java development best practices

Java Development Best PracticesSimon Brown, Senior Consultant

Ref: www.evolution.net

Contents

Presentation Objectives

Automated unit testing

Continuous integration

Project blogs

Other best practices

Summary



Provide an overview of the following Cormorant MFEdevelopment practices, how to implement them and how theyprovide real benefit

– Automated unit testing– Continuous integration– Project blogs

To discuss other best practices that we have used in the pastand/or should be using in the future


A quote from a blog entry…

On August 4 we had a session on software engineering. The aim of the sessionwas to share knowledge and experience about the way we develop software andto discuss the importance of doing it a certain way. After the break we had aworkshop that briefly touched the different parts of the software developmentprocess.

The quiz on current real-life practices raised a lot of discussion. While we allrecognize the importance of source control, automation of manual tasks, testing,documentation and proper incident management many of us fail in a properimplementation of these practices.

AMIS Technology Corner : On Software Engineeringhttp://technology.amis.nl/blog/index.php?p=695


Contents




Project blogs


Summary



Automated unit testing now an established technique– You write some code– Then you write more code to test it

Many frameworks exist for automated unit testing with Java– Most popular is Junit 3.8.x– Others include TestNG and JUnit 4.0


Test classReal class


method1

method2

methodN

testMethod1

testMethod2

testMethodN



Yes…– More code needs to be written– Estimates will increase– It’s a new way of working– It feels weird, perhaps pointless initially

But…– Automated unit testing is very powerful– Lets you regression test code for free!– Helps you write cleaner code– Provides a good milestone for completion– Provides confidence when changing, fixing or refactoring code– If you can write code, you can write a unit test!


Adoption of automated unit testing

New code– Write tests for new code

Existing code that needs to be modified…– Look at the unit tests– If tests exist, they will help ensure you don’t break anything

through unknown side effects– If tests don’t exist, write some to cover the area of the code you

are changing– No need to retrofit the entire code base with unit tests at once

• Too expensive!• Take an iterative approach



A defect is raised…– Look at the unit tests– Write a unit test to prove the bug - make sure its reproducible– Fix the bug– The new test will pass– Check-in the fix and new test– Chances of reoccurrence are greatly reduced



Don’t mandate 100% unit test coverage - it’s too hard and tooexpensiveDo use a code coverage tool (more on this later)Do add tests when you see they don’t already existDo write tests to prove bugsDo run your tests frequentlyDo make sure the tests execute quicklyDon’t let the tests become out of dateDon’t throw them away when they stop passing - fix them!Do treat them as an important deliverableDo include them in code reviews


Contents




Project blogs


Summary


Developer PC

Server

Cormorant development environment

Check-out code

Commit codeSource code

Control(Subversion)

WeblogContinuousIntegration

Server

Developer PC

Developer PC

Developer PC


Manual build process

Manual builds performed using Eclipse and command linetoolsScripted builds performed using Ant and existing script

– Compile Java code– Build EAR file– Generate distribution for release to system test


Scheduled, scripted builds

Scheduled, scripted builds performed by CruiseControl andAnt

– Build scheduled every hour/30 minutes– Clean copy of code checked out from Subversion– Compile, build EAR file and run unit (JUnit) tests– Build results published to CruiseControl web application– Build results also published to build blog

CruiseControl was our sixth team member!


Benefits of scheduled, scripted builds

Forces more frequent, iterative integration rather than big-bang approach

– Forces compilation of clean codebase– Finds compilation problems where developers have not updated

their local copy of code before checking in changes– Frequent (continuous) integration is easier and quicker to

perform, reducing risk of slippageForces execution of unit tests

– Automatically runs all unit tests whenever the codebase changes– Finds problems when developers have not run tests before

checking in changes– Provides a level of continuous quality assurance


Setting up continuous integration

CruiseControl installed on a PC (can be developer PC)– Configured to look at the repository every hour for changes– If changes are found, code is checked out and build executed

CruiseControl provides native integration with CVS,Subversion, ClearCase, etcAlso look at other continuous integration servers such asAnthill


Contents




Project blogs


Summary


What is a blog?

Blog, short for weblog : a web-based log or diaryLess formal than static project websites or wikisInformation stored on a temporal basisUseful for recording snippets of information as they are encountered

– Project information, development tips, environment gotchas, logininformation, links to documents, documents, instructions, guidelines,links to external resources, status reports, etc

– Also build information and test resultsAn alternative to sending out short e-mail memosCan be searched, archived and exportedWeb-based access means easy distribution of informationLow maintenance


Project blogsRather than have asingle blog for theproject, there are two:

• Team blog (used forproject information).

