Fail number 1: Absolutely no place to park my bike. This has been pretty much the case ever since the undergrads have been back. Rice built two new colleges right next to the building I work in, but didn’t consider what an increased resident population would do to bike rack space: The undergrads, of course, store their bikes semi-permanently on the bike racks that we need to commute.

This is what the bike racks looked like shortly after 9 AM this morning:

Overfull Duncan Hall Bike Rack, 9:15 AM

I have been lobbying for more bike racks for over a year now, to no avail. I guess I’m going to be taking my bike up into my building from now on.

Fail number 2: I still don’t have my Texas drivers license, even though it has been 67 days since I renewed it. It’s even been over three weeks since I first contacted the DPS and was told the license would be remade and resent. Today I found out why it’s taking so long:

You will be mailed out a temporary permit today while you receive your license in the mail. Apparently the license was not remade when the visitor status was updated. I sincerely apologize for the inconvenience this has caused you.

In essence, they cut up my old drivers license, updated their internal database, and never mailed me a new license. Good job, Texas DPS. I’m glad I have an international drivers license as a backup.

DrJava isn’t the barista behind the counter at Starbucks. But the doc still serves a pretty potent brew — and more than a million customers can’t be wrong.

DrJava is a lightweight, integrated development environment for writing programs in Java, the popular, cross-platform programming language developed in the ’90s by Sun Microsystems. Using Java is the simplest way to write programs that run on all major computer platforms, like Windows, Linux and Mac OS. As a result, Java is now the most commonly used programming language, as measured by the Programming Language Popularity index LangPop.com. For several years, universities and high schools have also been using Java in many of their computer science classes.

Our team at Rice University started building DrJava in 2001, and it has now been downloaded more than a million times.

Mathias Ricken is a Ph.D. candidate in computer science at Rice. (Photo by JEFF FITLOW)

The JavaPLT group at Rice continues to develop DrJava as a SourceForge open-source project, primarily to give students an intuitive interface as they learn programming skills. DrJava users can easily evaluate Java code in an “interactions pane” that shows precisely how their creation is working. The environment also includes powerful features for advanced developers.

The development of DrJava began in 2001, led by Robert Cartwright, a Rice professor of computer science. From its initial release the following spring, DrJava source code emphasized the use of Java generics, a method for reducing duplication in code by factoring out certain repeating patterns. Early in the evolution of DrJava, support for Java generics was added to the interactions pane. After the addition of a project facility in 2004 and improved support for large projects beginning in 2006, DrJava experienced a sharp increase in popularity.

DrJava supports several Java compilers, including Oracle/Sun’s JDK, OpenJDK and the Eclipse Java Compiler, as well as such research compilers as NextGen and Java Mint. In 2005, DrJava introduced support for a hierarchy of Java language levels, a pedagogic framework that helps beginners learn Java by partitioning the language into levels of increasing complexity.

More than 60 Rice students have contributed to DrJava over the years through Dr. Cartwright’s class on production programming or as part of independent study projects. DrJava is now being used at institutions across the globe, including Princeton University, the University of Pennsylvania, Cornell University, Georgia Tech, the University of California-San Diego, the University of Washington, Université de Nice Sophia-Antipolis and National University Singapore, as well as Rice.

DrJava has also been used as a teaching tool in books published by Pearson Education and Wiley Higher Education.

DrJava is freely distributed under the BSD License. Download it at http://drjava.org/.

—Mathias Ricken is a Ph.D. candidate in computer science at Rice.

(Reposted from Rice News.)

There was concurrency and parallelism everywhere, just like at SIGCSE earlier this year, but perhaps without as much panic (“We have no idea how to teach this!”).

I wish I had been up for more even more socializing, but for my kind of personality, talking to people is work. I still enjoyed the conference tremendously.

The slides for the talk have become much cleaner over the last few days. We will make them available on the Java Mint website soon.

Eddy Presenting Mint at PLDI 2010

The best part were really the questions and comments I got. There were questions about reducing code duplication, whether we mostly see a kind of fold behavior for staged programs (this occurs in accumulators, but we can do much more), and much more.

Luke also had three crucial pieces of advice:

1. The introductory slide comparing a general power function to a specialized power17 function and giving performance figures like 41 ns and 9 ns was weak. This ends up defining MSP and our work, and if we lose the audience’s interest here, we probably won’t get it back. We really need to open with a bang. A short opening statement about what MSP is would have been good too.
2. At PLDI, we need to have a short explanation of how we benchmarked, and using what JVMs. I was able to answer this in the Q&A period, but it should briefly preface the benchmark table.
3. An animation of scope extrusion showing the objects, from a memory/stack/heap point of view, could be useful in helping explain code extrusion, and it would break up the text monotony.

