Software Architecture - Principles Patterns and Practices - OSI Days Workshop - 2016
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Are you a developer or designer aspiring to become an architect? Do you want to learn about the architecture of open source applications? Do you want to learn software architecture through case studies and examples? If you have answered “yes” to any of these questions, this workshop is certainly for you. This workshop will introduce you to key topics in software architecture including architectural principles, constraints, non-functional requirements (NFRs), architectural styles and design patterns, viewpoints and perspectives, and architecture tools. A special feature of this workshop: it covers examples and case studies from open source applications. What’s more, you’ll also get exposed to some free or open source tools used by practicing software architects. http://opensourceindia.in/osidays/workshops-osi-2016/
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Software Architecture - Principles Patterns and Practices - OSI Days Workshop - 2016
- 1. Ganesh Samarthyam ganesh@codeops.tech www.codeops.tech Software Architecture: Principles, Patterns, and Practices
- 2. Why do you want to become an architect? What skills are required for an architect? Who is an architect? What essential knowledge is required for an architect?
- 3. What is software architecture? How to evolve an architecture? What is the software architecture development process? What factors influences software architecture?
- 4. Generalist Specialist Source: Software Architecture for Developers, Simon Brown, LeanPub, 2014
- 6. “The software architecture of a program or computing system is the structure or structures of the system, which comprise software elements, the externally visible properties of those elements, and the relationships among them” Source: So)ware Architecture in Prac2ce (2nd edi2on), Bass, Clements, Kazman; Addison-Wesley 2003:
- 7. “Architecture is a set of principal design decisions about a software system” Source: R. N. Taylor, N. Medvidovic, and E. M. Dashofy. 2009. Software Architecture: Foundations, Theory, and Practice. Wiley Publishing.
- 8. “The architecture of a deployed software is determined by those aspects that are hardest to change” Source: R. N. Taylor, N. Medvidovic, and E. M. Dashofy. 2009. Software Architecture: Foundations, Theory, and Practice. Wiley Publishing.
- 9. Architecture represents the significant design decisions that shape a system, where significant is measured by cost of change. - Grady Booch (2006)
- 10. NFRs Constraints TechnologyCross-cutting concerns Others (e.g.: overall structure) Dimensions of ADs
- 11. Cross-cutting concerns Error/Exception handling ConcurrencyPersistence Event handling Interaction and presentation Source: SWEBOK v3
- 15. Source: Software Architecture for Developers, Simon Brown, LeanPub, 2014
- 16. Architecture/design determines qualities Understandability Changeability Extensibility Reusability Testability Reliability Arch/ Design impacts impacts impacts
- 17. Architecture principles and styles Architectural principles: Axis, symmetry, rhythm, datum, hierarchy, transformation
- 18. Dravidian styleRenaissance style Mughal style Post-modern style
- 19. What architectural style is this? Image source: http://ashokbasnet.com.np/wp-content/uploads/2011/03/wx_thumb-5B1-5D.jpg
- 20. Example: Abstracting for portability using layering • Helps'abstract'pla-orm0 specific'details'abstrac4ng' hardware'specific'aspects'' Hardware' Abstrac4on' Layer'(HAL)' • Abstracts'OS'specific' func4onality'and'provides' a'generic'interface'to' underlying'OS' Opera4ng' System' Abstrac4on' Layer'(OSAL)' • Hides'database'specific' aspects'by'providing'a' generic'interface'' Database' Abstrac4on' Layer'(DAL)'
- 21. Layering style: Benefits + Reuse of layers + Support for standardization + Dependencies are kept local + Exchangeability Frank Buschmann, Regine Meunier, Hans Rohnert, Peter Sommerlad, and Michael Stal. 1996. Pattern-Oriented Software Architecture: A System of Patterns. John Wiley & Sons, Inc., NY, USA.
- 22. Layering style: Liabilities - Cascades of changing behavior - Lower efficiency - Unnecessary work - Difficulty in establishing the correct granularity of layers Frank Buschmann, Regine Meunier, Hans Rohnert, Peter Sommerlad, and Michael Stal. 1996. Pattern-Oriented Software Architecture: A System of Patterns. John Wiley & Sons, Inc., NY, USA.
- 23. What architectural style is this?
