OSGi Evangelism and OO Design Principles

OSGi adds a higher layer of granularity to OO abstraction, information hiding, design by contract, etc. I like this quote  from Modular Mind: "Software development has advanced in large part by increasing the granularity of the aggregations that we have to work with.". In this presentation, Module Systems and Architectures, on OSGI, Martin Lippert also shows another evolution that can be seen in OSGi:


Good Old Design Principles
DIP SOC LSP ADP TDA DRY AIP
ISP SCP OCP IHP SRP SDP

New Design Principles
Use services ---> Separate between interface and implementation
Use extensions ---> working but extensible

Here's a breakdown of Martin's shortlist of "good old design principles":

Class Design Principle

• Separation Of Concerns (SoC)
• Tell, Don't Ask (TDA)
• Don't Repeat Yourself (DRY)
• Dependency Injection Principle (DIP)
• Liskov Substitution Principle (LSP)
• Open Closed Principle (OCP)
• Single Responsibility Principle (SRP)
• Interface Segregation Principle (ISP)

Package Design Principles

Cohesion Principles: 

• Reuse/Release Equivalency Principle (REP)
• Common Reuse Principle (CRP) 
• Common Closure Principle (CCP)

Coupling Principles:

• Acyclic Dependencies Principle (ADP)
• Stable Dependencies Principle (SDP)
• Stable Abstractions Principle (SAP)

  Object-Oriented Reengineering - Principles of OOD - Radu Marinescu,
  OO Design Principles - Stefan Kluth,

Emergent Design

TODO:

• Tracer Bullet Development (see Ship It, ch. 4)

• do light-weight, up front design, create a system of mock objects, and add appropriate automated tests
• System Objects: Encapsulate and Separate 
• incrementally add functionality to the system  
• Incremental Improvements: Iterations
• benefits: scalability, encapsulation, decoupled code, parallel code development, flexible to requirements creep

Static Code Analysis, Defect Detection, Code Smells, Architecture Smells, Dependency Analysis

FindBugs Descriptions

• Bad Practice
• Correctness
• Experimental
• Malicious Code Vulnerability
• Multithreaded Correctness
• Performance
• Security
• Dodgy Practices

PMD Rulesets

Lint4J checks for

• Architectual problems
• Contracts defined in the Java core API
• Java Language Constructs
• Immature code
• Performance
• Code portability
• The Serialization and Externalization contracts
• Suspicious coding and likely bugs
• Java Synchronization and Scalability
• Coding patterns that impact readability and code size
• Violations of the EJB specification

JLint Program Checker

Coverity Static Analysis, Dynamic Analysis , Architectural Analysis

NASA's JPF (Java Path Finder)
Which defects can be found by JPF? Out of the box, JPF can search for deadlocks and unhandled exceptions (e.g. NullPointerExceptions and AssertionErrors), but the user can provide own property classes, or write listener-extensions to implement other property checks. A number of such extensions, like race condition and heap bounds checks are included in the JPF distribution 

Hammurabi Hammurapi is a code quality governance platform to mitigate risks of outsourcing* of software development.

Structure 101

OSGi For Modularizing Large Projects

OSGi helps establish good practices in software development by effectively applying at a macro level these good OO practices:

• hide implementation details (design by interface contract)
• minimize dependencies (high cohesion, low coupling)

Declarative programming and in particular declarative services promote:

• extensibility (e.g. wrapping a web server)
• writing POJOs and using in a larger context

Keeping the data model and visual representation separate promotes:

• not writing too much from scratch
• maintaining the reusability of core logic
• allowing different app versions per audience
• grow or shrink app

Messaging Patterns Used In CORBA

• Synchronous with Timeout Method Invocation (SMI) – the client is blocked until a response is received from the server or a timeout occurs (client might spawn a thread so main thread is not blocked)

• Asynchronous Method Invocation (AMI) – the client is not blocked but receives a callback from the server

• One-way Method Invocation (OMI) – like AMI except no callback is received

Presentation And Diagramming Links

• Presentation Zen : lots of whitespace, few pretty pictures, a presentation should be worthless without the presenter to explain it,...
• 10 Powerpoint Tips for Preparing a Professional Presentation No sentences, never read your slides, talk freely have a take away message,...
• Mindmapping: I find the PowerPoint SmartArt template "Horizontal Hierarchy" best.
• TimeLine: PowerPoint SmartArt has a good timeline template under "Process"
• Lovely Charts: web-based graphic builder
• Web Sequence Diagrams
  
• Gliffy, Online Diagramming 
• MindTools: Lots of good descriptions of visualizations for conveying ideas (e.g. fishbone, SWOT, affinity diagram, Gantt chart, PMI, grid analyis, etc.)

Programmer Productivity Tips

1. Use a modern IDE such as Eclipse.
2. Content Assist (or Code Completion, tab completion, Intellisense, etc.)  Content assist provides you with a list of suggested completions for partially entered strings. In Eclipse type something in the editor window and then ctrl-space. (e.g in Eclipse: Preferences->Java->Editor->Content Assist->Advanced)
3. Code Templates: For example, type sysout and then ctrl-space and it spits out System.out.println(); with the cursor in the right spot. Type "for" ctrl-space and get a for...loop, type "try" ctrl-space and get a try...catch block.  (Eclipse: Window->Preferences->Java->Editor->Templates) 
4. Code Generation: Faster Java coding in Eclipse Galileo (IBM), Useful Eclipse Shortcuts (SO) , Eclipse Shortcuts (Vogella)
5. Compiler Warnings: Using Eclipse Java Compiler Errors/Warnings – Improving your code quality, CheckStyle
   
6. Syntax Highlighting
7. Focus (i.e. turn off email, browser, im when possible)
8. Google
9. Dual Monitors
10. Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems
11. Caffeine
12. Debugger Java Debugging With Eclipse (Vogella)
    
13. Sound isolating headphones
14. Design Patterns
15. XML Binding (no need to write DOM and SAX code any more)