Managing Success: We made it, now we're screwed

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Managing Success We made it, now we're screwed

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You == Pain

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(NIH) Not Invented Here

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Why?

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Conway's Law

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Organizations which design systems are constrained to produce designs which are copies of the communication structures of these organizations. - Melvin Conway

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"Ruby is designed to make programmers happy." - Matz

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#1 Problem?

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Monolithic

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Models

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Testing

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TDD != QA

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Pain

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Pain

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Pain

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Cost Time Cost per change (bugs, new features, etc) Non-TDD TDD

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Models Controllers/Routes Views/Helpers Application In Browser Cost per test

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Models Controllers/Routes Views/Helpers Application In Browser ROI per test

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Monolithic Models

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2 Rules

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1) Delarative

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2) Level of Abstraction

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<%= link_to "#{tag.name} (#{tag.articles.length})", tag_path(tag) %>

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<%= link_to "#{tag.name} (#{tag.article_count})", tag_path(tag) %>

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<%= link_to "#{tag.name} (#{tag.article_count})", tag_path(tag) %>

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class Tag < ActiveRecord::Base belongs_to :article def article_count self.articles.count end end

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class Tag < ActiveRecord::Base belongs_to :article def article_count # Performance hack # faster than SELECT COUNT(*) self.articles.select(:id).count end end

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Monolithic Views

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<% if @course.available? && @course.self_enrollment && @course.open_enrollment && (!@course_enrollment || !@course_enrollment.active?) && !session["role_course_#{@course.id}"] %> <%= render :partial => "join_course", :object => @course %> <% elsif @course_enrollment && @course_enrollment.self_enrolled && @course_enrollment.active? && (!session["role_course_#{@course.id}"]) %> <%= render :partial => "drop_course", :locals => { :course => @course, :enrollment => @course_enrollment } %> <% elsif temp_type = session["role_course_#{@course.id}"] %>

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<% end %>

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Helpers

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<% if can_join_course?(@course, @enrollment) %> <%= render :partial => "join_course", :object => @course %> <% elsif can_drop_course?(@course, @enrollment) %> <%= render :partial => "drop_course", :locals => { :course => @course, :enrollment => @course_enrollment } %> <% elsif temp_type = temp_permissions_to(@course) %>

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<% end %>

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Presenters

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module CourseHelper def can_join_course? course, enrollment course.available? && course.self_enrollment && course.open_enrollment && (!enrollment || !enrollment.active?) && !temp_permissions_to(course) end def can_drop_course? course, enrollment enrollment && enrollment.self_enrolled && enrollment.active? && !temp_permissions_to(course) end def temp_permissions_to course session["role_course_#{course.id}"] end end

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<% if @presenter.can_join_course? %> <%= render :partial => "join_course", :object => @presenter.course %> <% elsif @presenter.can_drop_course? %> <%= render :partial => "drop_course", :locals => { :course => @presenter.course, :enrollment => @presenter.enrollment } %> <% elsif @presenter.temp_permissions %>

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<% end %>

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class CourseShowPresenter # this is a ViewModel, really attr_accessor :course, :enrollment, :current_user, :session def can_join_course? @course.available? && @course.self_enrollment && @course.open_enrollment && (!@enrollment || [email protected]?) && !temp_permissions end def can_drop_course? @enrollment && @enrollment.self_enrolled && @enrollment.active? && !temp_permissions end def temp_permissions @session["role_course_#{@course.id}"] end end

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1) Delarative

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2) Level of Abstraction

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Monolithic Apps

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Monolithic Apps

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What is code?

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“Underlying our approach to this subject is our conviction that “computer science” is not a science and that its signiﬁcance has little to do with computers. ... The computer revolution is a revolution in the way we think and in the way we express what we think.

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... we want to establish the idea that a computer language is not just a way of getting a computer to perform operations but rather that it is a novel formal medium for expressing ideas about methodology. Thus, programs must be written for people to read, and only incidentally for machines to execute.

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... we believe that the essential material to be addressed by a subject at this level is not the syntax of particular programming-language constructs, nor clever algorithms for computing particular functions efﬁciently, nor even the mathematical analysis of algorithms and the foundations of computing, ...

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but rather the techniques used to control the intellectual complexity of large software systems.”

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but rather the techniques used to control the intellectual complexity of large software systems.”

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Intellectual Complexity

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Human Activity

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“Often people, especially computer engineers, focus on the machines. They think, “By doing this, the machine will run faster. By doing this, the machine will run more effectively. By doing this, the machine will something something something.” They are focusing on machines...

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But in fact we need to focus on humans, on how humans care about doing programming or operating the application of the machines. We are the masters. They are the slaves.” -Matz