- 24. $ cat limerick.txt There was a young lady of Niger Who smiled as she rode on a tiger. They returned from the ride With the lady inside And a smile on the face of the tiger.
- 25. $ cat limerick.txt | tr -cs "[:alpha:]" "n" | awk '{print length(), $0}' | sort | uniq 1 a 2 as 2 of 2 on 3 And 3 Who 3 she 3 the 3 was 4 They 4 With 4 face 4 from 4 lady 4 ride 4 rode 5 Niger 5 There 5 smile 5 tiger 5 young 6 inside 6 smiled 8 returned
- 26. List<String> lines = Files.readAllLines(Paths.get("./limerick.txt"), Charset.defaultCharset()); Map<Integer, List<String>> wordGroups = lines.stream() .map(line -> line.replaceAll("W", "n").split("n")) .flatMap(Arrays::stream) .sorted() .distinct() .collect(Collectors.groupingBy(String::length)); wordGroups.forEach( (count, words) -> { words.forEach(word -> System.out.printf("%d %s %n", count, word)); }); 1 a 2 as 2 of 2 on 3 And 3 Who 3 she 3 the 3 was 4 They 4 With 4 face 4 from 4 lady 4 ride 4 rode 5 Niger 5 There 5 smile 5 tiger 5 young 6 inside 6 smiled 8 returned
- 28. Pipe-and-filter: Benefits + Flexibility by filter exchange + Flexibility by recombination + Reuse of filter components + Rapid prototyping of pipelines Frank Buschmann, Regine Meunier, Hans Rohnert, Peter Sommerlad, and Michael Stal. 1996. Pattern-Oriented Software Architecture: A System of Patterns. John Wiley & Sons, Inc., NY, USA.
- 29. Pipe-and-filter: Liabilities - Sharing state information is expensive or inflexible - Efficiency gain by parallel processing is often an illusion - Data transformation overhead - Difficult to handle errors Frank Buschmann, Regine Meunier, Hans Rohnert, Peter Sommerlad, and Michael Stal. 1996. Pattern-Oriented Software Architecture: A System of Patterns. John Wiley & Sons, Inc., NY, USA.
- 30. POSA - before and after
- 32. What is the architecture style followed by World Wide Web (WWW)?
- 35. SOA (Service Oriented Architecture) Lambda Style Microservices REST (Representational State Transfer) Map-Reduce CQRS (Command-Query Responsibility Segregation ) Software Containers Event Sourcing
- 36. Command Query Responsibility Segregation (CQRS) pattern source: https://msdn.microsoft.com/en-us/library/jj591573.da82141c6f9950d64c1263fa4da825ec(l=en-us).png
- 37. Event Sourcing pattern source: https://msdn.microsoft.com/en-us/library/dn589792.aspx
- 38. Map-Reduce pattern Input Sara Booch Thayer Merlin Sara Ralph Merlin Tim Sara Christian Ralph Cormen … Computer Cluster map map map Sara, 1 Ralph, 1 Merlin, 1 Tim, 1 Sara, 1 Booch, 1 Thayer, 1 Merlin, 1 Sara, 1 Christian, 1 Ralph, 1 Cormen, 1 reduce reduce Sara, 3 Booch, 1 Thayer,1 Merlin, 2 Ralph, 2 Tim, 1 Christian, 1 Cormen, 1 … OutputSara, 1 Sara, 1 Sara, 1 Booch, 1 Thayer, 1 Merlin, 1 Merlin, 1 Ralph, 1 Ralph, 1 Tim, 1 Christian, 1 Cormen, 1
- 39. What style is this? Batch layer Serving layerSpeed layer
- 41. Microservices is an architectural style
- 42. Complex application = composed of tiny services
- 43. Communicate over REST API HTTPGET HTTPPUT HTTP POST HTTPDELETE
- 44. Underlying philosophy “do one thing and do it well”
- 45. Monolithic
- 46. Microservices
- 47. Conway’s law “Any organization that designs a system… will inevitably produce a design whose structure is a copy of the organization's communication structure”
- 48. Conway’s law Team 1 Team 2Team 3 Team 4
- 49. Conway’s law Team 1 Team 2 Team 3 Team 4
- 52. Service = manageable by “two pizza” team
- 53. Amazon’s rules for teams • All teams will henceforth expose their data and functionality through service interfaces. • Teams must communicate with each other through these interfaces. • There will be no other form of inter-service/team communication allowed: no direct linking, no direct reads of another team’s datastore, no shared memory model, no backdoors whatsoever. • The only communication allowed is via service interface calls over the network. • It doesn’t matter what technology they [other services] use. • All service interfaces, without exception, must be designed from the ground up to be externalizable. • That is to say, the team must plan and design to be able to expose the interface to developers in the outside world.
