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  • How to assign WPF resources to other resource tags

    - by Tom
    This is quite obscure, I may just be missing something extremely simple. Scenario 1 Lets say I create a gradient brush, like this in my <Window.Resources> section: <LinearGradientBrush x:Key="GridRowSelectedBackBrushGradient" StartPoint="0,0" EndPoint="0,1"> <GradientStop Color="#404040" Offset="0.0" /> <GradientStop Color="#404040" Offset="0.5" /> <GradientStop Color="#000000" Offset="0.6" /> <GradientStop Color="#000000" Offset="1.0" /> </LinearGradientBrush> Then much later on, I want to override the HighlightBrushKey for a DataGrid. I have basically done it like this (horrible); <LinearGradientBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" GradientStops="{Binding Source={StaticResource GridRowSelectedBackBrushGradient}, Path=GradientStops}" StartPoint="{Binding Source={StaticResource GridRowSelectedBackBrushGradient}, Path=StartPoint}" EndPoint="{Binding Source={StaticResource GridRowSelectedBackBrushGradient}, Path=EndPoint}" /> This is obviously not the most slick way of referencing a resource. I also came up with the following problem, which is almost identical. Scenario 2 Say I created two colors in my <Window.Resources> markup, like so: <SolidColorBrush x:Key="DataGridRowBackgroundBrush" Color="#EAF2FB" /> <SolidColorBrush x:Key="DataGridRowBackgroundAltBrush" Color="#FFFFFF" /> Then later on, I want to supply them in an Array, which feeds the ConverterParameter on a Binding so I can supply the custom Converter with my static resource instances: <Setter Property="Background"> <Setter.Value> <Binding RelativeSource="{RelativeSource Mode=Self}" Converter="{StaticResource BackgroundBrushConverter}"> <Binding.ConverterParameter> <x:Array Type="{x:Type Brush}"> <SolidColorBrush Color="{Binding Source={StaticResource DataGridRowBackgroundBrush}, Path=Color}" /> <SolidColorBrush Color="{Binding Source={StaticResource DataGridRowBackgroundAltBrush}, Path=Color}" /> </x:Array> </Binding.ConverterParameter> </Binding> </Setter.Value> </Setter> What I've done is attempt to rereference an existing resource, but in my efforts I've actually recreated the resource, and bound the properties so they match. Again, this is not ideal. Because I've now hit this problem at least twice, is there a better way? Thanks, Tom

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  • How to pass operators as parameters

    - by Rodion Ingles
    I have to load an array of doubles from a file, multiply each element by a value in a table (different values for different elements), do some work on it, invert the multiplication (that is, divide) and then save the data back to file. Currently I implement the multiplication and division process in two separate methods. Now there is some extra work behind the scenes but apart from the specific statements where the multiplication/division occurs, the rest of the code is identical. As you can imagine, with this approach you have to be very careful making any changes. The surrounding code is not trivial, so its either a case of manually editing each method or copying changes from one method to the other and remembering to change the * and / operators. After too many close calls I am fed up of this and would like to make a common function which implements the common logic and two wrapper functions which pass which operator to use as a parameter. My initial approach was to use function pointers: MultiplyData(double data) { TransformData(data, &(operator *)); } DivideData(double data) { TransformData(data, &(operator /)); } TransformData(double data, double (*func)(double op1, double op2)) { /* Do stuff here... */ } However, I can't pass the operators as pointers (is this because it is an operator on a native type?), so I tried to use function objects. Initially I thought that multiplies and divides functors in <functional> would be ideal: MultiplyData(double data) { std::multiplies<double> multFunct; TransformData(data, &multFunct); } DivideData(double data) { std::divides<double> divFunct; TransformData(data, &divFunct); } TransformData(double data, std::binary_function<double, double, double> *funct) { /* Do stuff here... */ } As you can see I was trying to use a base class pointer to pass the functor polymorphically. The problem is that std::binary_function does not declare an operator() member for the child classes to implement. Is there something I am missing, or is the solution to implement my own functor heirarchy (which really seems more trouble than it is worth)?

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  • using a Singleton to pass credentials in a multi-tenant application a code smell?

    - by Hans Gruber
    Currently working on a multi-tenant application that employs Shared DB/Shared Schema approach. IOW, we enforce tenant data segregation by defining a TenantID column on all tables. By convention, all SQL reads/writes must include a Where TenantID = '?' clause. Not an ideal solution, but hindsight is 20/20. Anyway, since virtually every page/workflow in our app must display tenant specific data, I made the (poor) decision at the project's outset to employ a Singleton to encapsulate the current user credentials (i.e. TenantID and UserID). My thinking at the time was that I didn't want to add a TenantID parameter to each and every method signature in my Data layer. Here's what the basic pseudo-code looks like: public class UserIdentity { public UserIdentity(int tenantID, int userID) { TenantID = tenantID; UserID = userID; } public int TenantID { get; private set; } public int UserID { get; private set; } } public class AuthenticationModule : IHttpModule { public void Init(HttpApplication context) { context.AuthenticateRequest += new EventHandler(context_AuthenticateRequest); } private void context_AuthenticateRequest(object sender, EventArgs e) { var userIdentity = _authenticationService.AuthenticateUser(sender); if (userIdentity == null) { //authentication failed, so redirect to login page, etc } else { //put the userIdentity into the HttpContext object so that //its only valid for the lifetime of a single request HttpContext.Current.Items["UserIdentity"] = userIdentity; } } } public static class CurrentUser { public static UserIdentity Instance { get { return HttpContext.Current.Items["UserIdentity"]; } } } public class WidgetRepository: IWidgetRepository{ public IEnumerable<Widget> ListWidgets(){ var tenantId = CurrentUser.Instance.TenantID; //call sproc with tenantId parameter } } As you can see, there are several code smells here. This is a singleton, so it's already not unit test friendly. On top of that you have a very tight-coupling between CurrentUser and the HttpContext object. By extension, this also means that I have a reference to System.Web in my Data layer (shudder). I want to pay down some technical debt this sprint by getting rid of this singleton for the reasons mentioned above. I have a few thoughts on what an better implementation might be, but if anyone has any guidance or lessons learned they could share, I would be much obliged.

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  • How does your team work together in a remote setup?

    - by Carl Rosenberger
    Hi, we are a distributed team working on the object database db4o. The way we work: We try to program in pairs only. We use Skype and VNC or SharedView to connect and work together. In our online Tuesday meeting every week (usually about 1 hour) we talk about the tasks done last week we create new pairs for the next week with a random generator so knowledge and friendship distribute evenly we set the priority for any new tasks or bugs that have come in each team picks the tasks it likes to do from the highest prioritized ones. From Tuesday to Wednesday we estimate tasks. We have a unit of work we call "Ideal Developer Session" (IDS), maybe 2 or 3 hours of working together as a pair. It's not perfectly well defined (because we know estimation always is inaccurate) but from our past shared experience we have a common sense of what an IDS is. If we can't estimate a task because it feels too long for a week we break it down into estimatable smaller tasks. During a short meeting on Wednesday we commit to a workload we feel is well doable in a week. We commit to complete. If a team runs out of committed tasks during the week, it can pick new ones from the prioritized queue we have in Jira. When we started working this way, some of us found that remote pair programming takes a lot of energy because you are so focussed. If you pair program for more than 5 or 6 hours per day, you get drained. On the other hand working like this has turned out to be very efficient. The knowledge about our codebase is evenly distributed and we have really learnt lots from eachother. I would be very interested to hear about the experiences from other teams working in a similar way. Things like: How often do you meet? Have you tried different sprint lengths (one week, two week, longer) ? Which tools do you use? Which issue tracker do you use? What do you do about time zone differences? How does it work for you to integrate new people into the team? How many hours do you usually work per week? How does your management interact with the way you are working? Do you get put on a waterfall with hard deadlines? What's your unit of work? What is your normal velocity? (units of work done per week) Programming work should be fun and for us it usually is great fun. I would be happy about any new ideas how to make it even more fun and/or more efficient.

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  • Search row with highest number of cells in a row with colspan

    - by user593029
    What is the efficient way to search highest number of cells in big table with numerous colspan (merge cells ** colspan should be ignored so in below example highest number of cells is 4 in first row). Is it js/jquery with reg expression or just the loop with bubble sorting. I got one link as below explainig use of regex is it ideal way ... can someone suggest pseudo code for this. High cpu consumption due to a jquery regex patch <table width="156" height="84" border="0" > <tbody> <tr style="height:10px"> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> </tr> <tr style="height:10px"> <td width="10" style="width:10px; height:10px" colspan="2"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> </tr> <tr style="height:10px"> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px" colspan="2"/> </tr> <tr style="height:10px"> <td width="10" style="width:10px; height:10px" colspan="2"/> <td width="10" style="width:10px; height:10px"/> <td width="10" style="width:10px; height:10px"/> </tr> </tbody> </table>

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  • ANSI C as core of a C# project? Is this possible?

