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• Maven webapp with Eclipse and WTP plugin deploy files in stranges ways in Tomcat

  - by hokkos

  Hi, I use Eclipse J2EE 3.5 with Maven and tomcat. To deploy my maven webapp with WTP I added a Dynamic Web Module facet and changed the "org.eclipse.wst.common.component" file of the project because the webapp is not in a WebContent directory, here is the content of the file: <?xml version="1.0" encoding="UTF-8"?> <project-modules id="moduleCoreId" project-version="1.5.0"> <wb-module deploy-name="tkey-ca-web"> <wb-resource deploy-path="/" source-path="/src/main/webapp"/> <wb-resource deploy-path="/WEB-INF/classes" source-path="/src/main/java"/> <wb-resource deploy-path="/WEB-INF/classes" source-path="/src/main/resources"/> <property name="context-root" value="toto"/> <property name="java-output-path" value="/toto/target/classes"/> </wb-module> </project-modules> But it never deploy the content correctly, in "workspace.metadata.plugins\org.eclipse.wst.server.core\tmp1\wtpwebapps\toto\" the directory structure is correct with WEB-INF and META-INF but empty, the jsp, html, css files are in "workspace.metadata.plugins\org.eclipse.wst.server.core\tmp1\wtpwebapps\toto\WEB-INF\classes\" with another WEB-INF and META-INF structure but with the files. I don't understand this at all, thanks.

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• F# passing an operator with arguments to a function

  - by dan

  Can you pass in an operation like "divide by 2" or "subtract 1" using just a partially applied operator, where "add 1" looks like this: List.map ((+) 1) [1..5];; //equals [2..6] // instead of having to write: List.map (fun x-> x+1) [1..5] What's happening is 1 is being applied to (+) as it's first argument, and the list item is being applied as the second argument. For addition and multiplication, this argument ordering doesn't matter. Suppose I want to subtract 1 from every element (this will probably be a common beginners mistake): List.map ((-) 1) [1..5];; //equals [0 .. -4], the opposite of what we wanted 1 is applied to the (-) as its first argument, so instead of (list_item - 1), I get (1 - list_item). I can rewrite it as adding negative one instead of subtracting positive one: List.map ((+) -1) [1..5];; List.map (fun x -> x-1) [1..5];; // this works too I'm looking for a more expressive way to write it, something like ((-) _ 1), where _ denotes a placeholder, like in the Arc language. This would cause 1 to be the second argument to -, so in List.map, it would evaluate to list_item - 1. So if you wanted to map divide by 2 to the list, you could write: List.map ((/) _ 2) [2;4;6] //not real syntax, but would equal [1;2;3] List.map (fun x -> x/2) [2;4;6] //real syntax equivalent of the above Can this be done or do I have to use (fun x -> x/2)? It seems that the closest we can get to the placeholder syntax is to use a lambda with a named argument.

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• How do I pass a const reference in C#?

  - by Maciek

  In C++, passing const references is a common practice - for instance : #include <iostream> using namespace std; class X { public : X() {m_x = 0; } X(const int & x) {m_x = x; } X(const X & other) { *this = other; } X & operator = (const X & other) { m_x = other.m_x; return *this; } void print() { cout << m_x << endl; } private : int m_x; }; void main() { X x1(5); X x2(4); X x3(x2); x2 = x1; x1.print(); x2.print(); x3.print(); } This very simple example illustrates how it's done - pretty much. However I've noticed that in C# this doesn't seem to be the case. Do I have to pass const references in C# ? what do I need the "ref" keyword for? Please note that I know and understand what C# reference and value types are.

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• Vertical-Align: A Full Explanation

  - by Livvy Jeffs

  I've been struggling with vertical alignments, a seemingly simple enough process that has a lot of idiosyncrasies throughout different languages and element types. I've done a lot of reading through stackexchange and can't seem to find a common thread of understanding. Here are the rules that I have been able to gather: 1) Vertical-align does not work in <\div>s, you have to set div {display: table-cell; vertical-align: middle} This seems like a big hassle, especially since table-cells override the height limitation even when overflow is set to hidden and expands to fit content, which means the vertical "center" is variable. I just read some source-code from Pinterest where button {vertical-align: middle}, but no other vertical-align commands seem to work. It seems as if button is by default aligned in the middle. Can someone provide a clear explanation for the vertical-align attribute? What html elements respond to vertical-align? Which html elements have default vertical-align attributes? Which html elements have non-overridable vertical-align attributes? And any clues as to understanding the idiosyncracies would help as well! Thanks in advance!