Thanks for the opportunity, Purdue CS, and thanks for organizing this for me, Jan and Luke.

Mint: A Multi-stage Extension of Java (Mathias Ricken) from Mathias Ricken on Vimeo.

From the Houston Chronicle, Jan. 9, 2009:

Legal immigrants battle red tape

Pakistan native Adeel Mehmood started building a life in Houston after the U.S. government granted him asylum more than two years ago.

He graduated from the University of Houston, settled into a home in Garden Oaks and saved money from his restaurant job to buy his dream car: a new Toyota Camry.

The 25-year-old still faithfully makes payments on the Camry — and on his insurance — even though the state of Texas in December denied his application to renew his driver’s license, citing a new policy that took effect Oct. 1 requiring specific documentation to prove an applicant’s legal immigration status.

Three months after the policy took effect, critics are pointing to a growing list of cases involving legal immigrants who have been significantly delayed or outright rejected in their efforts to get or renew licenses, despite being authorized to live and work legally in the U.S.

“I have always maintained my legal status,” Mehmood said. “It’s not fair to people who want to live here and follow the law.”

Under the policy change, only applicants who have documents showing they have permission to stay in the U.S. for at least six months are eligible for Texas driver’s licenses.

But immigration attorneys are reporting that people who meet that criterion — but are unable to produce documents required by the DPS to prove their legal status — are still being turned away.

For example, Mehmood said he was rejected by the DPS after being told his letter from U.S. Citizenship and Immigration Services granting him asylum wasn’t specifically listed on DPS’s list of acceptable forms.

The Texas chapter of the American Immigration Lawyers Association is pushing for revisions to the policy, adopted by the Texas Public Safety Commission in August, saying the list of acceptable DPS documents needs to be expanded to include several forms of legal status that allow for a six-month stay or longer in the U.S. They also are pushing the state to make allowances for delays in processing times sometimes caused by USCIS.

“This is going to end up impacting lots and lots of people,” said John Nechman, a Houston immigration attorney. “Every day there seems to be another example.”

Designed to curb fraud

Supporters of the new policy, including Gov. Rick Perry, said the state is safer because of the more stringent document checks, which are designed to stop illegal immigrants from getting licenses and to combat fraud and identity theft. The agency has issued more than 15,000 “visitor” licenses to immigrants statewide since October, said Tela Mange, a DPS spokeswoman.

Allan Polunsky, chairman of the Public Safety Commission, which oversees the DPS, said the policy change was not intended to deny legal immigrants the opportunity to drive.

“If there is a problem in the process, then it should and will be addressed,” Polunsky said. “We have to look at all the facts before we make any changes, but certainly we want to be fair.”

D. Jackson Chaney, an immigration attorney in Irving, said the DPS did not consult any immigration lawyers or experts when it put together the rule and left out several forms of legal status that allow immigrants to stay in the country beyond six months. The list includes refugees as well as some immigrants who were granted green cards before those documents had expiration dates.

“They’re being denied licenses on ridiculous grounds, frankly, because DPS simply does not know immigration law,” Chaney said. “It’s really a mess.”

Paperwork delay

In some cases, even though driver’s license applicants have immigration documents that appear to expire within six months, they may still have legal status from USCIS as long as they have a pending application for an extension, attorneys said. But it can sometimes take immigration officials six to 12 months or longer to process the paperwork, leaving applicants unable to drive legally for months at a time.

Mathias Ricken, a doctoral candidate and computer science instructor at Rice University, made four trips to the DPS office in November and December to get his temporary driver’s license approved.

Ricken, who is in the U.S. on a student visa from Germany, called ahead on Nov. 19 to find out what documents he needed, but each time he went to the office, he was asked for more. He eventually got approved for the license after presenting documents including: his Texas ID card, his German passport, three different immigration forms, a Social Security card, a certificate of enrollment, a tuition receipt and a signed and stamped letter from the director of Rice’s Office of International Students and Scholars.

The letter was not required, but Ricken thought it might help. “I think it’s right to require that you identify yourself in the proper way and show that you are in the country legally,” he said. “The problem is more in the details.”

Unusual case

The problem has turned into more than a nuisance for Mehmood.

His driver’s license expired in November. Mehmood has made multiple visits to DPS offices since then, each time carrying a thick three-ring binder of immigration documents and his work authorization.

Mehmood said he was told that his letter granting asylum and other immigration documents were not sufficient proof of his legal status. He also was told he was ineligible because his “I-94,” a standard U.S. customs form for foreigners, had no expiration date, which is common for asylees, who are allowed to stay in the U.S. indefinitely.