    - by Nektarios
    I'm writing a NON-GUI app which I want to be cross platform between OS X and Windows. I'm looking at the following architecture, but I don't know if it will work on the windows side: (Platform specific entry point) - ANSI C main loop = ANSI C model code doing data processing / logic = (Platform specific helpers) So the core stuff I'm planning to write in regular ANSI C, because A) it should be platform independent, B) I'm extremely comfortable with C, C) It can do the job and do it well (Platform specific entry point) can be written in whatever necessary to get the job done, this is a small amount of code, doesn't matter to me. (Platform specific helpers) is the sticky thing. This is stuff like parsing XML, accessing databases, graphics toolkit stuff, whatever. Things that aren't easy in C. Things that modern languages/frameworks will give for free. On OS X this code will be written in Objective-C interfacing with Cocoa. On Windows I'm thinking my best bet is to use C# So on Windows my architecture (simplified) looks like (C# or C?) - ANSI C - C# Is this possible? Some thoughts/suggestions so far.. 1) Compile my C core as a .dll -- this is fine, but seems there's no way to call my C# helpers unless I can somehow get function pointers and pass them to my core, but that seems unlikely 2) Compile a C .exe and a C# .exe and have them talk via shared memory or some kind of IPC. I'm not entirely opposed to this but it obviously introduces a lot of complexity so it doesn't seem ideal 3) Instead of C# use C++, it gets me some nice data management stuff and nice helper code. And I can mix it pretty easily. And the work I do could probably easily port to Linux. But I really don't like C++, and I don't want this to turn in to a 3rd-party-library-fest. Not that it's a huge deal, but it's 2010.. anything for basic data management should be built in. And targetting Linux is really not a priority. Note that no "total" alternatives are OK as suggested in other similar questions on SO I've seen; java, RealBasic, mono.. this is an extremely performance intensive application doing soft realtime for game/simulation purposes, I need C & friends here to do it right (maybe you don't, but I do)

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  • Multi domain rails app. How to intelligently use MVC?

    - by denial
    Background: We have app a, b, and plan to add more apps into this same application. The apps are similar enough they could share many views, assets, and actions. Currently a,b live in a single rails app(2.3.10). c will be similar enough that it could also be in this rails app. The problem: As we continue to add more apps to this one app, there's going to be too much case logic that the app will soon become a nightmare to maintain. There will also be potential namespace issues. However, the apps are very similar in function and layout, it also makes sense to keep them in one app so that it's one app to maintain(since roughly 50% of site look/functionality will be shared). What we are trying to do is keep this as clean as possible so it's easy for multiple teams to work on and easy to maintain. Some things we've thought about/are trying: Engines. Make each app an engine. This would let us base routes on the domain. It also allows us to pull out controllers, models and views for the specific app. This solution does not seem ideal as we won't be reusing the apps any time soon. And explicitly stating the host in the routes doesn't seem right. Skinning/themes. The auth logic would be different between the apps. Each user model would be different. So it's not just a skinning problem. In app/view add folder sitea for sitea views, siteb for siteb views and so on. Do the same for controllers and models. This is still pretty messy and since it didn't follow naming conventions, it did not work with rails so nicely and made much of the code messier. Making another rails app. We just didn't want to maintain the same controller or view in 2 apps if they are identical. What we want to do is make the app intelligently use a controller based on the host. So there would be a sessions controller for each app, and perhaps some parent session controller for shared logic(not needed now). In each of these session controllers, it handles authentication for that specific app. So if the domain is a.mysite.com, it would use session controller for app a and know to use app a's views,models,controllers. And if the domain is b.mysite, it would use the session controller for b. And there would be a user model for a and user model for b, which also would be determined by the domain. Does anyone have any suggestions or experience with this situation? And ideally using rails 2.3.x as updating to rails 3 isn't an option right now.

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  • In R, how do you get the best fitting equation to a set of data?

    - by Matherion
    I'm not sure wether R can do this (I assume it can, but maybe that's just because I tend to assume that R can do anything :-)). What I need is to find the best fitting equation to describe a dataset. For example, if you have these points: df = data.frame(x = c(1, 5, 10, 25, 50, 100), y = c(100, 75, 50, 40, 30, 25)) How do you get the best fitting equation? I know that you can get the best fitting curve with: plot(loess(df$y ~ df$x)) But as I understood you can't extract the equation, see Loess Fit and Resulting Equation. When I try to build it myself (note, I'm not a mathematician, so this is probably not the ideal approach :-)), I end up with smth like: y.predicted = 12.71 + ( 95 / (( (1 + df$x) ^ .5 ) / 1.3)) Which kind of seems to approximate it - but I can't help to think that smth more elegant probably exists :-) I have the feeling that fitting a linear or polynomial model also wouldn't work, because the formula seems different from what those models generally use (i.e. this one seems to need divisions, powers, etc). For example, the approach in Fitting polynomial model to data in R gives pretty bad approximations. I remember from a long time ago that there exist languages (Matlab may be one of them?) that do this kind of stuff. Can R do this as well, or am I just at the wrong place? (Background info: basically, what we need to do is find an equation for determining numbers in the second column based on the numbers in the first column; but we decide the numbers ourselves. We have an idea of how we want the curve to look like, but we can adjust these numbers to an equation if we get a better fit. It's about the pricing for a product (a cheaper alternative to current expensive software for qualitative data analysis); the more 'project credits' you buy, the cheaper it should become. Rather than forcing people to buy a given number (i.e. 5 or 10 or 25), it would be nicer to have a formula so people can buy exactly what they need - but of course this requires a formula. We have an idea for some prices we think are ok, but now we need to translate this into an equation.

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  • Where are the function literals c++?

    - by academicRobot
    First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one.

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  • Truth tables in code? How to structure state machine?

    - by HanClinto
    I have a (somewhat) large truth table / state machine that I need to implement in my code (embedded C). I anticipate the behavior specification of this state machine to change in the future, and so I'd like to keep this easily modifiable in the future. My truth table has 4 inputs and 4 outputs. I have it all in an Excel spreadsheet, and if I could just paste that into my code with a little formatting, that would be ideal. I was thinking I would like to access my truth table like so: u8 newState[] = decisionTable[input1][input2][input3][input4]; And then I could access the output values with: setOutputPin( LINE_0, newState[0] ); setOutputPin( LINE_1, newState[1] ); setOutputPin( LINE_2, newState[2] ); setOutputPin( LINE_3, newState[3] ); But in order to get that, it looks like I would have to do a fairly confusing table like so: static u8 decisionTable[][][][][] = {{{{ 0, 0, 0, 0 }, { 0, 0, 0, 0 }}, {{ 0, 0, 0, 0 }, { 0, 0, 0, 0 }}}, {{{ 0, 0, 1, 1 }, { 0, 1, 1, 1 }}, {{ 0, 1, 0, 1 }, { 1, 1, 1, 1 }}}}, {{{{ 0, 1, 0, 1 }, { 1, 1, 1, 1 }}, {{ 0, 1, 0, 1 }, { 1, 1, 1, 1 }}}, {{{ 0, 1, 1, 1 }, { 0, 1, 1, 1 }}, {{ 0, 1, 0, 1 }, { 1, 1, 1, 1 }}}}; Those nested brackets can be somewhat confusing -- does anyone have a better idea for how I can keep a pretty looking table in my code? Thanks! Edit based on HUAGHAGUAH's answer: Using an amalgamation of everyone's input (thanks -- I wish I could "accept" 3 or 4 of these answers), I think I'm going to try it as a two dimensional array. I'll index into my array using a small bit-shifting macro: #define SM_INPUTS( in0, in1, in2, in3 ) ((in0 << 0) | (in1 << 1) | (in2 << 2) | (in3 << 3)) And that will let my truth table array look like this: static u8 decisionTable[][] = { { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 1, 1 }, { 0, 1, 1, 1 }, { 0, 1, 0, 1 }, { 1, 1, 1, 1 }, { 0, 1, 0, 1 }, { 1, 1, 1, 1 }, { 0, 1, 0, 1 }, { 1, 1, 1, 1 }, { 0, 1, 1, 1 }, { 0, 1, 1, 1 }, { 0, 1, 0, 1 }, { 1, 1, 1, 1 }}; And I can then access my truth table like so: decisionTable[ SM_INPUTS( line1, line2, line3, line4 ) ] I'll give that a shot and see how it works out. I'll also be replacing the 0's and 1's with more helpful #defines that express what each state means, along with /**/ comments that explain the inputs for each line of outputs. Thanks for the help, everyone!