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• Matlab-Bisection-Newton-Secant , finding roots?

  - by i z

  Hello and thanks in advance for your possible help ! Here's my problem: I have 2 functions f1(x)=14.*x*exp(x-2)-12.*exp(x-2)-7.*x.^3+20.*x.^2-26.*x+12 f2(x)=54.*x.^6+45.*x.^5-102.*x.^4-69.*x.^3+35.*x.^2+16.*x-4 Make the graph for those 2, the first one in [0,3] and the 2nd one in [-2,2]. Find the 3 roots with accuracy of 6 decimal digits using a) bisection ,b) newton,c)secant.For each root find the number of iterations that have been made. For Newton-Raphson, find which roots have quadratic congruence and which don't. What is the main common thing that roots with no quadratic congruence (Newton's method)? Why ? Excuse me if i ask silly things, but i'm asked to do this with no Matlab courses and I'm trying to learn it myself. There are many issues i have with this exercise . Questions : 1.I only see 2 roots in the graph for the f1 function and 4-5 (?) roots for the function f2 and not 3 roots as the exercise says. Here's the 2 graphs : http://postimage.org/image/cltihi9kh/ http://postimage.org/image/gsn4sg97f/ Am i wrong ? Do both have only 3 roots in [0,3] and [-2,2] ? Concerning the Newton's method , how am i supposed to check out which roots have quadratic congruence and which not??? Accuracy means tolerance e=10^(-6), right ?

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• Duck type testing with C# 4 for dynamic objects.

  - by Tracker1

  I'm wanting to have a simple duck typing example in C# using dynamic objects. It would seem to me, that a dynamic object should have HasValue/HasProperty/HasMethod methods with a single string parameter for the name of the value, property, or method you are looking for before trying to run against it. I'm trying to avoid try/catch blocks, and deeper reflection if possible. It just seems to be a common practice for duck typing in dynamic languages (JS, Ruby, Python etc.) that is to test for a property/method before trying to use it, then falling back to a default, or throwing a controlled exception. The example below is basically what I want to accomplish. If the methods described above don't exist, does anyone have premade extension methods for dynamic that will do this? Example: In JavaScript I can test for a method on an object fairly easily. //JavaScript function quack(duck) { if (duck && typeof duck.quack === "function") { return duck.quack(); } return null; //nothing to return, not a duck } How would I do the same in C#? //C# 4 dynamic Quack(dynamic duck) { //how do I test that the duck is not null, //and has a quack method? //if it doesn't quack, return null }

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• HTML & CSS Horizontal menu with items on left & right

  - by Fabian Vilers

  Hi all, I'm building an horizontal menu in html+css. The current result is fine, except I want to have some items on the left, and others on the right. I couldn't find usefull result on Google with such common keywords so I'm asking on SO. Here's my code so far: #menu { background-color: #383838; height: 65px; margin-bottom: 20px; } #menu ul li { float: left; } <div id="menu"> <ul> <li>Link 1</li> <li>Link 2</li> <li>Link 3</li> </ul> </div> I'd like to have Link 3 on the right, so the space between link 2 and 3 should be filled at maximum. I don't want a filler <li> tag, but instead apply a class to the last <li> on the left, or the first <li> on the right. Don't want to adjust the width as I've a :hover background color changing effet on the links. I suppose margin or padding should do the trick but I can't manage to find how. Any clue? Thanks in advance, Fabian

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• In SQL, if we rename INNER JOIN as INTERSECT JOIN, LEFT OUTER JOIN as LEFT UNION JOIN, and FULL OUTE

