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  • How are minimum system requirements determined?

    - by Michael McGowan
    We've all seen countless examples of software that ships with "minimum system requirements" like the following: Windows XP/Vista/7 1GB RAM 200 MB Storage How are these generally determined? Obviously sometimes there are specific constraints (if the program takes 200 MB on disk then that is a hard requirement). Aside from those situations, many times for things like RAM or processor it turns out that more/faster is better with no hard constraint. How are these determined? Do developers just make up numbers that seem reasonable? Does QA go through some rigorous process testing various requirements until they find the lowest settings with acceptable performance? My instinct says it should be the latter but is often the former in practice.

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  • What if I can't make my unit test fail in "Red, Green, Refactor" of TDD?

    - by Joshua Harris
    So let's say that I have a test: @Test public void MoveY_MoveZero_DoesNotMove() { Point p = new Point(50.0, 50.0); p.MoveY(0.0); Assert.assertAreEqual(50.0, p.Y); } This test then causes me to create the class Point: public class Point { double X; double Y; public void MoveY(double yDisplace) { throw new NotYetImplementedException(); } } Ok. It fails. Good. Then I remove the exception and I get green. Great, but of course I need to test if it changes value. So I write a test that calls p.MoveY(10.0) and checks if p.Y is equal to 60.0. It fails, so then I change the function to look like so: public void MoveY(double yDisplace) { Y += yDisplace; } Great, now I have green again and I can move on. I've tested not moving and moving in the positive direction, so naturally I should test a negative value. The only problem with this test is that if I wrote the test correctly, then it doesn't fail at first. That means that I didn't fit the principle of "Red, Green, Refactor." Of course, This is a first-world problem of TDD, but getting a fail at first is helpful in that it shows that your test can fail. Otherwise this seemingly innocent test that is just passing for incorrect reasons could fail later because it was written wrong. That might not be a problem if it happened 5 minutes later, but what if it happens to the poor-sap that inheirited your code two years later. What he knows is that MoveY does not work with negative values because that is what the test is telling him. But, it really could work and just be a bug in the test. I don't think that would happen in this particular case because the code sample is so simple, but if it were a large complicated system that might not be the case. It seems crazy to say that I want to fail my tests, but that is an important step in TDD, for good reasons.

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  • Creating PHP Forms with show/hide functionality [migrated]

