Table of Contents
[hemmerling] System Design
Related pages:
Organizations & Events
Organizations
- oose Innovative Informatik GmbH, Hamburg.
Events
- BarCamp system.camp berlin in Berlin.
- 2015-04-18 - I joined.
- 2016-04-16.
- Systemcamp.
- BarCamp Modeling Craftsmanship Camp in Hannover, 2016-11-19 - I joined.
- Barcamp syscamp.nord in Hamburg, 2016-12-03.
Famous Quotations "The determined Real Programmer can write FORTRAN programs in any language"
- Ed Post, "Real Programmers Don't Use Pascal", DATAMATION, July 1983, pp. 263-265 (Readers' Forum) - “Besides, the determined Real Programmer can write FORTRAN programs in any language”
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Best Practices for "Maintainable Code" & "Good Software Development Structure & Tools
- SOLID.
- Clean Code.
- Design Pattern.
- Encapsulation.
- Code Review.
- DRY ( Don´t Repeat Yourself ).
- MVC / MVVM.
- Law of Demeter.
- TDD.
- Refactoring.
- 4 Rules of Simple Design.
- KISS.
- Diagnostic Exception Handling.
- BUS-Factor ( how many team members must leave to kill the project...).
Agile Development - Procedure Models / Process Models
Arc42
- “arc42 contains a template for development, documentation and communication of software architectures”.
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- arc42 - Resourcen für Software-Architekten "Die Sommer-Aktion" - Pree paper book.
- arc42 - Resourcen für Software-Architekten ( German ).
- Wiki arc42 Wiki - “arc42 Templates (international...)”.
Architecture Tradeoff Analysis Method ( ATAM )
Attribute-Driven Design ( ADD )
Command Query Responsibility Segregation ( CQRS ) & Event Sourcing ( ES )
CQRS and the CAP Theorem / CAP Triangle
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- Consistency ( all nodes see the same data at the same time )
- Availability ( a guarantee that every request receives a response about whether it was successful or failed )
- Partition tolerance
- Classical IT design, including relational ( SQL ) databases, covers “Consistency” and “Availability”.
- CQRS, as often implemented in NoSQL databases, covers “Availability” and “Partition tolerance”.
- Messages: Commands vs. events:
- Commands are imperative, sometimes they are not for every party, there might be exceptions.
- Events are past, they happened. Events which happened can´t be changed.
Cross-Cutting Concern - The "Opposite"
Resources
- According to experts, CQRS is not intended and useful for:
- CRUD applications.
- Big data storage ( e.g. massive data acquisition ).
- Blog Wordpress "CQRS".
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- Slides SlideShare, ndrssmn "Eventzentrierte Architekturen" → Advertising of SoCraMOB 2014.3
. - Slides SlideShare, mbild, "CQRS + Event Sourcing", @Frankfurt 2013.
- Video YouTube "DDD Lean Hangout", 2013-09-15.
Experts
- CQRS+ES expert CodeBetter "Greg Young", CQRS Info - Command Query Responsibility Segregation ( cqrsinfo.com ).
- CQRS+ES expert Distributed Podcast. CQRS, DDD, Cloud computing and much more! ( Jonathan Oliver ,.. ).
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- Marco Heimeshoff "gist:5540636" - “If you have two days to learn the very basics of modelling, Domain-Driven Design, CQRS and Event Sourcing, here's what you should do”....
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Tools
- Github "petrjanda / node-cqrs" - “Node.js implementation of CQRS”.
Convention based Framework vs. Configuration based Framework
- Configuration based framework .
- An XML file contains the configuration, which has to be created, edited and maintained ( by the user using an XML editor,..). Legacy in 2015.
- Convention based framework.
Database Application Design by Data Flow Diagrams ( DFD ) & Entity Relationship Diagrams ( ER )
Tools for Database Application Design by Data Flow Diagrams ( DFD )
Resources
Design by Contract / Contract-Driven Development
Codius
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- Hackathon Meetup "Bitcoin Startups Berlin", Event "Codius Hackathon", 2015-01-14.
D
Resources
Design Patterns
Microservices
Best Practices 2016
- With web applications built by Microservices, each Microservice is running in its own process ( i.e. with a Java engine, consuming 256 MB RAM ) and not just as Java task within a single Java engine.
