Mphasis Digital - Use Go (gloang) for system programming, distributed systems and cloud workloads

Mphasis Digital - Use Go (gloang) for system programming, distributed systems and cloud workloads

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  1Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis Mphasis Digital POV Use Go for System Programming, Distributed Systems and Cloud Workloads PoV by Aniruddha Chakrabarti AVP Digital, Mphasis
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  2Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis Abstract C and C++ are widely accepted and used as de-facto standard for systemprogramming language.In spite of the tremendous success and adoption of C and C++, there was always need for a more modern system programming language that would not only have performance characteristics of C and C++, but also the flexibility of other modern languages such as Python, Pascal, Modula and Smalltalk. In recent past (since 2000) we have seen three moderately successful system programming languages being born – D (in 2001), Go (in 2009) and Rust (in 2012). Among them, while D is a close follower of C and C++, if not predecessor and hence the name D, Go takes a unique and differentiated approach than C and C++. We believe this is the strongest reason behind Go’s success. Go is also well suited for web development. There are multiple web development frameworks and middle tiers for Go that have received success in recent times, including Martini, Gin, Negroni, Revel, Beego, Gorilla and Net/HTTP. Go is also supported by multiple PaaS platforms including Google Cloud Platform (App Engine), Cloud Foundry (including Pivotal Web Service) and Heroku. AWS Elastic Beanstalk also supports deploying Go applications. We strongly believe that in future Go would come out as a strong alternate of C and C++ in the area of system programming, web development, large scale distributed systems and cloud workloads.0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 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0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 1 0 0 1 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 Overview of Go Go or Golang is an open source programming language developed at Google, specially targeted at system programming and for building large scale distributed systems. It is natively compiled (does not need a VM to run), statically typed language following the footsteps of system programming languages such as C and C++. But Go is garbage collected, unlike C and C++. Go is designed with the philosophy of “Less is exponentially more”. In a blog post dated June 2012, Rob Pike, one of the designers of the language, reported how a language with less but well-designed features is far better than a language. Go is not an object-oriented language. While Go support types, methods and interfaces, it does not support classes, inheritance, overloading of methods or operators. History of Go • Go language was originated as an outcome of an experiment by Robert Griesemer, Rob Pike and Ken Thompson at Google, to design a new system programming language in 2007 • Officially announced in November 2009, it is used in some of Google's production systems as well as by other firms • Version 1.0 was released in March 2012 and between 2012 and 2015, multiple versions were released • Version 1.5 was released in August 2015, which is the current stable version When you think about system programming, think Go - developed at Google for advanced technology demands
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  3Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis New Programming Languages Programming Language Backed by / Developed at First public release Success Paradigm Suitable for Go (also called golang) Google November 2009 High Procedural - Designed from ground up with concurrency in mind. Supports Actor model based concurrency. System programming, large scale distributed systems, cloud workloads, web back ends D Facebook December 2001 Medium Procedural, Object-oriented System programming, large scale distributed systems, web back ends Rust Mozilla 2010 Medium Procedural, Object-oriented with functional programming constructs. System programming R Bell Laboratories Late 90s High Object-oriented with functional and procedural constructs. Statistical computing, Big Data analytics Scala Open Source 2004 High Object oriented with influences functional programming Programming. Supports actor model based concurrency. General purpose Groovy Apache Foundation 2004 Medium Object oriented programming language with dynamic typing – designed for scripting in mind General purpose, scripting focused Clojure Open Source 2007 Low Functional – Is a dialect of Lisp General purpose Dart Google 2011 Low Object-oriented with scripting and functional programming constructs. Designed from group up for web development. Supports Actor model based concurrency. Web development TypeScript Microsoft 2012 Medium Scripting language with Object oriented constructs. Designed from group up for web development Web development F# Microsoft 2005 Medium Functional programming language that supports object oriented concepts General purpose Ceylon Red