    - by ronquiq
    I want to create two reports and submit the report data to database by using two functions defined in a class: Here I have two buttons: "Create ES" and "Create RP". Rightnow, my forms are working fine, I can insert data successfully, but the problem was when I click on submit after filling the form data, the content is hiding and displays the fist div content "cs_content" and again I need to onclick to submit again. Could anyone give a solution for this. Requirement : When I click on "Create CS", I should be able to fill the form and submit data successfully with a message within "cs_content" and any form input errors, the errors should display within "cs_content". When I click on "Create RP", I should be able to fill the form and submit data successfully with a message within "rp_content" and any form input errors, the errors should display within "rp_content". home.php <?php require 'classes/class.report.php'; $report = new Report($db); ?> <html> <head> <script src="js/jqueryv1.10.2.js"></script> <script> $ (document).ready(function () { //$("#cs_content").show(); $('#cs').click(function () { $('#cs_content').fadeIn('slow'); $('#rp_content').hide(); }); $('#rp').click(function () { $('#rp_content').fadeIn('slow'); $('#cs_content').hide(); }); }); </script> </head> <body> <div class="container2"> <div style="margin:0px 0px;padding:3px 217px;overflow:hidden;"> <div id="cs" style="float:left;margin:0px 0px;padding:7px;"><input type="button" value="CREATE CS"></div> <div id="rp" style="float:left;margin:0px 0px;padding:7px;"><input type="button" value="CREATE RP"></div><br> </div> <div id="cs_content"> <?php $report->create_cs_report(); ?> </div> <div id="rp_content" style="display:none;"> <?php $report->create_rp_report(); ?> </div> </div> </body> </html> class.report.php <?php class Report { private $db; public function __construct($database){ $this->db = $database; } public function create_cs_report() { if (isset($_POST['create_es_report'])) { $report_name = htmlentities($_POST['report_name']); $from_address = htmlentities($_POST['from_address']); $subject = htmlentities($_POST['subject']); $reply_to = htmlentities($_POST['reply_to']); if (empty($_POST['report_name']) || empty($_POST['from_address']) || empty($_POST['subject']) || empty($_POST['reply_to'])) { $errors[] = '<span class="error">All fields are required.</span>'; } else { if (isset($_POST['report_name']) && empty($_POST['report_name'])) { $errors[] = '<span class="error">Report Name is required</span>'; } else if (!ctype_alnum($_POST['report_name'])) { $errors[] = '<span class="error">Report Name: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['from_address']) && empty($_POST['from_address'])) { $errors[] = '<span class="error">From address is required</span>'; } else if (filter_var($_POST['from_address'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid From address</span>'; } if (isset($_POST['subject']) && empty($_POST['subject'])) { $errors[] = '<span class="error">Subject is required</span>'; } else if (!ctype_alnum($_POST['subject'])) { $errors[] = '<span class="error">Subject: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['reply_to']) && empty($_POST['reply_to'])) { $errors[] = '<span class="error">Reply To is required</span>'; } else if (filter_var($_POST['reply_to'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid Reply-To address</span>'; } } if (empty($errors) === true) { $query = $this->db->prepare("INSERT INTO report(report_name, from_address, subject, reply_to) VALUES (?, ?, ?, ?) "); $query->bindValue(1, $report_name); $query->bindValue(2, $from_address); $query->bindValue(3, $subject); $query->bindValue(4, $reply_to); try { $query->execute(); } catch(PDOException $e) { die($e->getMessage()); } header('Location:home.php?success'); exit(); } } if (isset($_GET['success']) && empty($_GET['success'])) { header('Location:home.php'); echo '<span class="error">Report is succesfully created</span>'; } ?> <form action="" method="POST" accept-charset="UTF-8"> <div style="font-weight:bold;padding:17px 80px;text-decoration:underline;">Section A</div> <table class="create_report"> <tr><td><label>Report Name</label><span style="color:#A60000">*</span></td> <td><input type="text" name="report_name" required placeholder="Name of the report" value="<?php if(isset($_POST["report_name"])) echo $report_name; ?>" size="30" maxlength="30"> </td></tr> <tr><td><label>From</label><span style="color:#A60000">*</span></td> <td><input type="text" name="from_address" required placeholder="From address" value="<?php if(isset($_POST["from_address"])) echo $from_address; ?>" size="30"> </td></tr> <tr><td><label>Subject</label><span style="color:#A60000">*</span></td> <td><input type="text" name="subject" required placeholder="Subject" value="<?php if(isset($_POST["subject"])) echo $subject; ?>" size="30"> </td></tr> <tr><td><label>Reply To</label><span style="color:#A60000">*</span></td> <td><input type="text" name="reply_to" required placeholder="Reply address" value="<?php if(isset($_POST["reply_to"])) echo $reply_to; ?>" size="30"> </td></tr> <tr><td><input type="submit" value="create report" style="background:#8AC007;color:#080808;padding:6px;" name="create_es_report"></td></tr> </table> </form> <?php //IF THERE ARE ERRORS, THEY WOULD BE DISPLAY HERE if (empty($errors) === false) { echo '<div>' . implode('</p><p>', $errors) . '</div>'; } } public function create_rp_report() { if (isset($_POST['create_rp_report'])) { $report_name = htmlentities($_POST['report_name']); $to_address = htmlentities($_POST['to_address']); $subject = htmlentities($_POST['subject']); $reply_to = htmlentities($_POST['reply_to']); if (empty($_POST['report_name']) || empty($_POST['to_address']) || empty($_POST['subject']) || empty($_POST['reply_to'])) { $errors[] = '<span class="error">All fields are required.</span>'; } else { if (isset($_POST['report_name']) && empty($_POST['report_name'])) { $errors[] = '<span class="error">Report Name is required</span>'; } else if (!ctype_alnum($_POST['report_name'])) { $errors[] = '<span class="error">Report Name: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['to_address']) && empty($_POST['to_address'])) { $errors[] = '<span class="error">to address is required</span>'; } else if (filter_var($_POST['to_address'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid to address</span>'; } if (isset($_POST['subject']) && empty($_POST['subject'])) { $errors[] = '<span class="error">Subject is required</span>'; } else if (!ctype_alnum($_POST['subject'])) { $errors[] = '<span class="error">Subject: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['reply_to']) && empty($_POST['reply_to'])) { $errors[] = '<span class="error">Reply To is required</span>'; } else if (filter_var($_POST['reply_to'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid Reply-To address</span>'; } } if (empty($errors) === true) { $query = $this->db->prepare("INSERT INTO report(report_name, to_address, subject, reply_to) VALUES (?, ?, ?, ?) "); $query->bindValue(1, $report_name); $query->bindValue(2, $to_address); $query->bindValue(3, $subject); $query->bindValue(4, $reply_to); try { $query->execute(); } catch(PDOException $e) { die($e->getMessage()); } header('Location:home.php?success'); exit(); } } if (isset($_GET['success']) && empty($_GET['success'])) { header('Location:home.php'); echo '<span class="error">Report is succesfully created</span>'; } ?> <form action="" method="POST" accept-charset="UTF-8"> <div style="font-weight:bold;padding:17px 80px;text-decoration:underline;">Section A</div> <table class="create_report"> <tr><td><label>Report Name</label><span style="color:#A60000">*</span></td> <td><input type="text" name="report_name" required placeholder="Name of the report" value="<?php if(isset($_POST["report_name"])) echo $report_name; ?>" size="30" maxlength="30"> </td></tr> <tr><td><label>to</label><span style="color:#A60000">*</span></td> <td><input type="text" name="to_address" required placeholder="to address" value="<?php if(isset($_POST["to_address"])) echo $to_address; ?>" size="30"> </td></tr> <tr><td><label>Subject</label><span style="color:#A60000">*</span></td> <td><input type="text" name="subject" required placeholder="Subject" value="<?php if(isset($_POST["subject"])) echo $subject; ?>" size="30"> </td></tr> <tr><td><label>Reply To</label><span style="color:#A60000">*</span></td> <td><input type="text" name="reply_to" required placeholder="Reply address" value="<?php if(isset($_POST["reply_to"])) echo $reply_to; ?>" size="30"> </td></tr> <tr><td><input type="submit" value="create report" style="background:#8AC007;color:#080808;padding:6px;" name="create_rp_report"></td></tr> </table> </form> <?php //IF THERE ARE ERRORS, THEY WOULD BE DISPLAY HERE if (empty($errors) === false) { echo '<div>' . implode('</p><p>', $errors) . '</div>'; } } }//Report CLASS ENDS