Mange, the DPS spokeswoman, said she would look into Mehmood’s case.

Note: I am a legal non-resident alien, not an immigrant.

Here are some frames from the video:

On Wednesday, August 26 I got up bright and early. I had already packed, so instead I could work on integrating ConcJUnit support into DrJava. I really did work until the last minute: Even at IAH Terminal A I was still making changes. I just figured the demo of ConcJUnit wasn’t very exciting from a visual perspective, so using it inside DrJava might make it a bit better. I think this was the right idea.

My flight had a short layover in Salt Lake City, Utah. The mountains seemed great from the air. Maybe some day I can spend some more time there. It did look rather dry there though; in fact, even the airport was lacking water fountains, and I couldn’t refill my water bottle for the flight to Calgary. I got to Calgary around 10 PM (11 PM CDT). I had just used carry-on luggage (although the airplanes were so small that I couldn’t in fact carry it with me), so getting my stuff didn’t take long.

The immigration examination was pretty thorough: The officer asked me what I was doing in Calgary (“I’ll speak at a conference.”), what conference it was (“PPPJ at the University of Calgary.”), and what kind of a conference it was (“It’s a computer science conference.”). She then asked what my status in the US was (“I’m an F1 international student.”) and “what I was taking”. I didn’t understand that question. I guess she was asking what classes I was taking. I finally responded with “I’m a computer scientist.” Customs, on the other hand, was very easy. I took a taxi to the hotel and then had some late-night McDonald’s. I hate getting fast food, but I didn’t want to search for restaurants that were still open at 11 PM.

On both Thursday and Friday I got up at 6:30, used the coffee maker in my room and got dressed, then headed down for the complimentary breakfast, which was pretty good. On Friday, though, it was swamped with Austrian tourists. I pretended not to understand them. Then, around 8:45, I headed to the conference venue. I got back around 9 PM on both days and then continued to work at home.

The conference was pretty small — it seemed like nearly everyone that was there was also presenting. The highlights for me were definitely Michael Ernst‘s tutorial on pluggable type-checking, Borys Bradel‘s presentation on trace-based parallelization of recursive Java programs, and the work by Danilo Ansaloni et al, particularly MAJOR.

Danilo’s MAJOR presentation was just before mine, and it was really an impressive demonstration of aspect-oriented programming for instrumenting programs. He shocked me by saying, as an aside, that in their aspect-oriented version of ReCrash they can also detect uncaught exceptions in all threads. They do this by applying an advice at a join point at the end of the Thread.run() method.

This seems a lot cooler than how I’m doing it, and I have to admit that I was stunned and that my presentation suffered. My approach, ConcJUnit, however, is simpler and uses standard Java, so it does have its merits.

The conference was enjoyable. I met some very smart, interesting and genuinely nice people. In addition to Borys, Danilo and Michael, I want to mention Ben Stephenson, the General Chair of the conference; Ondrej Lhotak, the keynote speaker; and Dave Hughes, chair of the CS department at Brock University and user of DrJava.

I did feel pretty tired afterward, though, and except for dinner downtown on Friday night, I didn’t have any time to go sightseeing. Consequently, the only pictures I took are from inside my nice hotel room and of a rather gigantic rabbit on the campus of the University of Calgary:

On Saturday morning, I got up at 4:30 and had coffee, then shared a taxi to the airport with David Hughes. The flight back via Minneapolis, Minn. was uneventful, and again I got a decent amount of work done. There was no free wireless network at either of the airports (at least none that I could get to work), so in Minneapolis I used tethering on my Palm Treo to submit my changes to Perforce and Subversion.

I thank my advisor and co-author Corky Cartwright for letting me attend this conference; the School of Engineering for partially supporting me; and the conference organizers and reviewers for their hard work.

Now I’m back, and I’ve spent the last few days improving the ConcJUnit integration in DrJava. As of yesterday, it is now possible to select a JUnit or ConcJUnit jar file and use it instead of the built-in JUnit. If ConcJUnit is used, the Java runtime library can also be processed at the touch of a button.

Again, I feel like I have to make the comment that I didn’t write because I worked so much, not because there was nothing to write about. Blogging just has a very low priority for me right now.

Perhaps the biggest story is that Corky and I have published a paper together: ConcJUnit: Unit Testing for Concurrent Programs has been accepted at PPPJ 2009. The 7th International Conference on the Principles and Practice of Programming in Java will be held in Calgary, Canada at the end of August.