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  • iPad web app: Prevent input focus AFTER ajax call

    - by Mike Barwick
    So I've read around and can't for the life of me figure out of to solve my issue effectively. In short, I have a web app built for the iPad - which works as it should. However, I have an Ajax form which also submits as it should. But, after the callback and I clear/reset my form, the "iPad" automatically focuses on an input and opens the keyboard again. This is far from ideal. I managed to hack my way around it, but it's still not perfect. The code below is run on my ajax callback, which works - except there's still a flash of the keyboard quickly opening and closing. Note, my code won't work unless I use setTimeout. Also, from my understanding, document.activeElement.blur(); only works when there's a click event, so I triggered one via js. IN OTHER WORDS, HOW DO I PREVENT THE KEYBOARD FROM REOPENING AFTER AJAX CALL ON WEB APP? PS: Ajax call works fine and doesn't open the keyboard in Safari on the iPad, just web app mode. Here's my code: hideKeyboard: function () { // iOS web app only, iPad IS_IPAD = navigator.userAgent.match(/iPad/i) != null; if (IS_IPAD) { $(window).one('click', function () { document.activeElement.blur(); }); setTimeout(function () { $(window).trigger('click'); }, 500); } } Maybe it's related to how I'm clearing my forms, so here's that code. Note, all inputs have tabindex="-1" as well. clearForm: function () { // text, textarea, etc $('#campaign-form-wrap > form')[0].reset(); // checkboxes $('input[type="checkbox"]').removeAttr('checked'); $('#campaign-form-wrap > form span.custom.checkbox').removeClass('checked'); // radio inputs $('input[type="radio"]').removeAttr('checked'); $('#campaign-form-wrap > form span.custom.radio').removeClass('checked'); // selects $('form.custom .user-generated-field select').each(function () { var selection = $(this).find('option:first').text(), labelFor = $(this).attr('name'), label = $('[for="' + labelFor + '"]'); label.find('.selection-choice').html(selection); }); optin.hideKeyboard(); }

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  • Mobile Safari text selection after input field focus

    - by Andy
    I have some legacy html that needs to work on old and new browsers (down to IE7) as well as the iPad. The iPad is the biggest issues because of how text selection is handled. On a page there is a textarea as well as some text instructions. The instructions are in a <div> and the user needs to be able to select the instructions. The problem is that once focus is placed in the textarea, the user cannot subsequently select the text instructions in the <div>. This is because the text cannot receive focus. According to the Safari Web Content Guide: Handling Events (especially, "Making Elements Clickable"), you can add a onclick event handler to the div you want to receive focus. This solution works (although it is not ideal) in iOS 6x but it does not work in iOS 5x. Does anyone have a suggestion that minimizes changes to our existing code and produces consistant user interaction. Here is sample code that shows the problem. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <script src="http://code.jquery.com/jquery-1.8.2.js"></script> <!-- Resources: Safari Web Content Guide: Handling Events (especially, "Making Elements Clickable") http://developer.apple.com/library/safari/#documentation/appleapplications/reference/safariwebcontent/HandlingEvents/HandlingEvents.html#//apple_ref/doc/uid/TP40006511-SW1 --> </head> <body> <div style="width:550"> <div onclick='function() { void(0); }'> <p>On the iPad, I want to be able to select this text after the textarea has had focus.</p> </div> <textarea rows="20" cols="80">After focus is in the textarea, can you select the text above?</textarea> </div> </body> </html>

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  • JQuery, Load() contents with plugins

    - by Galas
    I know this is not a completely new question, but none of the answers solved my problem... I have built a little menu that uses load() to load image galleries (as external html files) into a specified div ("content"). The said galleries make use of a JQuery plugin (SlideJS). Now I know that load() does not work for script tags and that I need to use $.getscript in the callback function in order to run the scripts, but it does not work. I have two .js files that need to be loaded: one is the plugin itself and another one is a smaller script with a preloader and the animations for the captions. I can't seem to merge them together; if I put them into the same document, the script won't run. So I tried just using $.getscript to load the two files. I tried using two callbacks as suggested in other answer (I know it's not ideal...): $("#proposal").click(function(){ $(this).addClass('selected'); $("a:not(:#proposal)").removeClass('selected'); $("#content").load("works/proposal/proposal.html", function(){ $.getScript("js/slide.js", function (){ $.getScript("js/slidepage.js"); }); }); }); and I tried a variable (read about it in some other faq, not sure if the syntax is correct) $("#proposal").click(function(){ $(this).addClass('selected'); $("a:not(:#proposal)").removeClass('selected'); $("#content").load("works/proposal/proposal.html", function(){ var scripts = ['js/slide.js','js/slidepage.js']; $.getScript(scripts); }); }); So none of these work. What am I doing wrong? I'm just starting on jquery and my js knowledge is very limited. Should I just merge the two .js files together using minify or something? One of them is already minified, but I've tried with a non-minified version and it does not work either. Can anyone suggest any other solution around this problem? I thought of just having the div embedded in the main document and just showing it on click, but I'll have at least 4 galleries with about 8 to 10 images each... its a lot of images to load in the main page, so I don't think its the best way. if you need me to post any more code, please ask! Thanks in advance for all your help!

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  • Encapsulating a Windows.Forms.Button

    - by devoured elysium
    I want to define a special kind of button that only allows two possible labels: "ON" and "OFF". I decided to inherit from a Windows.Forms.Button to implement this but now I don't know I how should enforce this rule. Should I just override the Text property like this? public override string Text { set { throw new InvalidOperationException("Invalid operation on StartStopButton!"); } } The problem I see with this is that I am breaking the contract that all buttons should have. If any code tries something like foreach (Button button in myForm) { button.Text = "123"; } they will get an Exception if I have any of my special buttons on the form, which is something that isn't expectable. First, because people think of properties just as "public" variables, not methods, second, because they are used to using and setting whatever they want to buttons without having to worry with Exceptions. Should I instead just make the set property do nothing? That could also lead to awkward results: myButton.Text = "abc"; MessageBox.Show(abc); //not "abc"! The general idea from the OO world is to in this kind of cases use Composition instead of inheritance. public class MySpecialButton : <Some class from System.Windows.Forms that already knows how to draw itself on forms> private Button button = new Button(); //I'd just draw this button on this class //and I'd then only show the fields I consider //relevant to the outside world. ... } But to make the Button "live" on a form it must inherit from some special class. I've looked on Control, but it seems to already have the Text property defined. I guess the ideal situation would be to inherit from some kind of class that wouldn't even have the Text property defined, but that'd have position, size, etc properties available. Upper in the hierarchy, after Control, we have Component, but that looks like a really raw class. Any clue about how to achieve this? I know this was a long post :( Thanks

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  • Delaying NIS & NFS startup till after network interface is fully ready on Fedora 17