Hat 2011 Low Object oriented General purpose Swift Apple 2014 High Object oriented with influences from functional programming General purpose Other System Programming Languages Language  Originator  Birth Date  Influenced by  Used for  ESPOL Burroughs Corporation 1961 Algol 60 MCP PL/I IBM , SHARE 1964 Algol, FORTRAN , some COBOL Multics PL360 Niklaus Wirth 1968 Algol 60 Algol W C Dennis Ritchie 1969 BCPL Unix PL/S IBM 196x PL/I OS/360 BLISS Carnegie Mellon University 1970 Algol-PL/I(5) VMS (portions) PL/8 IBM 197x PL/I AIX PL-6 Honeywell. Inc 197x PL/I CP-6 SYMPL CDC 197x JOVIAL NOS subsystems, most complters, FSE editor C++ Bjarne Stroustrup 1979 C. Simula See C++ Applications(6) Ada Jean Ichbiah. S. Tucker Taft 1983 Algol 68, Pascal, C++, Java, Effel Embedded systems, OS kernels, compilers, games, simulations, Cubesat, air traffic control, and avionics D Digital Mars 2001 C++ XomB Go Google 2009 C, Pasacal, CSP Some Google systems.(7) Docker, Kubernetes, CoreOS(a) Rust Mozilla Research(8) 2012 C++, Haskell, Erlang, Ruby Servo layput engine System Programming Languages Developed after 2000
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  4Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis Go Usage • Many Google web properties and systems including YouTube, Kubernetes containers and download server dl.google.com • Docker, a set of tools for deploying Linux containers • Dropbox, migrated some of their critical components from Python to Go • SoundCloud, for many of their systems • Cloud Foundry, a platform as a service (PaaS) • Couchbase, Query and Indexing services within the Couchbase Server • MongoDB, tools for administering MongoDB instances • ThoughtWorks, some tools and applications around continuous delivery and instant messages • SendGrid, a transactional email delivery and management service • The BBC, in some games and internal projects • Novartis, for an internal inventory system For a complete list of apps and systems that use Go refer- https://en.wikipedia.org/wiki/Go_(programming_language)#Notable_users and https://github.com/golang/go/wiki/GoUsers Features that made Go a success Pointers Interface Rich Standard Library Structs and Methods First class functions Actor Model Based Concurrency First class functions Go supports first class functions - Functions could be assigned to variables and passed as parameter to other functions. They could be even returned from other functions. Go supports anonymous functions, multiple return values from functions and all concepts supported by functional programming languages. Anonymous Functions Anonymous Functions are functions without name – they are typically assigned to variable. func main(){ add := func(x int, y int) int {return x+y} var sub = func(x int, y int) int {return x-y} fmt.Println(add(20,30)) fmt.Println(sub(20,30)) }
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  5Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis Functions can be passed to other functions as parameters. In the below example higherOrderFunc is a higher order function that accepts another function (f func(x int, y int) int) as parameter - func main(){ add := func(x int, y int) int {return x+y} var sub = func(x int, y int) int {return x-y} fmt.Println(add(20,30)) fmt.Println(sub(20,30)) fmt.Println(higherOrderFunc(add, 30, 20)) fmt.Println(higherOrderFunc(sub, 30, 20)) } func higherOrderFunc(f func(x int, y int) int, num1 int, num2 int) int{ return f(num1 * num1, num2 * num2) } Now the function definition for higherOrderFunc is a bit complicated and could get even more complicated if it accepts multiple functions as input parameter. This could be simplified by defining a user defined function type. func main(){ add := func(x int, y int) int {return x+y} var sub = func(x int, y int) int {return x-y} fmt.Println(add(20,30)) fmt.Println(sub(20,30)) fmt.Println(higherOrderFunc(add, 30, 20)) fmt.Println(higherOrderFunc(sub, 30, 20)) } type HigherFunc func(x int, y int) int // user defined function type func higherOrderFunc(f HigherFunc, num1 int, num2 int) int{ return f(num1 * num1, num2 * num2) } Similarly a higher order function could return another function – func main(){ var result = higherOrderFunc2() fmt.Println(result(30, 20)) // 50 } func higherOrderFunc() func(x int, y int)int { add := func(x int, y int) int {return x+y} return add } Go can also return multiple values from a function – func swap(x, y int) (int, int){ return y, x } var x,y int = 10,20 fmt.Println(x,y) // 10 20 var p,q int = swap(x,y) fmt.Println(p,q) // 20 10