- At start of a Java engine, you may set the RAM memory allocation.
- So a 64-bit computer with 4 Gbyte of RAM is suitable to run about 10-12 Microservices.
- Every Microservice of a web applicatoin may be deployed on a different physical or virtual machine.
- The developers are forced to respect interfaces.
- Each Microservice may be developed by a different team.
- For very-large web applications, it might be useful if several Microservices are responsible for a single Web page ( controlled by a major Webservice ). For normal-size web applications, it's best if a single Web page is controlled by a single Microservice.
Best Practices 2017-02, according to ThoughtWorks
- If you mustn´t do it, don´t do it.
- Principle.
- Microservices should be designed by the principle of separation of business functions. So a domain-driven development might be a success factor.
- Every microservice shall have it's own database, at least it's own database scheme. E.g. With NoSQL databses, e.g. “Cassandra Keyspaces” provide this separation.
- Communications:
- REST ist the Suggested protocol between microservides.
- Synchronous communications is prefered. Asynchronous communications, e.g. message driven systems, is very complex and might be just considered for very-large systems.
- It might not be useful with a startup project, to generate microservides. But it is useful to design a application at startup, that it can be later devided into microservices.
- A good time to start with microservices is, after the startup company got it's first paying customer and makes revenues.
- The implementation of API gateways might be useful. By that the external user just knows a generic API, while the API gateway service distributes the data to inner systems with more complex APIs.
- UI / HTML interface by microservices: A sceleton HTML page might be feeded by server-side includes from seeral microservices, e.g. in a webshop
- Design:
- Microservice for product description.
- Another microservice for the user recommendations.
- Microservices allow to write each microservice in a different programming language and/or a different framework.
Multitenancy
- Experts told me, that:
- Multitenancy is a design decision and so a design pattern, which can´t be easily implemented in a software after non-multitenancy implementation afterwards.
- So after e.g. 3 years of successful non-multitenancy implementation, there is no affordable way to implement multitenancy as additional feature, as multitenancy must be concerned at almost any business function and so almost any code function.
- It might be cheaper, also with server-based applications, to start a new application instance for each tenant, even if there are “hundreds” of different tenants.
Patterns
Flexibilty by Patterns ( Patterns which enable to create flexible Software )
- Factory and Dependency.
- Strategy Pattern ( Policy Pattern ).
- EN.Wikipedia "Strategy pattern", EN.Wikipedia "Strategie (Entwurfsmuster)" - “According to the strategy pattern, the behaviors of a class should not be inherited. Instead they should be encapsulated using interfaces”.
- Decorator Pattern.
Some other important Patterns
- Github.io "Flux - Application Architecture for Building User Interfaces", GitHub "facebook/flux" for Javascript.
- Amir Salihefendic "Flux vs. MVC" - “A look at how Facebook’s Flux pattern solves things differently, especially in relation to the Model-View-Controller (MVC) pattern”.
- EN.Wikipedia "Model–view–presenter", DE.Wikipedia "Model-View-Presenter" for some Java GUI Frameworks like Java Swing and JavaFX.
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- The ViewModel is the controller of the traditional Model-View-Controller. The pattern is designed for automatic testing.
- Requirements: A software framework which provides “DataBinding”. Microsoft .NET 4.5 does!
- Microsoft WPF, Microsoft Silverlight, Microsoft Windows 8 Phone and Microsoft Windows 8 Apps are predestined for MVVC, as Databinding is provided.
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- Microsoft suggeet using MVC with Microsoft ASP.NET, by providing an software framework which support MVC!
- YouTube Channel "envyads" - The series of videos “MVC Public Service Announcement”.
- “Code Behind” Paradigma.
- With “Windows Forms”, “Code Behind” programming is standard, which is in contrast to the objectives of MVC or MVVM to separate behaviour code from view.
- Microsoft does not provide an MVC or MVVM framework, for “Windows Forms”.
Resources
- dofactory - #1 in design pattern - ”.NET Design Patterns and Architectures in C# and VB”.
- dofactory "Design Patterns" in C#.
- JavaCamp.org "Java Design Patterns At a Glance" - Design patterns, with implementation in Java.
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Literature
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- The acompanying website O'Reilly "Entwurfsmuster von Kopf bis Fuß".
