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  • Where do I start ?

    - by Panthe
    Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be learning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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  • Help with infrequent segmentation fault in accessing boost::unordered_multimap or struct

    - by Sarah
    I'm having trouble debugging a segmentation fault. I'd appreciate tips on how to go about narrowing in on the problem. The error appears when an iterator tries to access an element of a struct Infection, defined as: struct Infection { public: explicit Infection( double it, double rt ) : infT( it ), recT( rt ) {} double infT; // infection start time double recT; // scheduled recovery time }; These structs are kept in a special structure, InfectionMap: typedef boost::unordered_multimap< int, Infection > InfectionMap; Every member of class Host has an InfectionMap carriage. Recovery times and associated host identifiers are kept in a priority queue. When a scheduled recovery event arises in the simulation for a particular strain s in a particular host, the program searches through carriage of that host to find the Infection whose recT matches the recovery time (double recoverTime). (For reasons that aren't worth going into, it's not as expedient for me to use recT as the key to InfectionMap; the strain s is more useful, and coinfections with the same strain are possible.) assert( carriage.size() > 0 ); pair<InfectionMap::iterator,InfectionMap::iterator> ret = carriage.equal_range( s ); InfectionMap::iterator it; for ( it = ret.first; it != ret.second; it++ ) { if ( ((*it).second).recT == recoverTime ) { // produces seg fault carriage.erase( it ); } } I get a "Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address..." on the line specified above. The recoverTime is fine, and the assert(...) in the code is not tripped. As I said, this seg fault appears 'randomly' after thousands of successful recovery events. How would you go about figuring out what's going on? I'd love ideas about what could be wrong and how I can further investigate the problem. Update I added a new assert and a check just inside the for loop: assert( carriage.size() > 0 ); assert( carriage.count( s ) > 0 ); pair<InfectionMap::iterator,InfectionMap::iterator> ret = carriage.equal_range( s ); InfectionMap::iterator it; cout << "carriage.count(" << s << ")=" << carriage.count(s) << endl; for ( it = ret.first; it != ret.second; it++ ) { cout << "(*it).first=" << (*it).first << endl; // error here if ( ((*it).second).recT == recoverTime ) { carriage.erase( it ); } } The EXC_BAD_ACCESS error now appears at the (*it).first call, again after many thousands of successful recoveries. Can anyone give me tips on how to figure out how this problem arises? I'm trying to use gdb. Frame 0 from the backtrace reads "#0 0x0000000100001d50 in Host::recover (this=0x100530d80, s=0, recoverTime=635.91148029170529) at Host.cpp:317" I'm not sure what useful information I can extract here. Update 2 I added a break; after the carriage.erase(it). This works, but I have no idea why (e.g., why it would remove the seg fault at (*it).first.

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  • Are your personal insecurities screwing up your internal communications?