- 54. Service = a team can DURS (Deploy, Update, Replace, Scale) Microservices = Damn U R Sexy
- 55. Amazon case study 2-tier architecture SOA Microservices
- 57. Triggering microservices Source: DevOps: A Software Architect's Perspective, Len Bass, Ingo Weber, Liming Zhu, Addison-Wesley Professional, 2015
- 59. A process for architecting using scenarios Source: http://msdn.microsoft.com/en-us/library/ee658084.aspx
- 60. Strategies and tactics A tactic is a design decision that influences the control of a quality attribute response A collection of tactics is known as “strategies” Source: Len Bass, Paul Clements, and Rick Kazman. 2003. Software Architecture in Practice (2 ed.). Addison-Wesley Longman Publishing Co., Inc., Boston, MA, USA.
- 61. Example: Security tactics Security Resisting Attacks Detecting Attacks Recovering From attack ! Authenticate users ! Authorize users ! Maintain data confidentiality ! Maintain integrity ! Limit exposure ! Limit access Restoration Identification Stimulus: Attack Response: System detects, resists, or recovers from attacks See “Availability“ Audit Trail Intrusion Detection Source: Len Bass, Paul Clements, and Rick Kazman. 2003. Software Architecture in Practice (2 ed.). Addison-Wesley Longman Publishing Co., Inc., Boston, MA, USA.
- 62. Exercise: Tactics for achieving qualities Availability The property of software that it there and ready to carry out its task when you need it to be Testability The ease with which software can be made to demonstrate its faults through (typically execution-based) testing Security Measure of the system’s ability to protect data and information from unauthorised access while still providing access to people and systems that are authorized Performance The software’s ability to meet timing requirements Modifiability The ease with which the software can be modified (with minimal risk and cost) Source: Len Bass, Paul Clements, and Rick Kazman. 2003. Software Architecture in Practice (2 ed.). Addison-Wesley Longman Publishing Co., Inc., Boston, MA, USA.
- 63. Tactics for availability Use$fault$detec,on$tac,cs$such$as$ ping/echo,$heartbeat,$,me$ stamping,$sanity$checking,$ condi,on$monitoring,$and$self:test$ Use$fault$recovery$tac,cs$such$as$ rollback$(to$a$previous$known$ good$state),$providing$“spares”$for$ redundancy,$retry$the$opera,on,$ ignoring$faulty$behavior,$and$ degrade$(gracefully$reduce$system$ func,onality)$ Use$fault$preven,on$tac,cs$such$ as$removal$from$service$ (temporarily$remove$the$faulty$ component),$use$transac,onal$ seman,cs$(ACID$proper,es),$ prevent$system$excep,ons$from$ occurring.$ Source: Len Bass, Paul Clements, and Rick Kazman. 2003. Software Architecture in Practice (2 ed.). Addison-Wesley Longman Publishing Co., Inc., Boston, MA, USA.
- 64. Tactics for modifiability Reduce&size&of&the&module,&for& example&by&spli7ng&module&(to& reduce&the&average&cost&of&future& changes)& Increase&seman>c&cohesion&of&the& module&(by&ensuring&that&the&a& responsibili>es&serving&the&same& purpose&are&placed&in&the&same& module)& Reduce&coupling&through& encapsula>on&(by&providing&explicit& interfaces&and&hiding&internal&details),& introducing&intermediate& dependencies&(e.g.,&introduce& dynamic&lookup&of&services&with&SOA& using&directory&as&an&intermediary)&&& Source: Len Bass, Paul Clements, and Rick Kazman. 2003. Software Architecture in Practice (2 ed.). Addison-Wesley Longman Publishing Co., Inc., Boston, MA, USA.