Don't repeat yourself ( DRY ) vs. Write Everything Twice ( WET ) & Because What If I Need It Later ( BWIINIL )
Fundamental Modeling Concepts ( FMC )
Embedded Systems - The Evolution of System Design for Embedded Systems
- Assembly language.
- C.
- C++.
- Objectoriented Software design
- Advanced
- Interfaces instead of inheritance.
- State machines.
- Mockup.
- Application wireing.
Fully Communication Oriented Information Modeling ( FCO-IM )
- FCO-IM does not model reality, but it models the communications about reality.
- The commercial tool CaseTalk - “free limited book edition, free student edition, free 30 days evaluation edition”.
Functional Flow Block Diagram ( FFBD ), extended Function Flow Block Diagram ( eFFBD )
- 3SL Cradle - November 2006 [Cradle 5.4] "eFFBD Reference Functions" - “The symbols provided in extended Function Flow Block Diagrams (eFFBDs) in the Essential and Implementation domains have been extended to include reference functions”.
ICONIX
- Use of just 4 UML diagrams, in this very-special order ( CLASS diagram not as second, but last diagram ):
- UML user case diagram
- UML robustness diagram.
- UML sequence diagram.
- UML class diagram.
"Imperative Programming" vs "Declarative Programming"
Old-fashioned "Structured Programming" aka "Imperative Programming"
- The commercial CASE TOOL EasyCode ( formerly: SIEMENS EasyCase ).
- The commercial CASE tool GSK Gesellschaft für Konzeption, Entwicklung und Optimierung von Software und Systemen mbH "MyFriend".
Resources
Interface Description Language ( IDL )
Literate Programming
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- Literate Programming "Download" - “CWEB”.
- “CWEB for Win32 - Download”, “CWEB Examples”.
Model Driven Architecture ( MDA ) & Dynamic System Initiative
- Book Jack Greenfield, Wojtek Kozaczynski: "Software Factories" - the book about the “Dynamic System Initiative”.
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- The free Kennedy Carter "iUMLLite" is shipped on CD with the book. The “lite” version supports class and use case diagrams, but no sequence diagrams.
Modelling SA/SD - Structured Analysis ( SA ) and Structured Design ( SD )
Object Oriented Design, Object Oriented Programming
Dependency inversion principle
Application Wireing Frameworks
- Google Code "pococapsule. An IoC and DSM framework for C/C++ applications" - “PocoCapsule is an Inversion of Control (IoC) container, a.k.a Dependency Injection (DI) framework (see article IoC vs DI), as well as a Domain Specific Modeling (DSM) engine (see article DSM in IoC)”.
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- StackOverflow "What is PocoCapsule current status?" - “I have been looking for this myself for some time now, and came realize that there are no good IoC Containers in C++. There are a lot of problems implementing this. Getting something like the C# IoC Containers (Castle Windsor, Unity, etc.) is out of reach”.
- GitHub "shdwshard/PocoCapsule" - “Poco Capsule Git Clone ”.
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Resources
- EN.Wikipedia "Inversion of control", DE.Wikipedia "Inversion of Control", EN.Wikipedia "Hollywood principle" - “Don't call us, we'll call you”
- “Tell, don´t ask”.
- Martin Fowler "TellDontAsk", 2013-09-15.
- If your favourite object oriented programming language does not have “Interfaces”, you may alternatively also use an “Abstract Class”.
Javascript - Concepts of Javascript
- Prototype-based - “JavaScript uses prototypes ( EN.Wikipedia "Prototype-based programming", DE.Wikipedia "Prototypenbasierte Programmierung" ) where many other object oriented languages use classes for inheritance”:
- Prototypes.
- Functions as object constructors.
- Functions as methods.
- Implicit and Explicit Delegation - JavaScript is a Delegation Language ( EN.Wikipedia "Delegation (programming)", DE.Wikipedia "Delegation (Softwareentwicklung)" )
- Functions as Roles ( Traits and Mixins ).
Object Calisthenics
- Rules.
- Use only one level of indentation per method.
- Don’t use the else keyword.
- Wrap all primitives and strings.
- Use only one dot per line.
- Don’t abbreviate.
- Keep all entities small.
- Don’t use any classes with more than two instance variables.
- Use first-class collections.
- Don’t use any getters/setters/properties.