    - by obmarg
    I've recently set up a fedora 17 server for our network, and I've been having trouble getting the NIS service to work on startup. Here's some logs from the system: Aug 21 12:57:12 cairnwell ypbind-pre-setdomain[718]: Setting NIS domain: 'indigo-nis' (environment variable) Aug 21 12:57:13 cairnwell ypbind: Binding NIS service Aug 21 12:57:13 cairnwell rpc.statd[730]: Unable to prune capability 0 from bounding set: Operation not permitted Aug 21 12:57:13 cairnwell systemd[1]: nfs-lock.service: control process exited, code=exited status=1 Aug 21 12:57:13 cairnwell systemd[1]: Unit nfs-lock.service entered failed state. Aug 21 12:57:14 cairnwell setroubleshoot: SELinux is preventing /usr/sbin/rpc.statd from using the setpcap capability. For complete SELinux messages. run sealert -l 024bba8a-b0ef-43dc-b195-5c9a2d4c4d41 Aug 21 12:57:15 cairnwell kernel: [ 18.822282] bnx2 0000:02:00.0: em1: NIC Copper Link is Up, 1000 Mbps full duplex Aug 21 12:57:15 cairnwell kernel: [ 18.822925] ADDRCONF(NETDEV_CHANGE): em1: link becomes ready Aug 21 12:57:15 cairnwell NetworkManager[621]: <info> (em1): carrier now ON (device state 20) Aug 21 12:57:15 cairnwell NetworkManager[621]: <info> (em1): device state change: unavailable -> disconnected (reason 'carrier-changed') [20 30 40] Aug 21 12:57:15 cairnwell NetworkManager[621]: <info> Auto-activating connection 'System em1'. Aug 21 12:57:15 cairnwell NetworkManager[621]: <info> Activation (em1) starting connection 'System em1' Aug 21 12:57:15 cairnwell NetworkManager[621]: <info> (em1): device state change: disconnected -> prepare (reason 'none') [30 40 0] ....... Aug 21 12:57:19 cairnwell sendmail[790]: YPBINDPROC_DOMAIN: Domain not bound Aug 21 12:57:26 cairnwell sendmail[790]: YPBINDPROC_DOMAIN: Domain not bound Aug 21 12:57:31 cairnwell sendmail[790]: YPBINDPROC_DOMAIN: Domain not bound Aug 21 12:57:35 cairnwell sendmail[790]: YPBINDPROC_DOMAIN: Domain not bound Aug 21 12:58:00 cairnwell ypbind: Binding took 47 seconds Aug 21 12:58:00 cairnwell ypbind: NIS server for domain indigo-nis is not responding. Aug 21 12:58:01 cairnwell ypbind: Killing ypbind with PID 733. Aug 21 12:58:01 cairnwell ypbind-post-waitbind[734]: /usr/lib/ypbind/ypbind-post-waitbind: line 51: kill: SIGTERM: invalid signal specification Aug 21 12:58:01 cairnwell systemd[1]: ypbind.service: control process exited, code=exited status=1 Aug 21 12:58:01 cairnwell systemd[1]: Unit ypbind.service entered failed state. By the looks of these logs the ypbind service is starting up at 12:57:12 but the network interface isn't coming up till 12:57:15. My guess is that this is causing ypbind to time out when trying to connect. As a knock-on effect the NIS failure is causing problems with NFS which is no longer able to map UIDs properly. This problem doesn't seem to be fixed by actually starting ypbind etc. so I've had to set all my NFS shares to noauto. I have tried manually adding NETWORKDELAY and NETWORKWAIT in /etc/sysconfig/network and also running systemctl enable NetworkManager-wait-online.service as I've seen suggested in some places, but neither of these have had any effect. It is relatively easy to fix manually by restarting ypbind & mounting NFS shares after the network has started up, but it's less than ideal to have to do this every time the server has been rebooted. Does anyone know of an easy (and preferably hack-free) way of delaying the ypbind startup till after the network interface is fully ready?

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  • Determining cause of high NFS/IO utilization without iotop

    - by Matt
    I have a server that is doing an NFSv4 export for user's home directories. There are roughly 25 users (mostly developers/analysts) and about 40 servers mounting the home directory export. Performance is miserable, with users often seeing multi-second lags for simple commands (like ls, or writing a small text file). Sometimes the home directory mount completely hangs for minutes, with users getting "permission denied" errors. The hardware is a Dell R510 with dual E5620 CPUs and 8 GB RAM. There are eight 15k 2.5” 600 GB drives (Seagate ST3600057SS) configured in hardware RAID-6 with a single hot spare. RAID controller is a Dell PERC H700 w/512MB cache (Linux sees this as a LSI MegaSAS 9260). OS is CentOS 5.6, home directory partition is ext3, with options “rw,data=journal,usrquota”. I have the HW RAID configured to present two virtual disks to the OS: /dev/sda for the OS (boot, root and swap partitions), and /dev/sdb for the home directories. What I find curious, and suspicious, is that the sda device often has very high utilization, even though it only contains the OS. I would expect this virtual drive to be idle almost all the time. The system is not swapping, according to "free" and "vmstat". Why would there be major load on this device? Here is a 30-second snapshot from iostat: Time: 09:37:28 AM Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 0.00 44.09 0.03 107.76 0.13 607.40 11.27 0.89 8.27 7.27 78.35 sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sda2 0.00 44.09 0.03 107.76 0.13 607.40 11.27 0.89 8.27 7.27 78.35 sdb 0.00 2616.53 0.67 157.88 2.80 11098.83 140.04 8.57 54.08 4.21 66.68 sdb1 0.00 2616.53 0.67 157.88 2.80 11098.83 140.04 8.57 54.08 4.21 66.68 dm-0 0.00 0.00 0.03 151.82 0.13 607.26 8.00 1.25 8.23 5.16 78.35 dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 dm-2 0.00 0.00 0.67 2774.84 2.80 11099.37 8.00 474.30 170.89 0.24 66.84 dm-3 0.00 0.00 0.67 2774.84 2.80 11099.37 8.00 474.30 170.89 0.24 66.84 Looks like iotop is the ideal tool to use to sniff out these kinds of issues. But I'm on CentOS 5.6, which doesn't have a new enough kernel to support that program. I looked at Determining which process is causing heavy disk I/O?, and besides iotop, one of the suggestions said to do a "echo 1 /proc/sys/vm/block_dump". I did that (after directing kernel messages to tempfs). In about 13 minutes I had about 700k reads or writes, roughly half from kjournald and the other half from nfsd: # egrep " kernel: .*(READ|WRITE)" messages | wc -l 768439 # egrep " kernel: kjournald.*(READ|WRITE)" messages | wc -l 403615 # egrep " kernel: nfsd.*(READ|WRITE)" messages | wc -l 314028 For what it's worth, for the last hour, utilization has constantly been over 90% for the home directory drive. My 30-second iostat keeps showing output like this: Time: 09:36:30 PM Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util sda 0.00 6.46 0.20 11.33 0.80 71.71 12.58 0.24 20.53 14.37 16.56 sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sda2 0.00 6.46 0.20 11.33 0.80 71.71 12.58 0.24 20.53 14.37 16.56 sdb 137.29 7.00 549.92 3.80 22817.19 43.19 82.57 3.02 5.45 1.74 96.32 sdb1 137.29 7.00 549.92 3.80 22817.19 43.19 82.57 3.02 5.45 1.74 96.32 dm-0 0.00 0.00 0.20 17.76 0.80 71.04 8.00 0.38 21.21 9.22 16.57 dm-1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 dm-2 0.00 0.00 687.47 10.80 22817.19 43.19 65.48 4.62 6.61 1.43 99.81 dm-3 0.00 0.00 687.47 10.80 22817.19 43.19 65.48 4.62 6.61 1.43 99.82

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  • iptables - quick safety eval & limit max conns over time

    - by Peter Hanneman
    Working on locking down a *nix server box with some fancy iptable(v1.4.4) rules. I'm approaching the matter with a "paranoid, everyone's out to get me" style, not necessarily because I expect the box to be a hacker magnet but rather just for the sake of learning iptables and *nix security more throughly. Everything is well commented - so if anyone sees something I missed please let me know! The *nat table's "--to-ports" point to the only ports with actively listening services. (aside from pings) Layer 2 apps listen exclusively on chmod'ed sockets bridged by one of the layer 1 daemons. Layers 3+ inherit from layer 2 in a similar fashion. The two lines giving me grief are commented out at the very bottom of the *filter rules. The first line runs fine but it's all or nothing. :) Many thanks, Peter H. *nat #Flush previous rules, chains and counters for the 'nat' table -F -X -Z #Redirect traffic to alternate internal ports -I PREROUTING --src 0/0 -p tcp --dport 80 -j REDIRECT --to-ports 8080 -I PREROUTING --src 0/0 -p tcp --dport 443 -j REDIRECT --to-ports 8443 -I PREROUTING --src 0/0 -p udp --dport 53 -j REDIRECT --to-ports 8053 -I PREROUTING --src 0/0 -p tcp --dport 9022 -j REDIRECT --to-ports 8022 COMMIT *filter #Flush previous settings, chains and counters for the 'filter' table -F -X -Z #Set default behavior for all connections and protocols -P INPUT DROP -P OUTPUT DROP -A FORWARD -j DROP #Only accept loopback traffic originating from the local NIC -A INPUT -i lo -j ACCEPT -A INPUT ! -i lo -d 127.0.0.0/8 -j DROP #Accept all outgoing non-fragmented traffic having a valid state -A OUTPUT ! -f -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT #Drop fragmented incoming packets (Not always malicious - acceptable for use now) -A INPUT -f -j DROP #Allow ping requests rate limited to one per second (burst ensures reliable results for high latency connections) -A INPUT -p icmp --icmp-type 8 -m limit --limit 1/sec --limit-burst 2 -j ACCEPT #Declaration of custom chains -N INSPECT_TCP_FLAGS -N INSPECT_STATE -N INSPECT #Drop incoming tcp connections with invalid tcp-flags -A INSPECT_TCP_FLAGS -p tcp --tcp-flags ALL ALL -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags ALL NONE -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags ACK,FIN FIN -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags ACK,PSH PSH -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags ACK,URG URG -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags ALL FIN,PSH,URG -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags FIN,RST FIN,RST -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags SYN,RST SYN,RST -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags ALL SYN,FIN,PSH,URG -j DROP -A INSPECT_TCP_FLAGS -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP #Accept incoming traffic having either an established or related state -A INSPECT_STATE -m state --state ESTABLISHED,RELATED -j ACCEPT #Drop new incoming tcp connections if they aren't SYN packets -A INSPECT_STATE -m state --state NEW -p tcp ! --syn -j DROP #Drop incoming traffic with invalid states -A INSPECT_STATE -m state --state INVALID -j DROP #INSPECT chain definition -A INSPECT -p tcp -j INSPECT_TCP_FLAGS -A INSPECT -j INSPECT_STATE #Route incoming traffic through the INSPECT chain -A INPUT -j INSPECT #Accept redirected HTTP traffic via HA reverse proxy -A INPUT -p tcp --dport 8080 -j ACCEPT #Accept redirected HTTPS traffic via STUNNEL SSH gateway (As well as tunneled HTTPS traffic destine for other services) -A INPUT -p tcp --dport 8443 -j ACCEPT #Accept redirected DNS traffic for NSD authoritative nameserver -A INPUT -p udp --dport 8053 -j ACCEPT #Accept redirected SSH traffic for OpenSSH server #Temp solution: -A INPUT -p tcp --dport 8022 -j ACCEPT #Ideal solution: #Limit new ssh connections to max 10 per 10 minutes while allowing an "unlimited" (or better reasonably limited?) number of established connections. #-A INPUT -p tcp --dport 8022 --state NEW,ESTABLISHED -m recent --set -j ACCEPT #-A INPUT -p tcp --dport 8022 --state NEW -m recent --update --seconds 600 --hitcount 11 -j DROP COMMIT *mangle #Flush previous rules, chains and counters in the 'mangle' table -F -X -Z COMMIT