- 65. Tactics for performance Control'resource'demand'through'requiring' smaller'demand'on'resources'to'service'the' events;'for'instance,'reducing'the'sampling' frequency'(for'capturing'environmental'data),' limi;ng'event'response'(by'queuing'the'events),' priori;zing'events'(by'ranking'the'events' according'to'their'importance'and'processing' them),'reducing'overheads'(by'consuming'lesser' resources),'bound'execu;on';mes,'and'increase' resource'efficiency.' Manage'the'resources'more'effec;vely'by' increasing'resources,'introducing'concurrency,' maintaining'mul;ple'copies'of'computa;on,' bounding'queue'sizes,'and'scheduling'resources.'' Source: Len Bass, Paul Clements, and Rick Kazman. 2003. Software Architecture in Practice (2 ed.). Addison-Wesley Longman Publishing Co., Inc., Boston, MA, USA.
- 66. Tactics for security Detect%a'acks%by%looking%for% known%pa'erns%of%intrusion,% detec8ng%service%denial,% verifying%message%integrity% before%using%them,%detec8ng% message%delay%(to%detect%man= in=the=middle%a'acks).% Resist%a'acks%by%iden8fying,% authen8ca8ng,%and%authorizing% actors%(note:%actors%are%sources% of%external%input%to%the%system),% limi8ng%access%to%resources,%and% limi8ng%exposure%of%the%system.% React%to%a'acks%when%an%a'ack% is%underway%by%revoking%access,% lock%computer,%or%inform% relevant%actors.%% Source: Len Bass, Paul Clements, and Rick Kazman. 2003. Software Architecture in Practice (2 ed.). Addison-Wesley Longman Publishing Co., Inc., Boston, MA, USA.
- 67. Tactics for testability Control'and'observe'system'state'by' providing'specializing'interfaces,'record/ playback'faults,'localize'state'storage' (instead'of'distribu;ng'the'state),' abstract'input'data'sources,'sandbox'(by' isola;ng'the'system'from'the'real'world),' and'introduce'executable'asser;ons'(to' check'if'the'program'is'in'a'faulty'state)' Limit'complexity'(by'reducing'cyclic' dependencies,'limi;ng'dependencies'to' external'components,'etc;'in'OO' systems,'limit'depth'of'inheritance'tree,' reduce'dynamic'calls;'and'having'high' cohesion,'low'coupling'and'separa;on'of' concerns);'also'limit'nonCdeterminism.' Source: Len Bass, Paul Clements, and Rick Kazman. 2003. Software Architecture in Practice (2 ed.). Addison-Wesley Longman Publishing Co., Inc., Boston, MA, USA.
- 68. InFusion/InCode
- 69. PMD CPD
- 73. Nitric
- 74. “Cities grow, cities evolve, cities have parts that simply die while other parts flourish; each city has to be renewed in order to meet the needs of its populace… Software-intensive systems are like that. They grow, they evolve, sometimes they wither away, and sometimes they flourish…” Grady Booch in the foreword for “Refactoring for Software Design Smells: Managing Technical Debt”, Girish Suryanarayana, Ganesh Samarthyam, Tushar Sharma, Morgan Kaufmann/Elsevier, 2014.
- 75. CodeCity tool
- 77. Code Query Language (NDepend, Architect, …)
- 78. Look at the world differently for creative design solutions
- 79. Who coined the term “code smell”? Hint: He also originated the terms TDD and XP
- 80. Kent Beck
- 81. Who coined the acronym “SOLID”? (as in SOLID principles) Hint: He is the author of the book “Working effectively with legacy code”
- 82. Michael Feathers S Single Responsibility Principle Every object should have a single responsibility and that should be encapsulated by the class O Open Closed Principle Software should be open for extension, but closed for modification L Liskov’s Substitution Principle Any subclass should always be usable instead of its parent class I Interface Segregation Principle Many client specific interfaces are better than one general purpose interface D Dependency Inversion Principle Abstractions should not depend upon details. Details should depend upon abstractions
- 83. Who coined the term “technical debt”? Hint: He is the creator of “wiki”
- 93. "This is a good book about ‘Design Smells’ – actually a great book – nicely organized - clearly written with plenty of examples and a fair sprinkling of anecdotes." - Will Tracz (Principal Research Scientist & Fellow, Lockheed Martin) (review in ACM SIGSOFT Software Engineering Notes)
- 94. Believe in your ideas: how small or “insignificant” it may appear to be!
