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  • Enlarging everything on 16" 1920x1080 notebook display in Windows 7

    - by Rob
    Does Windows 7 have an option to enlarge everything on the screen, e.g. via a spi setting? How well does this work? i.e. do the objects look clear when enlarged? I ask this because sometimes software that enlarges non-photographic bitmap images e.g. icons and symbols can leave them artifacted with harsh jaggier slopes and blurred lines. I've tried the dpi setting in Windows XP but it doesn't enlarge everything, and some things are not so clear as described above. I'm looking at a notebook/laptop with this spec. I've already enjoyed using a 15.4" 1920x1200 display for 5 years. I've tried the dpi setting in Windows XP but it doesn't enlarge everything, and some things are not so clear as described above. I am buying a laptop for my father who will probably prefer larger objects on the screen, although I want to provide some future proofing by allowing more on the screen if needed. I'm not interested in answers that debate the effectiveness or otherwise merits of 1920x1080 on a 16" display, please. The alternative option of 1366x768 seems too little.

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  • Silverlight Firestarter thoughts, and thanks to one and all!

    - by Dave Campbell
    A few metrics that of course got out of hand, but some may find interesting:   1/2 My share of the MVP of the Year award in February of 2009 with Laurent Bugnion 2 Number of degrees I hold: B.S., M.S. Electrical Engineering 3 Number of years in the U.S. Army 3.5 Number of years SilverlighCream has been posted 4 Number of times awarded MVP 6 Number of professional positions I've worked: Antenna Rigger, Boilermaker, Musician, Electronic Technician, Hardware Engineer, Software Engineer 16 Number of companies I've worked for during my career as an Engineer 19 Age at which I turned my first line of code 28 Age at which I hit the workforce as an Engineer 33 Number of years working as an Engineer 43 Number of years writing code 62 Number of years since instantiation 116 Number of tags to search SilverlightCream with 645 Number of blogs I view to find articles (at this moment) 664 Number of articles tagged wp7dev at SilverlightCream right now 700 Number of Twitter followers for WynApse 981 Number of individual bloggers in the SilverlightCream database 1002 Number of SilverlightCream blogposts 1100 Number of people live in Redmond for the Firestarter (I think) 1428 Number of total blogposts at GeeksWithBlogs (not counting this one) 4200 Number of Feedburner subscribers (approximately) 6500 Number of Twitter followers for SilverlightNews (approximately) 7087 Number of posts tagged and aggregated at SilverlightCream right now 13000 Number of people registered to watch the Firestarter online (I think) The overwhelming feeling I have returning from the Silverlight Firestarter: Priceless There is absolutely no way that I could personally thank everyone that over the last few years has held their hand out and offered me a step up to get to the point that Scott Guthrie called me out in his keynote. So I'm just going to hit the highlights here... Scott Guthrie Thanks for not only being the level you are at Microsoft, but for being so approachable, easy to talk to, willing to help everyone, and above all knowledgable. My first level manager at my last position asked if Visual Studio was a graphics program... and you step up to a laptop at a conference and type "File->New Program" ... 'nuff said... oh yeah, thanks for the shoutout! John Papa Thanks for being a good friend, ramroding the Firestarter, being a great guy to be around, and for the poster... holy crap is that cool. Tim Heuer Thanks for all you did as a great DE in Phoenix, and for helping out so many of us, of course being a great guy, and for the poster as well... I think you and John shared that task. In no order at all my buddy Michael Washington, Laurent Bugnion (the other half of the first Silverlight MVP of the Year) Tim Sneath, Mike Harsh, Chad Campbell and Bryant Likes (from back in the day), Adam Kinney, Jesse Liberty, Jeff Paries, Pete Brown, András Velvárt, David Kelly, Michael Palermo, Scott Cate, Erik Mork, and on and on... don't feel bad if your name didn't appear, I have simply too many supporters to name. Silverlight Firestarter Indeed All the people mentioned here, and all the MVPs knew Silverlight was NOT dead, but because of a very unfortunate circumstance, the popular media opinion became that. Consequently the Firestarter exploded from a laid-back event to a global conference. People worked their ass off getting bits ready and presentations using those bits. All to stem the flow of misinformation. All involved please accept my personal thanks for an absolutely awesome job. I had the priviledge of watching the 'prep' on Wednesday afternoon, and was blown away the first time I saw the 3D demo... and have been blown away every time I've seen it since. Not to mention all the other goodness in Silverlight 5. Yes I hit 1000 on my blog, but more importantly, all of you are blogging and using Silverlight, and Microsoft hit one completely out of the park... no... they knocked it out of the neighborhood with the Firestarter. It was amazing to be there for it, and it will be awesome to use the new bits as we get them. Keep reading, there's tons more to come with Silverlight and SilverlightCream following along behind. As usual, this old hacker is humbled to be allowed to play with all the cool kids... Thanks one and all for everything, and Stay in the 'Light

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  • Dissing Architects, or "What's wrong with the coffee?"

    - by Bob Rhubart
    In my conversations with people in architect roles, tales of animosity, disrespect, and outright hostility aren't uncommon. And it's clear that in more than a few organizations architects regularly face a tough uphill climb. For architects with the requisite combination of technical, organizational, and people skills, that rough treatment is grossly undeserved. But tales of unqualified people in positions up and down the IT food chain are also easy to come by. So what's the other side of the architect story? Are some architects tarnishing the role and making life miserable for their more qualified colleagues? The various quotes included below were culled from a variety of sources. The criticism is harsh, and the people behind these quotes clearly have issues with architects. Still, whether based on mere opinion or actual experience, the comments shed some light on behaviors that should raise red flags for anyone pursuing a career as an architect. If you're an architect, and you've ever noticed that your coffee tastes like window cleaner, or your car is repeatedly keyed, or no one ever holds the elevator for you, maybe you need to do a little soul searching... Those Who Can, Code; Those Who Can't, Architect | Joe Winchester [May 18, 2007] "At the moment there seems to be an extremely unhealthy obsession in software with the concept of architecture. A colleague of mine, a recent graduate, told me he wished to become a software architect. He was drawn to the glamour of being able to come up with grandiose ideas - sweeping generalized designs, creating presentations to audiences of acronym addicts, writing esoteric academic papers, speaking at conferences attended by headless engineers on company expense accounts hungrily seeking out this year's grail, and creating e-mails with huge cc lists from people whose signature footer is more interesting than the content. I tried to re-orient him into actually doing some coding, to join a team that has a good product and keen users both of whom are pushing requirements forward, to no avail. Somehow the lure of being an architecture astronaut was too strong and I lost him to the dark side." Don't Let Architecture Astronauts Scare You | Joel Spolsky [April 21, 2001] "It's very hard to get them to write code or design programs, because they won't stop thinking about Architecture. They're astronauts because they are above the oxygen level, I don't know how they're breathing. They tend to work for really big companies that can afford to have lots of unproductive people with really advanced degrees that don't contribute to the bottom line. Remember that the architecture people are solving problems that they think they can solve, not problems which are useful to solve." Non Coding Architects Suck | Richard Henderson [May 24, 2010] "If a guy with a badge saying 'system architect' looks blank on low-level issues then he is not an architect, he is a business-analyst who went on a course. He will probably wax lyrical on all things high-level and 'important.' He will produce lovely object hierarchies without a clue to implementation. He will have a moustache and play golf." Architects Play Golf | Sunir Shah [August 15, 2012] "Often arrogant architects are difficult to get a hold of during the implementation phase because they no longer feel the need to stick around. Especially around midnight when most of the poor sob [sic] developers are still banging away. After all, they've already solved the problem--the rest is just an implementation exercise." Engineer vs Architect(Part of a discussion on the IT Architect Network Group on LinkedIn) "[An] architect spends his time producing white papers full of acronyms he does not understand but that impress his boss [while the] engineer keeps his head down and does the actual job." Architects Don't Code | [Author Unknown] "Faulty belief: System Architects don't need to code anymore. They know what they are talking about by virtue of the fact that they are System Architects."