I’m quite excited about having this paper published, for two reasons: First, despite having worked with Corky for years now, this is actually the first paper we have co-authored. Second, I really only worked on the draft for four days before submitting it. On Monday night, April 20, I was at the Bill Bryson reading downtown, and when I was in line for autographs and checked my email, I saw a message from Corky that the PPPJ publication deadline had been postponed to Friday. He suggested that I submit something on unit testing concurrent programs.

Of course, right at that moment I thought “Four days? How am I supposed to do that?” and it seemed like a huge pain. But I decided I could pull a few things out of my thesis, enhance them a bit and give it a shot. Tuesday and Wednesday I experimented and added another feature to ConcJUnit, the concurrent unit testing framework I had developed, and Thursday and Friday I wrote the paper. It was rather short, a little under five pages, but I was happy with it. Friday night I almost got killed by a road-raged driver, but around 2 AM on Saturday night I submitted the paper (the submission deadlines are often on midnight at the international date line, i.e. 6 AM in Houston).

A few weeks passed while the paper was under review, but on June 5 we were notified that the paper had been accepted. I was in Finland at the time, so it was fortunate that the submission deadline of the camera-ready version had been postponed by a few weeks, so I didn’t have to work in Finland and could enjoy my vacation fully.

The other big story during the last half year was my work on Mint, a multi-stage extension of Java. This has been really interesting work. I was mostly involved in creating the implementation, creating sample programs and benchmarks, and writing some of the non-mathy parts of the paper. I’m still not nearly as quick thinking about many of the multi-stage constructs as some of the other researchers, but I’m getting there.

In the implementation, we started off with the OpenJDK compiler and added brackets (<| |> and <| { } |>), escapes (`) and the separable keyword. Brackets gets turned into a constructor call to a code object, and this code object contains an AST of the source inside the brackets. When a code object is run, we send the AST back into the compiler (at runtime!) and then call the created code.

This project felt a bit like a hack, like self-modifying code. It was great. I got a pretty good tour of the Java compiler too, more than I got to see with my xajavac experiments. We’re having some overhead from the compiler, but once that’s done we can speed up our code by factors of 5 to 20, depending on the benchmark. Explaining all these things in detail is too complicated here, so I’ll refer the interested reader to our technical report.

We first submitted a paper to GPCE 2009, but it got rejected. Initially I found this quite surprising, since I had so many strong collaborators, but it really came down to the wire with the submission deadline, and our paper still had many rough edges. Now we wrote the aforementioned technical report (which isn’t quite finished yet, actually, the appendix is still missing), and we submitted an improved version to POPL 2010. I dearly hope that the hard work of the last half year will pay off and reward us with a publication. I’ll probably continue to work on this for a bit, since I will probably be supported by Walid during the next year.

Something cool, although not significant from a professional point of view happened early this summer: Someone from VDM Verlag, a German academic publisher, contacted me and asked if I would like to publish my MS thesis as a book. It’s available on Amazon and other websites now. I have to stress that this is merely a republication of my MS thesis. There was no additional peer review beyond what my thesis committee did. As such, it should not be viewed as book or monograph, but it’s cool nonetheless:

Nothing much has happened with DrJava since the last post. We made a few bugfixes and improvements, and we’re planning to push out a new stable version soon.

I’ll close with some very nice reviews I got in my COMP 402 teaching evaluation:

Great course that introduces coding on a well establish code base. Completely different type of programming than that of lower level COMP classes. Taught a lot of practical programming techniques.

The course is good if you want to practice in Java. And it’s awesome that you can do some real work in the development of a real software.

Knows the code base well and good at helping students without doing the work for them. The few lecturers were interesting and well presented. Good professor for this class.

This class was more of independent study. The teacher was ready to help on completing a task whenever you asked him to. I learned a lot about production programming as a whole.

Mathias is a good instructor. He is very helpful when we have some trouble in work. And he always replies email very quickly. He is a nice guy. In addition, he is really great in DrJava.

Thank you for the kind words, and thanks to the School of Engineering, the department chair Joe Warren, and my advisor Corky for giving me this opportunity.

I’m also starting to look at the Java multi-stage programming project again, and I discovered that the OpenJDK people have added a Compiler Grammar project. This project is trying to replace the hand-coded parser for javac by a parser generated from an ANTLR grammar file. I haven’t fully checked how far this has progressed, but it is interesting. Modifying the grammar to allow annotations on statements and expressions should be easier than rewriting the interpreter by hand. It seems like there is a Java 5 grammar that integrates into javac, but of course there is no JSR 308 grammar, so I’d have to develop that first.

