And that’s how you teach CMPT 383

August 22nd, 2010, 10:48 pm PST by Greg

I have now completed my first offering of CMPT 383, Comparative Programming Languages.

I had forgotten how much work a new course prep is, particularly as I am anal-retentive enough to not be able to make much use of any other instructor’s course materials. Other instructors just do things… wrong. The only way for a course to feel right is to do it my way, for myself. Giving lectures from somebody else’s notes is like wearing somebody else’s underwear: technically probably just fine, but you just feel dirty.

That’s not to say other people who teach the same courses I do do a bad job: they are generally excellent instructors teaching excellent courses. They just do it wrong, is all.

But, looking at my plan for 383, I came in pretty close to the plan. The final balance of topics was more like 6 weeks, 4 weeks, 3 weeks, but that’s astonishingly close for somebody who usually just stops somewhere around the midterm and thinks “does that feel like about half of the material? Okay good.”

Overall, I’m very happy with it. First offerings of a course are supposed to be bumpy and full of things that you wish you could have done better. Honestly, this was one of my favourite course offerings ever: there are tweaks I’d do for my next offering, but all are fairly minor.

Specifics:

  • The weekly exercises were (to my mind, at least) a total win. My goal throughout was basically to say “remember that thing I talked about this week? Practice it” and I think it worked for the students. I liked them to the point that I’m planning that every course I teach from now on will have weekly exercises, including 470. (More on 470 in a later post.)
  • Some of the more involved examples I put together were among my favourite learning objects ever. (God, I can’t believe I just used the term “learning objects“. I have become everything I hate.)
  • I think I actually convinced them that Haskell was practical. Was that irresponsible?
  • Prolog sucks, but I’m still convinced it’s a worthwhile exercise.
  • The “language concepts” section felt a bit like a laundry list of topics. I don’t know that there’s really any way around that. Maybe I could re-order things a bit so they flow together better.
  • The project was interesting for all concerned. I’d probably cut down to three or four language choices in the future, just to keep the TA from losing his mind.
  • I’m not particularly happy with the exams, but I’m never happy with my exams.
  • Ted was an invaluable sounding board throughout the semester, taking time he didn’t have to listen to my meanderings on the course. Thanks be to Ted, who will do an excellent job teaching the course in the fall. (Excellent, but wrong.)

The feedback I have had from the student side has been very good so far (with the real teaching evaluations still outstanding). I have never before had so many students who had nothing to do with a course talk to me about it. Random students in the hall thought my project was a good idea; everybody and their dog knew about my first assignment; people with friends in the course want to know when I’m teaching it again.

I’ll take that as creating a “buzz” and call it a good thing.

Everything I know about databases is wrong. Also, right.

June 24th, 2010, 12:48 pm PST by Greg

I have been teaching CMPT 470 for six years now, with my 13th offering going on right now. Anybody doing that is going to pick up a thing or two about web systems.

I was there for the rise of the MVC frameworks and greeted them with open arms. I watched Web 2.0 proclaim “screw it, everything is JavaScript now” and listed with suspicion, but interest. I am currently watching HTML5/CSS3 develop with excitement but wondering why nobody is asking whether IE will support any of it before the sun burns out.

There’s another thing on the horizon that is causing me great confusion: NoSQL.

The NoSQL idea is basically that relational databases (MySQL, Oracle, MSSQL, etc.) are not the best solution to every problem, and that there is a lot more to the data-storage landscape. I can get behind that.

But then, the NoSQL aficionados keep talking. “Relational databases are slow” they say. “You should never JOIN.” “Relational databases can’t scale.” These things sound suspicious. Relational databases have a long history of being very good at their job: these are big assertions that should be accompanied by equally-big evidence.

So, I’m going to try to talk some of this through. Let’s start with the non-relational database types. (I’ll stick to the ones getting a lot of NoSQL-related attention.)

Key-value stores
(e.g. Cassandra, Memcachedb) A key-value store sounds simple enough: it’s a collection of keys (that you lookup with) and each key has an associated value (which is the data you want). For Memcachedb, that’s exactly what you get: keys (strings) and values (strings/binary blobs that you interpret to your whim).