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  • Nest reinvents smoke detectors. Introduces smart and talking smoke detector that keeps quite when you wave

    - by Gopinath
    Nest, the leading smart thermostat maker has introduced a smart home device today- Nest Protect, a smart, talking smoke & carbon monoxide detector that can quite when you wave your hand. Less annoyances and more intelligence Smoke detectors are around for hundreds of years and playing a major role in providing safety from fire accidents at home. But the technology of these devices is stale and there is no major innovation for the past several years. With the introduction of Nest Protect, the landscape of smoke detectors is all set to change just like how Nest thermostat redefined the industry two years ago. Nest Protect is internet enabled and equipped with motion- and smoke-detection sensors so that when it starts beeping you can silence it by waving hand instead of doing circus feats to turn off the alarm. Everyone who cooks in a home equipped with smoke detector would know how annoying it is to turn off sensitive smoke detectors that goes off control quite often. Apart from addressing the annoyances of regular smoke detector, Nest Protect has talking capabilities. It can alert users with clear & actionable instructions when it detects a danger. Instead of harsh beeps it actually speak to you so you know what is happening. It will tell you what smoke it has detected and in which room it is detected. Multiple Nest Protects installed in a home can communicate with each other. Lets say that there is a smoke in bed room, the Nest Protect installed in bed room shares this information to all Nest Protects installed in the home and your kitchen device can alert you that there is a smoke in bed room. There is an App for that The internet enabled Nest Protect has an app to view its status and various alerts. When the Protect is running on low battery it alerts you to replace them soon. If there is a smoke at home and you are away, you will get message alerts. The app works on all major smartphones as well as tablets. Auto shuts down gas furnaces/heaters on smoke Apart from forming a network with other Nest Protect devices installed at home, they can also communicate with Nest Thermostat if it is installed. When carbon monoxide is detected it can shut off your gas furnace automatically. Also with the help of motion detectors it improves Nest Thermostat’s auto-away functionality. It looks elegant and costs a lot more than a regular smoke detector Just like Nest Thermostat, Nest Protect is elegant and adorable. You just fall in love with it the moment you see it. It’s another master piece from the designer of Apple’s iPod. All is good with the Nest Protect, except the price!! It costs whooping $129, which is almost 4 times more expensive than the best selling conventional thermostats available at $30. A single bed room apartment would require at least 3 detectors and it costs around $390 to install Nest Protects compared to 90$ required for conventional smoke detectors. Though Nest Thermostat is an expensive one compared to conventional thermostats, it offered great savings through its intelligent auto-away feature. Users were able to able to see returns on their investments. If Nest Protect also can provide good return on investment the it will be very successful.

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  • How can I cleanly turn a nested Perl hash into a non-nested one?

    - by knorv
    Assume a nested hash structure %old_hash .. my %old_hash; $old_hash{"foo"}{"bar"}{"zonk"} = "hello"; .. which we want to "flatten" (sorry if that's the wrong terminology!) to a non-nested hash using the sub &flatten(...) so that .. my %h = &flatten(\%old_hash); die unless($h{"zonk"} eq "hello"); The following definition of &flatten(...) does the trick: sub flatten { my $hashref = shift; my %hash; my %i = %{$hashref}; foreach my $ii (keys(%i)) { my %j = %{$i{$ii}}; foreach my $jj (keys(%j)) { my %k = %{$j{$jj}}; foreach my $kk (keys(%k)) { my $value = $k{$kk}; $hash{$kk} = $value; } } } return %hash; } While the code given works it is not very readable or clean. My question is two-fold: In what ways does the given code not correspond to modern Perl best practices? Be harsh! :-) How would you clean it up?

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  • Turning a nested hash structure into a non-nested hash structure - is this the cleanest way to do it

    - by knorv
    Assume a nested hash structure %old_hash .. my %old_hash; $old_hash{"foo"}{"bar"}{"zonk"} = "hello"; .. which we want to "flatten" (sorry if that's the wrong terminology!) to a non-nested hash using the sub &flatten(...) so that .. my %h = &flatten(\%old_hash); die unless($h{"zonk"} eq "hello"); The following definition of &flatten(...) does the trick: sub flatten { my $hashref = shift; my %hash; my %i = %{$hashref}; foreach my $ii (keys(%i)) { my %j = %{$i{$ii}}; foreach my $jj (keys(%j)) { my %k = %{$j{$jj}}; foreach my $kk (keys(%k)) { my $value = $k{$kk}; $hash{$kk} = $value; } } } return %hash; } While the code given works it is not very readable or clean. My question is two-fold: In what ways does the given code not correspond to modern Perl best practices? Be harsh! :-) How would you clean it up?

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  • How would you go about parsing markdown?

    - by John Leidegren
    You can find the syntax here. The thing is, the source that follows with the download is written in perl. Which I have no intentions of honoring. It is riddled with regex and it relies on MD5 hashes to escape certain characters. Something is just wrong about that! I'm about to hard code a parser for markdown and I'm wonder if someone had some experience with this? Edit: If you don't have anything meaningful to say about the actual parsing of markdown, spare me the time. (This might sound harsh, but yes, I'm looking for insight, not a solution i.e. third-party library). To help a bit with the answers, regex are meant to identify patterns! NOT to parse an entire grammar. That people consider doing so is foobar. If you think about markdown, it's fundamentally based around the concept of paragraphs. As such, a reasonable approach might be to split the input into paragraphs. There are many kinds of paragraphs e.g. heading, text, list, blockquote, code. The challenge is thus to identify these paragraphs and in what context they occur. I'll be back with a solution, once I find it's worthy to be shared.

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  • if/else statement in a function: using onclick as a switch

    - by Aurora Schmidt
    I have looked for solutions to this on google for what seems like an eternity, but I can't seem to formulate my search correctly, or nobody has posted the code I'm looking for earlier. I am currently trying to make a function that will modify one or several margins of a div element. I want to use an if/else statement within the function, so that the onclick event will switch between the two conditions. This is what I have been working on so far; function facebookToggle() { if($('#facebooktab').style.margin-left == "-250px";) { document.getElementById("facebooktab").style.marginLeft="0px"; } else { document.getElementById("facebooktab").style.marginLeft="-250px"; } } I have tried twisting it around a little, like switching between "marginLeft" and "margin-left", to see if I was just using the wrong terms.. I'm starting to wonder if it might not be possible to combine jQuery and regular javascript? I don't know.. It's all just guesses on my part at this point. Anyway, I have a div, which is now positioned (fixed) so almost all of it is hidden outside the borders of the browser. I want the margin to change onclick so that it will be fully shown on the page. And when it is shown, I want to be able to hide it again by clicking it. I might be approaching this in the wrong way, but I really hope someone can help me out, or even tell me another way to get the same results. Thank you for any help you can give me. You can see it in action at: http://www.torucon.no/test/ (EDIT: By the way, I am a complete javascript novice, I have no experience with javascript prior to this experiment. Please don't be too harsh, as I am aware I probably made some really stupid mistakes in this short code.) EDITED CODE: function facebookToggle() { if($('#facebooktab').css('margin-left', '-250px') { $('#facebooktab').css('margin-left', '0px'); } else { $('#facebooktab').css('margin-left', '-250px'); } }

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  • Global Temporary Table "On commit delete rows" functionality discrepancy.

    - by TomatoSandwich
    I have a global temporary table. I called my GTT, for that was it's initials. My GTT never hurt anyone, and did everything I bade of it. I asked my GTT to delete rows on commit. This is a valid function in the creation script of my GTT in oracle. I wanted to be able to have different users see GTT with their own data, and not the data of other people's sessions. 'Delete rows on commit' worked perfectly in our test environment. GTT and I were happy. But then, I deployed GTT as part of an update to functionality to a client's database. The database doesn't like to play well with GTT. GTT called me up all upset and worried, because it wasn't holding any data any more, and didn't know why. GTT told me that if someone did: insert into my_GTT (description) values ('Happy happy joy joy') he would sing-song back: 1 row inserted. However, if the same person tried select * from my_GTT; GTT didn't know what to do, and he replied 0 rows returned. GTT was upset that he didn't know what his playmate had inserted. Please, Stackoverflow, why would GTT forget what was placed into him? He can remember perfectly well at home, but out in the cold harsh world, he just gets so scared. :(

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  • Serializing and deserializing a map with key as string

    - by Grace K
    Hi! I am intending to serialize and deserialize a hashmap whose key is a string. From Josh Bloch's Effective Java, I understand the following. P.222 "For example, consider the case of a harsh table. The physical representation is a sequence of hash buckets containing key-value entries. Which bucket an entry is placed in is a function of the hash code of the key, which is not, in general guaranteed to be the same from JVM implementation to JVM implementation. In fact, it isn't even guranteed to be the same from run to run on the same JVM implementation. Therefore accepting the default serialized form for a hash table would constitute a serious bug. Serializing and deserializing the hash table could yield an object whose invariants were seriously corrupt." My questions are: 1) In general, would overriding the equals and hashcode of the key class of the map resolve this issue and the map can be correctly restored? 2) If my key is a String and the String class is already overriding the hashCode() method, would I still have problem described above. (I am seeing a bug which makes me think this is probably still a problem even though the key is String with overriding hashCode.) 3)Previously, I get around this issue by serializing an array of entries (key, value) and when deserializing I would reconstruct the map. I am wondering if there is a better approach. 4) If the answers to question 1 and 2 are that I still can't be guaranteed. Could someone explain why? If the hashCodes are the same would they go to the same buckets across JVMs? Thanks, Grace

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  • Have you dealt with space hardening?