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  • Software design for non object oriented paradigm

    - by Dean
    I'm currently working on a project where I'm writing the firmware for an electronic system in C, and have been asked to produce documentation on the development/evolution of the software for the embedded devices. Having developed software in the object oriented paradigm I know to use UML to document the software such as class diagrams with objects, however this does not work for documenting the development of my embedded system. So what should I produce to document the development of my firmware?

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  • Does this syntax for specifying Django conditional form display align with python/django convention?

    - by andy
    I asked a similar question on Stackoverflow and was told it was better asked here. So I'll ask it slightly rephrased. I am working on a Django project, part of which will become a distributable plugin that allows the python/django developer to specify conditional form field display logic in the form class or model class. I am trying to decide how the developer must specify that logic. Here's an example: class MyModel(models.Model): #these are some django model fields which will be used in a form yes_or_no = models.SomeField...choices are yes or no... why = models.SomeField...text, but only relevant if yes_or_no == yes... elaborate_even_more = models.SomeField...more text, just here so we can have multiple conditions #here i am inventing some syntax...i am looking for suggestions!! #this is one possibility why.show_if = ('yes_or_no','==','yes') elaborate_even_more.show_if = (('yes_or_no','==','yes'),('why','is not','None')) #help me choose a syntax that is *easy*...and Pythonic and...Djangonic...and that makes your fingers happy to type! #another alternative... conditions = {'why': ('yes_or_no','==','yes'), 'elaborate_even_more': (('yes_or_no','==','yes'),('why','is not','None')) } #or another alternative... """Showe the field whiche hath the name *why* only under that circumstance in whiche the field whiche hath the name *yes_or_no* hath the value *yes*, in strictest equality.""" etc... Those conditions will be eventually passed via django templates to some javascript that will show or hide form fields accordingly. Which of those options (or please propose a better option) aligns better with conventions such that it will be easiest for the python/django developer to use? Also are there other considerations that should impact what syntax I choose?

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  • How to add a subclass to a viewcontroller in storyboard

    - by Ken Barlo
    Here's what I've created I created a view controller element (in storyboard) I created a new viewcontroller .h and .m file Here's my issue Can't seem to figure out how to get the content that I've added to the .m file to show up on the view controller element in the storyboard once the app is launched and the selection for that view controller element is made in the iPhone simulator. Although I am able to see content that is already added to a .m file on the home screen and activity screen when the selection is made in the iPhone simulator. Hope that makes sense, if not please ask and I'll be more than happy to provide more info.