  - by Jian Lin

  In SQL, the name Join gives an idea of "merging" or a sense of "union", making something bigger. But in fact, as in the other post http://stackoverflow.com/questions/2706051/in-sql-a-join-is-actually-an-intersection-and-it-is-also-a-linkage-or-a-sidew it turns out that a Join (Inner Join) is actually an Intersection. So if we think of Join = Inner Join = Intersect Join Left Outer Join = Left Union Join Full Outer Join = Full Union Join = Union Join then we always get a feel of what's happening, and maybe never forget what they are easily. In a way, we can think of Intersect as "making it less", therefore it is excluding something. That's why the name "Join" won't go with the idea of "Intersect". But in fact, both Intersect and Union can be thought of as: Union: bringing something together and merge them unconditionally. Intersect: bringing something together and merge them based on some condition. so the "bringing something together" is probably what "Join" is all about. It is like, Intersection is a "half glass of water" -- we can thinking of it as "excluding something" or as "bringing something together and accepting the common ones". So if the word "Intersect Join" is used, maybe a clear picture is there, and "Union Join" can be a clear picture too. Maybe the word "Inner Join" and "Outer Join" is very clear when we use SQL a lot. Somehow, the word "Outer" tends to give a feeling that it is "outside" and excluding something rather than a "Union".

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• Viewstate in a .ashx Handler?

  - by Matt Dawdy

  I've got a handler (list.ashx for example) that has a method that retrieves a large dataset, then grabs only the records that will be shown on any given "page" of data. We are allowing the users to do sorting on these results. So, on any given page run, I will be retrieving a dataset that I just got a few seconds/minutes ago, but reordering them, or showing the next page of data, etc. My point is that my dataset really hasn't changed. Normally, the dataset would be stuck into the viewstate of a page, but since I'm using a handler, I don't have that convenience. At least I don't think so. So, what is a common way to store the viewstate associated with a current user's given page when using a handler? Is there a way to take the dataset, encode it somehow and send that back to the user, and then on the next call, pass it back and then rehydrate a dataset from those bits? I don't think Session would be a good place to store it since we might have 1000 users all viewing different datasets of different data, and that could bring the server to its knees. At least I think so. Does anyone have any experience with this kind of situation, and can you give me any advice?

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• Using of Templated Helpers in MVC 2.0 : How can use the name of the property that I'm rendering insi

  - by Andrey Tagaew

  Hi. I'm reviewing new features of ASP.NET MVC 2.0. During the review i found really interesting using Templated Helpers. As they described it, the primary reason of using them is to provide common way of how some datatypes should be rendered. Now i want to use this way in my project for DateTime datatype My project was written for the MVC 1.0 so generating of editbox is looking like this: <%= Html.TextBox("BirthDate", Model.BirthDate, new { maxlength = 10, size = 10, @class = "BirthDate-date" })%> <script type="text/javascript"> $(document).ready(function() { $(".BirthDate-date").datepicker({ showOn: 'button', buttonImage: '<%=Url.Content("~/images/i_calendar.gif") %>', buttonImageOnly: true }); }); </script> Now i want to use Template Helper, so i want to have above code once i type next sentence: <%=Html.EditorFor(f=>f.BirthDate) %> According to the manual I create DataTime.ascx partial view inside Shared/EditorTemplates folder. I put there above code and stacked with the problem. How can i pass the name of the property that I'm rendering with template helper? As you can see from my example, i really need it, since I'm using the name of the property to specify data value and parameter name that will be send during the POST requsest. Also, I'm using it to generate class name for JS calendar building. I tried to remove my partial class for template helper and made MVC to generate its default behavior. Here what it generated for me: <input type="text" value="04/29/2010" name="LoanApplicationDays" id="LoanApplicationDays" class="text-box single-line"> As you can see, it used the name of the property for "name" and "id" attributes. This example let me to presume that Template Helper knows about the name of the property. So, there should be some way of how to use it in custom implementation. Thanks for your help!

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• Specific programming text editor for simple open/close editing

  - by queen3

  I'm looking for very specific text editor: Closes on ESC, no project management or tabs Syntax highlighting - preferably with color themes (e.g. can apply different color themes without changing C# coloring definition) or, at least, can load/save themes; support for C/C#/XML/HTML/JavaScript/etc - common MS/.NET world - out of box Configurable keys, or: Shift-Tab shifts blocks XML/HTML auto-completion support - well, optional I use synplus plugin for Total Commander currently, but it has few drawbacks (e.g. crashes sometimes ;-), no auto-completion, etc). Basically I want fast Visual-Studio-like editor that I open, do edits, and then close using ESC. I remember I tried Notepad++, etc - most of them open files in tabs, don't close on ESC... - that is, behave like IDE. At least I've just downloaded Notepad++, it doesn't close on ESC even if I setup keybindings to do so. Autocompletion is optional (though it is to be simple as just tags completion), what I really look for is closing on ESC, not getting in the way with all the tabs and IDE-like, and good coloring. Plus shift-tab is must have for blocks manipulation. Update: any open-source one that I can easily tweak to close on ESC? ;-) Seems like ESC (and reasonable color highlighting) is the core requirement. I've just tried many editors - Programmer's Notepad, E, Crimson, etc - I can't set any of them to close on ESC. Any external tool to close selected program on ESC? ;-) UPDATE: Hm, found an awesome utility for my latest thought: http://www.autohotkey.com. Easy to setup to close any window on ESC (as well as many other tricks). Seems like the most tough requirements is gone - I can use ANY text editor ;-)