    - by Tim Post
    I am very eager to study best practices when it comes to space hardening. For instance, I've read (though I can't find the article any longer) that some core parts of the Mars rovers did not use dynamic memory allocation, in fact it was forbidden. I've also read that old fashioned core memory may be preferable in space. I was looking at some of the projects associated with the Google Lunar Challenge and wondering what it would feel like to get code on the moon, or even just into space. I know that space hardened boards offer some sanity in such a harsh environment, however I'm wondering (as a C programmer) how I would need to adjust my thinking and code if I was writing something that would run in space? I think the next few years might show more growth in private space companies, I'd really like to at least be somewhat knowledgeable regarding best practices. Can anyone recommend some books, offer links to papers on the topic or (gasp) even a simulator that shows you what happens to a program if radiation, cold or heat bombards a board that sustained damage to its insulation? I think the goal is keeping humans inside of a space craft (as far as fixing or swapping stuff) and avoiding missions to fix things. Furthermore, if the board maintains some critical system, early warnings seem paramount.

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  • iOS layout; I'm not getting it

    - by Tbee
    Well, "not getting it" is too harsh; I've got it working in for what for me is a logical setup, but it does not seem to be what iOS deems logical. So I'm not getting something. Suppose I've got an app that shows two pieces of information; a date and a table. According to the MVC approach I've got three MVC at work here, one for the date, one for the table and one that takes both these MCVs and makes it into a screen, wiring them up. The master MVC knows how/where it wants to layout the two sub MVC's. Each detail MVC only takes care of its own childeren within the bounds that were specified by the master MVC. Something like: - (void)loadView { MVC* mvc1 = [[MVC1 alloc] initwithFrame:...] [self.view addSubview:mvc1.view]; MVC* mvc2 = [[MVC2 alloc] initwithFrame:...] [self.view addSubview:mvc2.view]; } If the above is logical (which is it for me) then I would expect any MVC class to have a constructor "initWithFrame". But an MVC does not, only view have this. Why? How would one correctly layout nested MVCs? (Naturally I do not have just these two, but the detail MVCs have sub MVCs again.)

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  • Computing, storing, and retrieving values to and from an N-Dimensional matrix

    - by Adam S
    This question is probably quite different from what you are used to reading here - I hope it can provide a fun challenge. Essentially I have an algorithm that uses 5(or more) variables to compute a single value, called outcome. Now I have to implement this algorithm on an embedded device which has no memory limitations, but has very harsh processing constraints. Because of this, I would like to run a calculation engine which computes outcome for, say, 20 different values of each variable and stores this information in a file. You may think of this as a 5(or more)-dimensional matrix or 5(or more)-dimensional array, each dimension being 20 entries long. In any modern language, filling this array is as simple as having 5(or more) nested for loops. The tricky part is that I need to dump these values into a file that can then be placed onto the embedded device so that the device can use it as a lookup table. The questions now, are: What format(s) might be acceptable for storing the data? What programs (MATLAB, C#, etc) might be best suited to compute the data? C# must be used to import the data on the device - is this possible given your answer to #1?

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  • This program isn't asking for the predetermined 5 numbers from the array?

    - by user1801781
    Okay, so this question is difficult to state. I'm a beginner at C++, and I rarely run into problems with these simple assignments, but something is majorly wrong here and I cannot identify it. I've been trying for hours. This program is supposed to read 5 numbers from an array that the user enters, and then print the largest one. (I know it's easier to just write a for-loop, but our professor wanted us to call a function). The only problem is that instead of asking for 5 numbers, it asks for 2. It works other than that, I JUST NEED IT TO ASK FOR 5 NUMBERS. haha. Your input would be greatly appreciated. I aspire to be a programmer one day, so don't be afraid to go harsh on me. #include <iostream> using namespace std; int largest_number(int score[], int max) { for (int i=1; i<5; i++) { cin >> score[i]; if(score[i] > max) max=score[i]; return (max); } } int main () { int score[5], max, z; cout << "Enter 5 numbers: " <<endl; cin >> score[0]; max = score[0]; z = largest_number(score, max); cout << "The largest number is: " << z <<endl; system("pause"); return 0; }

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  • Just a small help about switch's use

    - by Laurent Fournier
    If an answer on this already exist, my apologies i've not found on this question... is this statement correct if i want presice actions on integers from -2 to 0, and for those between 1 and 6 apply the same methods with only my integer who'll change ? Like this: public void setCaseGUI(Point pt, int i, boolean b){ plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setSelected(b); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setIcon(null); switch(i) { case -2: plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setText("F"); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setForeground(Color.red); break; case -1: plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setText("B"); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setForeground(Color.red); break; case 0: plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setText(""); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setForeground(null); break; case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 8: plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setText(String.valueOf(i)); plateau.cellule[(int)pt.getAbs()][(int)pt.getOrd()].setForeground(null); break; default: System.out.println("Erreur de changement d'état/case !"); } } Please don't be too harsh on me i've started to learn dev only a few month ago

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  • The illusion of Competence

    - by tony_lombardo
    Working as a contractor opened my eyes to the developer food chain.  Even though I had similar experiences earlier in my career, the challenges seemed much more vivid this time through.  I thought I’d share a couple of experiences with you, and the lessons that can be taken from them. Lesson 1: Beware of the “funnel” guy.  The funnel guy is the one who wants you to funnel all thoughts, ideas and code changes through him.  He may say it’s because he wants to avoid conflicts in source control, but the real reason is likely that he wants to hide your contributions.  Here’s an example.  When I finally got access to the code on one of my projects, I was told by the developer that I had to funnel all of my changes through him.  There were 4 of us coding on the project, but only 2 of us working on the UI.  The other 2 were working on a separate application, but part of the overall project.  So I figured, I’ll check it into SVN, he reviews and accepts then merges in.  Not even close.  I didn’t even have checkin rights to SVN, I had to email my changes to the developer so he could check those changes in.  Lesson 2: If you point out flaws in code to someone supposedly ‘higher’ than you in the developer chain, they’re going to get defensive.  My first task on this project was to review the code, familiarize myself with it.  So of course, that’s what I did.  And in familiarizing myself with it, I saw so many bad practices and code smells that I immediately started coming up with solutions to fix it.  Of course, when I reviewed these changes with the developer (guy who originally wrote the code), he smiled and nodded and said, we can’t make those changes now, it’s too destabilizing.  I recommended we create a new branch and start working on refactoring, but branching was a new concept for this guy and he was worried we would somehow break SVN. How about some concrete examples? I started out by recommending we remove NUnit dependency and tests from the application project, and create a separate Unit testing project.  This was met with a little bit of resistance because - “How do I access the private methods?”  As it turned out there weren’t really any private methods that weren’t exposed by public methods, so I quickly calmed this fear. Win 1 Loss 0 Next, I recommended that all of the File IO access be wrapped in Using clauses, or at least properly wrapped in try catch finally.  This recommendation was accepted.. but never implemented. Win 2  Loss 1 Next recommendation was to refactor the command pattern implementation.  The command pattern was implemented, but it wasn’t really necessary for the application.  More over, the fact that we had 100 different command classes, each with it’s own specific command parameters class, made maintenance a huge hassle.  The same code repeated over and over and over.  This recommendation was declined, the code was too fragile and this change would destabilize it.  I couldn’t disagree, though it was the commands themselves in many cases that were fragile. Win 2 Loss 2 Next recommendation was to aid performance (and responsiveness) of the application by using asynchronous service calls.  This on was accepted. Win 2 Loss 3 If you’re paying any attention, you’re wondering why the async service calls was scored as a loss.. Let me explain.  The service call was made using the async pattern.  Followed by a thread.sleep  <facepalm>. Now it’s easy to be harsh on this kind of code, especially if you’re an experienced developer.  But I understood how most of this happened.  One junior guy, working as hard as he can to build his first real world application, with little or no guidance from anyone else.  He had his pattern book and theory of programming to help him, but no real world experience.  He didn’t know how difficult it would be to trace the crashes to the coding issues above, but he will one day.  The part that amazed me was the management position that “this guy should be a team lead, because he’s worked so hard”.  I’m all for rewarding hard work, but when you reward someone by promoting them past the point of their competence, you’re setting yourself and them up for failure.  And that’s lesson 3.  Just because you’ve got a hard worker, doesn’t mean he should be leading a development project.  If you’re a junior guy busting your ass, keep at it.  I encourage you to try new things, but most importantly to learn from your mistakes.  And correct your mistakes.  And if someone else looks at your code and shows you a laundry list of things that should be done differently, don’t take it personally – they’re really trying to help you.  And if you’re a senior guy, working with a junior guy, it’s your duty to point out the flaws in the code.  Even if it does make you the bad guy.  And while I’ve used “guy” above, I mean both men and women.  And in some cases mutant dinosaurs. 