Cassandra add another layer of indirection: each “value” can itself be a dictionary of key-value pairs. So, the “value” associated with the key “ggbaker” might be {"fname":"Greg", "mi":"G", "lname":"Baker"}. Each of those sub-key-values is called a “column”. So, the record “ggbaker” has a column with name “fname” and value “Greg” (with a timestamp). Each record can have whatever set of columns are appropriate.

Document stores
(e.g. CouchDB, MongoDB) The idea here is that each “row” of your data is basically a collection of key-value pairs. For example, one record might be {"fname":"Greg", "mi":"G", "lname":"Baker"}. Some other records might be missing the middle initial, or have a phone number added: there is no fixed schema, just rows storing properties. I choose to think of this as a “collection of JSON objects that you can query” (but of course the internal data format is probably not JSON).

Mongo has a useful SQL to Mongo chart that summarizes things nicely.

Tabular
(e.g. BigTable, Hbase) The big difference here seems to be that the tabular databases use a fixed schema. So, I have to declare ahead of time that I will have a “people” table and entries in there can have columns “fname”, “lname”, and “mi”. Not every column has to be filled for each row, but there’s a fixed set.

There are typically many of these “tables”, each with their own schema.

Summary: There’s a lot of similarity here. Things aren’t as different as I thought. In fact, the big common thread is certainly less-structured data (compared to the relational style of foreign keys and rigid data definition). Of course, I haven’t gotten into how you can actually query this data, but that’s a whole other thing.

Let’s see if I can summarize this (with Haskell-ish type notation, since that’s fresh in my head).

data Key,Data = String
memcacheDB :: Map Key Data
data CassandraRecord = Map Key (Data, Timestamp)
cassandraDB :: Map Key CassandraRecord

data JSON = Map Key (String | Number | … | JSON)
mongoDB,couchDB :: [JSON]

data Schema = [Key]
data BigTable = (Schema, [Map Key Data]) -- where only keys from Schema are allowed in the map
bigTableDB :: Map Key BigTable -- key here is table name

The documentation for these projects is generally somewhere between poor and non-existent: there are a lot of claims of speed and efficiency and how they are totally faster than MySQL. What’s in short supply are examples/descriptions of how to actually get things done. (For example, somewhere in my searching, I saw the phrase “for examples of usage, see the unit tests.”)

That’s a good start. Hopefully I can get back to this and say something else useful on the topic.

How to not attend a lecture

May 28th, 2010, 12:06 am PST by Greg

I teach at a university. That comes with certain parameters: most of my students are in their late teens or early twenties, the average student is reasonably bright but occasionally unmotivated, and I don’t really have any way to compel students to come to lectures.

I do my best to give interesting, informative, and entertaining lectures. I’m successful enough that most students come most of the time, and that’s awesome.

Sometimes students don’t come to lecture. They don’t need a good reason, and they don’t have to tell me about it. I’m okay with that too: part of being at university is being responsible about that kind of thing and I’m happy to assume that whatever reason they have is a good one.

But what really annoys me is when students feel the need to email me, tell me the stupid reason they didn’t come to lecture, and then ask me to tell them what I covered.

I already spent an hour (or three hours) of my time giving the lecture and they had an opportunity to attend. I put a great deal of time and effort into explaining the material in the best way I can and pointing out the things that I think are important. I did all of this because I think I can actually do a decent job of getting material across in the lecture format and I think the material I’m talking about is important.

These emails leave me with two choices: (1) reduce a carefully-prepared lecture to a pointless list of topics and thus implying that I might as well have read them the textbook, or (2) spending another hour repeating the lecture in email form. Neither one of those is very attractive, but there’s also the third option that I have started to avail myself of: telling the students to shove off.

I’ll say here what I said to my CMPT 165 class last semester: if you miss a lecture, you ask a friend in the class for their notes. If you don’t have a friend in the class, ask the person sitting beside you; if at all possible, try to do this when you are sitting beside someone who you find attractive and offer to buy them coffee in return.