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• Resizing video best practices (frame size)

  - by undefined

  I have read the following which is from Best Practices for Encoding Video with the VP6 Codec on the Adobe website here - http://www.adobe.com/devnet/flash/articles/encoding_video_print.html. It is talking about common video ratios (320x240, 640x480) Although these ratios are standard, and should be used to avoid distorting the video, the size of the encoded video is not set in stone. The original web video sizes used heights and widths that were evenly divisible by 16. This was mandatory for many early codecs. Although this is not necessary for modern codecs, you should stick to even heights and widths. What do they mean by 'even heights and widths'. I am thinking about encoding my video at 400x300 to make it slightly bigger, this is still 4x3 format but should I just stick at 320x240 and resize it on the screen? Clearly there are benefits to this in terms of storage size and delivery costs. In some places on my site I want to show the video at 400x300 but in others I want it to play full screen so this is why I am wondering if a larger original size (400x300) will give better results when blown up. Any thoughts?

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• What is the best way to attach extenstion methods to static classes rather than to instances of a cl

  - by John Gietzen

  If I have a method for calculating the greatest common divisor of two integers as: public static int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); } What would be the best way to attach that to the System.Math class? Here are the three ways I have come up with: public static int GCD(this int a, int b) { return b == 0 ? a : b.GCD(a % b); } // Lame... var gcd = a.GCD(b); and: public static class RationalMath { public static int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); } } // Lame... var gcd = RationalMath.GCD(a, b); and: public static int GCD(this Type math, int a, int b) { return b == 0 ? a : typeof(Math).GCD(b, a % b); } // Neat? var gcd = typeof(Math).GCD(a, b); The desired syntax is Math.GCD since that is the standard for all mathematical functions. Any suggestions? What should I do to get the desired syntax?

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• Abstract Methods in "Product" - Factory Method C#

  - by Regina Foo

  I have a simple class library (COM+ service) written in C# to consume 5 web services: Add, Minus, Divide, Multiply and Compare. I've created the abstract product and abstract factory classes. The abstract product named WS's code: public abstract class WS { public abstract double Calculate(double a, double b); public abstract string Compare(double a, double b); } As you see, when one of the subclasses inherits WS, both methods must be overridden which might not be useful in some subclasses. E.g. Compare doesn't need Calculate() method. To instantiate a new CompareWS object, the client class will call the CreateWS() method which returns a WS object type. public class CompareWSFactory : WSFactory { public override WS CreateWS() { return new CompareWS(); } } But if Compare() is not defined as abstract in WS, the Compare() method cannot be invoked. This is only an example with two methods, but what if there are more methods? Is it stupid to define all the methods as abstract in the WS class? My question is: I want to define abstract methods that are common to all subclasses of WS whereas when the factory creates a WS object type, all the methods of the subclasses can be invoked (overridden methods of WS and also the methods in subclasses). How should I do this?

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• How to Manage project in this scenario

  - by vijay.shad

  Hi All, I am working on a web application which has got good amount of static or pre-login pages. These pages can have some simple forms as well where we would like to capture the visitor's details. Post login, I have got my main application. I am confused about the development and deployment architecture of my application. Post login part of my application has a release cycle of 1-2 months while pre-login pages are to be updated on a weekly basis. It is difficult to make a release of pre-login pages as the overall war also contains post-login application & which sometimes is not release ready. Currently, I have got both these parts bundled in the single war project. Please help me by letting me know the best practices whereby I can achieve following: Manage the releases of these two parts independently. I am using Maven. So is there a way I can share the resources, such as CSS, images etc between these two parts. Header and footer of my application is going to be same on pre-login & post-login pages. I was thinking of deploying these apps as two war files in my tomcat container. But then how will I manage the common resources like Css, images etc. Rgds Vijay

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• Am I correctly extracting JPEG binary data from this mysqldump?