    - by Lucy Boyes
    I do some internal comms as part of my job. Quite a lot of it involves talking to people about stuff. I’m spending the next couple of weeks talking to lots of people about internal comms itself, because we haven’t done a lot of audience/user feedback gathering, and it turns out that if you talk to people about how they feel and what they think, you get some pretty interesting insights (and an idea of what to do next that isn’t just based on guesswork and generalising from self). Three things keep coming up from talking to people about what we suck at  in terms of internal comms. And, as far as I can tell, they’re all examples where personal insecurity on the part of the person doing the communicating makes the experience much worse for the people on the receiving end. 1. Spending time telling people how you’re going to do something, not what you’re doing and why Imagine you’ve got to give an update to a lot of people who don’t work in your area or department but do have an interest in what you’re doing (either because they want to know because they’re curious or because they need to know because it’s going to affect their work too). You don’t want to look bad at your job. You want to make them think you’ve got it covered – ideally because you do*. And you want to reassure them that there’s lots of exciting work going on in your area to make [insert thing of choice] happen to [insert thing of choice] so that [insert group of people] will be happy. That’s great! You’re doing a good job and you want to tell people about it. This is good comms stuff right here. However, you’re slightly afraid you might secretly be stupid or lazy or incompetent. And you’re exponentially more afraid that the people you’re talking to might think you’re stupid or lazy or incompetent. Or pointless. Or not-adding-value. Or whatever the thing that’s the worst possible thing to be in your company is. So you open by mentioning all the stuff you’re going to do, spending five minutes or so making sure that everyone knows that you’re DOING lots of STUFF. And the you talk for the rest of the time about HOW you’re going to do the stuff, because that way everyone will know that you’ve thought about this really hard and done tons of planning and had lots of great ideas about process and that you’ve got this one down. That’s the stuff you’ve got to say, right? To prove you’re not fundamentally worthless as a human being? Well, maybe. But probably not. See, the people who need to know how you’re going to do the stuff are the people doing the stuff. And those are the people in your area who you’ve (hopefully-please-for-the-love-of-everything-holy) already talked to in depth about how you’re going to do the thing (because else how could they help do it?). They are the only people who need to know the how**. It’s the difference between strategy and tactics. The people outside of your bubble of stuff-doing need to know the strategy – what it is that you’re doing, why, where you’re going with it, etc. The people on the ground with you need the strategy and the tactics, because else they won’t know how to do the stuff. But the outside people don’t really need the tactics at all. Don’t bother with the how unless your audience needs it. They probably don’t. It might make you feel better about yourself, but it’s much more likely that Bob and Jane are thinking about how long this meeting has gone on for already than how personally impressive and definitely-not-an-idiot you are for knowing how you’re going to do some work. Feeling marginally better about yourself (but, let’s face it, still insecure as heck) is not worth the cost, which in this case is the alienation of your audience. 2. Talking for too long about stuff This is kinda the same problem as the previous problem, only much less specific, and I’ve more or less covered why it’s bad already. Basic motivation: to make people think you’re not an idiot. What you do: talk for a very long time about what you’re doing so as to make it sound like you know what you’re doing and lots about it. What your audience wants: the shortest meaningful update. Some of this is a kill your darlings problem – the stuff you’re doing that seems really nifty to you seems really nifty to you, and thus you want to share it with everyone to show that you’re a smart person who thinks up nifty things to do. The downside to this is that it’s mostly only interesting to you – if other people don’t need to know, they likely also don’t care. Think about how you feel when someone is talking a lot to you about a lot of stuff that they’re doing which is at best tangentially interesting and/or relevant. You’re probably not thinking that they’re really smart and clearly know what they’re doing (unless they’re talking a lot and being really engaging about it, which is not the same as talking a lot). You’re probably thinking about something totally unrelated to the thing they’re talking about. Or the fact that you’re bored. You might even – and this is the opposite of what they’re hoping to achieve by talking a lot about stuff – be thinking they’re kind of an idiot. There’s another huge advantage to paring down what you’re trying to say to the barest possible points – it clarifies your thinking. The lightning talk format, as well as other formats which limit the time and/or number of slides you have to say a thing, are really good for doing this. It’s incredibly likely that your audience in this case (the people who need to know some things about your thing but not all the things about your thing) will get everything they need to know from five minutes of you talking about it, especially if trying to condense ALL THE THINGS into a five-minute talk has helped you get clear in your own mind what you’re doing, what you’re trying to say about what you’re doing and why you’re doing it. The bonus of this is that by being clear in your thoughts and in what you say, and in not taking up lots of people’s time to tell them stuff they don’t really need to know, you actually come across as much, much smarter than the person who talks for half an hour or more about things that are semi-relevant at best. 3. Waiting until you’ve got every detail sorted before announcing a big change to the people affected by it This is the worst crime on the list. It’s also human nature. Announcing uncertainty – that something important is going to happen (big reorganisation, product getting canned, etc.) but you’re not quite sure what or when or how yet – is scary. There are risks to it. Uncertainty makes people anxious. It might even paralyse them. You can’t run a business while you’re figuring out what to do if you’ve paralysed everyone with fear over what the future might bring. And you’re scared that they might think you’re not the right person to be in charge of [thing] if you don’t even know what you’re doing with it. Best not to say anything until you know exactly what’s going to happen and you can reassure them all, right? Nope. The people who are going to be affected by whatever it is that you don’t quite know all the details of yet aren’t stupid***. You wouldn’t have hired them if they were. They know something’s up because you’ve got your guilty face on and you keep pulling people into meeting rooms and looking vaguely worried. Here’s the deal: it’s a lot less stressful for everyone (including you) if you’re up front from the beginning. We took this approach during a recent company-wide reorganisation and got really positive feedback. People would much, much rather be told that something is going to happen but you’re not entirely sure what it is yet than have you wait until it’s all fixed up and then fait accompli the heck out of them. They will tell you this themselves if you ask them. And here’s why: by waiting until you know exactly what’s going on to communicate, you remove any agency that the people that the thing is going to happen to might otherwise have had. I know you’re scared that they might get scared – and that’s natural and kind of admirable – but it’s also patronising and infantilising. Ask someone whether they’d rather work on a project which has an openly uncertain future from the beginning, or one where everything’s great until it gets shut down with no forewarning, and very few people are going to tell you they’d prefer the latter. Uncertainty is humanising. It’s you admitting that you don’t have all the answers, which is great, because no one does. It allows you to be consultative – you can actually ask other people what they think and how they feel and what they’d like to do and what they think you should do, and they’ll thank you for it and feel listened to and respected as people and colleagues. Which is a really good reason to start talking to them about what’s going on as soon as you know something’s going on yourself. All of the above assumes you actually care about talking to the people who work with you and for you, and that you’d like to do the right thing by them. If that’s not the case, you can cheerfully disregard the advice here, but if it is, you might want to think about the ways above – and the inevitable countless other ways – that making internal communication about you and not about your audience could actually be doing the people you’re trying to communicate with a huge disservice. So take a deep breath and talk. For five minutes or so. About the important things. Not the other things. As soon as you possibly can. And you’ll be fine.   *Of course you do. You’re good at your job. Don’t worry. **This might not always be true, but it is most of the time. Other people who need to know the how will either be people who you’ve already identified as needing-to-know and thus part of the same set as the people in you’re area you’ve already discussed this with, or else they’ll ask you. But don’t bring this stuff up unless someone asks for it, because most of the people in the audience really don’t care and you’re wasting their time. ***I mean, they might be. But let’s give them the benefit of the doubt and assume they’re not.

