indicthreads-pune12-typesafe stack software development on the jvm

7/30/2019 IndicThreads-Pune12-Typesafe Stack Software Development on the JVM

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Typesafe Stack Software

Development On The JVM

Sushanta Pradhan

Talentica Software (I) Pvt. Ltd.


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History of Hardware Architecture

Single core era moore's law achieved by increasing clock cycles

Multi core era moore's law achieved by increasing # of cores


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Moores Law


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PPP Grand Challenge

Parallel programming as easy as sequential

programming Mooress law of performance speed up 2 times yearon year

Eliminate concurrency bugs


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History of software applications

pre .com era

standalone desktop apps .com era

web sites - static web pages, automated businessprocesses

data controlled by software vendor

deployed on data centers


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contd ..

web2.0/semantic web era

web/networked applications

Smart apps

data not controlled by vendor but by the users

deployed on cloud


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Properties of modern day App

Scalability

Distributed Parallel & Concurrent

Dynamic

Agile & Swift


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Parallelism & Concurrency

Parallel Programming

parallel execution of programs

can't be performed without parallel hardware

programs get faster


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Parallelism & Concurrency

Concurrent Programming

simultaneous execution of programs can be performed without parallel hardware

programs get more responsive

Both are too hard !!


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Why Hard?

non-determinism due to shared mutable state byconcurrent threads

encapsulate state in actors or transactors but fundamental

problems still remains

non-determinism = parallel processing + mutable state


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Remedy?

PREVENTION IS BETTER THAN CURE !!

Avoid mutable state and get deterministic processing

Which means program functionally

S


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Space vs Time

Space(functional/parallel)

Time(imperative/concurrent)

S l


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Scala

Hybrid functional & object oriented (pure)

strong static typing Agile - concise & expressive

Parallel & Sequential

intermixes well with Java

S l td


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Scala contd ..

Parallellism

parallel collections

distributed collections

Concurrency

Actors STM Akka

Futures

S l td


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Scala contd ..

Concise Java

Immutability Val & Var

Tuples & Multiple Assignments

Sensible Defaults

Operator Overloading

S l l


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Scala classes ..

Terse

Object keyword - Singleton Companion Objects

Type inference

Option[T] Some[T], None

Cl hi h


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Class hierarchy

Scala Functional Aspects


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Scala Functional Aspects

Functions too are objects

Higher Order Functions Partially applied Functions

Closures

Scala Inehritance


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Scala Inehritance

Traits

Mixins Type inference - implicit keyword

Scala collections


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Scala collections

Mutable & immutable

filter() Map()

foldLeft()

foldRight()

Scala Pattern Matching


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Scala Pattern Matching

Advanced switch case

Literals and constants WildCards

Tuples & Lists

Guards

Regular Expressions

Scala Concurrency


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Scala - Concurrency

actor()

Actor Class

receive() & recieveWithin()

react() & reachWithin()

loop() & loopwhile()

Akka Middleware


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Akka - Middleware

Concurrent, Scalable & fault-tolerant

based on actor model highly performant

event driven

location transparency

Actor system


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Actor system

ensemble of actors sharing common configuration

hierarchical structure heavyweight

has its own pool of resources threads

Supervision


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Supervision

dependency relationship between actors

supervisor - subordinate model

supervisor monitors and reacts to any errors reported

by subordinates

configurable supervision strategy

lifecycle monitoring

Supervision hierarchy


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Supervision hierarchy

root guardian

guardianshutdown system

guardianorder

Remoting


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Remoting

ActorPath

purely local - "akka://my-sys/user/service-a/worker1" local or remote - "akka://[email protected]:5678

/user/service-b"

Seamlessly send messages to actors on remote nodes

Routing


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Routing

route messages to actors(routees)

ideal for load balancing

Examples

RoundRobinRouter

RandomRouter

SmallestMailboxRouter BroadcastRouter

Dispatchers


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Dispatchers

make akka actors tick

manages the resources(threads) used by actors configure mailboxes of actors

Examples

fork-join-executor

thread-pool-executor


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Play contd ..


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y

an easy, out-of-the-box setup for unit and functional testing

asynchronous HTTP request handling

WebSocket support

cache support (e.g. memcached)

integrated JSON and XML handling

Progressive Stream Processing


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g g

Iteratees

Enumerators Enumeratees


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Q/A

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