Agile Development with Smalltalk - Long
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This presentation provides an overview of Smalltalk as an object-oriented programming language and object database for agile development. Smalltalk offers a simple yet powerful language with object persistence built into the language. It allows developers to focus on business logic and processes rather than data access layers. Smalltalk also enables productive development through its integrated IDE and support for agile practices like test-driven development and refactoring.
Agile Development with Smalltalk - Long
- 1. Agile Development with Smalltalk Tomas Kukol tomas.kukol@gmail.com
- 2. Agenda This presentation brings an overview of Smalltalk programming language and Smalltalk object database Describes Current situation in application development and maintenance Smalltalk as object programming language, object database and productive development platform
- 3. Current situation (AS-IS) We use object oriented languages (C# .NET, Java) These languages are very complicated (more than 300 rules) Mastering such language with related frameworks takes 3-4 years They change very often (every 2-3 years in Microsoft .NET) Every 2-3 years every developer must learn new language features, new frameworks and completely change development environment (in .NET) Persistence of data is not part of these programming languages We use relational (non-object) databases (Oracle, SQL Server) to store data Very difficult to be agile and response to business changing needs We talk more about database tables and not about objects, their behaviors and relations Hard to test or even to prepare test data Applications are more and more complicated – everybody loves feature rich web and mobile applications Again new languages, technologies and tools Every developer must know in detail HTML, CSS, JavaScript, AJAX, JQuery, JQuery Mobile, Web Services (these things are also changing)
- 4. Current situation (AS-IS) – cont. Finally, we must leave object world and dive into database world of tables, views, stored procedures, indices, constraints, triggers. Why? Only way how to update no more than hundreds of records in timely fashion Positives and negatives of such approach? Mostly negatives Business logic is in more places – stored procedures in database and application There are no objects - only tables and procedures, new languages (T-SQL, PL-SQL), new tools and even new database versions comes (databases change also every 3-4 years) Developers must know different technologies – OOP programming, procedural database programming (and very often also database optimizations – domain of DB Admins) Object database Relational database
- 5. Possible solution? We should use true object programming language and true object database that integrates program and database, support agile development, easy refactoring and testing approach Ideal candidate is Smalltalk object programming language and GemStone/S Smalltalk object database
- 6. Smalltalk is … Programming language Simple and powerful object oriented language Has only few basic rules Very stable and easy to learn Object database Stores complete objects in object database Everything is written in Smalltalk language Productive development environment Integrates all tools for rapid application development Ideal for web and mobile applications, web services and service oriented architectures
- 7. History of Smalltalk Smalltalk created at Xerox PARC in 1970's Created as part of Dynabook project in 1972 by team of Alan Kay, Dan Ingals, Adele Goldberg and others Dynabook - A Personal Computer For Children Of All Ages Final version of Smalltalk language and framework published in 1980 Used concept of Virtual Machine and Object Memory (which is persisted) Ideas from Dynabook and Smalltalk were used by Apple and others Graphical User Interface (GUI), Objective-C (syntax of Smalltalk with messages), mouse, Virtual Machine (also used in Java and .NET) GemStone/S Smalltalk object database shipped in 1982 Enterprise object database server with ACID transactions support (Atomicity, Consistency, Isolation, Durability) GemStone/S was acquired by VMware in 2010 Squeak Smalltalk created by original authors in 1996 New free implementation of original Smalltalk ST-80 Pharo Smalltalk – special version for development of web and mobile applications
- 8. Present of Smalltalk Smalltalk is gaining popularity Squeak Smalltalk with different projects like Seaside, Open Cobalt, One Laptop per Child, Etoys, Scratch, Morphic Pharo Smalltalk for rapid web and mobile application development GemStone/S object server Direct connection to/from Java and Oracle GLASS (GemStone/S, Linux, Apache, Seaside, Smalltalk) Support for Ruby on Rails (MagLev) Smalltalk systems are used in different industries Finance JPMorgan, Swiss National Bank, UBS, Merril Lynch, … Government Canadian Revenue Agency, Norwegian Directorate of Immigration, … Transportation / Shipping OOCL, Nippon Yusen Kaisha, … Part of Computer Science studies on many universities Smalltalk is used for teaching object oriented programming and design patterns
- 9. Object persistence in Smalltalk Object persistence is integrated into Smalltalk language Developer can focus on real business logic with business objects and business processes Persistence code is written in Smalltalk Up to 5 lines of code in Smalltalk vs. 30-50 in C# .NET No other language is needed No other tools required Complete objects are stored into object database Saves 60% – 90% of developer time to handle persistence No need to prepare database, tables, views, stored procedures, insert scripts, database update scripts, configurations for different environments, installation packages etc. Objects can be reused in other applications Allowed by Share Everything architecture Better code with well tested reused objects and components
- 10. Well designed simple object language Smalltalk programming language is very stable No changes in language and framework since 1980 (ST-80) No need to rewrite applications every 2-3 years Smalltalk is easy to learn and master Only objects and message sends, 5 keywords and 3 types of messages (unary, binary, keywords) Mastering Smalltalk takes 6 months vs. 3-4 years of C# .NET Source codes of the whole system are available Stable investment to Smalltalk knowledge Smalltalk is true object language Real inheritance, polymorphism and encapsulation High reuse of existing code (up to 80%) Usage of design patterns without performance impact and limits of other object oriented languages (C# or Java)
- 11. Development of web and mobile applications Seaside web framework For web and mobile applications development Support for Web 2.0 Support for mobiles and tablets Reusable visual components and work-flows Application code is written in Smalltalk No need to learn different languages and tools (only concepts) Seaside abstracts things like HTML, CSS, JavaScript, JQuery, AJAX Application code is written as easy as desktop application Work-flow components allows to write the whole application in one method Easy to read and maintain There is no equivalent in C# .NET or Java world Handling of “Back” button problem
- 12. Agile and test driven development Supports agile test driven development and refactoring All kind of tests (even database tests) are integral part of Smalltalk program Tests can be safely run by end user from web application Integrated IDE allows refactoring of code Rapid and cheap application prototyping with Pharo Smalltalk Contains all development tools with web server Complete IDE with class browser, debugger, object inspector, workspace, console, change tracker, version control, test browser, package browser (Monticello and Metacello) Whole suite takes about 40 MB on disk (with source codes)
- 13. Deployment under control Smalltalk application is distributed in packages Package contains Smalltalk code (objects and methods) Persistence and application code, tests, examples, documentation, data migration code (in 99% not needed, but can be useful) Packages are managed by Monticello (similar to DPKG or RPM) Monticello also contains concurrent version system Allows distributed development Easy deployment of Smalltalk applications with Metacello Metacello is packaging system (similar to APT or YUM) Resolves dependencies and can automatically update the whole system to new versions of packages Application can be directly published to GemStone/S object server via Metacello Even from web application by authorized user (ISO Admin)