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  • Amazon EC2 Instance - m1.medium Ubuntu 12.04 - Started to crash three days ago

    - by Joy
    The environment: Amazon EC2 Instance - m1.medium Ubuntu 12.04 Apache 2.2.22 - Running a Drupal Site Using MySQL DB Server RAM info: ~$ free -gt total used free shared buffers cached Mem: 3 1 2 0 0 0 -/+ buffers/cache: 0 2 Swap: 0 0 0 Total: 3 1 2 Hard drive info: Filesystem Size Used Avail Use% Mounted on /dev/xvda1 7.9G 4.7G 2.9G 62% / udev 1.9G 8.0K 1.9G 1% /dev tmpfs 751M 180K 750M 1% /run none 5.0M 0 5.0M 0% /run/lock none 1.9G 0 1.9G 0% /run/shm /dev/xvdb 394G 199M 374G 1% /mnt The problem About two days ago the site started failing becaue the MySQL server was shut down by Apache with the following message: kernel: [2963685.664359] [31716] 106 31716 226946 22748 0 0 0 mysqld kernel: [2963685.664730] Out of memory: Kill process 31716 (mysqld) score 23 or sacrifice child kernel: [2963685.664764] Killed process 31716 (mysqld) total-vm:907784kB, anon-rss:90992kB, file-rss:0kB kernel: [2963686.153608] init: mysql main process (31716) killed by KILL signal kernel: [2963686.169294] init: mysql main process ended, respawning That states that the VM was occupying 0.9GB, but my Ram has 2GB free, so 1GB was still left free. I understand that in Linux applications can allocate more memory than physically available. I don't know if this is the problme, it's the first time that it has started to happen. Obviously, the MySQL server tries to restart, but there's no memory for it apparently and it won't restart. Here is its error log: Plugin 'FEDERATED' is disabled. The InnoDB memory heap is disabled Mutexes and rw_locks use GCC atomic builtins Compressed tables use zlib 1.2.3.4 Initializing buffer pool, size = 128.0M InnoDB: mmap(137363456 bytes) failed; errno 12 Completed initialization of buffer pool Fatal error: cannot allocate memory for the buffer pool Plugin 'InnoDB' init function returned error. Plugin 'InnoDB' registration as a STORAGE ENGINE failed. Unknown/unsupported storage engine: InnoDB [ERROR] Aborting [Note] /usr/sbin/mysqld: Shutdown complete I simply restarted the Mysql service. About two hours later it happened again. I restarted it. Then it happened again 9 hours later. So then I thought of the MaxClients parameter of apache.conf, so I went to check it out. It was set at 150. I decided to drop it down to 60. As so: <IfModule mpm_prefork_module> ... MaxClients 60 </IfModule> <IfModule mpm_worker_module> ... MaxClients 60 </IfModule> <IfModule mpm_event_module> ... MaxClients 60 </IfModule> Once I did that, I had the apache2 service restart and it all went smoothly for 3/4 of a day. Since at night the MySQL service shut down once again, but this time it wasn't killed by the Apache2 service. Instead it called the OOM-Killer with the following message: kernel: [3104680.005312] mysqld invoked oom-killer: gfp_mask=0x201da, order=0, oom_adj=0, oom_score_adj=0 kernel: [3104680.005351] [<ffffffff81119795>] oom_kill_process+0x85/0xb0 kernel: [3104680.548860] init: mysql main process (30821) killed by KILL signal Now I'm out of ideas. Some articles state that the ideal thing to do is change the kernel behaviour with the following (include it to the file /etc/sysctl.conf ) vm.overcommit_memory = 2 vm.overcommit_ratio = 80 So no overcommits will take place. I'm wondering if this is the way to go? Keep in mind I'm no server administrator, I have basic knowldege. Thanks a bunch in advance.

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  • Using different SSDs types (not only SATA based) as system drive

    - by Hubert Kario
    Currently I have a Thinkpad X61s and want to make it both a bit faster and a bit more power efficient. For that reason I thought that adding SSD drive would make most sense. Unfortunately, because of financial reasons, buying SSD of over 200GB capacity is out of reach for me (not only it would be worth more than the rest of the laptop, but also I currently have a 500GB drive in it, so even such a drive would be kind of a downgrade for me). During preliminary testing with a cheap Transcend 4GB Class 6 (14MiB/s streaming, 9MiB/s random read) card I experienced boot times to be reduced by half so putting the OS only on it would already would be an improvement. Unfortunately, my system now is about 11GiB in size so anything less than 16GB would be constraining. In this laptop I can connect additional drives on at least 5 different ways: using SATA-ATA converter caddy in the X6 Ultrabase using internal mini PCIe slot using integrated SDHC slot using CardBus (a.k.a PCMCIA or PC Card) slot using USB Thankfully, because I use only Linux on this PC the bootability of them is irrelevant as I can put the /boot partition on internal HDD and / on any of the above mentioned Flash memories (as I already did for the SDHC test). From what I was able to research and from my own experience those options come with rather big downsides or other problems: SATA-ATA caddy It has three downsides: I have to carry the Ultrabse with me at all times (it's not really inconvenient, but those grams do add) and couldn't disconnect it when I want to disconnect the battery It makes the bay unusable for the optical drive and occasional quick access to other hard drives the only caddies I could buy have rather flaky controllers in them so putting my OS on it would hamper its stability Internal mini PCIe slot This would be an ideal solution, if only I could find real PCIe SSDs, not only devices that could talk only SATA or ATA over PCIe mechanical connection (the ones used in Dell Mini or Asus EEE). Theoretically Samsung did release such devices but I couldn't find them in retail anywhere. Integrated SDHC slot It's a nice solution with a single drawback: the fastest 16GB SDHC card on the market can only do around 35MiB/s read and 15MiB/s write while still costing like a normal 40GB SATA SSD that's 10 times faster. Not really cost-effective. CardBus (a.k.a PCMCIA or PC Card) slot Those cards are much faster than the SDHC option (there are ones that can do well over 50MiB/s read in benchmarks) and from what I could find the PCMCIA controller in my laptop does support UDMA so it should be able to deliver comparable speeds. They still cost similarly to SD cards but at least they provide streaming performance comparable to my current HDD. USB That's the worst option. Not only is it limited to 20-30MiB/s by the interface itself the drive would stick out of the laptop so it's a big no no. The question As such I think that going the "CF in a CardBus adapter" route will be the best option. My question is: did anyone try using CF cards in CardBus adapters as system drives with Linux on Thinkpad laptops? Laptops in general? What was the real-world performance? I don't have any CF cards so I can't check how well does it work with suspend/resume, or whatever it's easy to make it work in initramfs (I'm using ArchLinux and SD card was trivial — add 3 modules in single config line and rebuilding initramfs) so any tips/gotchas on this are welcome as well.