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  6Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis Structs and Methods Structs Go does not support Class, but supports Struct. Structs in Go are typed collections of named fields similar to other programming languages like C++ and Java. Structs can have methods apart from fields. Struct allows grouping of fields (data) and methods (behavior). type Employee struct { name string // field name of type string age int // field age of type int salary float32 // field salary of type float32 designation string // field designation of type string } Structs could be initialized either using new function (Option 1) or using JavaScript like object literal notation (Option 2) // Option 1 – using new function emp := new(Employee) emp.name = "Ken Thompson" emp.age = 50 emp.salary = 12345.678 emp.designation = "Distinguished Engineer" // Option 2 – using JavaScript like object literal notation emp := Employee{} emp.name = "Ken Thompson" emp.age = 50 emp.salary = 12345.678 emp.designation = "Distinguished Engineer" Another alternate is to specify field values as parameters in the same order fields are declared // Option 3 – parameters should be in the same order fields are declared emp := Employee{"Ken Thompson", 50, 12345.678, "Distinguished Engineer"} Note: ; are optional in Go similar to JavaScript. Local variables could be assigned without specifying their types using := instead of = Structs can have arrays and other child structs as fields type Employee struct{ Name string Age int Salary float32 Skills [4]string // Array field HomeAddress Address // Nested Child struct as property } type Address struct{ StreetAddress string City string Country string } func main(){ address := Address{"MG Road", "Blore", "IN"} skills := [4]string {"C","Go","Rwust"} emp := Employee{"Aniruddha", 40, 123.456, skills, address} fmt.Println(emp) // {Aniruddha 40 123.456 [C Go Rust] {MG Road Blore IN}} fmt.Println(emp.Skills) // [C Go Rust] fmt.Println(emp.HomeAddress.StreetAddress) // M G Road }
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  7Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis Go simplifies the process and reduces a lot of effort from programming perspective. Methods Apart from member fields, Go structs support defining methods (member functions). Methods of the struct are actually defined outside the struct declaration, which is unique in Go. type Employee struct { name string age int designation string } // Displayis declaredas a method for Employeestruct func (emp Employee) Display() { fmt.Println("Name:", emp.name, ", Designation:", emp.designation) } func main(){ emp := Employee{name:"Bill G", age:55, designation:"President"} emp.Display() // prints Name: Bill G , Designation: President } Methods can accept parameter similar to normal functions – type Employee struct { name string age int designation string } // Method for struct Employee that accepts a string input func (emp Employee) Display(message string) { fmt.Println(message, emp.name, ", Designation:", emp.designation) } func main(){ emp := Employee{name:"Bill G", age:55, designation:"President"} emp.Display("Hello") } Interfaces Go support interfaces, just like C++, Java and C# do. Interfaces are named collections of method signatures. They could be treated as blueprint as they do not provide implementation. Types that implement an interface is responsible for providing the actual implementation. Go is unique in the fact that types do not have to explicitly use “implements” or other similar declarations to specify that they are implementing an interface. To implement an interface, all that types have to do is provide implementation of methods defined in interface. // An interface called Human is declared with two methods – Walk and Talk type Human interface { Walk(miles int) Talk() } // A type called Employee is declared which would implement the interface Human // Note that the type does not specify that it would implement the interface type Employee struct { name string designation string }
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  8Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis Parallelism and concurrency are the key elements in Go design // Implementation of methods of Human interface func (emp Employee) Walk(miles int){ fmt.Println("I can walk", miles, "miles") } // Implementation of methods of Human interface func (emp Employee) Talk(){ fmt.Println("I can talk. My name is", emp.name, "and I am a", emp.designation) } func main(){ var emp Human = Employee{name:"Rob Pike", designation:"Architect"} emp.Walk(10) // I can walk 10 miles emp.Talk() // I can talk. My name is Rob Pike and I am a Architect } The type implementing the interface has to implement all the methods specified in the interface. Also, all the method signatures should match. If both of these conditions are not matched then compiler complains - type Contractor struct { name string } func (cont Contractor) Walk(miles string){ fmt.Println("I can walk", miles, "miles") } func main(){ var cont Human = Contractor{name:"John Smith"} cont.Walk("7") } Go compiler throws the following error for the above example – cannot use Contractor literal (type Contractor) as type Human in assignment: Contractor does not implement Human (missing Talk method) cannot use "7" (type string) as type int in argument to cont.Walk Concurrency (Goroutines and Channels) Go has been designed from ground up, keeping concurrency and parallelism in mind. Go’s concurrency is based on a concept called Communicating Sequential Processes (CSP) that was introduced by C.A.R. Hoare in a seminal paper in 1978. CSP is similar to the Actor model of currency, which was made popular by Erlang. CSP takes a different approach to concurrency, compared to thread / lock based concurrency. While in thread based concurrency, multiple threads use shared memory to communicate among themselves, in CSP, concurrent processes or actor or routines use message passing to communicate. They do not use shared memory thus avoiding synchronization and synchronization primitive (lock, mutex, monitor, semaphore etc) related issue. Thread 1 read and write read and write Thread 2 Thread 3 Shared Memory Thread based concurrency model with shared memory