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  • Data validation best practices: how can I better construct user feedback?

    - by Cory Larson
    Data validation, whether it be domain object, form, or any other type of input validation, could theoretically be part of any development effort, no matter its size or complexity. I sometimes find myself writing informational or error messages that might seem harsh or demanding to unsuspecting users, and frankly I feel like there must be a better way to describe the validation problem to the user. I know that this topic is subjective and argumentative. StackOverflow might not be the proper channel for diving into this subject, but like I've mentioned, we all run into this at some point or another. There are so many StackExchange sites now; if there is a better one, feel free to share! Basically, I'm looking for good resources on data validation and user feedback that results from it at a theoretical level. Topics and questions I'm interested in are: Content Should I be describing what the user did correctly or incorrectly, or simply what was expected? How much detail can the user read before they get annoyed? (e.g. Is "Username cannot exceed 20 characters." enough, or should it be described more fully, such as "The username cannot be empty, and must be at least 6 characters but cannot exceed 30 characters."?) Grammar How do I decide between phrases like "must not," "may not," or "cannot"? Delivery This can depend on the project, but how should the information be delivered to the user? Should it be obtrusive (e.g. JavaScript alerts) or friendly? Should they be displayed prominently? Immediately (i.e. without confirmation steps, etc.)? Logging Do you bother logging validation errors? Internationalization Some cultures prefer or better understand directness over subtlety and vice-versa (e.g. "Don't do that!" vs. "Please check what you've done."). How do I cater to the majority of users? I may edit this list as I think more about the topic, but I'm genuinely interest in proper user feedback techniques. I'm looking for things like research results, poll results, etc. I've developed and refined my own techniques over the years that users seem to be okay with, but I work in an environment where the users prefer to adapt to what you give them over speaking up about things they don't like. I'm interested in hearing your experiences in addition to any resources to which you may be able to point me.

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  • Network communication for a turn based board game

    - by randooom
    Hi all, my first question here, so please don't be to harsh if something went wrong :) I'm currently a CS student (from Germany, if this info is of any use ;) ) and we got a, free selectable, programming assignment, which we have to write in a C++/CLI Windows Forms Application. My team, two others and me, decided to go for a network-compatible port of the board game Risk. We divided the work in 3 Parts, namely UI, game logic and network. Now we're on the part where we have to get everything working together and the big question mark is, how to get the clients synchronized with each other? Our approach so far is, that each client has all information necessary to calculate and/or execute all possible actions. Actually the clients have all information available at all, aside from the game-initializing phase (add players, select map, etc.), which needs one "super-client" with some extra stuff to control things. This is the standard scenario of our approach: player performs action, the action is valid and got executed on the players client action is sent over the network action is executed on the other clients The design (i.e. no or code so far) we came up with so far, is something like the following pseudo sequence diagram. Gui, Controller and Network implement all possible actions (i.e. all actions which change data) as methods from an interface. So each part can implement the method in a way to get their job done. Example with Action(): On the player side's Client: Player-->Gui.Action() Gui-->Controller.Action() Controller-->Logic.Action (Logic.Action() == NoError)? Controller-->Network.Action() Network-->Parser.ParseAction() Network.Send(msg) On all other clients: Network.Recv(msg) Network-->Parser.Deparse(msg) Parser-->Logic.Action() Logic-->Gui.Action() The questions: Is this a viable approach to our task? Any better/easier way to this? Recommendations, critique? Our knowledge (so you can better target your answer): We are on the beginner side, in regards to programming on a somewhat larger projects with a small team. All of us have some general programming experience and basic understanding of the .Net Libraries and Windows Forms. If you need any further information, please feel free to ask.

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  • Some more multitasking java issues

    - by owca
    I had a task to write simple game simulating two players picking up 1-3 matches one after another until the pile is gone. I managed to do it for computer choosing random value of matches but now I'd like to go further and allow humans to play the game. Here's what I already have : http://paste.pocoo.org/show/200660/ Class Player is a computer player, and PlayerMan should be human being. Problem is, that thread of PlayerMan should wait until proper value of matches is given but I cannot make it work this way. When I type the values it sometimes catches them and decrease amount of matches but that's not exactly what I was up to :) Logics is : I check the value of current player. If it corresponds to this of the thread currently active I use scanner to catch the amount of matches. Else I wait one second (I know it's kinda harsh solution, but I have no other idea how to do it). Class Shared keeps the value of current player, and also amount of matches. By the way, is there any way I can make Player and Shared attributes private instead of public and still make the code work ? CONSOLE and INPUT-DIALOG is just for choosing way of inserting values. class PlayerMan extends Player{ static final int CONSOLE=0; static final int INPUT_DIALOG=1; private int input; public PlayerMan(String name, Shared data, int c){ super(name, data); input = c; } @Override public void run(){ Scanner scanner = new Scanner(System.in); int n = 0; System.out.println("Matches on table: "+data.matchesAmount); System.out.println("which: "+data.which); System.out.println("number: "+number); while(data.matchesAmount != 0){ if(number == data.which){ System.out.println("Choose amount of matches (from 1 to 3): "); n = scanner.nextInt(); if(data.matchesAmount == 1){ System.out.println("There's only 1 match left !"); while(n != 1){ n = scanner.nextInt(); } } else{ do{ n = scanner.nextInt(); } while(n <= 1 && n >= 3); } data.matchesAmount = data.matchesAmount - n; System.out.println(" "+ name+" takes "+n+" matches."); if(number != 0){ data.which = 0; } else{ data.which = 1; } } else{ try { Thread.sleep(1000); } catch(InterruptedException exc) { System.out.println("End of thread."); return; } } System.out.println("Matches on table: "+data.matchesAmount); } if(data.matchesAmount == 0){ System.out.println("Winner is player: "+name); stop(); } } }

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  • Wake up thread blocked on accept() call

    - by selbie
    Sockets on Linux question I have a worker thread that is blocked on an accept() call. It simply waits for an incoming network connection, handles it, and then returns to listening for the next connection. When it is time for the program to exit, how do I signal this network worker thread (from the main thread) to return from the accept() call while still being able to gracefully exit its loop and handle it's cleanup code. Some things I tried: 1. pthread_kill to send a signal. Feels kludgy to do this, plus it doesn't reliably allow the thread to do it's shutdown logic. Also makes the program terminate as well. I'd like to avoid signals if at all possible. pthread_cancel. Same as above. It's a harsh kill on the thread. That, and the thread may be doing something else. Closing the listen socket from the main thread in order to make accept() abort. This doesn't reliably work. Some constraints: If the solution involves making the listen socket non-blocking, that is fine. But I don't want to accept a solution that involves the thread waking up via a select call every few seconds to check the exit condition. The thread condition to exit may not be tied to the process exiting. Essentially, the logic I am going for looks like this. void* WorkerThread(void* args) { DoSomeImportantInitialization(); // initialize listen socket and some thread specific stuff while (HasExitConditionBeenSet()==false) { listensize = sizeof(listenaddr); int sock = accept(listensocket, &listenaddr, &listensize); // check if exit condition has been set using thread safe semantics if (HasExitConditionBeenSet()) { break; } if (sock < 0) { printf("accept returned %d (errno==%d)\n", sock, errno); } else { HandleNewNetworkCondition(sock, &listenaddr); } } DoSomeImportantCleanup(); // close listen socket, close connections, cleanup etc.. return NULL; } void SignalHandler(int sig) { printf("Caught CTRL-C\n"); } void NotifyWorkerThreadToExit(pthread_t thread_handle) { // signal thread to exit } int main() { void* ptr_ret= NULL; pthread_t workerthread_handle = 0; pthread_create(&workerthread, NULL, WorkerThread, NULL); signal(SIGINT, SignalHandler); sleep((unsigned int)-1); // sleep until the user hits ctrl-c printf("Returned from sleep call...\n"); SetThreadExitCondition(); // sets global variable with barrier that worker thread checks on // this is the function I'm stalled on writing NotifyWorkerThreadToExit(workerthread_handle); // wait for thread to exit cleanly pthread_join(workerthread_handle, &ptr_ret); DoProcessCleanupStuff(); }

