Motherhood and Apple Pie: Modularity in Modern Applications and Tools to Support it Steven P. Reiss Brown University 2013年 4月 1日 Page 1 

Motherhood and Apple Pie 13/04/01 Page 2 Motherhood and apple pie :: (US) Principles or values with which few disagree. 

What is Modularity Modularity is the ability to view everything related to a particular concern on one screen 13/04/01 Page 3 

What is Modularity The division of a system into a set of independent modules Where modules Represents a set of related concerns Communicate in a loosely-coupled fashion 13/04/01 Page 4 

Claim Absolute Modularity is Impossible 13/04/01 Page 5 

Claim There are many (very) different concerns and attempting to be modular for any reasonable subset is not possible. 13/04/01 Page 6 

Code Bubbles Demo Demonstration 13/04/01 Page 7 

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Concern The squiggle is sometimes out of place after a character is typed 13/04/01 Page 9 

Character Input •  Update editor buffer(s) •  For the character and other effects •  Compile and report errors •  Update underlying AST structure •  Repaint the screen •  Handle layout and reflow •  Handle reformatting 13/04/01 Page 10 

Character Input 13/04/01 Page 11 Event Dispatch Update Selection Auto Indent Repaint Request Document Dispatch Auto Completion Update Other Editors Repaint Text Compute Layout Update Eclipse Eclipse AST Update Update Error Set Eclipse Errors Update Annotations Error Notification Update elements Update Elements 

Squiggle Code On ProblemsUpdatedEvent •  Lock file { Update Problems } Unlock In update AST structure •  { Clear problems } Update tree { Update problems } Update Problems •  Maintain the set of active problems (incremental) •  Remove styles for nonexistent problems •  Add squiggle styles for new/cleared problems When drawing text w/ squiggle style •  Use squiggle paint to underline text 13/04/01 Page 12 

What Really Happens Type In Display 13/04/01 Page 13 

Is This Modularity? The code is modular ? The dynamics of the code are not Which is more important? 13/04/01 Page 14 

Modular View for Squiggle Source Code for relevant routines •  The code marked in red View of what happened at run time •  Where is succeeded •  Where it failed 13/04/01 Page 15 

Obstructions to Modularity Black box code (Swing, Eclipse) Separate interacting processes Unknown control flow •  Multiple threads running at once •  Callback orders Our issues are dynamic •  We want modularity to reflect the dynamics 13/04/01 Page 16 

Smart Sign Current Status 13/04/01 Page 17 

Smart Sign Code 13/04/01 Page 18 Controller Picture Frame (?) Calendar Checker Arduino (C) Bluetooth (C) Arduino Monitor Event Adder Events (Data) Sign Creator 

Is this Modular? In terms of code? Adding new events (NOTIN) was easy Adding calendar was so-so Adding a new sensor is messy 13/04/01 Page 19 

Obstructions to Modularity Externally imposed modularity •  Multiple languages •  Multiple processes •  Multiple machines •  External code (calendar, obexftp, hcitool) Part of the program is data •  Passed between applications •  Representing the rule set 13/04/01 Page 20 

Twitter Data Access Twitter Web Site demonstration 13/04/01 Page 21 

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Twitter Data Access 13/04/01 Page 23 Streamer Data Insertion Zip/District Encoder Web Server HTML Script CSS Data Database Twitter 

Twitter Modular Concerns Support word comparisons? Optionally normalize the tweet counts? 13/04/01 Page 24 

Obstructions to Modularity Multiple programs Messages (data) are part of the system Database is a system component Web application has its own constraints •  Front end: HTML, JavaScript, CSS •  Back end: JavaScript (Node.JS) •  Communication (json via web sockets) 13/04/01 Page 25 

S6 Code Search •  Code Search demonstration 13/04/01 Page 26 

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S6 Transforms 13/04/01 Page 28 TransformBase JavaTransform T1 T2 T3 Tn … 

Transforms Are Modular Easy to write •  Average 300 lines each (135-941) Independent •  Automatic configuration •  Automatic application/detection •  Adding a new transform is trivial 13/04/01 Page 29 

Problem Transform sequence blows up Transform process isn’t modular 13/04/01 Page 30 

Process Modularity We need heuristics to guide transforms •  While keeping transforms simple to write •  While keeping transforms independent •  While keeping it easy to add transforms We must modularize transform dynamics •  As well as their coding 13/04/01 Page 31 

Obstructions to Modularity Transformation dynamics not explicit •  Encoded in individual transforms Heuristics are spread throughout •  Difficult to get a modular view •  Difficult to understand what is going on Conflicting modularity concerns 13/04/01 Page 32 

What Have We Learned I have lots of fun coding 13/04/01 Page 33 

What Have We Learned Modularity is in the eye of the beholder 13/04/01 Page 34 

What We Have Learned Modularity is Difficult in Today’s Systems 13/04/01 Page 35 

Challenge There is no static modular view of a system 13/04/01 Page 36 

Challenge Modularity depends on the circumstances 13/04/01 Page 37 

Multiple View Systems Modularity can be a function of the view rather than the code itself We can view a system in different modular ways 13/04/01 Page 38 

