PMD comes with a set of handy rules, which more than often are sufficient for any project. In fact in many cases we would probably need to exclude some default rules being enforced, to avoid noise in the reports. However, in real life projects you also need some custom rules.

Though custom PMD rules can be written as Java code as well, this article talks about writing them using XPath queries, which is evidently an easier way to adopt. With XPath, we simply write a rule by specifying a code sample and an XPath query to verify that the violation is indeed detected. Of course PMD doesn’t apply the query on the Java code itself but rather on the Abstract Syntax Tree, which is a tree representation of the source code. More details on the AST can be found here.

Thankfully PMD also comes with a visual editor for writing the rules. This tool can be run using the designer.bat under /bin. If you are using Eclipse and have the PMD plugin installed then the designer is accessible under Eclipse Preferences > PMD. Lets now try writing a custom PMD rule. The particular rule we plan to write to enforce the use of StringBuilder instead of StringBuffer (where there are no concurrency issues, of course). For this we first write a code snippet, as follows, in the “Source code” box of the designer.

public class SomeClass {
     //Consider using StringBuilder, if there
     //are no concurrency issues expected
     StringBuffer sb = new StringBuffer("c");

     public void someMethod(){
         //Some code here
         StringBuffer sb = new StringBuffer("d");
     }
}

The next task is to write the XPath expression. Before we do that, we press the “Go” button under “XPath Query” section first. This will generated the corresponding AST in the box and help us write the query well. And since we haven’t written any XPath query as of now, the result section below the “XPath Query” section says “XPath Query field is empty”. Now, we want to detect the presence of a StringBuffer variable, whether at class or method level. If you see the generated AST we can easily detect that the following XPath expression will find the matching lines. We use the @Image attribute to specify the name we want to detect.

//AllocationExpression/ClassOrInterfaceType
[@Image='StringBuffer']

If we press the “Go” button again, the results of running the XPath query are displayed in the box below the “XPath Query” section. In our code we should get two matches, and we should see the exact matched strings if we click on the individual lines in the result Pane. We can refine the XPath query this way till we get the exact matches.

Lets now try to write another custom rule. This particular one will report a violation if the developer writes any non static method is a Utils class. We don’t want the Utils class to be instantiated for its methods to be used. Here, we assume that all our Utils class names end with the word “Utils”. As we did last time, we first insert the following code snippet:

public class MyUtils {
      //Any Utility class ending with "Utils" (note, its
      //not "Util") is regarded as a Utils class
      public static void myStaticUtilMethod(String x){
          //this is a static method as expected
      }

      public void myNonStaticUtilMethod(){
          //this method should be static and violates our rule
      }
}

The XPath query in this case, as follows, is quite straight forward. We are only checking for Classes (and skipping Interfaces) that end with the suffix “Utils” and then verify if there are any non-static methods in there. Click the Go button and it should detect a violation as our class does have a non-static method. To verify, change the method signature for myNonStaticUtilMethod() to make it static and press “Go” again. PMD should not report any violation now, confirming that our rule works.

//ClassOrInterfaceDeclaration
[@Interface='false'
and (ends-with(@Image, 'Utils'))
and (count(.//MethodDeclaration) > count(.//MethodDeclaration[@Static='true']))
]

The last step in getting our custom defined rules being used by PMD is to add them to a ruleset. Details on creating your own ruleset are provided here. The designer again will help you in creating the rule XMLs that you can easily copy paste in your ruleset file.

Lets create one for the last custom rule we created. To do this click Actions > Create Rule XML on the designer. You will get a pop-up which will ask you to specify the rule name and any description that goes along. For our ruleset we use the rule name as “OnlyStaticMethodsInUtilsClass” and the message text as “In Utility (ending with ‘Utils’) classes, all methods should be declared static.” which will show up as tool-tip on the IDE with violation report. We may also specify a description. Press “Create Rule XML” button and the designer will do so for you (see the screen grab below).

Note that the designer specifies the class for the rule as “net.sourceforge.pmd.rules.XPathRule” on its own. The rule priority is specified at default value of 3, but you can change that. PMD users would know that priority figures of 1 = error, high priority, 2 = error, normal priority, 3 = warning, high priority, 4 = warning, normal priority and 5 = information.

Before PMD could be used with Eclipse it must be imported in your IDE. On Eclipse Preferences under “PMD” select “Import Rule Set”, browse to the ruleset file you saved the custom rules to and you would notice them being imported. Of course, we can use the ruleset from the command line as well from our build script.

With our custom rules, our favourite code quality check tool is now even more useful.

You may see the plugin in action here.