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  • SQL SERVER – Weekly Series – Memory Lane – #050

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Executing Remote Stored Procedure – Calling Stored Procedure on Linked Server In this example we see two different methods of how to call Stored Procedures remotely.  Connection Property of SQL Server Management Studio SSMS A very simple example of the how to build connection properties for SQL Server with the help of SSMS. Sample Example of RANKING Functions – ROW_NUMBER, RANK, DENSE_RANK, NTILE SQL Server has a total of 4 ranking functions. Ranking functions return a ranking value for each row in a partition. All the ranking functions are non-deterministic. T-SQL Script to Add Clustered Primary Key Jr. DBA asked me three times in a day, how to create Clustered Primary Key. I gave him following sample example. That was the last time he asked “How to create Clustered Primary Key to table?” 2008 2008 – TRIM() Function – User Defined Function SQL Server does not have functions which can trim leading or trailing spaces of any string at the same time. SQL does have LTRIM() and RTRIM() which can trim leading and trailing spaces respectively. SQL Server 2008 also does not have TRIM() function. User can easily use LTRIM() and RTRIM() together and simulate TRIM() functionality. http://www.youtube.com/watch?v=1-hhApy6MHM 2009 Earlier I have written two different articles on the subject Remove Bookmark Lookup. This article is as part 3 of original article. Please read the first two articles here before continuing reading this article. Query Optimization – Remove Bookmark Lookup – Remove RID Lookup – Remove Key Lookup Query Optimization – Remove Bookmark Lookup – Remove RID Lookup – Remove Key Lookup – Part 2 Query Optimization – Remove Bookmark Lookup – Remove RID Lookup – Remove Key Lookup – Part 3 Interesting Observation – Query Hint – FORCE ORDER SQL Server never stops to amaze me. As regular readers of this blog already know that besides conducting corporate training, I work on large-scale projects on query optimizations and server tuning projects. In one of the recent projects, I have noticed that a Junior Database Developer used the query hint Force Order; when I asked for details, I found out that the basic concept was not properly understood by him. Queries Waiting for Memory Allocation to Execute In one of the recent projects, I was asked to create a report of queries that are waiting for memory allocation. The reason was that we were doubtful regarding whether the memory was sufficient for the application. The following query can be useful in similar cases. Queries that do not have to wait on a memory grant will not appear in the result set of following query. 2010 Quickest Way to Identify Blocking Query and Resolution – Dirty Solution As the title suggests, this is quite a dirty solution; it’s not as elegant as you expect. However, it works totally fine. Simple Explanation of Data Type Precedence While I was working on creating a question for SQL SERVER – SQL Quiz – The View, The Table and The Clustered Index Confusion, I had actually created yet another question along with this question. However, I felt that the one which is posted on the SQL Quiz is much better than this one because what makes that more challenging question is that it has a multiple answer. Encrypted Stored Procedure and Activity Monitor I recently had received questionable if any stored procedure is encrypted can we see its definition in Activity Monitor.Answer is - No. Let us do a quick test. Let us create following Stored Procedure and then launch the Activity Monitor and check the text. Indexed View always Use Index on Table A single table can have maximum 249 non clustered indexes and 1 clustered index. In SQL Server 2008, a single table can have maximum 999 non clustered indexes and 1 clustered index. It is widely believed that a table can have only 1 clustered index, and this belief is true. I have some questions for all of you. Let us assume that I am creating view from the table itself and then create a clustered index on it. In my view, I am selecting the complete table itself. 2011 Detecting Database Case Sensitive Property using fn_helpcollations() I received a question on how to determine the case sensitivity of the database. The quick answer to this is to identify the collation of the database and check the properties of the collation. I have previously written how one can identify database collation. Once you have figured out the collation of the database, you can put that in the WHERE condition of the following T-SQL and then check the case sensitivity from the description. Server Side Paging in SQL Server CE (Compact Edition) SQL Server Denali is coming up with new T-SQL of Paging. I have written about the same earlier.SQL SERVER – Server Side Paging in SQL Server Denali – A Better Alternative,  SQL SERVER – Server Side Paging in SQL Server Denali Performance Comparison, SQL SERVER – Server Side Paging in SQL Server Denali – Part2 What is very interesting is that SQL Server CE 4.0 have the same feature introduced. Here is the quick example of the same. To run the script in the example, you will have to do installWebmatrix 4.0 and download sample database. Once done you can run following script. Why I am Going to Attend PASS Summit Unite 2011 The four-day event will be marked by a lot of learning, sharing, and networking, which will help me increase both my knowledge and contacts. Every year, PASS Summit provides me a golden opportunity to build my network as well as to identify and meet potential customers or employees. 2012 Manage Help Settings – CTRL + ALT + F1 This is very interesting read as my daughter once accidently came across a screen in SQL Server Management Studio. It took me 2-3 minutes to figure out how she has created the same screen. Recover the Accidentally Renamed Table “I accidentally renamed table in my SSMS. I was scrolling very fast and I made mistakes. It was either because I double clicked or clicked on F2 (shortcut key for renaming). However, I have made the mistake and now I have no idea how to fix this. If you have renamed the table, I think you pretty much is out of luck. Here are few things which you can do which can give you an idea about what your table name can be if you are lucky. Identify Numbers of Non Clustered Index on Tables for Entire Database Here is the script which will give you numbers of non clustered indexes on any table in entire database. Identify Most Resource Intensive Queries – SQL in Sixty Seconds #029 – Video Here is the complete complete script which I have used in the SQL in Sixty Seconds Video. Thanks Harsh for important Tip in the comment. http://www.youtube.com/watch?v=3kDHC_Tjrns Advanced Data Quality Services with Melissa Data – Azure Data Market For the purposes of the review, I used a database I had in an Excel spreadsheet with name and address information. Upon a cursory inspection, there are miscellaneous problems with these records; some addresses are missing ZIP codes, others missing a city, and some records are slightly misspelled or have unparsed suites. With DQS, I can easily add a knowledge base to help standardize my values, such as for state abbreviations. But how do I know that my address is correct? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Hard crash when drawing content for CALayer using quartz