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  • DDD and validation of aggregate root

    - by Mik378
    Suppose an aggregate root : MailConfiguration (wrapping an AddressPart object). The AddressPart object is a simple immutable value object with some fields like senderAdress, recipentAddress (to make example simple). As being an invariant object, AddressPart should logically wrap its own Validator (by the way of external a kind of AddressValidator for respecting Single Responsibility Principle) I read some articles that claimed an aggregateRoot must validate its 'children'. However, if we follow this principle, one could create an AddressPart with an uncohesive/invalid state. What are your opinion? Should I move the collaborator AddressValidator(used in constructor so in order to validate immediately the cohesion of an AddressPart) from AddressPart and assign it to aggregateRoot (MailConfiguration) ?

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  • Writing drivers for a printer?

    - by user828584
    My goal is to be able to fax 20 page pdf documents for free. I've looked online, and there are some free fax services, but all of them have their limits. I do have an old fax machine, but the documents that need to be faxed are on the computer, and to print them would be far from free. Unfortunately, the only way to send a fax with the machine is by scanning it. What's strange is that it can scan to the computer and print from it, but it won't fax from it... :(. Is it possible to write something (preferably C#, but it's going to take some learning anyway) that will allow me to send a fax from the computer? I have very little software experience, and none in anything like this, so I have no idea where to start. If it is possible, where can I find all the information needed to write the program?

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  • EJB Lifecycle and Relation to WARs

    - by Adam Tannon
    I've been reading up on EJBs (3.x) and believe I understand the basics. This question is a "call for confirmation" that I have interpreted the Java EE docs correctly and that I understand these fundamental concepts: An EJB is to an App Container as a Web App (WAR) is to a Web Container Just like you deploy a WAR to a Web Container, and that container manages your WAR's life cycle, you deploy an EJB to an App Container, and the container manages your EJB's life cycle When the App Container fires up and deploys an EJB, it is given a unique "identifier" and URL that can be used by JNDI to look up the EJB from another tier (like the web tier) So, when your web app wants to invoke one of your EJB's methods, it looks the EJB up using some kind of service locator (JNDI) and invoke the method that way Am I on-track or way off-base here? Please correct me & clarify for me if any of these are incorrect. Thanks in advance!

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  • Live programming help

    - by frazras
    This idea has been floating around my head for a few years. I started some work on it but I just want to know if it is feasible, sensible, or if there is something else like it out there. Dont want to know I was wasting time on a solved issue. Whenever I have a programming issue, this is my sequence: Google it!: That usually brings up a lot of things: blogs, forums, stackoverflow, stackexchange, and even the official docs of the language/framework/cms. Ask on IRC: I format my question and try to get people on IRC to help me. Make a post: I create a post on forums/stackoverflow/stackexchange or shout on twitter with hashtags. Now a lot of the time I am in the middle of a project with a deadline. So I want answers NOW!!! Sometimes just 5-15 minutes worth of attention. Usually by the time I am failing at getting answers at #2, I am imagining how many people are ONLINE NOW with the skill and my exact answer but playing video games, watching youtube or idling online. However, if they were motivated, they would invest the 15 mintes helping me, that would make a world of a difference. I am even in positions where I would PAY for that 15 minutes of instant help. If your rate is as much as $100/hour (relatively good programmer) that is $25 that might save me 3 hours. This help would be live, text chat/skype/phone/screenshare. Should I continue developing this idea or is there a better alternative out there? Or is this even an unfeasible idea?

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  • lowering the use of the memory controller in OpenCL based applications

    - by user827992
    With my first experiments I noticed that OpenCL is a good technology but often hampered by the X86 architecture and finding a mid-range VGA driven by a low-end chipset is not that unusual in the real world scenarios, sometimes this can happen with some high-end VGA too. Are there some caching techniques? Something that can bypass this inconvenience in some ways. The amount of dedicated memory on today's VGA is usually high, it's possible to use this memory to create some kind of buffer with instructions.

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  • Writing or extending existing emacs packages: is it worth or should I move to Netbeans/Eclipse?