If you wish to display a custom photograph to go with the Author’s Profile you may install the User Photo. In absence of this plugin the ‘Author Spotlight” widget will fall-back to displaying the gravatar associated with the user.

Update (Oct 2010): From V2.0 onwards this plugin also supports the excellent “Co-Authors Plus” plugin. If your blog posts have multiple authors we recommend using the co-authors plus plugin. When this plugin is used “Author Spotlight” will display all co-author profiles on the sidebar for the blog-post.

Note that using either the “User Photo” or the  “Co-Author Plus” plugin is purely optional and our widget will work fine even without these plugins, but they are nice to have.

For installation instructions and details on the widget please visit the widget page on WordPress. If you face any issues with the plugin or have any suggestion/feature requests please do submit there at this place.

Author Profile WordPress Widget

Disclaimer: The information provided on this page comes without any warranty whatsoever. Use it at your own risk.

I had interviewed Dr Sugata Mitra for Hindi blogzine Nirantar about an year ago. While going through old emails I came across the original English interview and thought that I should post it online.

Dr Mitra, as you might be aware, is an award winning scientist. He has been known for the Hole in the wall (HIW) project where he proved that kids could learn computers without formal training and teachers. He started the HIW experiment at the slums at Kalkaji, Delhi in 1999. More kiosks were later setup at Shivpuri, Madhya Pradesh and Madantusi, Uttar Pradesh. Sugata calls this “Minimum Evasive Education“, referring to the environment where kids learn using their natural curiosity without the intervention of teachers. The experiment, scaled up to more than 23 kiosks in rural Indian was also repeated in Combodia in 2004.

I am not aware of the real implications of this experiment and whether it went past the academic interests and echoed in the corridors of the government, but the experiment surely suggested a way towards providing low-cost IT education in India.

In the Hole-In-The-Wall (HIW) experiment what is the hardware configuration of the PCs? How do these cope up with the dust/heat of open environment? And in rural areas how did you tackle the issue of dismal power supply? Did you use any customized software?

Dr Mitra: Personal computers, such as those used in homes and offices all over the world, are designed to work indoors, usually in a carefully conditioned and controlled environment. Such computers can not be placed in outdoor environments, without air-conditioning and with poor power conditions, such as those prevalent in rural India and Cambodia.

Over the period of the experiment, we evolved a design for an enclosure that would enable the usual personal computer to function in an outdoor environment. The enclosure consists of a brick structure resembling a narrow hut with the computer screens visible on the outside of the hut through glass panes fixed to rectangular “holes in the wall” on one side of the hut.

The conventional mouse used with home or office PCs does not function effectively for more than a few days when exposed to outdoors weather. We devised a new solid-state mouse (called ToBu) without any moving parts. The mouse consists of six small metal circles embedded on a plastic plate. These are called touch buttons and need only to be touched with a finger to activate their functions. Four to move the cursor in the left-right and up-down directions, and two for left and right “clicks”. The cursor can also be moved diagonally using a combination of the four touch buttons that control movement.

The keyboard and the ToBu mouse project out from below the monitor through the same rectangular opening in the wall. They are covered by a Perspex cowl that protects from dust. The user inserts his or her hand from under the cowl. The opening below the cowl is wide enough only for small hands to enter. A metal lid covers each monitor and keyboard combination (called the “faceplate”). This is opened during operational hours and forms a sun-shade over the computer. The height of the faceplate and lid are such that adults would need to stoop down at an awkward angle to see the screen. There is a seating rod in front of each computer, placed at a distance from the wall such that it is uncomfortable for tall people.

These design elements are necessary to ensure that only children (usually 13 years and less) access these computers. In rural settings in India, where many adults would not have seen a computer, there is a great deal of curiosity about the device and this can, sometimes, lead to situations where children are not given a chance to operate the computers. Each playground computer is equipped with a web camera and a microphone.

All electrical power is conditioned at the input to correct for voltage spikes, over and under voltage and frequency fluctuations. Four hours of battery back-up is provided for each installation. Sensors inside the enclosure and related software enable us to remotely monitor the following:

1. The temperature, humidity and illumination levels inside the enclosure.
2. Electrical conditions
3. Mouse movement history (when the mouse was moved last).
4. History of applications run on each computer
5. Screen images on each computer
6. Images of children using the computer
7. Voice recordings of children speaking
8. History of sites visited on the Internet

In addition, software controls ensure that:

1. No essential software of data is deleted or renamed.
2. The desktop icons are not removed
3. The system closes unused programs
4. The system restarts when and if a computer hangs.