    - by Lukasz
    I am trying to figure out why iOS crash my application in the harsh way (no crash logs, immediate shudown with black screen of death with spinner shown for a while). It happens when I render content for CALayer using Quartz. I suspected the memory issue (happens only when testing on the device), but memory logs, as well as instruments allocation logs looks quite OK. Let me past in the fatal function: - (void)renderTiles{ if (rendering) { //NSLog(@"====== RENDERING TILES SKIP ======="); return; } rendering = YES; CGRect b = tileLayer.bounds; CGSize s = b.size; CGFloat imageScale = [[UIScreen mainScreen] scale]; s.height *= imageScale; s.width *= imageScale; dispatch_async(queue, ^{ NSLog(@""); NSLog(@"====== RENDERING TILES START ======="); NSLog(@"1. Before creating context"); report_memory(); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); NSLog(@"2. After creating color space"); report_memory(); NSLog(@"3. About to create context with size: %@", NSStringFromCGSize(s)); CGContextRef ctx = CGBitmapContextCreate(NULL, s.width, s.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast); NSLog(@"4. After creating context"); report_memory(); CGAffineTransform flipTransform = CGAffineTransformMake(1.0, 0.0, 0.0, -1.0, 0.0, s.height); CGContextConcatCTM(ctx, flipTransform); CGRect tileRect = CGRectMake(0, 0, tileImageScaledSize.width, tileImageScaledSize.height); CGContextDrawTiledImage(ctx, tileRect, tileCGImageScaled); NSLog(@"5. Before creating cgimage from context"); report_memory(); CGImageRef cgImage = CGBitmapContextCreateImage(ctx); NSLog(@"6. After creating cgimage from context"); report_memory(); dispatch_sync(dispatch_get_main_queue(), ^{ tileLayer.contents = (id)cgImage; }); NSLog(@"7. After asgning tile layer contents = cgimage"); report_memory(); CGColorSpaceRelease(colorSpace); CGContextRelease(ctx); CGImageRelease(cgImage); NSLog(@"8. After releasing image and context context"); report_memory(); NSLog(@"====== RENDERING TILES END ======="); NSLog(@""); rendering = NO; }); } Here are the logs: ====== RENDERING TILES START ======= 1. Before creating context Memory in use (in bytes): 28340224 / 519442432 (5.5%) 2. After creating color space Memory in use (in bytes): 28340224 / 519442432 (5.5%) 3. About to create context with size: {6324, 5208} 4. After creating context Memory in use (in bytes): 28344320 / 651268096 (4.4%) 5. Before creating cgimage from context Memory in use (in bytes): 153649152 / 651333632 (23.6%) 6. After creating cgimage from context Memory in use (in bytes): 153649152 / 783159296 (19.6%) 7. After asgning tile layer contents = cgimage Memory in use (in bytes): 153653248 / 783253504 (19.6%) 8. After releasing image and context context Memory in use (in bytes): 21688320 / 651288576 (3.3%) ====== RENDERING TILES END ======= Application crashes in random places. Sometimes when reaching en of the function and sometime in random step. Which direction should I look for a solution? Is is possible that GDC is causing the problem? Or maybe the context size or some Core Animation underlying references?

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  • Of transactions and Mongo

    - by Nuri Halperin
    Originally posted on: http://geekswithblogs.net/nuri/archive/2014/05/20/of-transactions-and-mongo-again.aspxWhat's the first thing you hear about NoSQL databases? That they lose your data? That there's no transactions? No joins? No hope for "real" applications? Well, you *should* be wondering whether a certain of database is the right one for your job. But if you do so, you should be wondering that about "traditional" databases as well! In the spirit of exploration let's take a look at a common challenge: You are a bank. You have customers with accounts. Customer A wants to pay B. You want to allow that only if A can cover the amount being transferred. Let's looks at the problem without any context of any database engine in mind. What would you do? How would you ensure that the amount transfer is done "properly"? Would you prevent a "transaction" from taking place unless A can cover the amount? There are several options: Prevent any change to A's account while the transfer is taking place. That boils down to locking. Apply the change, and allow A's balance to go below zero. Charge person A some interest on the negative balance. Not friendly, but certainly a choice. Don't do either. Options 1 and 2 are difficult to attain in the NoSQL world. Mongo won't save you headaches here either. Option 3 looks a bit harsh. But here's where this can go: ledger. See, and account doesn't need to be represented by a single row in a table of all accounts with only the current balance on it. More often than not, accounting systems use ledgers. And entries in ledgers - as it turns out – don't actually get updated. Once a ledger entry is written, it is not removed or altered. A transaction is represented by an entry in the ledger stating and amount withdrawn from A's account and an entry in the ledger stating an addition of said amount to B's account. For sake of space-saving, that entry in the ledger can happen using one entry. Think {Timestamp, FromAccountId, ToAccountId, Amount}. The implication of the original question – "how do you enforce non-negative balance rule" then boils down to: Insert entry in ledger Run validation of recent entries Insert reverse entry to roll back transaction if validation failed. What is validation? Sum up the transactions that A's account has (all deposits and debits), and ensure the balance is positive. For sake of efficiency, one can roll up transactions and "close the book" on transactions with a pseudo entry stating balance as of midnight or something. This lets you avoid doing math on the fly on too many transactions. You simply run from the latest "approved balance" marker to date. But that's an optimization, and premature optimizations are the root of (some? most?) evil.. Back to some nagging questions though: "But mongo is only eventually consistent!" Well, yes, kind of. It's not actually true that Mongo has not transactions. It would be more descriptive to say that Mongo's transaction scope is a single document in a single collection. A write to a Mongo document happens completely or not at all. So although it is true that you can't update more than one documents "at the same time" under a "transaction" umbrella as an atomic update, it is NOT true that there' is no isolation. So a competition between two concurrent updates is completely coherent and the writes will be serialized. They will not scribble on the same document at the same time. In our case - in choosing a ledger approach - we're not even trying to "update" a document, we're simply adding a document to a collection. So there goes the "no transaction" issue. Now let's turn our attention to consistency. What you should know about mongo is that at any given moment, only on member of a replica set is writable. This means that the writable instance in a set of replicated instances always has "the truth". There could be a replication lag such that a reader going to one of the replicas still sees "old" state of a collection or document. But in our ledger case, things fall nicely into place: Run your validation against the writable instance. It is guaranteed to have a ledger either with (after) or without (before) the ledger entry got written. No funky states. Again, the ledger writing *adds* a document, so there's no inconsistent document state to be had either way. Next, we might worry about data loss. Here, mongo offers several write-concerns. Write-concern in Mongo is a mode that marshals how uptight you want the db engine to be about actually persisting a document write to disk before it reports to the application that it is "done". The most volatile, is to say you don't care. In that case, mongo would just accept your write command and say back "thanks" with no guarantee of persistence. If the server loses power at the wrong moment, it may have said "ok" but actually no written the data to disk. That's kind of bad. Don't do that with data you care about. It may be good for votes on a pole regarding how cute a furry animal is, but not so good for business. There are several other write-concerns varying from flushing the write to the disk of the writable instance, flushing to disk on several members of the replica set, a majority of the replica set or all of the members of a replica set. The former choice is the quickest, as no network coordination is required besides the main writable instance. The others impose extra network and time cost. Depending on your tolerance for latency and read-lag, you will face a choice of what works for you. It's really important to understand that no data loss occurs once a document is flushed to an instance. The record is on disk at that point. From that point on, backup strategies and disaster recovery are your worry, not loss of power to the writable machine. This scenario is not different from a relational database at that point. Where does this leave us? Oh, yes. Eventual consistency. By now, we ensured that the "source of truth" instance has the correct data, persisted and coherent. But because of lag, the app may have gone to the writable instance, performed the update and then gone to a replica and looked at the ledger there before the transaction replicated. Here are 2 options to deal with this. Similar to write concerns, mongo support read preferences. An app may choose to read only from the writable instance. This is not an awesome choice to make for every ready, because it just burdens the one instance, and doesn't make use of the other read-only servers. But this choice can be made on a query by query basis. So for the app that our person A is using, we can have person A issue the transfer command to B, and then if that same app is going to immediately as "are we there yet?" we'll query that same writable instance. But B and anyone else in the world can just chill and read from the read-only instance. They have no basis to expect that the ledger has just been written to. So as far as they know, the transaction hasn't happened until they see it appear later. We can further relax the demand by creating application UI that reacts to a write command with "thank you, we will post it shortly" instead of "thank you, we just did everything and here's the new balance". This is a very powerful thing. UI design for highly scalable systems can't insist that the all databases be locked just to paint an "all done" on screen. People understand. They were trained by many online businesses already that your placing of an order does not mean that your product is already outside your door waiting (yes, I know, large retailers are working on it... but were' not there yet). The second thing we can do, is add some artificial delay to a transaction's visibility on the ledger. The way that works is simply adding some logic such that the query against the ledger never nets a transaction for customers newer than say 15 minutes and who's validation flag is not set. This buys us time 2 ways: Replication can catch up to all instances by then, and validation rules can run and determine if this transaction should be "negated" with a compensating transaction. In case we do need to "roll back" the transaction, the backend system can place the timestamp of the compensating transaction at the exact same time or 1ms after the original one. Effectively, once A or B visits their ledger, both transactions would be visible and the overall balance "as of now" would reflect no change.  The 2 transactions (attempted/ reverted) would be visible , since we do actually account for the attempt. Hold on a second. There's a hole in the story: what if several transfers from A to some accounts are registered, and 2 independent validators attempt to compute the balance concurrently? Is there a chance that both would conclude non-sufficient-funds even though rolling back transaction 100 would free up enough for transaction 117 (some random later transaction)? Yes. there is that chance. But the integrity of the business rule is not compromised, since the prime rule is don't dispense money you don't have. To minimize or eliminate this scenario, we can also assign a single validation process per origin account. This may seem non-scalable, but it can easily be done as a "sharded" distribution. Say we have 11 validation threads (or processing nodes etc.). We divide the account number space such that each validator is exclusively responsible for a certain range of account numbers. Sounds cunningly similar to Mongo's sharding strategy, doesn't it? Each validator then works in isolation. More capacity needed? Chop the account space into more chunks. So where  are we now with the nagging questions? "No joins": Huh? What are those for? "No transactions": You mean no cross-collection and no cross-document transactions? Granted - but don't always need them either. "No hope for real applications": well... There are more issues and edge cases to slog through, I'm sure. But hopefully this gives you some ideas of how to solve common problems without distributed locking and relational databases. But then again, you can choose relational databases if they suit your problem.