- 95. "The critical design tool for software development is a mind well educated in design principles" - Craig Larman
- 96. Interface Segregation Principle (ISP) Clients should not be forced to depend upon interfaces they do not use
- 97. Example of ISP violation // using java.util.Date Date today = new Date(); System.out.println(today); $ java DateUse Wed Dec 02 17:17:08 IST 2015 Why should we get the time and timezone details if I only want a date (e.g., date of birth)? Can I get rid of these parts? No!
- 98. JSR 310: Java Date and Time API Stephen Colebourne
- 99. Example of a fix (java.time) // using java.time.LocalDate LocalDate today = LocalDate.now(); System.out.println(today); $ java DateUse 2015-12-02 I can use (and hence depend upon) only date related functionality (not time, zone, etc)
- 100. Example of a fix (java.time) You can use only date, time, or even timezone, and combine them as needed (in java.time)! LocalDate today = LocalDate.now(); System.out.println(today); LocalTime now = LocalTime.now(); System.out.println(now); LocalDateTime todayAndNow = LocalDateTime.now(); System.out.println(todayAndNow); ZonedDateTime todayAndNowInTokyo = ZonedDateTime.now(ZoneId.of("Asia/Tokyo")); System.out.println(todayAndNowInTokyo); 2015-12-02 17:37:22.647 2015-12-02T17:37:22.648 2015-12-02T21:07:22.649+09:00[Asia/Tokyo]
- 101. More types from java.time
- 103. Know and apply design principles
- 105. How to separate: a) code generation logic from node types? b) how to support different target types? class Plus extends Expr { private Expr left, right; public Plus(Expr arg1, Expr arg2) { left = arg1; right = arg2; } public void genCode() { left.genCode(); right.genCode(); if(t == Target.JVM) { System.out.println("iadd"); } else { // DOTNET System.out.println("add"); } } }
- 106. class Plus extends Expr { private Expr left, right; public Plus(Expr arg1, Expr arg2) { left = arg1; right = arg2; } public Expr getLeft() { return left; } public Expr getRight() { return right; } public void accept(Visitor v) { v.visit(this); } } class DOTNETVisitor extends Visitor { public void visit(Constant arg) { System.out.println("ldarg " + arg.getVal()); } public void visit(Plus plus) { genCode(plus.getLeft()); genCode(plus.getRight()); System.out.println("add"); } public void visit(Sub sub) { genCode(sub.getLeft()); genCode(sub.getRight()); System.out.println("sub"); } public void genCode(Expr expr) { expr.accept(this); } }
- 107. Source: “Design Patterns: Elements of Reusable Object-Oriented Software”, Erich Gamma, Richard Helm, Ralph Johnson and John Vlissides, Addison-Wesley,1994
- 108. ❖ Many distinct and unrelated operations need to be performed on objects in an object structure, and you want to avoid “polluting” their classes with these operations Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operations ❖ Create two class hierarchies: ❖ One for the elements being operated on ❖ One for the visitors that define operations on the elements
- 109. { mv = cw.visitMethod(ACC_PUBLIC + ACC_STATIC, "printOne", "()V", null, null); mv.visitCode(); mv.visitFieldInsn(GETSTATIC, "java/lang/System", "err", "Ljava/io/PrintStream;"); mv.visitLdcInsn("CALL println"); mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false); mv.visitFieldInsn(GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;"); mv.visitLdcInsn("Hello World"); mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false); mv.visitFieldInsn(GETSTATIC, "java/lang/System", "err", "Ljava/io/PrintStream;"); mv.visitLdcInsn("RETURN println"); mv.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V", false); mv.visitInsn(RETURN); mv.visitMaxs(2, 0); mv.visitEnd(); } Use of visitor pattern in ASM tool (coding example of usage) source: http://web.cs.ucla.edu/~msb/cs239-tutorial/
- 110. Apply relevant design patterns for creating high-quality designs
- 112. Extract Superclass
- 114. Modularize JDK & JRE Hide platform internal details such as sun.misc Provide a module system for Java developers Reference: http://paulbakker.io/java/java-9-modularity/
- 116. Perform periodic refactoring (floss or root canal)
- 117. When,&due&to&constraints,&I&design& quickly&and&dirty,&my&project&is& loaded&with&technical&debt&
- 119. Use technical debt approach to get buy-in for refactoring
- 122. Desirable relationship between architect and manager: partnership
- 123. Steve Jobs is viewed as an excellent speaker, business person, and leader. But not much as an architect. He is an excellent architect. Why?