The entire arrangement is usually placed such that the screens face the north-east. This is to avoid glare from sunlight on the screens. Such playground computers are placed in safe, public locations where their screens are clearly visible to passing adults. This ensures that there are few or no attempts at vandalism, theft or the usage of the computers for accessing pornography or other undesirable material

Amongst the 100 computers placed in the above manner throughout rural India and Cambodia, 4 have been damaged due to vandalism and the access to pornographic material has been estimated at 0.3% of available time, during the four years of the experiment.

With HIW concept we are talking about unmonitored teaching, san the teacher. Do you advocate applying the concept to pre-primary & primary education or would it yield results in higher education as well?

Dr Mitra: The hole in the wall arrangement is suitable for primary and pre-primary only. But the concept of collaborative, self-regulated instruction can be applied to all age groups.

One of the ironies of our present education system has been that it fails to prepare students for the real-world and get a job. Will such education translate to jobs?

Dr Mitra: Computer skills are essential for any job.

The project has received grants from World Bank and GOI. But how do you foresee the implementation of the idea? What kind of budgets will the government need? Do you think Governments would shelve money for such schemes if they were to continue spending on the conventional education route as well?

Dr Mitra: Not really. I think both methods will need to coexist. The Sarva Shiksha Avijan has funds for innovations and they are using this to put hole in the wall computers in remote areas of India.

Innovative projects like HIW comes, especially in a country like ours, from the stables of Private sector. Why do you think the sarkari think-tanks, who are fed on tax-payers money to germinate such ideas, are unable to device any?

Dr Mitra: I don’t think that is strictly true. There are many important ideas that have been developed by the Government. The Space program for example. However, speed and the ability to take new ideas to the market are lacking in the Government.

Can the Internet replace teachers? How do think we could counter the perils of pornography and the known risks of net-life to which kids are most vulnerable?

Dr Mitra: Most of these risks are non-existent in public hole in the wall computers. Visibility of the screen to passing adults and the fact that all usage is in groups ensure social control that prevents both misuse and vandalism.

One of the observations of the HIW that we read was that the children use metaphor for components. NIIT has been synonymous with computer education where you charge people to teach terminologies. Isn’t learning terminologies an important part of education?

Dr Mitra: Could be. Here, they are learning to use a computer. The learning is purely functional. Its like learning to drive a car – it doesn’t really matter whether you know what a carburetor is or how gears work.

Will NIIT consider adapting its course material based on the findings of HIW?

Dr Mitra: Yes.

In a way, we feel, the HIW experiment has shown that an informal, unconventional education system that teaches through games and provides interactive learning works better. Why do you think only computers can achieve that goal? Is it akin to simply aiming to creating computer-literate citizens suitable only for white-collared jobs?

Dr Mitra: Maybe there are other ways also. I am only trying to show that learning to use a computer can be self instructional for all children. I think every citizen will need to be computer literate, whatever work they do. Just like everyone needs to know arithmetic, not just white collar workers.

Edutainment probably forms the basis of HIW and Kids TV programs call themselves that. How do you rate the present TV programming for kids, especially in the cable TV era? Where do you think they have failed or need to improve on?

Dr Mitra: There are good and bad TV programs. The more the edutainment the better they are. For example, Natgeo, Discovery, etc. are very good.

There is a fact that many would find intriguing. We are nation where rural sector still doesn’t have basic infrastructure, there is wide-spread lack of basic health-care and education. And here we are talking about bridging the digital divide first. Isn’t this an urban dream really? Does it really matter for the real India?

Dr Mitra: Ask the village people. I think our urban idea about villages should and should not have is where we go wrong. They want cable TV, the Internet and Revlon, for example. But we in the cities think only we should have those things and not them.

Has HIW been implemented in other countries as well? How has been the response?

Dr Mitra: Yes, in Cambodia and South Africa. Results are identical to India.

What is usually the minimum age -group/education of the target group in any HIW experiment?

Dr Mitra: Age group: 6 or less to 15 or so. Education level – not important or required, even illiterates can learn to use the computer.

There is a lot of Indian language content now a day on the net. How do you see the trend? What has been the catalyst of this growth according to you? How do you foresee the future?

Dr Mitra: Indian content will come from Indians. The more the access the more the content will become. Eventually, one-sixth of the Internet will be in Indian languages, just as one-sixth of humanity is Indian.

We read about complex systems in an article of yours. Would you like to relate the ‘Social bookmarking sites” and “Blog Unconferences” to this paradigm?

Dr Mitra: Yes, they are all self organizing complex systems. I have two papers on the subject.

What are your views on the GOI rejecting the One Laptop per child grant? Do you agree with their arguments?