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  • Session Evaluations

    - by BuckWoody
    I do a lot of public speaking. I write, teach, present and communicate at many levels. I love to do those things. And I love to get better at them. And one of the ways you get better at something is to get feedback on how you did. That being said, I have to confess that I really despise the “evaluations” I get at most venues. From college to technical events to other locations, at Microsoft and points in between, I find these things to be just shy of damaging, and most certainly useless. And it’s not always your fault. Ouch. That seems harsh. But let me ask you one question – and be as honest as you can with the answer – think about it first: “What is the point of a session evaluation?” I’m not saying there isn’t one. In fact, I think there’s a really important reason for them. In my mind, it’s really this: To make the speaker / next session better. Now, if you look at that, you can see right away that most session evals don’t accomplish this goal – not even a little. No, the way that they are worded and the way you (and I) fill them out, it’s more like the implied goal is this: Tell us how you liked this speaker / session. The current ones are for you, not for the speaker or the next person. It’s a popularity contest. Don’t get me wrong. I want to you have a good time. I want you to learn. I want (desperately, oh, please oh please) for you to like me. But in fact, that’s probably not why you went to the session / took the class / read that post. No, you want to learn, and to learn for a particular reason. Remember, I’m talking about college classes, sessions and other class environments here, not a general public event. Most – OK, all – session evaluations make you answer the second goal, not the first. Let’s see how: First, they don’t ask you why you’re there. They don’t ask you if you’re even qualified to evaluate the session or speaker. They don’t ask you how to make it better or keep it great. They use odd numeric scales that are meaningless. For instance, can someone really tell me the difference between a 100-level session and a 200-level one? Between a 400-level and a 500? Is it “internals” (whatever that means) or detail, or length or code, or what? I once heard a great description: A 100-level session makes me say, “wow - I’m smart.” A 500-level session makes me say “wow – that presenter is smart.” And just what is the difference between a 6 and a 7 answer on this question: How well did the speaker know the material? 1  2  3  4  5  6  7  8  9  10 Oh. My. Gosh. How does that make the next session better, or the speaker? And what criteria did you use to answer? And is a “10” better than a “1” (not always clear, and various cultures answer this differently). When it’s all said and done, a speaker basically finds out one thing from the current session evals: “They liked me. They really really liked me.” Or, “Wow. I think I may need to schedule some counseling for the depression I’m about to go into.” You may not think that’s what the speaker hears, but trust me, they do. Those are the only two reactions to the current feedback sheets they get. Either they keep doing what they are doing, or they get their feelings hurt. They just can’t use the information provided to do better. Sorry, but there it is. Keep in mind I do want your feedback. I want to get better. I want you to get your money and time’s worth, probably as much as any speaker alive. But I want those evaluations to be accurate, specific and actionable. I want to know if you had a good time, sure, but I also want to know if I did the right things, and if not, if I can do something different or better. And so, for your consideration, here is the evaluation form I would LOVE for you to use. Feel free to copy it and mail it to me any time. I’m going to put some questions here, and then I’ll even include why they are there. Notice that the form asks you a subjective question right away, and then makes you explain why. That’s work on your part. Notice also that it separates the room and the coffee and the lights and the LiveMeeting from the presenter. So many presenters are faced with circumstances beyond their control, and yet are rated high or low personally on those things. This form helps tease those apart. It’s not numeric. Numbers are easier for the scoring committees but are useless for you and me. So I don’t have any numbers. We’re actually going to have to read these things, not put them in a machine. Hey, if you put in the work to write stuff down, the least we could do is take the time to read it. It’s not anonymous. If you’ve got something to say, say it, and own up to it. People are not “more honest” when they are anonymous, they are less honest. So put your name on it. In fact – this is radical – I posit that these evaluations should be publicly available. Forever. Just like replies to a blog post. Hey, if I’m an organizer, I would LOVE to be able to have access to specific, actionable information on the attendees and the speakers. So if you want mine to be public, go for it. I’ll take the good and the bad. Enjoy. ------------------------------------------------------------------------------------------------------------------------------------------- Session Evaluation – Date, Time, Location, Topic Thanks for giving us your time today. We know that’s valuable, and we hope you learned something you can use from the session. If you can answer these questions as completely as you can, it will help the next person who attends a session here. Your Name: What you do for a living: (We Need your background to evaluate your evaluation) How long you have been doing that: (Again, we need your background to evaluate your evaluation) Paste Session Description Here: (This is what I said I would talk about) Did you like the session?                     No        Meh        Yes (General subjective question – overall “feeling”. You’ll tell us why in a minute.)  Tell us about the venue. Temperature, lights, coffee, or the online sound, performance, anything other than the speaker and the material. (Helps the logistics to be better or as good for the next person) 1. What did you expect to learn in this session? (How did you interpret that extract – did you have expectations that I should work towards for the next person?) 2. Did you learn what you expected to learn? Why? Be very specific. (This is the most important question there is. It tells us how to make the session better for someone like you.) 3. If you were giving this presentation, would you have done anything differently? What? (Helps us to gauge you, the listener, and might give us a great idea on how to do something better. Thanks!) 4. What will you do with the information you got? (Every presenter wants you to learn, and learn something useful. This will help us do that as well or better)  