Object-relational Mapping
Type Composition and Inheritance
Ports and Adapters
- Alistair Cockburn "Hexagonal architecture" - “The Pattern: Ports and Adapters ('Object Structural')”#.
- Communication between different layers: “Think in slices, not in layers ( Lasagna )”!
Critical Review of the Success of OOP in General
Resource-oriented Computing
Clean Software Installation
Sideloading
Installation with Signature
- "Meet Microsoft Signature" - “PCs with Signature will help ensure you get the best experience with Windows 8. It is the cleanest Windows 8 experience with no junkware is installed – it’s clean and easy!”.
ITU-T Specification and Description Language (SDL)
SOLID ( S.O.L.I.D )
Specification by Example
SPES2020
Story Driven Modeling ( SDM )
Example "Mensch-Ärgere-Dich-Nicht"
- Textual use case description, of DE.Wikipedia "Mensch ärgere Dich nicht".
- Story Boarding (OOA) ( Test specification ) → Object diagram. # That's the new approach!
- Class diagram deviation ( OOD ).
- Behaviour deviation ( Coding ) → Activity Diagram. How may I change the object model, to get from one state to the next ? How may I proceed from one object ot the next object ? How do I generate behaviour for the objects ?
- Code generation.
- Validation ( Testing ).
Resources
- Albert Zündow.
- The free Fujaba.
- The commercial Yatta Solutions GmbH "UML LAB", Yatta Solutions GmbH "UML LAB" - “Round-Trip-Engineering. Intuitive class diagram editor. Individual CodeStyles”.
- Maybe there will be a book about this topic by Albert Zündow and Ulrich Norbisrath in the future ?!
Structured Program Theorem
Style Guides
Apple
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- Apple Developer "Mac OS X Reference Library" - “Guides. Conceptual and task-oriented information. Guides include overviews, tutorials, programming guides, server administration guides, and, for developer tools, user guides”.
- Classical Pre-MacOSX ( MacOS9, MacOS8, MacOS7.. ) Style Guides.
- “Apple Developer Connection - Apple's Developer Guides”.
- “Macintosh Human Interface Guidelines”.
- “Macintosh Toolbox Essentials”.
Atlassian
- Atlassian Design Guidelines - “Design principles, components, patterns and guidance for building awesome Atlassian products and add-ons”
Microsoft
- Microsoft MSDN "Windows User Experience Interaction Guidelines" for Vista, Win7.
Test Driven Design ( TDD )
Twelve-Factor App
- Heroku Devcenter "Architecting Applications for Heroku" - “The Twelve Factor app, written by Heroku co-founder Adam Wiggins, is a methodology for building software-as-a-service apps in modern deployment environments”.
UML, SysML
Unsupported Software Development :-(
Big Ball of Mud :-(
Rogue Programming :-(
- Gray Matter Systems "6 Causes of Rogue Programming In Manufacturing — and 5 Reasons You Need to Avoid it" - Free PDF.
- “I call the disease “rogue” programming, but it has other names. It is also called “unsupported software development”, “custom software development”, “skunkworks”, “homegrown applications” and many other names. Rogue development is usually performed in Microsoft Access, Microsoft Excel, or Visual Basic (including VBA) and sits on SQL Server or II S boxes.
- “Sometimes shop floor PCs are converted to servers by the addition of IIS. Rogue development typically starts small – as point solutions such as managing a specific group of people (i.e. Maintenance) or a specific process (i.e. test stands, or test loops)”.
- “Sometimes the application stays small and isolated, but it can also grow tentacles into other systems/groups and new functionality until it becomes business critical and complex”.
ImmediateAnnuities.com "Rogue Programming" - ”'Rogue Programming' is any software or other materials which contain a computer virus, trojan horse, timebomb, worm or other rogue programming”.
Usability
Use Case Planning ( Use Case Points, Use Case Point Method )
- “Use Case Planning” is not about the agile project managment method “Storytelling”.
- One of the latest development of this method is “Use Case Points 3.0” ( UCP 3.0 ).
Literature
- The free PDF book Cathleen Shamieh "Systems Engineering For Dummies. IBM Limited Edition" ( btw, I got a free paper issue, at an IBM event ).
Resources
Forums, Newsgroups, Communities
- PUDN - Programmers United Develop Art -“After registration, you should [upload] more than five source codes or program documents, then your account will be activated after the codes been checked by administrator”.
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