    - by Andrea
    I'm finishing my master degree course in CS and I've almost become addicted to Emacs. I've used it to write in C, Latex, Java, JSP,XML, CommonLisp, Ada and other languages no other editor supported, like AMPL. I'd like to improve the packages I've been using the most or create new ones, but, in practice, I find that the implementation of Emacs leaves a lot to be desired. There are a lot of poorly-featured/poorly-maintained packages with either overlapping functionalities or obscure incompatibilities, and Elisp just seems to foster the situation by lacking the common features modern lisps have. In contrast Eclipse and Netbeans are actively improved and it does seem they can be effective for non-mainstream languages. I tried Hibachi for Ada in Eclipse and it worked well, there's CUPS for Lisp in Eclipse and LambdaBeans built using NetBeans components. On the other hand those plugins seem to be less active than their Emacs' counterparts, for example Hibachi was archived last year. What's your opinion on this? Which editor should I write extension for? EDIT: To answer Larry Coleman (see comment below): I like Emacs as a user because it is efficient both for me and the computer I'm using. It's fast and the textual interface (i.e. minibuffer) allows for quick interaction. It's solid and packages are usually small and easy to manage. If I need to correct or remove something I usually just have to change a row in my .emacs or an elisp file, or delete a directory. Eclipse plugins rely on a more complicated process that screwed my Eclipse configuration a couple of times, forcing me to do a clean reinstall. Emacs works as long as I use the basic packages. If I need something more complicated the situation gets pretty hairy. As a "power user" I think that the best I can hope for is to write a severely crippled version of the extensions I'd actually like to have; in other words, that it's not worth the trouble. I'd like to write extensions for the things I'd like to have automated in Emacs, for example project support with automated tag-table update on file writing. There are a few projects on this that lack integration, documentation, extensibility and so forth. The best one is probably CEDET, for which I believe the Greenspun's 10th rule can be applied. EDIT: To comment Larry Coleman's answer I'm pretty sure I can pick elisp programming but the extensions I have in mind don't exist yet despite their relative simplicity and the effort more knowledgeable people poured into related projects.This makes me wonder whether it is so because of the way emacs is developed, i.e. people tend to write their own little extensions without coordination, or its implementation, its extension language not being able to keep up with the growing complexity.

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  • Should we choose Java over C# or we should consider using Mono?

    - by A. Karimi
    We are a small team of independent developers with an average experience of 7 years in C#/.NET platform. We almost work on small to average web application projects that allows us to choose our favorite platform. I believe that our current platform (C#/.NET) allows us to be more productive than if we were working in Java but what makes me think about choosing Java over C# is the costs and the community (of the open source). Our projects allow us even work with various frameworks as well as various platforms. For example we can even use Nancy. So we are able to decrease the costs by using Mono which can be deployed on Linux servers. But I'm looking for a complete ecosystem (IDE/Platform/Production Environment) that decreases our costs and makes us feel completely supported by the community. As an example of issues I've experienced with MonoDevelop, I can refer to the poor support of the Razor syntax on MonoDevelop. As another example, We are using "VS 2012 Express for Web" as our IDE to decrease the costs but as you know it doesn't support plugins and I have serious problems with XML comments (I missed GhostDoc). We strongly believe in strongly-typed programming languages so please don't offer the other languages and platforms such as Ruby, PHP, etc. Now I want to choose between: Keep going on C#, buy some products and be hopeful about openness of .NET ecosystem and its open source community. Changing the platform and start using the Java open source ecosystem

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  • Calculating 3d rotation around random axis

    - by mitim
    This is actually a solved problem, but I want to understand why my original method didn't work (hoping someone with more knowledge can explain). (Keep in mind, I've not very experienced in 3d programming, having only played with the very basic for a little bit...nor do I have a lot of mathematical experience in this area). I wanted to animate a point rotating around another point at a random axis, say a 45 degrees along the y axis (think of an electron around a nucleus). I know how to rotate using the transform matrix along the X, Y and Z axis, but not an arbitrary (45 degree) axis. Eventually after some research I found a suggestion: Rotate the point by -45 degrees around the Z so that it is aligned. Then rotate by some increment along the Y axis, then rotate it back +45 degrees for every frame tick. While this certainly worked, I felt that it seemed to be more work then needed (too many method calls, math, etc) and would probably be pretty slow at runtime with many points to deal with. I thought maybe it was possible to combine all the rotation matrixes involve into 1 rotation matrix and use that as a single operation. Something like: [ cos(-45) -sin(-45) 0] [ sin(-45) cos(-45) 0] rotate by -45 along Z [ 0 0 1] multiply by [ cos(2) 0 -sin(2)] [ 0 1 0 ] rotate by 2 degrees (my increment) along Y [ sin(2) 0 cos(2)] then multiply that result by (in that order) [ cos(45) -sin(45) 0] [ sin(45) cos(45) 0] rotate by 45 along Z [ 0 0 1] I get 1 mess of a matrix of numbers (since I was working with unknowns and 2 angles), but I felt like it should work. It did not and I found a solution on wiki using a different matirx, but that is something else. I'm not sure if maybe I made an error in multiplying, but my question is: this is actually a viable way to solve the problem, to take all the separate transformations, combine them via multiplying, then use that or not?

