Notes

Outline

Agenda Tradeoffs in Shrink-Wrap Software Patterns of Software Engineering Anti-Patterns

Core Tradeoffs Time Constraints Resource Constraints Feature Constraints

Other Tradeoffs Architectural Constraints Political Constraints

Patterns Architectural Patterns Organizational Patterns Development Patterns

Architectural Patterns Monolithic Application Pattern Frameworks Pattern Cross-Platform Framework Pattern Component Architecture Pattern

Architectural Pattern I Monolithic Application Pattern Objective: Develop product with eye towards time-to-market Related to: Frameworks, Waterfall Development Description: Creating single large application whose main purpose is to develop a product for release. Does not require modularity, reuse, OOP, etc. Advantages: Time-to-market Shorter design cycles Drawbacks: Reduced modularity Shorter life span Steep learning curves Longer QA cycles as product matures

Architectural Pattern II Frameworks Pattern Objective: Develop reusable architecture for multiple products Related to: Cross Platform Frameworks, Component Architecture Description: Create an architecture which supports common product constructs independent of individual products’ domains Advantages: Code reuse Abstraction of non-product specific code Increased modularity Drawbacks: Longer initial ramp-up development time Potential conflicting requirements Platform improvements require extra development

Architectural Pattern III Cross-Platform Framework Pattern Objective: Develop reusable architecture for multiple products on multiple OSs Related to: Platform Frameworks, Component Architecture Description: Same as Framework, but spanning multiple Operating Systems (e.g. Macintosh, Windows, NeXT, Xwindows) Advantages: Code reuse Abstraction of non-product specific code Abstraction of common platform capabilities Increased modularity Drawbacks: Longer initial ramp-up development time Potential conflicting requirements Platform improvements require extra development Features sometimes become Least Common Denominator

Architectural Pattern IV Component Architecture Pattern Objective: Develop reusable architecture for multiple products Related to: Frameworks, Evolutionary Delivery Description: Create a reusable and extensible architecture for one or more products by bundling features in components that plug-in to small backbone application Advantages: Code reuse Abstraction of common product functionality Increased modularity Increased flexibility in release schedules Drawbacks: Longer design phases Scheduling complexities

Organizational Patterns Core Technology Pattern Feature Teams Pattern Microsoft Pattern

Organizational Pattern I Core Technology Pattern Objective: Provide central organization to manage core components Related to: Component Architecture, Evolutionary Delivery Description: Organize a team to manage and deliver core components to multiple products Advantages: Central focus for process management Reducing duplication of effort Drawbacks: Politics Dependency management and scheduling complexities Conflicting requirements and development schedules

Organizational Pattern II Feature Teams Pattern Objective: Focus small groups on critical feature areas Related to: Component Architecture, Evolutionary Delivery Description: Organize a product team into multiple smaller teams along major feature divisions. Each team manages schedules, code, QA cycle, and feature completion. Advantages: High motivation Reduction of organizational burdens Drawbacks: Potential inconsistencies in process between teams Code integration complexities in QA and development Potential myopic focus of team members

Organizational Pattern III Microsoft Organizational Pattern Objective: Provide adequate support for all aspects of Waterfall type development Related to: Waterfall, Monolithic Apps, Staff Graphs Description: Organize a product team into multiple smaller teams, along the following divisions: Development QA Program Management Product Management Business Units Advantages: Most aspects of software development have clear ownership Thorough coverage of all areas Drawbacks: Requires adequate resources Technical knowledge and feature specifications live in different groups

Development Patterns Classic Waterfall Pattern Evolutionary Prototyping Pattern Evolutionary Development Pattern Parallel Team Pattern Component/Extensibility Development Pattern Goal-oriented Planning Pattern Staff Graph Pattern

Development Pattern I Classic Waterfall Pattern Marketing Requirements Document (MRD) Requirements Document Architectural Specification Project Schedule Milestone Chart UI Specifications Test Plans QA Schedule Debug Phase Release Candidate Release