When I looked at ANTLR and the Compiler Grammar project, I also noticed an interesting IDE that has been built to make developing grammars easier: ANTLRWorks. It integrates a several checking tools and a debugger and looks tremendously helpful. For example, it can explain how a grammar is ambiguous. In my case, an annotation on a parenthetical expression could be parsed in two different ways, so I’ll have to be careful there.

ANTLR Ambiguous Path Visualization

On MacOS, I’m still struggling a bit to get the Compiler Grammar project and ANTLRWorks running. It seems like Compiler Grammar needs SoyLatte to work, and I have managed to build the Compiler Grammar javac from the command line, but when I try to run it inside ANTLRWorks, then it seems like it is using the default Apple Java version 1.6.0-dp, which doesn’t work. Maybe I’ll take a look at it on Windows first.

I also need to start thinking about the COMP 202 final exam, and about a lecture schedule and programming tasks for COMP 402 next semester.

% svn co https://drjava.svn.sourceforge.net/svnroot/drjava/trunk/drjava
svn: PROPFIND request failed on '/svnroot/drjava/!svn/vcc/default'
svn: PROPFIND of '/svnroot/drjava/!svn/vcc/default': SSL negotiation failed:
SSL error: decryption failed or bad record mac (https://drjava.svn.sourceforge.net)

Has anyone else encountered this? I can’t find any useful search results. However, when I do a checkout with http instead of https, it works (although I haven’t attempted to commit anything):

% svn co http://drjava.svn.sourceforge.net/svnroot/drjava/trunk/drjava
A    drjava/strip-license
A    drjava/LICENSE
...

Any advice is appreciated. I’m starting to think this is a SourceForge issue again, because I have been finding a handful of SSL issues.

Judging by my experience in the last few months and all the support requests (“We’ve been making some changes, try again *request closed*”), SourceForge has turned into a steaming bucket of excrement. Someone please flush.

I do have some new pictures from today’s lecture about parsing and the extended visitor pattern, though. Explaining the extended visitor pattern with all the type parameters is more difficult than I thought. I’ve decided to spend another day on it.

Update

It turned out that an upgrade to the latest OpenSSL and Subversion software on our side took care of the problem. I figured that would be a more sensible first attempt, rather than downgrading to an ancient version of OpenSSL, which is what SourceForge recommended.

So I had to go back home during my lunch break to get the notebook. I should have just brought it in the first place.

I ended up going through detailed hand evaluations for the first and third sample program, both in call-by-value and call-by-name, and discussed the second program at a higher level, because it was less interesting.

I extracted some new pictures from today’s lecture, Dictionaries & Hashing (#22):

Take a picture of yourself right now.
Don’t change your clothes, don’t fix your hair…just take a picture. (should be super-easy with Photobooth)
Post that picture with NO editing.
Post these instructions with your picture.

from http://www.flickr.com/photos/raganwald/2909791653/

I think the role-playing went well, although next time I should perhaps let the students do all of it. This time, I was the “visitor”, so a lot of what was going on was decided by me. On the other hand, this allowed me to mix the role-playing exercise with telling what the algorithms did.

For the list algorithms, we talked about reversing and appending. For appending, I could not find an algorithm that required a helper; my algorithm didn’t need a helper, but it wasn’t tail-recursive. We briefly talked about tail-recursion optimization.

In general, I’m quite happy with today’s lecture, although the video showed that I do have quite a few “uh”s as speech disfluencies, and that I could vary my pitch more. I still couldn’t get into the lab using my ID card, but I’ll check again on my way home.

Using index cards and role-playing to teach the visitor design pattern in lecture 2.

Tomorrow, we’re flying again, this time to California. I hope bigger airports mean bigger brains when it comes to determining what couldn’t be a threat, so my brand-new 4 oz too-big tube of toothpaste may survive confiscation. I’ll probably have a score to settle when we return, but there’s one thing that I can do right now: I just bought 1-quart ziplock bags. The bags we had last time too. At the Kansas City airport, we were stripped of our bags because they were too large and were given sandwich-sized bags. So, here’s the size comparison.

This is the sandwich-sized bag with all my stuff crammed into it:

This is just my liquid stuff I want to take aboard: deo, toothpaste, two kinds of eye drops (I wear contacts), two bottles of shampoo swiped from a previous hotel, and a bottle of contact lens cleaner:

This is a comparison of the two bags: The smaller one, on the left and on top, is the TSA-issued bag. The bottom one is the 1-quart bag I just bought that meets TSA specification. As you can see, the TSA employees took away our 1-quart bags, which were fine, and gave us new bags that were about 25% smaller:

Here, finally is all my stuff, which now easily fits into the bag. I wonder if I could even throw in my 6 oz flask to make the flight a bit shorter ;)