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  9Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis Do not communicate by sharing memory; instead, share memory by communicating – GoLang website Goroutine Go uses goroutines for concurrency. A goroutine is a function that executes concurrently with other goroutines in the same address space; it’s quite lightweight as compared to OS threads and is managed by Go runtime. Multiple goroutines could be executed concurrently thus bringing in concurrency. Any function could be executed as a goroutine by prefixing it with go keyword – func main() { // add function is called as goroutine go add(20, 10) fmt.Println("add executed") fmt.Scanln() } func add(x int, y int){ fmt.Println(x+y) } Channel Channels are the conduit through which messages could be sent and received. For sending and receiving messages using channel <- operator is used. Channels could be created using make function. While creating the channel the type of message to be passed using the channel is specified – Goroutines make Go easy to use and help it keep concurrency intact. Actor 1 Actor 2 Actor 3 SharedMemory Asynchronous message passing Asynchronous message passing Asynchronous message passing Actor based concurrency model - no shared memory
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  10Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis // Declare and allocate a channel channel := make(chan string) // Send a message across the channel channel <- "message" // Receive message from the channel msg:= <- channel The below example creates two goroutines – one of them behaves as message sender and the other is message receiver. The message sender then sends the message via a channel and the message receiver receives the message. Message Receiver (ReceiveMessage goroutine) Message Sender (SendMessage goroutine) Message Channel func main(){ channel := make(chan string) go SendMessage(channel) go ReceiveMessage(channel) fmt.Scanln(); } // goroutine that sends the message func SendMessage(channel chan string) { for { channel <- "sending message @" + time.Now().String() time.Sleep(2 * time.Second) } } // goroutine that receives the message func ReceiveMessage(channel chan string) { for { message := <- channel fmt.Println(message) } } Message Receiver (ReceiveMessage goroutine) Message Sender (SendMessage goroutine) Acknowledgement Channel Message Channel Acknowledgement Message func main() { // Channel used to send the message from sender to receiver msgChannel := make(chan string) // Channel used to acknowledge the message receipt by receiver ackChannel := make(chan string) go SendMessage(msgChannel, ackChannel) go ReceiveMessage(msgChannel, ackChannel) fmt.Scanln() }
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  11Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis // goroutine that sends the message func SendMessage(msgChannel chan string, ackChannel chan string) { for { // Send the message to message channel msgChannel <- "Sending message @" + time.Now().String() time.Sleep(2 * time.Second) // Receive the acknowledgement from acknowledgement channel ack := <-ackChannel fmt.Println(ack) } } // goroutine that receives the message func ReceiveMessage(msgChannel chan string, ackChannel chan string) { for { // Receive the message from message channel message := <-msgChannel fmt.Println(message) // Send the acknowledgement to acknowledge channel ackChannel <- "Message received @" + time.Now().String() } } Pointers Unlike some of the new programming languages such as Java, C#, Ruby, Python and Swift, Go supports pointers. Pointers in Go behave much the same way as C and C++. Pointers reference a location in memory where a value is stored rather than the value itself. A pointer is represented using the * (asterisk) character followed by the type of the stored value. The & (ampersand) operator is used to denote the address of a variable. In the below example, a pointer is declared that points to an existing string variable (city). The address of the pointer and the value it’s pointing to is printed. var city string = "Bangalore" // Declare a pointer that points to the address of city variable ptrToCity := &city // Print the address of the pointer and value the pointer is pointing to fmt.Println("&ptrToCity = ", &ptrToCity); // prints the address of the pointer fmt.Println("*ptrToCity = ", *ptrToCity); // prints the value it’s pointing to Changing the value of the pointer changes the value of the original value it is pointing to - var city string = "Bangalore" var ctr int = 10 // Declare two pointers pointing to city and ctr variables ptrToCity := &city ptrToCtr := &ctr fmt.Println("city = ", city, ", *ptrToCity = ", *ptrToCity); fmt.Println("ctr = ", ctr, ", *ptrToCtr = ", *ptrToCtr); Go is one of the most advanced programming languages for a reason - it supports the use of pointers.
