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Micro Services
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Prasanna N Venkatesan
Developer with ThoughtWorks
http://prasans.info/blog @pvenk
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Expect for…
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Expect for…
• What are Micro services?
• Why we need a new pattern?
• Implementing a Micro Service
• When to use Micro Services
• Implications of using Micro Services
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Write programs that do one
thing and do it well.
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Micro Services should be…
Small
• aka Simple
• In terms of LOC.
• In terms of memory footprint.
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Micro Services should be…
Portable
Should be independent to deploy and run
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Micro Services should be…
Performs one thing
Adding many functionality to one service
will break the other 2 characteristics.
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Move the complexity to
Infrastructure
We've
pushed
a
lot
of
the
old
applica2on
complexity
down
to
infrastructure
level.
We
are
no
longer
bound
to
a
single
stack
or
language.
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Micro Services
A new Paradigm?
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Small is beautiful
Make each
program do one
thing well.
Build a prototype as
soon as possible.
Choose portability
over efficiency.
Use software
leverage to your
advantage.
Make every
program as filter.
UNIX
Philosophy
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Consumer-Driven
Contracts
Read
more
on:
h?p://mar2nfowler.com/ar2cles/consumerDrivenContracts.html
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No content
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• Provider Contracts
• Consumer Contracts
• Consumer Driven Contracts
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• Closed and complete
• Singular and nonauthoritative
• Bounded stability and
immutability
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Domain Driven Design
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• Project's
primary
focus
on
the
core
domain
and
domain
logic.
• Complex
designs
based
on
a
model
of
the
domain.
• Itera2vely
refine
a
conceptual
model
that
addresses
par2cular
domain
problems.
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Communication
• Mostly over HTTP and pass JSON between services.
• If serialization or de-serialization is expensive try
something like ProtoBuf/MessagePack
• ProtoBuf - Google uses Protocol Buffers for almost
all of its internal RPC protocols and file formats.
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Monitoring
• More possibility of small services to
just fail and fade away.
• Make sure services are running always
• Monitor usage and increase instances
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Monitoring Tools
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Testing Strategy
• Tes2ng
Micro
Services
are
not
so
cri2cal.
• Preferably
have
health-‐check
tests
in
CI.
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Where to use Micro Services
• Independent, small process worthy to try out in
different stack.
• Don’t want to break a legacy system.
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Implications
• Understanding how everything fits together
• Deployment
• Interactions between components
• Duplication of code across the services