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  • What seems to be plaguing my hard drives?

    - by Craig
    In a little bit of a tech nightmare here. I know oodles about software, not so much more than the above average user about hardware. I recently had to toss an old desktop of mine. It was gradually getting slower and slower, and after shutting the desktop down for long periods of time, it would choke up upon startup. Sometimes it'd give a disk read error, sometimes say no OS was found, etc. Restarting it about 5-15 times would eventually boot properly. Weird. I also noticed that startup programs were going missing, Dropbox was reindexing my entire folder, and Backblaze was backing up less than the number of files that it should. This lead me to believe it was probably a hard drive issue. I began to wonder why I'd have hard drive issues, and came to closure when I assumed it was because of recent power surges and outages. I'm sure that does a number on the drive. I bought a new desktop recently. It's not a beast or anything, but it's enough for what I do. It's an eMachines (I know, I know) Ultra-Slim (http://www.amazon.com/eMachines-Ultra-Slim-ER1401-57-Desktop-PC/dp/B00475OG9U). This is ideal for me because it's small and portable. It comes with an AC adapter and battery, like a laptop. Just to be safe, I bought an uninterruptable power supply on top of that. It's basically protected completely from any outages that might scramble the drive. I set this up a few days ago and for the past few days I've been perfecting settings, downloading the usual applications, etc. Two days ago, I noticed Dropbox was reindexing my entire Dropbox folder. I installed both Dropbox and Backblaze on this system, but it is very much more lightweight than the other. Only about 15 third-party applications installed. I thought that maybe Dropbox and Backblaze were stressing my system, so I turned off Backblaze. Still, Dropbox runs and comes across this infinite reindex issue. I noticed that upon a reboot recently, two applications did not start on startup either. Also, much like my old desktop, every 3rd or 4th reboot, I'll be forced into a chkdsk. This makes me incredibly nervous. What could possibly be going wrong with my old, years-old desktop that is immediately causing the same issues to my new one? I've considered all of the basics. I'm in a very air conditioned room. I take run routine virus scans. I'd like to think I take care of my systems very well. What is this issue that is haunting me? There's always the possibility that this new desktop has a junk hard drive, but it just seems way too coincidental.

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  • Pushing DNSSEC updates with offline keys

    - by eggyal
    In a non-professional capacity, I look after the DNS of some 18 domains: mostly personal/vanity domains for immediate family. I outsource the whole shebang to an inexpensive managed hosting provider with a web interface through which I manage the zones; since the provider also offers DNSSEC, I have successfully deployed that too. These domains are so unimportant that an attack targetted against them seems much less likely than a general compromise of my provider's systems, at which point the records of all their customers might be changed to misdirect traffic (perhaps with extremely long TTLs). DNSSEC could protect against such an attack, but only if the zone's private keys are not held by the hosting provider. So, I wonder: how can one keep DNSSEC private keys offline yet still transfer signed zones to an outsourced DNS host? The most obvious answer (to me, at least) is to run one's own shadow/hidden master (from which the provider can slave) and then copy offline-signed zonefiles to the master as required. The problem is that the only machine I (want to*) control is my personal laptop, which usually connects from a typical home ADSL (behind NAT over a dynamically-assigned IP address). Having them slave from that (e.g. with a very long Expiry time on the zone for periods when my laptop is offline/unavailable) would not only require a Dynamic DNS record from which they can slave (if indeed they can slave from a named host rather than a static IP address), but would also involve me running a DNS server on my laptop and opening both it and my home network up to the incoming zone transfer requests: not ideal. I would prefer a much more push-oriented design, whereby my laptop initiates transfer of offline-signed zonefiles/updates to the provider's servers. I looked into whether nsupdate could fit the bill: documentation is a little sketchy, but my testing (with BIND 9.7) suggests it can indeed update DNSSEC zones, but only where the server holds the keys to perform the zone signing; I have not found a way to have it take an update including the relevant RRSIG/NSEC/etc. records and have the server accept them. Is this a supported use-case? If not, I suspect the only solutions which could fit the bill will involve non-DNS-based transfer of the zone updates and would welcome recommendations that are supported by (hopefully inexpensive) hosting providers: SFTP/SCP? rsync? RDBMS replication? Proprietary API? Finally, what would be the practical implications of such a setup? Key rotation is jumping out at me as being an obvious difficulty, especially if my laptop is offline for extended periods. But the zones are extremely stable, so perhaps I could get away with long-lived ZSKs**...? * Whilst I could run a shadow/hidden master on e.g. an outsourced VPS, I dislike the overhead of having to secure / manage / monitor / maintain yet another system; not to mention the additional financial costs of so doing. ** Okay, this would enable a concerted attacker to replay outdated records—but the risk and impact of such are both tolerable in the case of these domains.

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  • Can spliting an access database cause printer and reporting issues?

    - by leeand00
    We have a setup in which our users log into an access database using MS Access 2003 over an RDP connection. The user's login to their own machines first using a roaming profile. They then click an rdp connection file on the desktop and login to the remote server, via RDP, where they use MS Access as the shell; they don't have any access to any of explorer.exe features such as the start menu. The database they are logging into is more of an application, and provides functionality for entering data, querying data, and running reports via form based menus. It all worked pretty well until we split the database as it was nearing 2GBs in size. We moved out the payroll data into a separate partition, a database with the same name in a different folder, both of them on the server. Only two tables were moved into this new database partition, and they were re-linked as external tables in the new partition. Now while everything appears to be working fine data-wise after the split, there's a new issue when our users login via RDP and attempt to run reports: often the report will not display and instead the user sees an error about the click event of the form. At first I didn't even know it was printer-related, as we didn't really change anything related to the printers as far as I knew. Confused about the error, I talked to the guy who previously worked here and who was in charge of splitting the database, and he told me to tell the users to set their default printers (on their local machines, not on the server) to the "printer" Microsoft XPS Document Writer which isn't a physical printer at all. This allowed the user's to display their reports, but if they want to print out reports, they are required to go to the File menu and select Print, clicking the print icon on the toolbar takes them to a Save As... dialog as would be expected when using the Microsoft XPS Document Writer as your default printer. It's easy to tell if the user is having a problem because a quick mouseover of the printer icon will yield a tooltip of (none) when they cannot access their reports, and a tooltip of Microsoft XPS Document Writer when they can view the reports. If the user's printer is set to anything other than Microsoft XPS Document Writer as the default on their local machine, then (none) is always displayed when they rdp to the database. The RDP settings are setup to transfer the local printer to the server. Telling the users to do this to print has been more of a band-aid on the whole situation until we find a better solution and an explanation as to why splitting a database would prevent users from printing or even viewing access database reports. Which is why I'm here asking this question. Also of note all the printers on the network now show up on the server so that when the users do click File->Print to print their reports on a physical printer, they have to look through a huge list of printers to find theirs in the dropdown. So the little band-aid fix we have is not ideal. Previously, only the printers on the user's local machine displayed here, and not all the printers on the network. My co-worker seems to think this has something to do with permissions, I personally think it has to do with roaming profiles, and Group Policies which is what I've been reading up on. I really don't know how to fix this or how it is related to splitting the database.