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  12Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis // Change the values of the pointers *ptrToCity = "Kolkata" *ptrToCtr = 20 // The original variables to which pointers are pointing is also changed fmt.Println("city = ", city, ", *ptrToCity = ", *ptrToCity); fmt.Println("ctr = ", ctr, ", *ptrToCtr = ", *ptrToCtr); Rich standard library Go comes with a large no of packages that provide common functionality such as File handling, IO, String handling, Cryptography etc. Below is a list of popularly used Go packages - Sl. No Description Package Name 1 String manipulation Strings 2 Input and Output io, bytes 3 Files and Folders os, path/filepath 4 Errors Errors 5 Containers & Sort container/list 6 Hashes and Cryptography hash, crypto 7 Encoding encoding/sob 8 Allows interacting with Go's runtime system, such as functions to control goroutines Runtime 9 Synchronization Primitives Sync 10 Server communication, RPC, HTTP, SMTP etc. net, http/rpc/jsonrpc 11 Math library Math 12 Zip, Archive, Compress archive, compress 13 Database related database, sql 14 Debugging Debug 15 Automated testing Testing Other highlights of Go 1. Go is statically typed 2. Natively compiled, but garbage collected 3. Go is statically typed with optional type inference 4. Supports Defer, Panic and Recover for error handling 5. Does not support classes and inheritance 6. Does not support overloading of methods and operators 7. Go compiler compiles source code very fast. 8. Does not support Generics Conclusion Go has evolved as a major programming language suitable for not only system programming, but also for cloud workloads. Go is supported by multiple cloud platforms, including Google Cloud Platform (App Engine), Cloud Foundry (including Pivotal Web Service), Heroku and AWS Elastic Beanstalk. Microsoft also added "experimental support" for Go into its Azure cloud service. Go is becoming a popular language of choice for system programming, web development, large scale distributed systems and cloud workloads. Further Reading • Less is exponentially more: A blog by Rob Pike - http://commandcenter.blogspot.de/2012/06/less-is-exponentially-more.html • Go website - https://golang.org • Go FAQ - https://golang.org/doc/faq#Is_Go_an_object-oriented_language • Go By Example - https://gobyexample.com/ • An Introduction to Programming in Go - https://www.golang-book.com/books/intro • Little Go Book - http://openmymind.net/assets/go/go.pdf • Effective Go - https://golang.org/doc/effective_go.html • Communicating Sequential Processes - https://en.wikipedia.org/wiki/Communicating_sequential_processes Copyright ©: The brand names mentioned in this POV (Go, D, Rust, C, C++, AWS, Heroku, Google Cloud Platform, Cloud Foundry, Pivotal Web Service, Azure etc.) belong to their respective owners.
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  13Use Go forSystem Programming, Distributed Systems and Cloud Workloads Mphasis Aniruddha Chakrabarti Associate Vice President, Digital, Mphasis Aniruddha has 16+ years of IT experience spread across systems integration, technology consulting, IT outsourcing and product development. He has extensive experience of delivery leadership, solution architecture, presales, technology architecture and program management of large scale distributed systems. As AVP, Digital in Mphasis, Aniruddha is responsible for Presales, Solutions, RFP/RFI and Capability Development of Digital Practice. Before as Sr. Manager & Sr. Principal Architect in Accenture, he was responsible for presales, architecture and leading large delivery teams. He had played delivery leadership and architecture focused roles in Microsoft, Target, Misys and Cognizant. His interests include digital, cloud, mobility, IoT, cognitive computing, NLP, distributed systems, web, open source, .NET, Java, programming languages and NoSQL. His industry experience spans Retail, Healthcare, Capital Markets, Insurance, Travel, Hospitality, Pharma and Medical Technology. VAS01/07/16USLETTERBASIL4020 For more information, contact: marketinginfo@mphasis.com USA 460 Park Avenue South Suite #1101 New York, NY 10016, USA Tel.: +1 212 686 6655 Fax: +1 212 683 1690 Copyright © Mphasis Corporation. All rights reserved. UKt88 Wood Street London EC2V 7RS, UK Tel.: +44 20 8528 1000 Fax: +44 20 8528 1001 INDIA Bagmane World Technology Center Marathahalli Ring Road DoddanakundhiVillage,Mahadevapura Bangalore 560 048, India Tel.: +91 80 3352 5000 Fax: +91 80 6695 9942 About Mphasis Mphasis is a global Technology Services and Solutions company specializing in the areas of Digital and Governance, Risk & Compliance. Our solution focus and superior human capital propels our partnership with large enterprise customers in their Digital Transformation journeys and with global financial institutions in the conception and execution of their Governance, Risk and Compliance Strategies. We focus on next generation technologies for differentiated solutions delivering optimized operations for clients. www.mphasis.com