggers the fallback method if defined. After a preset delay, the circuit will be in half-open state. ❖ Half Open State – On time out, the circuit breaker allows remote service calls. If request fails, the circuit will go to the open stage. Otherwise the circuit will go to the closed stage.
- 32. Service Mesh Service B Proxy Service C Proxy Service A Proxy Control Plane Pilot Mixer Citadel ❖ The data plane is composed of a set of intelligent proxies deployed as sidecars. These proxies mediate and control all network communication between microservices. ❖ The control plane manages and configures the proxies to route traffic, enforce policies and collect telemetry. Istio Service MeshConsul Connect A configurable infrastructure layer for a microservices application. It makes communication between service instances flexible, reliable, and fast. It provides service discovery, load balancing, encryption, authentication and authorization, support for the circuit breaker pattern, and other capabilities.
- 34. Containerization using docker ❖ A platform for developers and sysadmins to develop, deploy, and run applications with containers. ❖ Image: An image is an executable package that includes everything needed to run an application -the code, a runtime, libraries, environment variables, and configuration files. ❖ Container: A container is a runtime instance of an image. Infrastructure Host Operating System Docker Engine Container Container Container Bins/Libs App B Bins/Libs App C Bins/Libs App A Infrastructure Hypervisor VM VM VM Bins/Libs App B Bins/Libs App C Bins/Libs App A Guest OS Guest OS Guest OS ❖ Environment Standardization ❖ Isolation ❖ Light weight ❖ Portable ❖ Application Centric
- 35. Configuration Management Separating configuration from application code is an important discipline in cloud-native development. This helps the containerized application to run in multiple environments without modification. Micro Service B Configuration Server Micro Service A Micro Service C Configuration Store ❖ Share configurations with other services ❖ Centralized management ❖ Containerized apps once tested doesn’t require modifications. ❖ Easier administration
- 36. ❖ Low risk releases. ❖ Faster time to market. ❖ Higher quality. ❖ Lower costs. ❖ Better products. Continuous Delivery Develop Build TestDeploy Release Ability to get changes of all types—including new features, configuration changes, bug fixes and experiments—into production, or into the hands of users, safely and quickly in a sustainable way.
- 38. Log Aggregation Application must emit telemetry events. Categorize them into metrics and text-based logs. ELK for Log Aggregation ❖ Logstash - Collects log events from multiple types of sources using input plug-ins, transform using filter and codec plug-ins and send them to a number of destinations using output plug-ins. ❖ Elasticsearch - Elasticsearch is a distributed and scalable full-text search database. It Allows to store and search large volumes of log events. ❖ Kibana – Used for visualizing and analyzing logs stored in Elasticsearch.
- 39. Distributed Tracing Gateway Service A Service B Service C 1 2 3 5 6 7 9 8 4 ❖ Difficult to understand the flow of events across services. ❖ A single operation or transaction may involve calls to multiple services. ❖ To reconstruct the entire sequence of steps, each service should propagate a correlation ID that acts as a unique identifier for that operation. ❖ The correlation ID enables distributed tracing across services. ❖ Helps troubleshoot latency problems in microservice architectures.
- 40. ❖ Key metrics are identified and monitored at the host, infrastructure, and microservice levels. ❖ Host and infrastructure key metrics: CPU, RAM, Threads, File descriptors, Database connections etc. ❖ Microservice key metrics – Availability, SLA, Latency, Errors & Exception etc. ❖ Appropriate logging that accurately reflects the past states of the microservice. ❖ Easy to interpret dashboard which contains key metrics. ❖ Actional alerts and are defined by signal-providing thresholds. Application Metrics
- 41. Securing Micro Services JSON Web Token oAuth2 OpenID Connect Identity Servers
- 42. JSON Web Token (JWT) ❖ Defines a compact and self-contained way for securely transmitting information between parties as a JSON object. ❖ Information can be verified and trusted for digital signed tokens. ❖ JWTs can be encrypted to also provide secrecy between parties . JSON Web Tokens are an open, industry standard method for representing claims securely between two parties.
- 43. OAuth 2 OAuth 2 Roles ❖ Resource Owner - The resource owner is the user who authorizes an application to access their account ❖ Client - The client is the application that wants to access the user's account. ❖ Resource Server - The resource server hosts the protected resources. ❖ Authorization Server - Authorization server verifies the identity of the user then issues access tokens. OAuth 2 Tokens ❖ Access Token - The Access Token is a credential that can be used by an application to access an API. ❖ Refresh Token - Token that can be used to obtain a renewed access token. Client Resource Owner Authorization Server Identity Server Resource Server Micro Service The OAuth 2.0 authorization framework enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner by orchestrating an approval interaction between the resource owner and the HTTP service, or by allowing the third-party application to obtain access on its own behalf.
- 44. OAuth 2 Protocol Flows Client Resource Owner Authorization Server Identity Server Resource Server Micro Service Authorization Request Authorization Grant Authorization Grant Access Token Access Token Protected Resource ❖ Authorization Code: used with server-side Applications. This is a redirection-based flow, which means that the application must be capable of interacting with the user-agent (i.e. the user's web browser) and receiving API authorization codes that are routed through the user-agent. ❖ Implicit: used with Mobile Apps or Web Applications (applications that run on the user's device) ❖ Resource Owner Password Credentials: used with trusted Applications, such as those owned by the service itself ❖ Client Credentials: used with Applications API access
- 45. ❖ OpenID Connect is a simple identity layer on top of the OAuth 2.0 protocol. ❖ Allows Clients to verify the identity of the End-User based on the authentication performed by an Authorization Server, as well as to obtain basic profile information about the End-User in an interoperable and REST-like manner. ❖ While OAuth 2.0 is about resource access and sharing, OIDC is all about user authentication. ❖ Its purpose is to give you one login for multiple sites. Each time you need to log in to a website using OIDC, you are redirected to your OpenID site where you login, and then taken back to the website. ❖ ID Token – A JSON Web Token (JWT) that contains identity data. It is consumed by the application and used to get user information like the user's name, email, and so forth, typically used for UI display. Open Id Connect
- 46. Login Flow Micro Service Okta Identiy Server User Web Client User Authorization Flow (Authorization Code Grant Flow) Enter login credentials Exchange authorization code for access token authorize user access token + refresh token GET/ Pipeline (access_token) Pipeline Response opt token expired POST/token (grant_type=refresh_token, refresh_token) access token + refresh token Render dashboard validate refresh token Authorization Code Request client_id, client_secret, redirect_url response_type = code Authorization code authorize user
- 48. Reference Architecture Micro Front Ends Micro Services Platform Business Micro Services Supporting Services UI App UI App UI AppUI App UI App Generic Services Platform Core Components Core Services UI App Persistence Layer Micro Service Data Stores IntegrationGateway MicroServicesObservability API Gateway Data lake UI Framework Persistence Layer Platform Components Business Micro Services Micro Front Ends Third-party Service Providers Discovery Configuration Message Broker Identity Server Distributed Cache
- 49. Reference Architecture API Gateway Discovery Server UI Server Serves Static Assets Micro Services InfrastructureServices Monitoring Api Health Dashboard Performance Monitoring Log Aggregation & Analysis Container Dashboard Configuration Server Messaging Middleware Identity Server External API Consumers Distributed Cache Data Stores IntegrationGateway Third-party Service Providers
- 50. Thank You