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  • Error on 64 Bit Install of IIS &ndash; LoadLibraryEx failed on aspnet_filter.dll

    - by Rick Strahl
    I’ve been having a few problems with my Windows 7 install and trying to get IIS applications to run properly in 64 bit. After installing IIS and creating virtual directories for several of my applications and firing them up I was left with the following error message from IIS: Calling LoadLibraryEx on ISAPI filter “c:\windows\Microsoft.NET\Framework\v4.0.30319\aspnet_filter.dll” failed This is on Windows 7 64 bit and running on an ASP.NET 4.0 Application configured for running 64 bit (32 bit disabled). It’s also on what is essentially a brand new installation of IIS and Windows 7. So it failed right out of the box. The problem here is that IIS is trying to loading this ISAPI filter from the 32 bit folder – it should be loading from Framework64 folder note the Framework folder. The aspnet_filter.dll component is a small Win32 ISAPI filter used to back up the cookieless session state for ASP.NET on IIS 7 applications. It’s not terribly important because of this focus, but it’s a default loaded component. After a lot of fiddling I ended up with two solutions (with the help and support of some Twitter folks): Switch IIS to run in 32 bit mode Fix the filter listing in ApplicationHost.config Switching IIS to allow 32 Bit Code This is a quick fix for the problem above which enables 32 bit code in the Application Pool. The problem above is that IIS is trying to load a 32 bit ISAPI filter and enabling 32 bit code gets you around this problem. To configure your Application Pool, open the Application Pool in IIS Manager bring up Advanced Options and Enable 32 Bit Applications: And voila the error message above goes away. Fix Filters Enabling 32 bit code is a quick fix solution to this problem, but not an ideal one. If you’re running a pure .NET application that doesn’t need to do COM or pInvoke Interop with 32 bit apps there’s usually no need for enabling 32 bit code in an Application Pool as you can run in native 64 bit code. So trying to get 64 bit working natively is a pretty key feature in my opinion :-) So what’s the problem – why is IIS trying to load a 32 bit DLL in a 64 bit install, especially if the application pool is configured to not allow 32 bit code at all? The problem lies in the server configuration and the fact that 32 bit and 64 bit configuration settings exist side by side in IIS. If I open my Default Web Site (or any other root Web Site) and go to the ISAPI filter list here’s what I see: Notice that there are 3 entries for ASP.NET 4.0 in this list. Only two of them however are specifically scoped to the specifically to 32 bit or 64 bit. As you can see the 64 bit filter correctly points at the Framework64 folder to load the dll, while both the 32 bit and the ‘generic’ entry point at the plain Framework 32 bit folder. Aha! Hence lies our problem. You can edit ApplicationHost.config manually, but I ran into the nasty issue of not being able to easily edit that file with the 32 bit editor (who ever thought that was a good idea???? WTF). You have to open ApplicationHost.Config in a 64 bit native text editor – which Visual Studio is not. Or my favorite editor: EditPad Pro. Since I don’t have a native 64 bit editor handy Notepad was my only choice. Or as an alternative you can use the IIS 7.5 Configuration Editor which lets you interactively browse and edit most ApplicationHost settings. You can drill into the configuration hierarchy visually to find your keys and edit attributes and sub values in property editor type interface. I had no idea this tool existed prior to today and it’s pretty cool as it gives you some visual clues to options available – especially in absence of an Intellisense scheme you’d get in Visual Studio (which doesn’t work). To use the Configuration Editor go the Web Site root and use the Configuration Editor option in the Management Group. Drill into System.webServer/isapiFilters and then click on the Collection’s … button on the right. You should now see a display like this: which shows all the same attributes you’d see in ApplicationHost.config (cool!). These entries correspond to these raw ApplicationHost.config entries: <filter name="ASP.Net_4.0" path="C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_filter.dll" enableCache="true" preCondition="runtimeVersionv4.0" /> <filter name="ASP.Net_4.0_64bit" path="C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_filter.dll" enableCache="true" preCondition="runtimeVersionv4.0,bitness64" /> <filter name="ASP.Net_4.0_32bit" path="C:\Windows\Microsoft.NET\Framework\v4.0.30319\aspnet_filter.dll" enableCache="true" preCondition="runtimeVersionv4.0,bitness32" /> The key attribute we’re concerned with here is the preCondition and the bitness subvalue. Notice that the ‘generic’ version – which comes first in the filter list – has no bitness assigned to it, so it defaults to 32 bit and the 32 bit dll path. And this is where our problem comes from. The simple solution to fix the startup problem is to remove the generic entry from this list here or in the filters list shown earlier and leave only the bitness specific versions active. The preCondition attribute acts as a filter and as you can see here it filters the list by runtime version and bitness value. This is something to keep an eye out in general – if a bitness values are missing it’s easy to run into conflicts like this with any settings that are global and especially those that load modules and handlers and other executable code. On 64 bit systems it’s a good idea to explicitly set the bitness of all entries or remove the non-specific versions and add bit specific entries. So how did this get misconfigured? I installed IIS before everything else was installed on this machine and then went ahead and installed Visual Studio. I suspect the Visual Studio install munged this up as I never saw a similar problem on my live server where everything just worked right out of the box. In searching about this problem a lot of solutions pointed at using aspnet_regiis –r from the Framework64 directory, but that did not fix this extra entry in the filters list – it adds the required 32 bit and 64 bit entries, but it doesn’t remove the errand un-bitness set entry. Hopefully this post will help out anybody who runs into a similar situation without having to trouble shoot all the way down into the configuration settings and noticing the bitness settings. It’s a good lesson learned for me – this is my first desktop install of a 64 bit OS and things like this are what I was reluctant to find. Now that I ran into this I have a good idea what to look for with 32/64 bit misconfigurations in IIS at least.© Rick Strahl, West Wind Technologies, 2005-2011Posted in IIS7   ASP.NET  

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  • Week in Geek: FBI Back Door in OpenBSD Edition

    - by Asian Angel
    This week we learned how to migrate bookmarks from Delicious to Diigo, fix annoying arrows, play old-school DOS games, schedule smart computer shutdowns, use breaks in Microsoft Word to better format documents, check the condition of hard-disks using Linux disk utilities, & what the Linux fstab is and how it works. Photo by Jameson42. Random Geek Links Another week with extra news link goodness to help keep you up to date. Photo by justmakeit. Report of FBI back door roils OpenBSD community Allegations that the FBI surreptitiously placed a back door into the OpenBSD operating system have alarmed the computer security community, prompting calls for an audit of the source code and claims that the charges must be a hoax. Fortinet: Job outlook improving for cybercrooks In an ironic twist in the job market, more positions will open up for developers who can write customized malware packers, people who can break CAPTCHA codes, and distributors who can spread malicious code, according to Fortinet. Enisa: Malware for smartphones is a ’serious risk’ Businesses and consumers are at risk of data breaches through smartphone use, according to the European Network and Information Security Agency. The trick with the f: Google and Microsoft web sites distribute malware Last week, Google’s DoubleClick advertising platform and Microsoft’s rad.msn.com online ad network briefly distributed malware to other web sites in the form of advertising banners. New scam tactic: Fake disk defraggers It would appear that scammers are trying out new programs to see which might best confuse potential victims and evade detection by legitimate antivirus software. Microsoft closes IE and Stuxnet holes As previously announced, Microsoft has released 17 security updates to close 40 security holes. All four Windows holes so far disclosed in connection with Stuxnet have now been closed. Microsoft Offers H.264 Support to Firefox on Windows via Add-On The new HTML5 Extension for Windows Media Player Firefox Plug-in add-on from Microsoft offers users that are running Firefox on Windows 7 H.264 support for HTML5 video playback. Google proclaims Chrome business-ready Google has announced that Chrome is ready for corporate use. Microsoft Tells Exchange Customers to Think Twice Before Opting for Google Message Continuity This week, Microsoft is telling companies still running Exchange 2010’s precursors that they should carefully consider the implications of embracing Google Message Continuity. Who Google has in mind for its Chrome OS users Steven Vaughan-Nichols explains why he feels that Chrome OS will be ideal for either office-workers or people who need a computer, but do not know the first thing about how to use one safely. Oracle takes office suite to the cloud Oracle has introduced Cloud Office 1.0, a cloud-based version of its office suite, which is aimed at web and mobile users. Mozilla pays premiums for reports of vulnerabilities The Mozilla Foundation has followed Google’s example by expanding its rewards program for reports of vulnerabilities in its Web applications. Who bought those 882 Novell patents? Not just Microsoft The mysterious CPTN Holdings — the organization that bought the 882 Novell patents as part of the terms of the Attachmate acquisition of Novell – has been unmasked (Microsoft, Apple, EMC and Oracle). Appeals court: Feds need warrants for e-mail Police must obtain search warrants before perusing Internet users’ e-mail records, a federal appeals court ruled today in a landmark decision that struck down part of a 1986 law allowing warrantless access. Geek Video of the Week What happens when someone plays a wicked prank by shoveling crazy snow paths that lead to dead ends or turn back on themselves? Watch to find out! Photo by CollegeHumor. Janitor Snow Shoveling Prank Random TinyHacker Links The Oatmeal on Cat vs Internet What lengths will our poor neglected kitty hero have to go to in order to get some attention? Guide On Using JoliCloud With Windows JoliCloud is a nifty operating system that’s made for people who need a light-weight OS that’s mostly cloud based. Check this guide on using it with Windows. Use Cameyo to Easily Create Portable Programs Here’s a nifty tool to make portable apps out of programs in Windows. Check out the guide to do it. Better Family Tech Support A nice new site by Google to help members of family understand how computers work. Track Your Stolen Mobile Phone With F-Secure A useful anti-theft tool for your mobile phone. Super User Questions Another week with great answers to popular questions from Super User. What Chrome password manager fits my requirements? What’s the best way to be able to reimage windows computers? Could you suggest feature-rich disk-based personal backup program for linux (and I’ve seen a few)? What is IPv6 and why should I care? Is there any way to find out what programs are trying to connect to Internet on windows? How-To Geek Weekly Article Recap Here are our hottest articles full of geeky goodness from this past week at HTG. 20 OS X Keyboard Shortcuts You Might Not Know Microsoft Security Essentials 2.0 Kills Viruses Dead. Download It Now. Is Your Desktop Printer More Expensive Than Printing Services? Ask the Readers: Would You Be Willing to Give Windows Up and Use a Different O.S.? The Twelve Days of Geekmas One Year Ago on How-To Geek Enjoy reading through our latest batch of retro-geek goodness from one year ago. Macrium Reflect is a Free and Easy To Use Backup Utility How To Turn a Physical Computer Into A Virtual Machine with Disk2vhd How To Restore Windows 7 from a System Image How To Manage Hard Drive Space Used by Windows 7 Backup and Restore How To Manage Hibernate Mode in Windows 7 The Geek Note That is all we have for you this week, so see you back here again after the holidays! Got a great tip? Send it in to us at [email protected]. Photo by mitjamavsar. Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor Deathwing the Destroyer – WoW Cataclysm Dragon Wallpaper Drag2Up Lets You Drag and Drop Files to the Web With Ease The Spam Police Parts 1 and 2 – Goodbye Spammers [Videos] Snow Angels Theme for Windows 7 Exploring the Jungle Ruins Wallpaper Protect Your Privacy When Browsing with Chrome and Iron Browser