Dr Mitra: I don’t know their arguments. I don’t think one should accept or reject anything without first measuring their effectiveness.

What’s currently keeping you occupied?

Dr Mitra: Educational technology, self-organising systems etc.

Today I saw a spam comment who admitted that he was posting the comment through a software (as if we didn’t know that already) and ended up offering me a business proposition. Hilarious!

Webdunia.com has been launched, apart from Hindi, in Tamil, Telugu, Malayalam, Kannada, Punjabi, Marathi and Bangla. There is a search facility in each language and what’s more, the company has plans to enhance this to a full blown internet search engine. The Portal now sports a much improved picture gallery, greetings and email section apart from the regular channels covering a variety of subjects. My suggestions would be to add a “rediff.com” like commenting feature to encourage discussion on each news item, with facility to directly type in relevant language, a blog from the reporters of the newspaper similar to “ibnlive.com” and a magazine look for their literature section akin the “BBC Hindi patrika”. Of course I know they would do better not to copy others but these are some of the features that are probably a must for an interactive web.

Looking at the portal’s new incredible look and even the company website you can just sense the new zest and ambition. At the time when the Indian language newspapers are increasingly facing challenge from their English counterpart and have been forced to dilute the purity of the language, irking the language lovers, this is a fresh breeze of change. And when it comes from the people who have always worked towards enriching the language without compromising on values, you are assured of a committed growth of usage of Indian languages on the internet. Keep up the good work guys!

IMHO the problem with Video sharing sites is their likeliness to the email forwards; everyone wants them to be short and funny. In video parlance, this translates to sleaze, a mere glance on the home page of these sites will force to look around you, koi dekh to nahi raha, certainly these sites are not work-safe. But then, it’s a peril associated with most of the user-generated content.

AapkaVideo tagline is “Director ban jao” (become a movie director) which indicates a pious, if not unique, USP. They might have in mind those yuppie and extravagant Cell phones, with ever increasing recording time and video quality, people carry now days even in the toilets. Nokia was quick to realize this and has successfully tried to encourage movie making through these sneaky cameras. So yes, there is a market, but till that reaches a critical mass, you to have to be content watching those tacky snippets from Bollywood movies and Advt from the firang channels. The wait, meanwhile, for upcoming Mani Ratnams and Karan Johars may be prolonged though you could surely find umpteen Jagmohan Mundras.

I feel good when I see a glimpse of monetization plan in such ventures, apparently AapkaVideo has plans to use the ‘Special” segment where they could have featured videos or videos on a theme, Buzzfeed fans will find an instant liking for this. Combine this with anticipated market for projects such as “movie on demand” and you may have a niche market in your trap.

The site has a professional layout and since it’s still a beta, improvements are imperative, including the fact already discussed in the blogosphere: the videos don’t work on Firefox. The option to enlarge the video seems good, but they actually should provide the facility selectively to videos that will look good at higher screen resolutions. The site supports a vide range of video formats and allows uploads unto a 100 MB. And being a Java guy, it feels good to see the “.jsp” file extensions on browser.

I really envisage the days when such sites will also have a meaningful aspect to them, imagine breaking news videos from a citizen journalist, vlogs, interviews and technology reviews. AapkaVideo seems to have an inkling of this and you could spot categories such as “Techzone” and “News & Blogs”, which may take some time to generate relevant content.

Amidst all these video sites becoming the cynosure of eyes, even a blind can see the emerging trend, namely, the television making a move from the idiotbox to your computer monitor. TV on Internet and IPTV are being discussed since many years, the Golliaths like Yahoo, Google, Microsoft and the Telcos are involved in using the net as a medium of distribution of digital content, all this to take advantage of the interactivity with the viewer.

To most of the Indians this doesn’t mean much, atleast at the moment. Bandwidth is still a bottleneck, the availability graph is rising but the costs are still far off the affordability radar.

Another larger question that emerges, is the control over this user-generated content. YouTube has been in the docks for the same, sort of déjà vu of Napster, let’s face it: people are concerned over piracy issues.

The ultimate challenge for these companies is to provide superior video content on the net without ignoring the copyright and security issues (spyware, viruses), but if they are successful it would be win-win situation for both TV and Internet.

So be forewarned, the AapkaVideo jaadoo may actually end up mesmerizing you sooner than you think. Now, off to that video tagged “desi kiss”

[Disclaimer: This is a paid review for Reviewme, but the thoughts are my own.]

It may or may not be for the love of Blogger, all of us need a change, probably the reason we keep on changing our templates and themes so often. When Logahead came people immediately started touting it as a replacement of WordPress until the poor chap has to proclaim himself. Logahead wasn’t too superior a blogware but it did show a novel way to do things, for example getting rid of the cumbersome Admin console of WordPress an the AJAX way to effortlessly deploy widgets. If you ask me the refined UNU version of Logahead is far more superior to the original and can give a competition to the Goliath.

