As traditional
enterprises work to embrace business deployment agility of new age internet
companies and innovations in engineering practices, the modern application
development has grown increasingly complex. The large, monolithic codebases
that traditionally power enterprise applications make it difficult to quickly
launch new business capabilities. The application users are empowered and more
demanding than ever – the modern enterprises need to scale effectively and
enable continuous deployments to ensure customers are provided with high
performance with the seamless user experience.
Due to these
trends, there is a demand for a new software architecture pattern/style that
can address the requirements of the modern age enterprise apps. The
Microservices architecture style is the answer to business agility in the form
of scalability, modularity and rapid deployments.
What Is
Microservices?
It is an
architectural style to develop a small/coarse grained services separated by
business boundaries. Thus each service is autonomous in nature and can scale
independently. Each service can communicate each other via REST APIs and can be
deployed remotely or locally.
Monolithic pain
points
Before
Microservices, a common approach to design an application was to use a monolithic
architecture. In this mode of development, the application is deployed as a
single deployment artifact. Following are pain points associated with classic
monolithic codebases.
- Large
monolithic code base will have the challenge to release new services and
also difficulty in maintaining large code base
- Modules
can’t scale independently
- Enable /
Disable services without affecting existing features will be always a
challenge
- Any small
change in the code will introduce many regression testing/complex deployment
scenarios.
- Will have
challenges in continuous deployments
Difference with SOA
At outset, both
architecture styles look similar. But there are subtle differences, the
noteworthy are:
- SOA uses
ESBs while Microservices can leverage lightweight message gateways
- Microservices
are stateless implemented via REST APIs while SOA can be stateful
- SOA focuses
on reusability wherein Microservices is for decoupling
Tool support
Lightweight
containers like Docker will provide provides a runtime environment for deployment
and provides isolation with other services. There is many open sources / COTS
tooling support available for Microservices enablement.
Pros / Cons
Following table
summarizes briefly about Microservices advantages/disadvantages. The
Microservices architecture can’t be suited for each app. The recommended
approach is to gradually convert highly customer facing modules to
Microservices, stabilize the rapid deployment cycle and gain the experience by
maintaining these services over the period of time. This will have less impact
on development teams/organization change management activities as teams have to
adopt new way of developing the apps.
Advantages
- Decoupled
services can have isolated life cycle
- Faster time
to market; less regressions
- Modular in
nature, hence flexible development and deployment plans
- Can scale
independently
Disadvantages
- Monitoring
the many services
- Developer
skill set – For example: Microservices are distributed in nature. Hence
there will be added complexity such as network latency, network
unreliability, also understanding the DevOps culture
- Technology
learning curve – new set of tools to learn
