Software engineering Olli Alm Lecture 6: implementation, tools for software development

Software engineering

Olli Alm

Lecture 6: implementation, tools for software development

Software engineering tools

Development tools Integrated Developent Enviroment (IDE), application

server, database administration, tools for testing... Tools for communication

Email, phone, skype, conferencing tools, instant messaging, chat, twitting, facebook, google wave...

Content delivery & management Version control, document management / Content

Management Systems (CMS), wiki Documentation tools

Writing: e.g. Open Office, MS Office, Latex.. Diagrams: e.g. Jude, MS Visio, Eclipse plugins... Illustration / mock-ups: drawing tools, e.g. GIMP Presentations: e.g. Powerpoint

Software development tools: IDE

IDE: Integrated Development Environment (”ohjelmointiympäristö”)

Source code editor Compiler Debugger Builder Server management Binding classes & libraries Extensions

Version control, user interface development, testing, automatic code generation, …

The extreme opposite: text editor + command line compiling +

set of separate tools


An example: Eclipse www.eclipse.org


Examples on ”low level” assistance: Code highlightning Compile automatically Code assistance Resource linking (classes, libraries) Documentation linking Working with the workspaces, projects


Examples on ”high level” assistance: DB access: generate interface classes Unit tests: generate test classes Deploy web application immediately Import web service classes automatically Wrap the project into package for delivery /

publishing

Implementation issues

Coding What language to use? Best practices, coding conventions? Commenting, documentation IDE + assisting tools Web application or not? (installation, configuration,

concurrency, prototyping, updates, testing, availability?)

Best practices

Best practices: (for Java)

http://www.javapractices.com/home/HomeAction.do(for PHP)http://net.tutsplus.com/tutorials/php/30-php-best-

practices-for-beginners/http://weierophinney.net/matthew/uploads/

php_development_best_practices.pdf(incl. communication!)

Coding conventions

For PHP:http://www.evolt.org/node/60247http://drupal.org/coding-standardshttp://framework.zend.com/manual/en/coding-

standard.html

Commenting

Automatic generation of code documentation:(Javadoc example):

http://java.sun.com/j2se/javadoc/writingdoccomments/

Clarify unclear parts, do not repeat the code in comments Comments for clarifying what is missing (TODO, FIXME)

Dependable development (Sommerville: Ch.20)

Dependable process (SE8 ch.20 p.466) Predefined process model that defines the results and

activities Verification & validation Robustness: ability to recover from failed activities Emphasis on requirements

Requirements inspections Requirements management (keeping up-to-date)

Model consistency checking (CASE tools) Design & code inspections Static (code) analysis Test planning & management

Dependable development (CH.20)

Dependable programming (SE8 ch.20) Protect information (objects, accessor methods, private

data!), prefer strong typing! Anti-patterns for critical systems (avoid these if possible!):

Floating point numbers (use fixed points!) Pointers Dynamic memory allocation (reserve memory in

advance!), unbounded arrays Be careful on paralleism, concurrency, timing issues Recursion Interrupts, inheritance, aliasing (=naming conventions) (split the code into small enough parts)

Version control / distributed software development

Management of the code Easy when there is one person, difficult when there is

more people involved Code: text files

Same files are edited by many people The problem: how to propagate changes to people?

People in the same room vs. people in the other country? How to ensure that the different files are working correctly with

each other


An answer: communicate with email, send files? E.g. 3 people editing (the same) 4 files:







3 different versions of each file, 4^3: 64 different combinations of files Difficult!


Another answer: use version control software Version control

A software to maintain the state information of the files Usually centralized service on a server machine Used for

communication (add/remove/change file) revision history

Software: CVS, SVN (SubVersioN), GIT (by Linus Torvalds), Mercurial

An example: page history / revisions in MediaWiki (e.g. en.wikipedia.org)


Communicate with version control, E.g. 3 people editing (the same) 4 files:

Centralized service


Version control functionalities / jargon Checkout: get the local copy of the files from the server Update: update the local copy from the server Commit: send the (local) modifications to the server Revision: a numbered version of the server files

Revisions form the history of the project Merging: combining the two versions of a file

If possible, done automatically by the version control software

Version control platforms

Server-client:Subversion / SVN http://subversion.tigris.org/

Distributed: Mercurial http://mercurial.selenic.com/GIT http://git-scm.com/

http://en.wikipedia.org/wiki/Revision_control

http://en.wikipedia.org/wiki/List_of_revision_control_software

Communication

In a SE project, with the development team, with the customer, with other parties In the development process, how to:

report bugs? ask detailed information about a component? announce progress, current weeks schedule? announce meeting hours? negotiate change in requirements? ...

Communication

Email: Good in one-to-one communication Not the best tool for collaborative working (e.g. document

writing) Difficult to manage in one-to-many communications Good for ”archiving”, records daily activities, records

decisions made (=be careful)

Communication

Chat: Good for getting an immediate response (for a minor

issue) Usually the content (e.g. description, opinions) is

expressed in a relaxed way 'Is this ready?', 'What's the due for the component xx?'

Communication

Twitting, profile updates (e.g. in Facebook): Good for expessing low-priority (non-urgent) information

in one-to-many communications. Suitable for telling what you are doing today (~Scrum meetings)

One-way communication: not really expecting response for the message

Communication

Face-to-face, phone meetings For getting an agreement on something To get started on something, to explore, to analyze things,

meet face-to-face. (as opposed to messaging systems, urgent requests are

harder to discard / bypass.)

Communication

Indirect communication through the document or content management system is also possible:

e.g. wait for the specific document update, start working after that

Central repository with identified users Version control Support for tracking specific / recent changes

Wiki-engines Google docs

Documents

Software engineering Olli Alm Lecture 6: implementation, tools for software development