Microservices

Evolution of middleware

Ramesh KumarSenior web Developer

Today’s Agenda

• Monolithic System• Mircoservice and its Charecteristics?• Microservice Achitecture

• Legacy Systems• Monolitic Systems• SOA

• Monolithic vs Microservice• Advantage & Disadvantage.• Benefits of Microservices• Examples• Takeaway• Q&A

Monolithic Architecture

• A monolithic application is self-contained, and independent from other computing applications. The design philosophy is that the application is responsible not just for a particular task, but can perform every step needed to complete a particular function.

• Complete task, end to end• Work together• No Modularity • Reuse of parts of the application logic• Maintenance by allowing repair or replacement of parts

Basic Monolithic enterprise application

Examples

• Most programs you deal with day-to-day • word processing, spreadsheets , powerpoint • e-mail (?)• development environments • Compilers• many games

• Large, corporate batch systems • payroll• reports • astounding number of very large mainframe

Characteristics• Usually written in a single programming language. • Everything compiled and linked into a single (monolithic) application • May operate in both batch and GUI

• Data• – load into memory – write all back on explicit save • – No simultaneous data sharing

• May have concurrency • – multi-threading • – multi-processing (but only one executable)

Advantages

• Performance – Reading and writing of data can be optimized for performance without regard to issues such as multi-user data sharing. – read data directly from the disk via file system – read data less directly from the disk via layers of intervening software (e.g., RDBMS, OODBMS, distributed data server). – modifying data needn’t worry about writers in other address spaces.

• In-memory is massively quicker • Caching would present many subtle issues for shared data systems – No IPC overhead • Simplicity – less code to write – fewer issues to deal with• locking, transactions, integrity, performance, geographic distribution

Disadvantages• Lack of support for shared access, forces one-at-a-time access • Mitigate: • allowing datasets that merge multiple files • hybrid approaches• complex monolithic analysis software • simple data client/server update software

• Quantity of data– when quantity of data is too large to load into memory

– too much time to load too much virtual memory used – Depending on which is possible

– sequential access (lock db or shadow db)– selective access

Some Definitions...

• Microservices are small, autonomous services that work together.

• The microservice architectural style is an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms.

• A typically referenced guideline is the Two-Pizza Team rule, which states if you cannot feed the team building a microservice with two pizzas, your microservice is too big.

What is Microservice?

• Each service is loosely coupled / independently deployable.• Changes made only to this service.

• Each service has a bounded context.• Service should not know about surrounding service.

• Remotely accessible service (typically http).• Does “one thing” (and does it well?).• Executes stand alone in a container (JVM - in this case).• Can be composed into a larger service.

Challenges

• Scaling monolithic applications is challenging as we have just one degree of freedom to scale out

• The same challenge applies to replication• Innovation is constrained by the fact that we cannot easily mix different

technologies for implementing the various functionalities• Incremental Change is constrained by the fact that can’t incrementally

deploy new functionalities . We needto redeploy an entire subsystem.• Loose Coupling and High Cohesion are harder to achieve and especially

to preserve as the barriers” between functionalities are very thin

Why not monolithic?• Development Phase• Apps grow (teams grow too!)• Different parts change at different rates.• Different execution container needs (resources)• Different teams?• Company grows?

• Deployment Phase• Deploying a change to a microservice does not• Increase blood pressure as much as deploying the• ONE MASSIVE APP THAT RUNS EVERYTHING• Fear of deploying a change.• Risk of trying a new technique, new framework.

Why Microservices?

Characteristics

• Services• Products vs Projects• Smart endpoints / dumb pipes• Decentralized governance• Decentralised data management• Automation• Design for failure• Evolutionary design

Microservice Architectures

• Individual functionalities become unit of deployment and run in their own process

• Microservices communicate through some lightweight mechanism.

Monolithic vs. Mircoservice

• A monolithic applications merges multiple functionalities in the same executable.

Advantages

• Small code base / easier to test / maintain• Easy to scale - clone• Easy to throw away• Easy to deploy and track errors• Freedom to switch tech stack• Maximise team agility• Maximise resource utilisation• Debugging• Smooth deployments

Disadvantages

• Devops challenge on multiple fronts• Complexity in messaging and front end• Most container technologies still new• Freedom of tech stack not always good news (for the future

and for the CTO)• Cost • Performance• Deployment and• Operation

Anatomy of a Microservice• Decoupled Middleware design pattern• Microservices communicate across a Service Bus (Kafka, RabbitMQ, NATS.io)• Service Bus is centralised• Microservices are distributed• TCP communication is generally favoured• Microservices do 1 thing only, and they do it very well• Not restricted to a specific technology• Facilitates Circuit Breaker, Bulkhead, and Handshaking design patterns• Avoids cascading failure

Technical Benefits

• Eliminates dependencies• Failure is isolated• React to change quicker

• Scale is less expensive • More intuitive learning curve• Technology stack is not limited to specific skillsets• Shielded from legal pitfalls• Reusable components• Flexible – will bend rather than break under pressure

Micro Service and agility

• Modern agile practice can not ignore tech• No modern tech = no absolute agility• Micro services enable agility in a special way

• Enforce team creation• Enforce faster deployments / better & easier tests• CI / CD• Easier communication flow methods (APIs)• Each service = small scale product

Container Technology in micros

• Containers assist micro architecture in• Visualising services• Building / sharing services between coders• Deploying services• Utilising server resources to run containers• irrespective of underlying tech

• Popular container technologies• Docker• Rocket

Container Management

• Used to maintain and utilize containers /services• Make sure all services up and running• Make sure server utilisation is maxed out

• Popular container management technologies• CoreOS fleet• Docker-machine• Mesos• Kubernetes• AWS ECS / Google Container Engine

The Anatomy of a hybrid Service

List of Companies following Microservice Architecture

• Comcast• Cable• Uber• Netflix• Amazon• Ebay• Sound Cloud• Karma• Groupon• Hailo• Gilt