Development Pattern II Evolutionary Prototyping Pattern Objective: Fast time-to-market on new product Related to: Component Architecture, Evolutionary Delivery Description: Create quick initial prototype for proof of concept. Iterate on prototype until release candidate. Advantages: Quick implementation Fast feedback on concept Ability to measure progress Drawbacks: Typically requires frequent rearchitectures Stability usually questionable Difficult to verify or validate requirements

Development Pattern III Evolutionary Development Pattern Objective: Flexibility on new product feature requirements Related to: Component Architecture, Evolutionary Prototyping, Feature Teams Description: Create initial baseline product. Schedule multiple “mini-releases” using some other development cycle (Waterfall). Mix and match mini-releases to create desired product. Advantages: Quick responses to market changes possible Release schedule is flexible Ability to measure progress Drawbacks: Heavy dependencies bog down cycle Difficult to verify or validate requirements

Development Pattern IV Staff Graph Pattern Objective: Manage multiple projects with limited resources Related to: Waterfall, Feature Teams Description: Drive multiple product schedules by tracking resource usage across time. Advantages: Resource reallocation flexible Good for high-level planning Easy to identify inter-project timing relationships Drawbacks: Granularity level too coarse for detailed scheduling Outside dependencies not tracked

Other Development Patterns Parallel Team Pattern Component Development Pattern Goal-oriented Planning Pattern

Applying Patterns I Given Time Constraints Evolutionary Prototyping Evolutionary Development Example: RealJukebox Internet space Time-to-market key goal

Applying Patterns II Given Resource Constraints Core Technology Staff Graph Example: Edmark product line Consumer space Shrink-wrap multiple deliveries Maintaining cost overhead key goal

Applying Patterns III Given Feature Constraints Evolutionary Development Parallel Team Feature Teams Component Development Example: Adobe InDesign Shrink-wrap tools space Competitive product key goal

Anti-Patterns Not rearchitecting in-place Vision lemmings Hierarchy for the sake of hierarchy The 1-Milestone Project Plan Mismatching constraints and SE pattern

Anti-Pattern I Not Rearchitecting In-place Objective: To create a difficult development environment for future products Related to: Waterfall, Monolithic apps Description: Avoid any redesigns in your app, and allow most code to stagnate as much as possible. Keep glomming on features wherever you can until it takes years to update. Advantages: Don’t have to think too hard initially Most executives will like how much you’re “reusing” existing stuff You get to meet lots of new people (i.e. lots of turnover) Drawbacks: You have to think real hard on subsequent iterations You’ll be forced to rearchitect the whole thing or your product will ultimately die Nimble competition will eat your breakfast

Anti-Pattern II Vision Lemmings Objective: To create as many directions and visions for the product as possible Related to: Evolutionary Prototyping, Frameworks, Component Architectures Description: Key leaders continually redirect goals and feature set of the product to react to latest trends or political niceties. Employees follow directions blindly. Advantages: Every day is fairly exciting You get to meet lots of new people (i.e. lots of meetings) You get really good at writing strategy documents Drawbacks: Morale is not quite peachy Your project gets killed quickly in healthy organizations Your project lingers forever in dysfunctional organizations

Anti-Pattern III Hierarchy for the Sake of Hierarchy Objective: To create extra layers of hierarchy within a growing organization Description: As flat organizations grow, hierarchy is created to facilitate organization and communications. Advantages: Clear reporting structure Semblance of organization Most employees far removed from front-line decision-making Drawbacks: Exponential increase in communication issues Higher up in the hierarchy you go, the more divorced from the technology you are, the less you know

Anti-Pattern IV The 1-Milestone Project Plan Objective: To over-simplify development process Description: Create one milestone. Call it “Ship Product”. Cross your fingers. Advantages: No time spent planning No worry about dependency management Schedule tracking simplified High drama come release date Drawbacks: No risk management Highly unpredictable release date Not much to say at project reviews

Anti-Pattern V Mismatching constraints and SE pattern Multiple forms Parallel teams when resource constrained Doing a complete rewrite with political constraints

Conclusions Know the constraints on your project ahead of time Apply the proper pattern to your: Architecture Organization Development Cycle Learn from history Know your organizations anti-patterns and get rid of them Identify your competitors anti-patterns and take advantage of them