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  • How to convert a Bazaar repository to GIT repository?

    - by Naruto Uzumaki
    We have a large bazaar repository and we want to convert it to a git repository. The bazaar repository contains the folders of each of the interns. Any documentation/code prepared by interns is committed in their directory so there are a huge number of commits. What steps should be performed to securely convert the bazaar repository to a git repository so that we do not lose any commit information. We firstly need to create a backup of the existing bazaar repository and then convert it. Edit: I followed this link: http://librelist.com/browser//cville/2010/2/9/migrate-repository-bzr-to-git/ It's working fine on my system with Ubuntu. But when I try to run it on the actual server it gives me EOF error and crashes Starting export of 1036 revisions ... fatal: EOF in data (1825 bytes remaining) fast-import: dumping crash report to .git/fast_import_crash_11804 Edit 2: I also tried it on a new CentOS system and received the following error fatal: ambiguous argument 'HEAD': unknown revision or path not in the working tree. Use '--' to separate paths from revisions

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  • Push-Based Events in a Services Oriented Architecture

    - by Colin Morelli
    I have come to a point, in building a services oriented architecture (on top of Thrift), that I need to expose events and allow listeners. My initial thought was, "create an EventService" to handle publishing and subscribing to events. That EventService can use whatever implementation it desires to actually distribute the events. My client automatically round-robins service requests to available service hosts which are determined using Zookeeper-based service discovery. So, I'd probably use JMS inside of EventService mainly for the purpose of persisting messages (in the event that a service host for EventService goes down before it can distribute the message to all of the available listeners). When I started considering this, I began looking into the differences between Queues and Topics. Topics unfortunately won't work for me, because (at least for now), all listeners must receive the message (even if they were down at the time the event was pushed, or hadn't made a subscription yet because they haven't completed startup (during deployment, for example) - messages should be queued until the service is available). However, I don't want EventService to be responsible for handling all of the events. I don't think it should have the code to react to events inside of it. Each of the services should do what it needs with a given event. This would indicate that each service would need a JMS connection, which questions the value of having EventService at all (as the services could individually publish and subscribe to JMS directly). However, it also couples all of the services to JMS (when I'd rather that there be a single service that's responsible for determining how to distribute events). What I had thought was to publish an event to EventService, which pulls a configuration of listeners from some configuration source (database, flat file, irrelevant for now). It replicates the message and pushes each one back into a queue with information specific to that listener (so, if there are 3 listeners, 1 event would become 3 events in JMS). Then, another thread in EventService (which is replicated, running on multiple hots) would be pulling from the queue, attempting to make the service call to the "listener", and returning the message to the queue (if the service is down), or discarding the message (if the listener completed successfully). tl;dr If I have an EventService that is responsible for receiving events and delegating service calls to "event listeners," (which are really just endpoints on other services), how should it know how to craft the service call? Should I create a generic "Event" object that is shared among all services? Then, the EventService can just construct this object and pass it to the service call. Or is there a better answer to this problem entirely?

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  • Software development process for a part time University project for 1 developer?

    - by Pricey
    I will be doing a part time University project soon and the time frame for it is around 8 months with approximately 10-15 hours a week spent working on it, with a review by a tutor each quarter. My question is what software development process would you recommend using when the course requires you to work on your own in order to manage yourself as well as the project? I wanted to use a weekly or bi-weekly iterative approach to my work but a lot of the processes seem tailored to teams of people. I am looking at XP (Extreme Programming) OR Scrum as something that is less than the norm for University work but again Scrum I don't know a lot about yet, and a question I have is; can you say you are doing XP without pair-programming? because my tutor seems to think that I have to stick to all the practices otherwise I can't do it (nevermind if I am working alone). We can have external user input as well but due to the small timescales with part time work it may be more beneficial for myself to be the user as well, which is not what I prefer considering how I can get lost in the design.

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  • Does anyone prefer proportional fonts?