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  • Generating a twitter OAuth access key - the semi-manual way

    - by Piet
    [UPDATE] Apparently someone at Twitter was listening, or I’m going senile/blind. Let’s call it a combination of both. Instead of following all the steps below, you could just login with the Twitter account you want to use on http://dev.twitter.com, register your application and then click ‘Edit Details’ on the application overview page at http://dev.twitter.com/apps. Next click the ‘Application detail’ button on the right, followed by the ‘My Access Token’ button in order to get your Access Token and Access Token Secret. This makes the old post below rather obsolete. Clearly a case of me thinking everything is a nail and ruby is a hammer (don’t they usually say this about java coders?) [ORIGINAL POST] OAuth is great! OAuth allows your application to use your user’s data without the need to ask for their password. So Twitter made the API much safer for their and your users. Hurray! Free pizza for everyone! Unless of course you’re using the Twitter API for your own needs like running your own bot and don’t need access to other user’s data. In such cases a simple username/password combination is more than enough. I can understand however that the Twitter guys don’t really care that much about these exceptions(?). Most such uses for the API are probably rather spammy in nature. !!! If you have a twitter app that uses the API to access external user’s data: look for another solution. This solution is ONLY meant when you ONLY need access to your own account(s) through the API. Other Solutions Mr Dallas Devries posted a solution here which involves requesting and scraping a one-time PIN. But: I like to minimize the amount of calls I make to twitter’s API or pages to lessen my chances of meeting the fail whale. Also, as soon as the pin isn’t included in a div called ‘oauth_pin’ anymore, this will fail. However, mr Devries’ post was a starting point for my solution, so I’m much obliged to him posting his findings. Authenticating with the Twitter API: old vs new Acessing The Twitter API the old way: require ‘twitter’ httpauth = Twitter::HTTPAuth.new('my_account','my_secret_password') client = Twitter::Base.new(httpauth) client.update(‘Hurray!’) The OAuth way: require 'twitter' oauth = Twitter::OAuth.new('ve4whatafuzzksaMQKjoI', 'KliketyklikspQ6qYALcuNandsomemored8pQ6qYALIG7mbEQY') oauth.authorize_from_access('123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis', 'fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh') client = Twitter::Base.new(oauth) client.update(‘Hurray!’) In the above case, ve4whatafuzzksaMQKjoI is the ‘consumer key’ (sometimes also referred to as ‘consumer token’) and KliketyklikspQ6qYALcuNandsomemored8pQ6qYALIG7mbEQY is the ‘consumer secret’. You’ll get these from Twitter when you register your app. 123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis is the ‘access token’ and fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh is the ‘access secret’. This combination gives the registered application access to your account. I’ll show you how to obtain these by following the steps below. (Basically you’ll need a bunch of keys and you’ll have to jump a bit through hoops to obtain them for your server/bot. ) How to get these keys 1. Surf to the twitter apps registration page go to http://dev.twitter.com/apps to register your app. Login with your twitter account. 2. Register your application Enter something for Application name, Description, website,… as I said: they make you jump through hoops. If you plan on using the API to post tweets, Your application name and website will be used in the ‘5 minutes ago via…’ line below your tweet. You could use the this to point to a page with info about your bot, or maybe it’s useful for SEO purposes. For application type I choose ‘browser’ and entered http://www.hadermann.be/callback as a ‘Callback URL’. This url returns a 404 error, which is ideal because after giving our account access to our ‘application’ (step 6), it will redirect to this url with an ‘oauth_token’ and ‘oauth_verifier’ in the url. We need to get these from the url. It doesn’t really matter what you enter here though, you could leave it blank because you need to explicitely specify it when generating a request token. You probably want read&write access so set this at ‘Default Access type’. 3. Get your consumer key and consumer secret On the next page, copy/paste your ‘consumer key’ and ‘consumer secret’. You’ll need these later on. You also need these as part of the authentication in your script later on: oauth = Twitter::OAuth.new([consumer key], [consumer secret]) 4. Obtain your request token run the following in IRB to obtain your ‘request token’ Replace my fake consumer key and consumer secret with the one you obtained in step 3. And use something else instead http://www.hadermann.be/callback: although this will only give a 404, you shouldn’t trust me. irb(main):001:0> require 'oauth' irb(main):002:0> c = OAuth::Consumer.new('ve4whatafuzzksaMQKjoI', 'KliketyklikspQ6qYALcuNandsomemored8pQ6qYALIG7mbEQY', {:site => 'http://twitter.com'}) irb(main):003:0> request_token = c.get_request_token(:oauth_callback => 'http://www.hadermann.be/callback') irb(main):004:0> request_token.token => "UrperqaukeWsWt3IAlfbxzyBUFpwWIcWkHP94QH2C1" This (UrperqaukeWsWt3IAlfbxzyBUFpwWIcWkHP94QH2C1) is the request token: Copy/paste this token, you will need this next. 5. Authorize your application surf to https://api.twitter.com/oauth/authorize?oauth_token=[the above token], for example: https://api.twitter.com/oauth/authorize?oauth_token=UrperqaukeWsWt3IAlfbxzyBUFpwWIcWkHP94QH2C1 This will bring you to the ‘An application would like to connect to your account’- screen on Twitter where you can grant access to the app you just registered. If you aren’t still logged in, you need to login first. Click ‘Allow’. Unless you don’t trust yourself. 6. Get your oauth_verifier from the redirected url Your browser will be redirected to your callback url, with an oauth_token and oauth_verifier parameter appended. You’ll need the oauth_verifier. In my case the browser redirected to: http://www.hadermann.be/callback?oauth_token=UrperqaukeWsWt3IAlfbxzyBUFpwWIcWkHP94QH2C1&oauth_verifier=waoOhKo8orpaqvQe6rVi5fti4ejr8hPeZrTewyeag Which returned a 404, giving me the chance to copy/paste my oauth_verifier: waoOhKo8orpaqvQe6rVi5fti4ejr8hPeZrTewyeag 7. Request an access token Back to irb, use the oauth_verifier to request an access token, as follows: irb(main):005:0> at = request_token.get_access_token(:oauth_verifier => 'waoOhKo8orpaqvQe6rVi5fti4ejr8hPeZrTewyeag') irb(main):006:0> at.params[:oauth_token] => "123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis" irb(main):007:0> at.params[:oauth_token_secret] => "fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh" We’re there! 123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis is the access token. fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh is the access secret. Try it! Try the following to post an update: require 'twitter' oauth = Twitter::OAuth.new('ve4whatafuzzksaMQKjoI', 'KliketyklikspQ6qYALcuNandsomemored8pQ6qYALIG7mbEQY') oauth.authorize_from_access('123-owhfmeyAgfozdyt5hDeprSevsWmPo5rVeroGfsthis', 'fGiinCdqtehMeehiddenymDeAsasaawgGeryye8amh') client = Twitter::Base.new(oauth) client.update(‘Cowabunga!’) Now you can go to your twitter page and delete the tweet if you want to.

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