The craving for the much needed change did not spare the creators of WordPress either it seems now. WordPress was slated as the “ultimate blogware” but the core team of WordPress comprising of Chris Davis, Khaled, Michael (the Kubrick creator) has now left WordPress and are working on the nextgen open-source blogware termed as Habari, a Swahili word for “What’s up”. Habari would not be forked from WordPress (WordPress was based upon B-2), it’s been written from the scratch and would sue the most modern technologies such as PHP 5 (and PHP Data Objects), Habari code would be Object Oriented and Database independent.

The creator of WordPress Matt modestly wrote that Habari would probably be Drupal meets Serendipity. He not only pledged his support for the initiative but also offered his servers. Despite of this the unrest in the WP camp is quite noticeable. Some said that this is the outcome of politics of people pissed off from not getting appointed at Automattic. Habari’s Skippy clarified this wasn’t so but wasn’t wary of terming the spam-prevention capability of WordPress as Band-Aid code. The Habari team is hopeful of cutting a relapse before 6 months and yes this will have the capability of “importing from WordPress”. Owen on the other hand said that there are no hard feelings and he would continue to be with WordPress as well.

Right now the only blog running on Habari is Chris’s, it might not seem too different but the team claims it would be fast and modern. Habari may be used with other databases as well, apart from MySQL. I wonder how popular it would be until they go for a hosted solution. If you ask people like me, who pay for their hosting, PHP 5 is not what my Hosting service would provide in near future and even I would be wary of going for it, it might break my other applications. yet I am excited by the fact that Habari is talking of community and using new things once in a while is so much better.

However, last month’s activities at the site indicates that Rick has probably lost his interest in the effort. Since last month the sites’ services have had technical hiccups, most of the sites, including Chittha Vishwa, a Hindi blog aggregator, throw errors (java.lang.NoClassDefFoundError: Could not initialize class com.sun.tools.javac.main.RecognizedOptions) and scores of people have been registering their complaints but to no avail. Javalobby’s Mathew acknowledged that the problem appear post upgrade to JDK1.6 with Resin not being able to find the new javac but was non-committal, “We’ll look into whether we can get it fixed.” And perhaps that’s the reason the problem hasn’t been fixed till date.

People like me who use the “free” service obviously cannot demand much but it is painful to see the excellent service languish this way. If Javalobby has really lost interest, I would have appreciated a candid formal announcement.

When I switched to WordPress, I learnt that it provides many flavours of feed including RSS, TDF and Atom. It is awesome but confusing, because you never get to know, exactly how many people are actually reading your blog through newsreaders.

Recently, it occurred to me that somebody must have thought about it before and I just Googled and quite easily stumbled upon this amazing plugin from OrderedList. It’s called the “Feedburner Plugin” and it simply helps you divert all your WordPress feed subscribers to your Feedburner feed. Yes, it really routes all of them, whether they use your blog’s Atom or RSS feed; even the comment feeds could be routed this way. The best part of all this, your readers do not even get to know about this. Steve, you rock!

For the blog owner it is a myriad of benefits. Not only do you get to keep track of your readers, proudly flash the count (even if it’s peanuts) and analyze the feed usage, you get benefit of all the Feedburner featurettes, like the “Feed Via Email” feature that probably ends the need for separate service like FeedBlitz. Feedburner now has an interesting lineup of features under one roof, there are BuzzBoost & Headline Animator that lest you display latest blog headlines on any other site, Pinging service, feed analysis and so on. You may password protect your feed and can even make money from it. There are host of others, including “paid” ones like SmartCast for podcasters. Fabulous!

Look for the Feed Icon in the newly added Subscribe section below, that’s the fruit of this labour apart from this post.

I could now stop myself from playing a bit with it and I created “Chittha Khoji” (Hindi for Hindi blog explorer) that would search the Hindi blog aggregator Narad and Chittha Charcha a Hindi blog review site that I am part of. I think the collaboration theme is quite evident in the effort and anyone can solicit volunteer contribution to their engines, Google marker is there to quickly add sites. The Site look and feel is customizable though I noticed that it does not accepts Unicode yet.

And there is much more. You can create the complete engine using XML and can even AJAXify it using their API. Refinements allow you to allow labels to filter the search results; again, Unicode characters weren’t being supported yet. So English is what would work now, I hope other languages would be supported soon.

Here is a glimpse of search results from “Chittha Khoji”