  - by Glenn

  I have a very old .sql backup of a vbulletin site that I ran around 8 years ago. I am trying to see the file attachments that are stored in the DB. The script below extracts them all and is verified to be JPEG by hex dumping and checking the SOI (start of image) and EOI (end of image) bytes (FFD8 and FFD9, respectively) according to the JPEG wiki page. But when I try to open them with evince, I get this message "Error interpreting JPEG image file (JPEG datastream contains no image)" What could be going on here? Some background info: sqldump is around 8 years old vbulletin 2.x was the software that stored the info most likely php 4 was used most likely mysql 4.0, possibly even 3.x the column datatype these attachments are stored in is mediumtext My Python 3.1 script: #!/usr/bin/env python3.1 import re trim_l = re.compile(b"""^INSERT INTO attachment VALUES\('\d+', '\d+', '\d+', '(.+)""") trim_r = re.compile(b"""(.+)', '\d+', '\d+'\);$""") extractor = re.compile(b"""^(.*(?:\.jpe?g|\.gif|\.bmp))', '(.+)$""") with open('attachments.sql', 'rb') as fh: for line in fh: data = trim_l.findall(line)[0] data = trim_r.findall(data)[0] data = extractor.findall(data) if data: name, data = data[0] try: filename = 'files/%s' % str(name, 'UTF-8') ah = open(filename, 'wb') ah.write(data) except UnicodeDecodeError: continue finally: ah.close() fh.close() update The JPEG wiki page says FF bytes are section markers, with the next byte indicating the section type. I see some that are not listed in the wiki page (specifically, I see a lot of 5C bytes, so FF5C). But the list is of "common markers" so I'm trying to find a more complete list. Any guidance here would also be appreciated.

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• Java File IO Compendium

  - by Warren Taylor

  I've worked in and around Java for nigh on a decade, but have managed to ever avoid doing serious work with files. Mostly I've written database driven applications, but occasionally, even those require some file io. Since I do it so rarely, I end up googling around for quite some time to figure out the exact incantation that Java requires to read a file into a byte[], char[], String or whatever I need at the time. For a 'once and for all' list, I'd like to see all of the usual ways to get data from a file into Java, or vice versa. There will be a fair bit of overlap, but the point is to define all of the subtle different variants that are out there. For example: Read/Write a text file from/to a single String. Read a text file line by line. Read/Write a binary file from/to a single byte[]. Read a binary file into a byte[] of size x, one chunk at a time. The goal is to show concise ways to do each of these. Samples do not need to handle missing files or other errors, as that is generally domain specific. Feel free to suggest more IO tasks that are somewhat common and I have neglected to mention.

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• My simple program runs on Android emulator, but not on my Nexus One

  - by noisesolo

  To clarify, I have no trouble getting the Nexus One connected in developer's mode. I can actually get Eclipse to "run" my program on my Nexus One. However, my Nexus One simply gets stuck in a reboot loop. I've also created an .apk file and put it onto my Nexus One, installing it with apkInstaller. However, it crashed while installing. I see my app on my phone, but I'm kind of afraid to run it. I am not doing anything fancy in my program; all it does is generate text by shuffling a couple arrays of strings together. It uses a bunch of text views, two buttons, and a spinner. I have only edited the main source file, the strings XML file, and the layout XML file, nothing else. It's a 2.1-update1 program and it runs fine on the emulator. Does anyone have any idea what's going on? I'm using Windows 7 (32 bit) and my Nexus One is running Cyanogen 5.0.7.1. I'm pretty sure it's my code that's causing the problem. Now I'm just wondering if there are any common mistakes that would lead my app to run on the emulator but not on my device. Thanks in advance.