Seriously… do I have to explain everything?

cf. entitlement generation.

CMPT 383: for real this time

April 19th, 2010, 6:09 pm PST by Greg

I have mentioned here before that I was planning to teach CMPT 383. It ended up being a no-go this semester because of a very productive capstone project team (more on that later).

But, I’m on-deck to teach it in the summer. The class is full; the waiting list is full; must be time to plan a course. After much soul-searching, I have decided there will be three main topics in the course and they will be covered in this order:

Functional programming (and Haskell)

This will be most students’ first introduction to a non-imperative programming paradigm (and associated language). Every little while I think this won’t take long, then I remember the list of things that have to be introduced to get anywhere with Haskell: being really good at recursion, list comprehensions, lazy evaluation, type inference, higher-order functions, and other stuff to be discovered as I try to teach the language.

From my perspective, there are two reasons to be talking about functional programming. First, it’s finding some relevance, probably because people want to parallelize things (e.g. CouchDB). Second, there are important lessons from functional programming that can be transferred to OO programming.

“Language Features”

This section contains the big concepts of the course: type systems (static/dynamic, strong/weak, type coercion, duck-typing, late/early binding, …), interpreted vs compiled, pointers vs references, memory management, reflection, runtime environments, first-class functions, objects, exceptions, mutable/immutable objects, ….

The basic question here is: what are the real differences between the programming languages you have to choose from? How might they affect your choice of language for a project?

Logic programming (and Prolog)

As much as I am aware that Prolog is pretty much confined to old school AI researchers, I still think there’s some value in being exposed to logic programming. It should be possible to translate back to the OO world the idea of expressing a problem as a series of constraints and then looking to satisfy those constraints.

To be fair, this is the chunk I am most unsure of. Part of the reason it comes last is that if anything should fall off the end of a full semester, it’s this.

The exact balance of the topics remains to be seen. I’ll guess 5 weeks, 5 weeks, 3 weeks.

As for getting marks, I am as far as:

  • Lab exercises: weekly hour-or-two chances to practice the concrete skills.
  • Assignments: like… two of them? One Haskell, one Prolog?
  • Project: pick a somewhat obscure language from a list I provide. Explore it by writing a report and some programs with it.
  • A midterm and a final exam.

No idea what I’ll ask on the exams. Maybe Warren has some old ones I can look at.

So there it is. Unless I change my mind.

Exam craziness

December 11th, 2009, 9:32 am PST by Greg

Yesterday, I had both of my CMPT 165 exams (on-campus and distance) back to back. The exams were different enough that students talking for the few minutes between exams wouldn’t get anything useful from it, but no more than that.

Six hours is too goddamn long to be in exams. I can think of no way to describe the day other than a list of happenings:

[tl;dr Go for 2b, 3ab, 4b.]