    - by Jason Baker
    I was reading the wikipedia article on programming style and noticed something in an argument against vertically aligned code: Reliance on mono-spaced font; tabular formatting assumes that the editor uses a fixed-width font. Most modern code editors support proportional fonts, and the programmer may prefer to use a proportional font for readability. To be honest, I don't think I've ever met a programmer who preferred a proportional font. Nor can I think of any really good reasons for using them. Why would someone prefer a proportional font?

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  • Client-Server connection response timeout issues

    - by Srikar
    User creates a folder in client and in the client-side code I hit an API to the server to make this persistent for that user. But in some cases, my server is so busy that the request timesout. The server has executed my request but timedout before sending a response back to client. The timeout set is 10 seconds in client. At this point the client thinks that server has not executed its request (of creating a folder) and ends up sending it again. Now I have 2 folders on the server but the user has created only 1 folder in the client. How to prevent this? One of the ways to solve this is to use a unique ID with each new request. So the ID acts as a distinguisher between old and new requests from client. But this leads to storing these IDs on my server and do a lookup for each API call which I want to avoid. Other way is to increase the timeout duration. But I dont want to change this from 10 seconds. Something tells me that there are better solutions. I have posted this question in stackoverflow but I think its better suited here. UPDATE: I will make my problem even more explicit. The client is a webbrowser and the server is running nginx+django+mysql (standard stack). The user creates a folder in webbrowser. As a result I need to hit a server API. The API call responds back, thereby client knows API call was success. This is normal scenario. Sometimes though, server successfully completes the API request but the client-side (webbrowser) connection timesout before server can respond back. The client has no clue at this point. The user thinks the request was a fail & clicks again. This time it was a success but when the UI refreshes he sees 2 folders. I want to remedy this situation.

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  • How to keep background requests in sequence

    - by Jason Lewis
    I'm faced with implementing interfaces for some rather archaic systems, for handling online deposits to stored value accounts (think campus card accounts for students). Here's my dilemma: stage 1 of the process involves passing the user off to a thrid-party site for the credit card transaction, like old-school PayPal. Step two involves using a proprietary protocol for communicating with a legacy system for conducting the actual deposit. Step two requires that each transaction have a unique sequence number, and that the requests' seqnums are in order. Since we're logging each transaction in Postgres, my first thought was to take a number from a sequence in the DB, guaranteeing uniqueness. But since we're dealing with web requests that might come in near-simultaneously, and since latency with the return from the off-ste payment processor is beyond our control, there's always the chance for a race condition in the order of requests passed back to the proprietary system, and if the seqnums are out of order, the request fails silently (brilliant, right?). I thought about enqueuing the requests in Redis and using Resque workers to process them (single worker, single process, so they are processed in order), but we need to be able to give the user feedback as to whether the transaction was processed successfully, so this seems less feasible to me. I've tried to make this application handle concurrency well (as much as possible for a Ruby on Rails app), but now we're in a situation where we have to interact with a system that is designed to be single process, single threaded, and sequential. If it at least gave an "out of order" error, I could just increment (or take the next value off the sequence), but it's designed to fail silently in the event of ANY error. We are handling timeouts in a way that blocks on I/O, but since the application uses multiple workers (Unicorn), that's no guarantee. Any ideas/suggestions would be appreciated.

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  • Web application deployment and Dependencies

    - by Reith
    I have a free software web application that using other free software scripts for appearance. I have trouble to decide whether should I copy source code of used scripts to my project main repository or list them as dependencies and ask user to install them himself? Since some of scripts solving browser compatibilities issues and I'm not a good web designer (i hate to check my web site on IE to see compatibility) using the newest version of scripts is preferable and second solution works here. But it has problem with scripts aren't backward-compatible with versions I've used them for development. Maybe another method is well-known for this issues that I don't know them.

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  • KISS principle applied to programming language design?

    - by Giorgio
    KISS ("keep it simple stupid", see e.g. here) is an important principle in software development, even though it apparently originated in engineering. Citing from the wikipedia article: The principle is best exemplified by the story of Johnson handing a team of design engineers a handful of tools, with the challenge that the jet aircraft they were designing must be repairable by an average mechanic in the field under combat conditions with only these tools. Hence, the 'stupid' refers to the relationship between the way things break and the sophistication available to fix them. If I wanted to apply this to the field of software development I would replace "jet aircraft" with "piece of software", "average mechanic" with "average developer" and "under combat conditions" with "under the expected software development / maintenance conditions" (deadlines, time constraints, meetings / interruptions, available tools, and so on). So it is a commonly accepted idea that one should try to keep a piece of software simple stupid so that it easy to work on it later. But can the KISS principle be applied also to programming language design? Do you know of any programming languages that have been designed specifically with this principle in mind, i.e. to "allow an average programmer under average working conditions to write and maintain as much code as possible with the least cognitive effort"? If you cite any specific language it would be great if you could add a link to some document in which this intent is clearly expressed by the language designers. In any case, I would be interested to learn about the designers' (documented) intentions rather than your personal opinion about a particular programming language.