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• Adding StyleSheets Programmatically in Asp.Net

  - by Braveyard

  I want to add StyleSheets programmatically in the head section but one of the examples I saw seemed to need to many lines of code to add just one style sheet even though I may need a lot: Example Code: HtmlLink css = new HtmlLink(); css.Href = "css/fancyforms.css"; css.Attributes["rel"] = "stylesheet"; css.Attributes["type"] = "text/css"; css.Attributes["media"] = "all"; Page.Header.Controls.Add(css); I also use Page.Header.RenderControl() method but it didn't work either. Object null something error was thrown. I also used Page.Header.InnerHtml and InnerText += "<link .... "/> things but they threw the Literal error which is I think common error. I used this code : List<Literal> cssFiles = new List<Literal>(); cssFiles.Add(new Literal() { Text = @"<link href=""" + ResolveUrl("~/Resources/Styles/MainMaster/MainDesign.css") + @""" type=""text/css"" rel=""stylesheet"" />" }); cssFiles.Add(new Literal() { Text = @"<link href=""" + ResolveUrl("~/Resources/Styles/MainMaster/MainLayout.css") + @""" type=""text/css"" rel=""stylesheet"" />" }); AddStyleRange(cssFiles); private void AddStyleRange(List<Literal> cssFiles) { foreach (Literal item in cssFiles) { this.Header.Controls.Add(item); } } It worked at first but when I change the pages it stopped working. I am using Master Page and I am writing these codes on Master.cs file and also some people recommended to use this.Header instead of Page.Header but when I built it throws an error which says I cannot declare that like this. It shouldn't be that hard to add many styles. It is getting complicated.

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• Need Advice on designing ATL inproc Server (dll) that serves as both a soure and a sink of events.

  - by Andrew

  Hi, I need to design an ATL inproc server that besides exposing methods and properties, also can fire events (source) and serve as a sink for a third party COM control that fires events. I would assume that this is a fairly common requirement. I can also foresee several "gotchas" that I would like to read up on before commencing the design. My questions/concerns are: Can someone point me to an example? Which threading model to use? Should I have a seperate COM object for the sink? Should I, and how do I, protect certain memory. For example, my server will receive data from the third party control. It will save this, and in some cases, fire an event to interested clients. The interested clients will request the data through a standard method or property. I did try to research this myself. I can find many examples of COM servers that are soures, and some that are sinks, but never both. The only post I did find was this: http://www.generation-nt.com/us/atl-control-an-event-source-sink-help-9098542.html Which strongly advocates putting the sink on a seperate COM object. Any leads, tutorials or ideas would be much appreciated. Thanks, Andrew

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• DNS-Based Environment Determination

  - by zvolkov

  Found the following here. The questions is: where can I find more details on how exactly implement this on Windows? Any guide or how-to anybody? Or maybe you can provide your invaluable suggestions? Specifically, how do I make so that "all QA servers would first resolve entries in qa.example.com first and then if that lookup failed they would try example.com" (I'm a dev, not a DNS specialist, but our IT Support has refused to help on this:() Use DNS Based Environment Determination for your servers. Do this by initially splitting your top level domain into a number of sub domains depending on their function, and then creating DNS Service Names in each of the sub domains pointing to the relevant server for that service. Based on the list above we would then have: * clientdb.prod.example.com for Production * clientdb.perf.example.com for Performance Testing * clientdb.qa.example.com for QA * clientdb.dev.example.com for Development Servers then resolve entries in their relevant sub domain by function. That is, all QA servers would first resolve entries in qa.example.com first and then if that lookup failed they would try example.com. This allows you to have a single configuration entry for your client database hostname (clientdb) that would resolve correctly in all environments. This technique has the added advantage of still having global services defined in a common top level domain. Here's one related (but not equivalent) SO question: http://stackoverflow.com/questions/774490/dns-resolving-based-on-client-ip This seems to be related to Providing "split horizon" DNS service. Reading that, I see that I will probably need separate DNS Server for each environment. Is this true or does Windows support some form of "tagging" the records to be visible depending on the requestor's IP? Also, cross-posted on ServerFault

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• How do you deal with denormalization / secondary indexes in database sharding?

  - by Continuation

  Say I have a "message" table with 2 secondary indexes: "recipient_id" "sender_id" I want to shard the "message" table by "recipient_id". That way to retrieve all messages sent to a certain recipient I only need to query one shard. But at the same time, I want to be able to make a query that ask for all messages sent by a certain sender. Now I don't want to send that query to every single shard of the "message" table. One way to do this is to duplicate the data and have a "message_by_sender" table sharded by "sender_id". The problem with that approach is that every time a message has been sent, I need to insert the message into both "message" and "message_by_sender" tables. But what if after inserting into "message" the insertion into "message_by_sender" fail? In that case the message exists in "message" but not in "message_by_sender". How do I make sure that if a message exists in "message" then it also exists in "message_by_sender" without resorting to 2 phase commit? This must be a very common issue for anyone who shards their databases. How do you deal woth it?