  1. Pre exam:
    1. The first exams start at 8:30. At 7:45, not one but two of my colleagues were still trying to photocopy their exams for big sections. Office photocopier was jamming every two seconds; grad photocopier was down.
    2. Critical mobile phone usage #1: realizing Amanda would already be in her office, I phoned her and got one colleague into the photocopier in the Dean’s Office.
    3. “Wait… did I tell that student she could start a half hour early? Where was she going to meet me?” Send TA running to the room with an exam paper, just in case. (No student.)
  2. On campus section:
    1. Before the exam, a girl flagged me down and told me she “had cancer before” and had been feeling lightheaded this morning. If she had to leave during the exam, that was why. I tried to get her to Health Services right away, but she insisted on staying. At the end of the exam, I convinced her to at least go and get her blood pressure taken or something.
    2. Two minutes into the exam, after sitting there for three or four minutes before it started, looking at the exam cover sheet (which says “CMPT 165”) and me, a student put up his hand and said “this isn’t CMPT 120” and left.
    3. Freakin’ piles of questions, including “can you give me a hint” and “what time does the exam end”. Many more questions than the distance section.
  3. Distance ed section:
    1. About 10 minutes into an exam, one of the kids that had run in a few minutes late flagged a TA over and said “I feel like I might pass out.” I talked to him for a few seconds and he was not entirely conscious: able to answer yes or no questions, but that’s about it. He probably couldn’t have walked out of the room at that point.
    2. Critical mobile phone usage #2: phoned SFU security for a medical emergency. To the credit of security: they came quickly and handled it quietly and with a minimum amount to spectacle to distract everybody else. They took the student to Health Services.
    3. After all this, I start to realize that I have been getting lightheaded when standing up: I’m hungry and totally dehydrated from four hours running up and down hot lecture halls. A litre of water and snack later, I’m feeling much better.
    4. A guy came in 45 minutes late after “car problems”. A girl came in about 1:15 late after a car accident on the way from Abbotsford.
    5. With an hour left in the exam, passed-out student came back! He wanted to finish his exam and was pretty sure he could get it done. I took this as a sign of not yet being fully capable of making decisions and sent him to the distance ed office to schedule an alternate time.
    6. Critical mobile phone usage #3: phoned distance ed and told them the story so they’d deal with this kid appropriately. Apparently he wrote the exam later in the afternoon anyway (but at least he had the full three hours).
  4. After the exams:
    1. I’m barely standing at this point.
    2. I was talking to Anne, and told her the story of my day. Anne is preparing to teach a course like 165 in Uruguay (since she is currently on study leave). She was translating the course outline to Spanish and kept asking me things like “what wording do you like better?” I must have said three times: “Anne… you know I don’t speak Spanish, right?!”
    3. I might have eventually just wandered out of her office while she was still talking. I don’t really remember.

There was probably more. That’s all that’s coming to mind at the moment.

Spring plan: DDP projects

December 1st, 2009, 11:15 pm PST by Greg

As I said before, I’m not teaching CMPT 383 in the spring (but I will be doing it in the summer). The alternate plan involves the “capstone” project that our dual-degree students have to do.

I’m going to be supervising a group of students on the technical side of their project. Since I’m me, the plan is to do a web project. I thought about this for about 8 seconds before I realized what I must do… there’s an obvious set of web projects that I understand, students understand, and need to me done.

We have some very old and clunky web tools around the School that work, but aren’t pretty and don’t have much hope of improving in the future. Students will know our gradebook and assignment submission tools, but there are a bunch more that aren’t student-facing.

My plan: replace as much as possible with modern, integrated, functional tools. The plan goes (or at least start) like this:

  • Global: Unified CAS authentication. A useful “dashboard” for everybody displaying recent activity relevant to them (upcoming due dates, recently posted grades, recent assignment submissions, etc). Instructors should be able to copy an old offering to a new one (copying grading info, due dates, etc).
  • Gradebook: the basics as currently implemented, with calculated columns, released/unreleased columns, AJAX-y sorting and display of class lists, email notification of new grades (?).
  • Submission: Per-assignment configuration (e.g. assignment 1 requires submission of a text file for part 1, and a .java file for part 2; both are submitted as distinct files).
  • Marking: Instructor sets up a marking key for TAs; TAs give grades and comments; info returned to students and grades automatically put into gradebook.

Additional functionality suggestions welcome. I have some cool “maybe” features to throw in if things go well.

I’m going to be treating whatever group I have as a development team, not a class. So, I’ll be whipping them much more to get good-quality code, not a class project.

There’s certainly a possibility of catastrophic failure, but I’d say a reasonable chance of success. We’ll see what happens.

No CMPT 383 for me

November 6th, 2009, 1:53 pm PST by Greg

I know the schedule for the spring semester was announced with me teaching CMPT 383, but that is no more. I have been moved from 383 to something else that I’m sure I will have much to say about later.

Yarolsav Litus will (likely) be taking over the spring 383 offering.

I should be teaching CMPT 383 in the summer, though.

My latest project: web lint

October 15th, 2009, 11:30 pm PST by Greg

I have alluded to this in a status update, but I think it’s time to look more widely for feedback…

A while ago, I started thinking about all of the annoying things my CMPT 165 students do in their HTML, and then started thinking about ways to get them to stop. I started working on an automated checker to give them as much personalized feedback as possible without me actually having to talk to them.