- 125. In the movie Steve Jobs, he gives an example of a music composer. The composer directs the people and focuses on the orchestra. That is the case with a software architect as well.
- 126. So, what’s next?
- 127. Examples from Open Source architectures • Architecture descriptions from well-known open source software from key contributors • You can get insights on the architecture from practical illustrations http://www.aosabook.org/en/index.html
- 128. Practical book on SA • Useful to get an overview of software architecture • Especially useful if you are a programmer • Complete presentation available here.
- 129. Good first book on SA • Shares practical experiences in architecting enterprise IT systems • If you want to learn about enterprise architecture, read this
- 130. SEI’s book on SA • Good coverage of Attribute Driven Design, Architecture Trade-off Analysis Method, Quality Attributes, etc • If you want an in-depth understanding, read this
- 131. In-depth treatment on SA • Covers a wide range of topics in detail (stypes, modelling, visualisation, analysis, etc) • Perhaps the most comprehensive/in-depth discussion on important SA topics • Slides available online here
- 132. THE book on design patterns • One of the earliest and best books on design patterns • Presents a catalog of 23 design patterns • Classified as creational, structural, and behavioral patterns
- 133. THE book on architectural patterns • One of the earliest and best books on architectural patterns • Presents a catalog of architectural patterns with detailed discussion • Referred to as POSA book • First book in the series of books on patterns/ styles
- 134. Anti-patterns in development, architecture, … • A practical book that covers anti-patterns in software architectures as well as projects • Important to know anti- patterns so that we can avoid them
- 135. Architectural refactoring is tough! • The focus is on refactoring techniques, tools, and processes in the large- scale (i.e., architectural level) • Covers architectural smells as well
- 136. Getting a systems perspective • Emphasises on working with stakeholders, and using viewpoints and perspectives • Read this if you are looking for gaining an in-depth understanding of working with stakeholders and using viewpoints and perspectives
- 137. An early take on SA • Provides a good overview of architectural patterns • If you are interested in architectural styles, tools, languages and notations, etc, read this
- 138. Tips/ techniques perspective on SA • Provides a collection of advices from working architects • If you are already an architect and want to know best practices, read this
- 139. And don’t forget ours! Forewords by Grady Booch and Dr. Stephane Ducasse
- 140. Upcoming bootcamps Mod. Sw. Arch (5 Nov) SOLID Principles (19 Nov) IoT (26 Nov) S/w Arch (10 Oct)
- 141. What were your key takeaways?
- 142. Image Credits • http://it-ebooks.info/images/ebooks/3/restful_web_services_cookbook.jpg • http://southfloridaclassicalreview.com/wp-content/uploads/ 2012/11/03THECLEVELANDORCHESTRA-CPJ.jpg • http://www.ndepend.com/NS/images/CodeQuery.jpg • https://www.toadworld.com/cfs-file/__key/communityserver-blogs-components- weblogfiles/00-00-00-00-57/DN_2D00_4a.jpg • http://d152tffy3gbaeg.cloudfront.net/2015/02/AIBA-World-Boxing- Championships.jpg • http://www.lucidica.com/wp-content/uploads/2014/03/www.jpg • http://restfulwebapis.org/images/rws-cover.jpg • http://akamaicovers.oreilly.com/images/0636920021575/cat.gif • http://it-ebooks.info/images/ebooks/6/pro_rest_api_development_with_node.js.jpg • https://www.packtpub.com/sites/default/files/9781783285754.jpg • https://www.packtpub.com/sites/default/files/ B04843_RESTful%20Web%20Services%20with%20Scala_.jpg • http://i.ndtvimg.com/i/2015-02/sholay-still_640x480_61423213425.jpg
- 143. ganesh@codeops.tech @GSamarthyam www.codeops.tech slideshare.net/sgganesh +91 98801 64463 bit.ly/sgganesh