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• PHP sessions causing Apache to hang indefinitely

  - by Kmaid

  The problem is that every so often a page that writes to a Session will cause apache to hang forever for a particular session. Once this error occurs for one user any further modifications to any session of any user will cause the website to hang for this user. This problem has been my sole focus for days. I have a development VPS running Windows 2003 and default latest version of XAMPP using the standard PHP session handler. The code in question actually runs on two other machines perfectly normally so although my common sense says it’s a web server configuration issue but at this point I am willing to try anything. On further investigation there are no errors in the Apache, PHP or System event log. Resources are abundant and there is no “AJAX shit storm” or more than a couple writes to a session per page. I have also implemented session_write_close() wherever possible to try and help elevate the problem. I have checked the session’s directory which is set to “C:\windows\Temp” and found that once a user enters this hanging phase that the corresponding session file is exclusively locked and the only way to resolve this is to stop Apache and wait a few moments for the files to become unlocked and delete them. I am not wondering if deletion is required. The Sessions themselves only contain 4 bits of information. ShoppingCartID, UserID, UserLevel and Refering URL and are alphanumerical with an occasional slash. My PHP.INI’s session section is configured like this: session.save_handler = files session.save_path = "C:\WINDOWS\Temp" session.use_cookies = 1 session.name = PHPSESSID session.auto_start = 0 session.cookie_lifetime = 0 session.cookie_path = / session.cookie_domain = session.cookie_httponly = session.serialize_handler = php session.gc_probability = 1 session.gc_divisor = 100 session.gc_maxlifetime = 1440 session.bug_compat_42 = 1 session.bug_compat_warn = 1 session.referer_check = session.entropy_length = 0 session.entropy_file = session.cache_limiter = nocache session.cache_expire = 180 session.use_trans_sid = 0 session.hash_function = 0 session.hash_bits_per_character = 4 I have tried everything I can think of and the whole problem is now a blur to me. Any ideas would be appreciated and thanks for your time reading this :)

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• How do I begin reading source code?

  - by anonnoir

  I understand the value of reading source code, and I am trying my best to read as much as I can. However, every time I try getting into a 'large' (i.e. complete) project of sorts, I am overwhelmed. For example, I use Anki a lot when revising languages. Also, I'm interested in getting to know how an audio player works (because I have some project ideas), hence quodlibet on Google Code. But whenever I open the source code folders for the above programs, there are just so many files that I don't know where or what to begin with. I think that I should start with files marked init.py but I can't see the logical structure of the programs, or what reasoning was applied when the original writer divided his modules the way he did. Hence, my questions: How/where should I begin reading source? Any general tips or ideas? How does a programmer keep in mind the overall structure and logic of the program, especially for large projects, and is it common not to document that structure? As an open source reader, must I look through all of the code and get a bird's eye view of the code and libraries, before even being able to proceed? Would an IDE like Eclipse SDK (with PyDev) help with code-reading? Thanks for the help; I really appreciate your helping me.

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• Interactive Web Collaboration Platform

  - by user1477586

  I am currently unsatisfied with most, if not all, web-based collaboration tools I've ever used. Examples of what I'm considering a "web-based collaboration tool" are TWiki, WebEx, etc. What I have in mind of developing is to develop my own. The target "market" is for software/hardware developers who will likely be working on separate projects linked by a common goal. Example: You work at a company who is designing a brand new printer. So, one man is working on the ink cartridge, another on the paper feed, one on the circuitry of the printer and one more is working on the drivers. What I would like to make (unless it already exists) is a website that, upon loading, presents the user with a web that has each project within it's own bubble, graphically. These bubbles would all be linked to the central bubble of "[Company Name]". Upon selecting an individual bubble the browser would focus and zoom in on that project bubble and expand more information (in bullets or with more affiliated bubbles) about subprojects, progress, setbacks, etc. Then, at a terminal "node" (i.e. a bubble with no sub-bubbles) a selection would then load a page with information relevant to that node. That's a lot of monologue. In short, I want to know how I might approach this. My background is with algorithmic use of Python and C++. I've never done interactive web design like this; though, I have gone through the W3C tutorials on HTML4/5. I'm willing to learn a new language I'm just wondering which language/set of languages seem(s) most appropriate for this project. Thanks, world, for imparting your knowledge to me. An example of what the start page might look like is:

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