Pecan 13/04/01 Page 39 

Garden 13/04/01 Page 40 

Field 13/04/01 Page 41 

Desert 13/04/01 Page 42 

Multiple View Systems •  Scott Myers: SPG-based representation •  CMU Sheets •  IBM Visual Age •  Grundy’s & Hosking’s Mviews •  Hon’s Fluid AOP •  Taivalsaari’s Multidimensional Browsing •  Microsoft’s Intentional Programming •  … 13/04/01 Page 43 

These Don’t (and Won’t) Work Database View-Update Problem •  View updates are ambiguous in general •  No single representation supports all views Program View-Update Problem is worse •  More complex semantics •  More complex representations 13/04/01 Page 44 

Multiple View Systems Severely restrict allowed editable views •  Predetermined set, strong restrictions Explicitly define editing operations •  Making view creation prohibitive Use read-only views •  Limiting their uses and applicability 13/04/01 Page 45 

Virtual Modularity Construct a virtual view by displaying the subset of the original source relevant to a particular concern 13/04/01 Page 46 

Code Bubbles 13/04/01 Page 47 

Code Bubbles Modularity Code Bubbles Working Sets •  Are static modular views of a system •  That can be build dynamically Modularization Techniques •  Show individual functions or components •  Use elision within the components •  Include all types of software artifacts •  Allow save/restore of working sets 13/04/01 Page 48 

This is Only a Start •  Virtual Modularizations •  Dynamic Modularizations 13/04/01 Page 49 

Challenges Paper titles for Modularity 201x •  Automatic creation of modular views •  Dynamic modularity •  Programmer-specified editable modular views •  Static views of a program’s dynamic behavior •  Behavioral modularity •  Dynamic modularity across threads •  Modular views of a multilingual web application •  Automatic creation of dynamic modular views 13/04/01 Page 50 

Questions / Suggestions 2013年 4月 1日 51 

What is Modularity? •  Modularity refers to the compartmentalization and inter-relation of the parts of a software package •  Modularity is designing a system that is divided into a set of functional units (named modules) that can be composed into a larger application. A module represents a set of related concerns. It can include a collection of related components, such as features, views, or business logic, and pieces of infrastructure, such as services for logging or authenticating users. Modules are independent of one another but can communicate with each other in a loosely coupled fashion. •  The use of individually distinct functional units, as in assembling an electronic or mechanical system. •  Modularity is a general systems concept, typically defined as a continuum describing the degree to which a system's components may be separated and recombined. •  Modularity is the property of computer programs that measures the extent to which they have been composed out of separate parts called modules. 13/04/01 Page 52 

Defining Modularity •  What is a module? •  Source code, documentation, design notes, requirements, … •  What is a concern? •  Whatever we need to look at •  For coding, debugging, understanding, … 13/04/01 Page 53 

Measuring Modularity •  Various measures of metrics for dependencies and relationships •  How much work to add, modify, or understand a concern •  Can you fit the code for one concern on one screen 13/04/01 Page 54 

S6 Input Flow 13/04/01 Page 55 SVIWEB (GWT) Firewall XML Engine Request Servlet Test Builder Ant Script Test Prototype File Tester Output Generator Solution Set 

Problem •  Adding a new input test feature •  Contracts, security constraints •  Requires Changing •  GWT code, XML, Servlet code, Request structure, Engine, Test builder, test prototype, Ant script 13/04/01 Page 56 

Difficulties •  Modularity constrained by system •  Separate programs are needed •  Communications protocols are part of code •  Multiple languages •  Including non-languages (ant) •  Including data languages 13/04/01 Page 57 

Challenge True Modularity is Impossible 13/04/01 Page 58 

Solutions Modularity can be a function of the view rather than the code itself? 13/04/01 Page 59 

Dynamic Modularity Show the proper modularization for a particular dynamic problem 13/04/01 Page 60 

Dynamic Software Visualization Visualization for Program Understanding •  Needs to be done in the programmer’s terms •  Needs to be done using proper abstractions Requires dynamic modular views 13/04/01 Page 61 

JIVE 13/04/01 Page 62 

Jove 13/04/01 Page 63 

Dyper Performance Analysis 13/04/01 Page 64 

Dymem 13/04/01 Page 65 

Dylock 13/04/01 Page 66 

Dynamic Visualizations Generic tools only solve generic problems •  They don’t solve specific problems •  Generic views aren’t modular 13/04/01 Page 67 

VELD 13/04/01 Page 68 

VUIT: Setting Up VELD 13/04/01 Page 69 

VUIT Events 13/04/01 Page 70 

Why This Doesn’t Work The set of thread states is not intuitive nor is the set of events. The whole process is too complex. 13/04/01 Page 71 

Automating the Process Can we build these models automatically •  In general? For particular classes of problems •  Threads, Tasks, and Transactions 13/04/01 Page 72 

Threads, Tasks, Transactions Automatically •  Find event handlers •  Find significant subtasks •  Find Threads and tasks •  Find Thread Queues •  Based on programmer’s problem definition Provide customized time-based views 13/04/01 Page 73 

Dyvise on S6 Server 13/04/01 Page 74 

Dyvise on Web Crawler 13/04/01 Page 75