• Build blog (used forbuild reports).


Team blogThis is the project teamblog and is used forsharing informationabout any aspect of theproject.

• All Evolution teammembers can contributeto this and have accessto do so.

• Anybody in theextended team can leavecomments, but only theEvolution team can addcontent.

• Instead of writing e-mail memos, content ispublished to the blog anda link sent to the team.

• Since blog content isHTML, it’s easy to embedimages and link toproject artefacts.

• With an RSS readerinstalled on eachdesktop, the team isautomatically notified ofnew content.


Build blogThis is the project buildblog and is used topublish build summaries.

• CruiseControl performsa checkout/build eachhour and publishes theresults.

• With an RSS reader, theteam is automaticallynotified after builds occur.

• Anybody can leavecomments, but this bloghas been configured sothat only CruiseControlcan publish content.


Summary pageThis is the summarypage for both blogs,showing the last threeentries that have beenposted to each.

• Navigation is the samefor the other blogs andclicking on links in thecalendar shows allcontent for that period.

• The Today link (top)shows all contentpublished today acrossboth blogs.

• The RSS/RDF/Atomlinks (top) allow anewsreader application tosubscribe to both blogsvia a single feed.


Blog is green,build is clean!Through somecustomization, the blog isused as a form ofextreme feedback device:

• Green means the lastbuild was successful.

• Red means the lastbuild failed.

• The main page of theblog is set toautomatically refreshevery few minutes.


Contents




Project blogs


Summary


Roundtable discussion about other best practices

Code coverage– Clover, jcoverage, etc

Automatic conformance to standards– Checkstyle, PMD, etc

Tracking metrics over time– QALab

Automated acceptance testing– HttpUnit, Canoo WebTest, etc

Demos of Clover and Canoo WebTest


Clover in IntelliJ IDEA


Clover HTML reports


Canoo WebTest script<!DOCTYPE project SYSTEM "../WebTest.dtd"[

<!ENTITY definition SYSTEM "../includes/definition.xml"> <!ENTITY config SYSTEM "../includes/config.xml">

]><project name="test" basedir="." default="main">

&definition;

<target name="main">

<webtest name="login"> &config;

<steps> <invoke description="Request secured resource" url="/login.secureaction" /> <verifyInputField name="j_username" value="" /> <verifyInputField name="j_password" value="" />

<setInputField name="j_username" value="simon" /><clickButton label="Login" />

<verifyText description="Check user logged in" text="Logged in as simon" /> </steps>

</webtest> </target>

</project>


Contents




Project blogs


Summary


Automated unit testing summary

Easy to setupEasy to get to grips withIncreases confidence that a solution/fixes/changes workEnsures a certain level of continuous quality assurance


Automated unit testing software

JUnit– Open source– Easy to install and configure– Integrates with Ant for scripted builds– Integrated with Eclipse allowing tests to be written and run very

quickly– http://www.junit.org


Continuous integration summary

Easy to setupDoesn’t require much processing powerDoesn’t require a dedicated boxDoesn’t require expensive software

– Open source software used in MFE development environmentProvides early warning signs to integration problems

– Code not compiling– Unit tests failing

Helps developers integrate more smoothlyEnsures a certain level of continuous quality assurance


Continuous integration software

CruiseControl– Open source– Easy to install and configure– Native integration with all leading/standard source code control

interfaces– Can publish build reports via e-mail, XML, HTML, blogs, etc– Only performs builds when code in repository has changed– http://cruisecontrol.sourceforge.net


Project blog summary

Also don’t require much processing power, a dedicated boxor expensive softwareProvides a way to easily publish information to the projectteam

– Can be searched, archived and exported– Easily distributed to extended project team

Team members can subscribe to the information they want toreceiveA useful feedback mechanism when combined withcontinuous integration


Project blog software

Pebble– Open source– Easy to install and configure– Runs on most J2EE web/application servers (e.g. Tomcat)– Flexible security roles– Integrates with enterprise authentication mechanisms– Supports standard interfaces such as Atom/RSS newsfeed

formats and XML-RPC– http://pebble.sourceforge.net


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java development best practices

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