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  • The Product Owner

    - by Robert May
    In a previous post, I outlined the rules of Scrum.  This post details one of those rules. Picking a most important part of Scrum is difficult.  All of the rules are required, but if there were one rule that is “more” required that every other rule, its having a good Product Owner.  Simply put, the Product Owner can make or break the project. Duties of the Product Owner A Product Owner has many duties and responsibilities.  I’ll talk about each of these duties in detail below. A Product Owner: Discovers and records stories for the backlog. Prioritizes stories in the Product Backlog, Release Backlog and Iteration Backlog. Determines Release dates and Iteration Dates. Develops story details and helps the team understand those details. Helps QA to develop acceptance tests. Interact with the Customer to make sure that the product is meeting the customer’s needs. Discovers and Records Stories for the Backlog When I do Scrum, I always use User Stories as the means for capturing functionality that’s required in the system.  Some people will use Use Cases, but the same rule applies.  The Product Owner has the ultimate responsibility for figuring out what functionality will be in the system.  Many different mechanisms for capturing this input can be used.  User interviews are great, but all sources should be considered, including talking with Customer Support types.  Often, they hear what users are struggling with the most and are a great source for stories that can make the application easier to use. Care should be taken when soliciting user stories from technical types such as programmers and the people that manage them.  They will almost always give stories that are very technical in nature and may not have a direct benefit for the end user.  Stories are about adding value to the company.  If the stories don’t have direct benefit to the end user, the Product Owner should question whether or not the story should be implemented.  In general, technical stories should be included as tasks in User Stories.  Technical stories are often needed, but the ultimate value to the user is in user based functionality, so technical stories should be considered nothing more than overhead in providing that user functionality. Until the iteration prior to development, stories should be nothing more than short, one line placeholders. An exercise called Story Planning can be used to brainstorm and come up with stories.  I’ll save the description of this activity for another blog post. For more information on User Stories, please read the book User Stories Applied by Mike Cohn. Prioritizes Stories in the Product Backlog, Release Backlog and Iteration Backlog Prioritization of stories is one of the most difficult tasks that a Product Owner must do.  A key concept of Scrum done right is the need to have the team working from a single set of prioritized stories.  If the team does not have a single set of prioritized stories, Scrum will likely fail at your organization.  The Product Owner is the ONLY person who has the responsibility to prioritize that list.  The Product Owner must be very diplomatic and sincerely listen to the people around him so that he can get the priorities correct. Just listening will still not yield the proper priorities.  Care must also be taken to ensure that Return on Investment is also considered.  Ultimately, determining which stories give the most value to the company for the least cost is the most important factor in determining priorities.  Product Owners should be willing to look at cold, hard numbers to determine the order for stories.  Even when many people want a feature, if that features is costly to develop, it may not have as high of a return on investment as features that are cheaper, but not as popular. The act of prioritization often causes conflict in an environment.  Customer Service thinks that feature X is the most important, because it will stop people from calling.  Operations thinks that feature Y is the most important, because it will stop servers from crashing.  Developers think that feature Z is most important because it will make writing software much easier for them.  All of these are useful goals, but the team can have only one list of items, and each item must have a priority that is different from all other stories.  The Product Owner will determine which feature gives the best return on investment and the other features will have to wait their turn, which means that someone will not have their top priority feature implemented first. A weak Product Owner will refuse to do prioritization.  I’ve heard from multiple Product Owners the following phrase, “Well, it’s all got to be done, so what does it matter what order we do it in?”  If your product owner is using this phrase, you need a new Product Owner.  Order is VERY important.  In Scrum, every release is potentially shippable.  If the wrong priority items are developed, then the value added in each release isn’t what it should be.  Additionally, the Product Owner with this mindset doesn’t understand Agile.  A product is NEVER finished, until the company has decided that it is no longer a going concern and they are no longer going to sell the product.  Therefore, prioritization isn’t an event, its something that continues every day.  The logical extension of the phrase “It’s all got to be done” is that you will never ship your product, since a product is never “done.”  Once stories have been prioritized, assigning them to the Release Backlog and the Iteration Backlog becomes relatively simple.  The top priority items are copied into the respective backlogs in order and the task is complete.  The team does have the right to shuffle things around a little in the iteration backlog.  For example, they may determine that working on story C with story A is appropriate because they’re related, even though story B is technically a higher priority than story C.  Or they may decide that story B is too big to complete in the time available after Story A has tasks created, so they’ll work on Story C since it’s smaller.  They can’t, however, go deep into the backlog to pick stories to implement.  The team and the Product Owner should work together to determine what’s best for the company. Prioritization is time consuming, but its one of the most important things a Product Owner does. Determines Release Dates and Iteration Dates Product owners are responsible for determining release dates for a product.  A common misconception that Product Owners have is that every “release” needs to correspond with an actual release to customers.  This is not the case.  In general, releases should be no more than 3 months long.  You  may decide to release the product to the customers, and many companies do release the product to customers, but it may also be an internal release. If a release date is too far away, developers will fall into the trap of not feeling a sense of urgency.  The date is far enough away that they don’t need to give the release their full attention.  Additionally, important tasks, such as performance tuning, regression testing, user documentation, and release preparation, will not happen regularly, making them much more difficult and time consuming to do.  The more frequently you do these tasks, the easier they are to accomplish. The Product Owner will be a key participant in determining whether or not a release should be sent out to the customers.  The determination should be made on whether or not the features contained in the release are valuable enough  and complete enough that the customers will see real value in the release.  Often, some features will take more than three months to get them to a state where they qualify for a release or need additional supporting features to be released.  The product owner has the right to make this determination. In addition to release dates, the Product Owner also will help determine iteration dates.  In general, an iteration length should be chosen and the team should follow that iteration length for an extended period of time.  If the iteration length is changed every iteration, you’re not doing Scrum.  Iteration lengths help the team and company get into a rhythm of developing quality software.  Iterations should be somewhere between 2 and 4 weeks in length.  Any shorter, and significant software will likely not be developed.  Any longer, and the team won’t feel urgency and planning will become very difficult. Iterations may not be extended during the iteration.  Companies where Scrum isn’t really followed will often use this as a strategy to complete all stories.  They don’t want to face the harsh reality of what their true performance is, and looking good is more important than seeking visibility and improving the process and team.  Companies like this typically don’t allow failure.  This is unhealthy.  Failure is part of life and unless we learn from it, we can’t improve.  I would much rather see a team push out stories to the next iteration and then have healthy discussions about why they failed rather than extend the iteration and not deal with the core problems. If iteration length varies, retrospectives become more difficult.  For example, evaluating the performance of the team’s estimation efforts becomes much more difficult if the iteration length varies.  Also, the team must have a velocity measurement.  If the iteration length varies, measuring velocity becomes impossible and upper management no longer will have the ability to evaluate the teams performance.  People external to the team will no longer have the ability to determine when key features are likely to be developed.  Variable iterations cause the entire company to fail and likely cause Scrum to fail at an organization. Develops Story Details and Helps the Team Understand Those Details A key concept in Scrum is that the stories are nothing more than a placeholder for a conversation.  Stories should be nothing more than short, one line statements about the functionality.  The team will then converse with the Product Owner about the details about that story.  The product owner needs to have a very good idea about what the details of the story are and needs to be able to help the team understand those details. Too often, we see this requirement as being translated into the need for comprehensive documentation about the story, including old fashioned requirements documentation.  The team should only develop the documentation that is required and should not develop documentation that is only created because their is a process to do so. In general, what we see that works best is the iteration before a team starts development work on a story, the Product Owner, with other appropriate business analysts, will develop the details of that story.  They’ll figure out what business rules are required, potentially make paper prototypes or other light weight mock-ups, and they seek to understand the story and what is implied.  Note that the time allowed for this task is deliberately short.  The Product Owner only has a single iteration to develop all of the stories for the next iteration. If more than one iteration is used, I’ve found that teams will end up with Big Design Up Front and traditional requirements documents.  This is a waste of time, since the team will need to then have discussions with the Product Owner to figure out what the requirements document says.  Instead of this, skip making the pretty pictures and detailing the nuances of the requirements and build only what is minimally needed by the team to do development.  If something comes up during development, you can address it at that time and figure out what you want to do.  The goal is to keep things as light weight as possible so that everyone can move as quickly as possible. Helps QA to Develop Acceptance Tests In Scrum, no story can be counted until it is accepted by QA.  Because of this, acceptance tests are very important to the team.  In general, acceptance tests need to be developed prior to the iteration or at the very beginning of the iteration so that the team can make sure that the tasks that they develop will fulfill the acceptance criteria. The Product Owner will help the team, including QA, understand what will make the story acceptable.  Note that the Product Owner needs to be careful about specifying that the feature will work “Perfectly” at the end of the iteration.  In general, features are developed a little bit at a time, so only the bit that is being developed should be considered as necessary for acceptance. A weak Product Owner will make statements like “Do it right the first time.”  Not only are these statements damaging to the team (like they would try to do it WRONG the first time . . .), they’re also ignoring the iterative nature of Scrum.  Additionally, a weak product owner will seek to add scope in the acceptance testing.  For example, they will refuse to determine acceptance at the beginning of the iteration, and then, after the team has planned and committed to the iteration, they will expand scope by defining acceptance.  This often causes the team to miss the iteration because scope that wasn’t planned on is included.  There are ways that the team can mitigate this problem.  For example, include extra “Product Owner” time to deal with the uncertainty that you know will be introduced by the Product Owner.  This will slow the perceived velocity of the team and is not ideal, since they’ll be doing more work than they get credit for. Interact with the Customer to Make Sure that the Product is Meeting the Customer’s Needs Once development is complete, what the team has worked on should be put in front of real live people to see if it meets the needs of the customer.  One of the great things about Agile is that if something doesn’t work, we can revisit it in a future iteration!  This frees up the team to make the best decision now and know that if that decision proves to be incorrect, the team can revisit it and change that decision. Features are about adding value to the customer, so if the customer doesn’t find them useful, then having the team make tweaks is valuable.  In general, most software will be 80 to 90 percent “right” after the initial round and only minor tweaks are required.  If proper coding standards are followed, these tweaks are usually minor and easy to accomplish.  Product Owners that are doing a good job will encourage real users to see and use the software, since they know that they are trying to add value to the customer. Poor product owners will think that they know the answers already, that their customers are silly and do stupid things and that they don’t need customer input.  If you have a product owner that is afraid to show the team’s work to real customers, you probably need a different product owner. Up Next, “Who Makes a Good Product Owner.” Followed by, “Messing with the Team.” Technorati Tags: Scrum,Product Owner

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