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  • Does TDD's "Obvious Implementation" mean code first, test after?

    - by natasky
    My friend and I are relatively new TDD and have a dispute about the "Obvious Implementation" technique (from "TDD By Example" by Kent Beck). My friend says it means that if the implementation is obvious, you should go ahead and write it - before any test for that new behavior. And indeed the book says: How do you implement simple operations? Just implement them. Also: Sometimes you are sure you know how to implement an operation. Go ahead. I think what the author means is you should test first, and then "just implement" it - as opposed to the "Fake It ('Till You Make It)" and other techniques, which require smaller steps in the implementation stage. Also after these quotes the author talks about getting "red bars" (failing tests) when doing "Obvious Implementation" - how can you get a red bar without a test?. Yet I couldn't find any quote from the book saying "obvious" still means test first. What do you think? Should we test first or after when the implementation is "obvious" (according to TDD, of course)? Do you know a book or blog post saying just that?

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  • Nested entities in Google App Engine. Do I do it right?

    - by Aleksandr Makov
    Trying to make most of the GAE Datastore entities concept, but some doubts drill my head. Say I have the model: class User(ndb.Model): email = ndb.StringProperty(indexed=True) password = ndb.StringProperty(indexed=False) first_name = ndb.StringProperty(indexed=False) last_name = ndb.StringProperty(indexed=False) created_at = ndb.DateTimeProperty(auto_now_add=True) @classmethod def key(cls, email): return ndb.Key(User, email) @classmethod def Add(cls, email, password, first_name, last_name): user = User(parent=cls.key(email), email=email, password=password, first_name=first_name, last_name=last_name) user.put() UserLogin.Record(email) class UserLogin(ndb.Model): time = ndb.DateTimeProperty(auto_now_add=True) @classmethod def Record(cls, user_email): login = UserLogin(parent=User.key(user_email)) login.put() And I need to keep track of times of successful login operations. Each time user logs in, an UserLogin.Record() method will be executed. Now the question — do I make it right? Thanks. EDIT 2 Ok, used the typed arguments, but then it raised this: Expected Key instance, got User(key=Key('User', 5418393301680128), created_at=datetime.datetime(2013, 6, 27, 10, 12, 25, 479928), email=u'[email protected]', first_name=u'First', last_name=u'Last', password=u'password'). It's clear to understand, but I don't get why the docs are misleading? They implicitly propose to use: # Set Employee as Address entity's parent directly... address = Address(parent=employee) But Model expects key. And what's worse the parent=user.key() swears that key() isn't callable. And I found out the user.key works. EDIT 1 After reading the example form the docs and trying to replicate it — I got type error: TypeError('Model constructor takes no positional arguments.'). This is the exacto code used: user = User('[email protected]', 'password', 'First', 'Last') user.put() stamp = UserLogin(parent=user) stamp.put() I understand that Model was given the wrong argument, BUT why it's in the docs?

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  • Is there a precedent for the license on a compiler restricting the kind of development you can use it for?

    - by Jim McKeeth
    It was recently let slip that the new EULA for Delphi XE3 will prohibit Client Server development with the Professional edition without the additional purchase of a Client Server license pack. This is not to say the Professional version will lack the features, but the license will specifically prohibit the developer from using the compiler for a specific class of development, even with 3rd party or home grown solutions. So my question is if there is a precedent of a compiler or similar creative tool prohibiting the class of work you can use it for. Specifically a commercially licensed "professional" tool like Delphi XE3. Also, would such a restriction be legally enforceable? I know there have been educational edition or starter edition tools in the past that have restricted their use for commercial purposes, but those were not sold as "professional" tools. Also I know that a lot of computing software and equipment will have a disclaimer that it is not for use in "life support equipment" or "nuclear power" but that is more of avoiding liability than prohibiting activity. Seems like I recall Microsoft putting a restriction in FrontPage that you couldn't use it to create a web site that reflected poorly on Microsoft, but they pulled that restriction before it could be tested legally.

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