They already use an HTML validator which checks documents against the HTML/XHTML syntax, but it’s amazing what kind of things actually pass the validator. In the list: resizing images with width/height on <img />; saving their source as UTF-16 (no idea how they do it); putting spaces in their URLs; using class names like “red” instead of “important”; not specifying the natural language/character encoding of the document; etc.

As the list became longer, the thing became sort of a general HTML lint: the thing you go to after your code is valid to check for other common problems, annoyances, and omissions. The more I look at it, the more I think it’s a useful tool for CMPT 165 students as well as a good way to make others think a little more about the code they are producing.

I’m now at the point of wanting some feedback. There are still some missing strings and help text, but hopefully you get the idea. I don’t want to guarantee that this link will exist forever, but have a look at my web lint.

As with any “lint”, the goal here probably isn’t for authors to get zero warnings, but just to think about why they are ignoring the warnings that remain. (No, I don’t need you to tell me that some of my pages produce some warnings.)

At this point, I’m most interested in:

  • Links to input that causes an exception (500 Internal Server Error) or other truly broken behaviour.
  • Feedback on the warnings presented and their “level”. I have deliberately hidden levels 4 and 5 in the default display: I’m aware that the tool is pretty anal-retentive.
  • Are there things you can thing of (that could be automatically-checkable) that should get a warning but don’t? I have a few more on my list, but the core is in there.
  • I don’t think the URL validation (for <a>, <link>, <img>) is perfect: I still need to go back to the RFC and check the details. Any cases you notice that don’t pass but should would be appreciated.
  • Any spelling/grammar errors?
  • I’m trying not to duplicate functionality of the HTML validators: they already do their job well. But, notice the links to “other checkers” on the right. Didn’t know about all of them, did you? Any others I should include?

My intention is to GPL the code and CC license the text, but let’s take one step at a time.

More DDP Fun

September 24th, 2009, 4:02 pm PST by Greg

Partially (but not entirely) because of my my last adventure with the DDP (Chinese Dual Degree) students, I have started to feel a certain affection for the group.

Today there was a welcome reception for the ones that just got here this semester. They were a surprisingly talkative group (considering we were talking in English), and it was nice to have the chance to welcome them.

A common question from me: “What have you done in Vancouver so far?” Most are pretty new and haven’t done much. But one answer stood out:

DDP Girl: “We have gone to UBC, and we went to the beach.”
Me: “Oh, which beach?” (grabs for convenient map of Vancouver)
DDP Girl: “The one *giggle* at UBC.”
Me: “… oh!” [For those not in the know, Wreck Beach is the local clothing-optional beach.]

The implication was that they just saw a sign for “beach” and thought they’d have a look. That’d be quite a shock: five minutes off the plane from China, and being surprised by some fat naked white guy walking down the beach.

So, that was the funniest image I had had in my head for a while.

Then five minutes later:

Different DDP Girl: “Oh, I haven’t done much yet, but I want to go to UBC and the beach.”

You know that feeling when you’re trying not to laugh, but can’t even look like you’re trying not to laugh? I swear pulled a muscle in my face to keep from smiling.

Apparently Wreck Beach is the first stop for DDP students showing up in Vancouver.

I’m back, baby!

September 14th, 2009, 10:12 pm PST by Greg

I woke up last Tuesday to the cold realization that my study leave was over: there was no choice but to admit that I was back at work. My first lectures were Wednesday: one hour of CMPT 165 and three of CMPT 470.

After the 165 lecture, Diana stuck her head into my office. She hadn’t been teaching in the summer semester, so she was also coming back to teaching. “Did you have your first lecture yet? Were you… excited?” Apparently she was so excited to get back to teaching that she was a little befuddled in her first lecture. This is why I love Diana.

I don’t know that I was particularly excited before my lectures, but now that I’ve done a full week, I’m feeling good about being back.

There’s something about being in front of a lecture room that feels right, especially with 165 and 470. Those courses are really the equivalent of comfort food for me and I think I’m going to have fun this semester.

So, I guess a year of study leave really does help one’s attitude. At least for the first week.

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