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  • Change the content of a <style> element through JavaScript

    - by paercebal
    The Problem I have the following code: <html> <head> <style id="ID_Style"> .myStyle { color : #FF0000 ; } </style> </head> <body> <p class="myStyle"> Hello World ! </p> </body> </html> And I want to modify the contents of <style> through JavaScript. The Expected Solution The first solution was to use the innerHTML property of the style element (retrieved through its id), but while it works on Firefox, it fails on Internet Explorer 7. So, I used pure DOM methods, that is, creating an element called style, a text node with the desired content, and append the text node as a child of the style node, etc. It fails, too. According to MSDN, the <style> element has an innerHTML property, and according to W3C, the <style> element is a HTMLStyleElement, which derives from HTMLElement, deriving from Element deriving from Node, which has the appendChild method. It seems to behave as if the content of a <style> element was readonly on Internet Explorer. The Question So the question is: Is there a way to modify the content of a <style> element on Internet Explorer? While the current problem is with IE7, a cross-browser solution would be cool, if possible. Appendix Sources: Style Element (MSDN): http://msdn.microsoft.com/en-us/library/ms535898.aspx HTMLStyleElement (W3C): http://www.w3.org/TR/2003/REC-DOM-Level-2-HTML-20030109/html.html#ID-16428977 Complete Test Code You can use this test code if you want to reproduce your problem: <html> <head> <style id="ID_Style"> .myStyle { color : #FF0000 ; } </style> <script> function replaceStyleViaDOM(p_strContent) { var oOld = document.getElementById("ID_Style") ; var oParent = oOld.parentNode ; oParent.removeChild(oOld) ; var oNew = document.createElement("style") ; oParent.appendChild(oNew) ; oNew.setAttribute("id", "ID_Style") ; var oText = document.createTextNode(p_strContent) ; oNew.appendChild(oText) ; } function replaceStyleViaInnerHTML(p_strContent) { document.getElementById("ID_Style").innerHTML = p_strContent ; } </script> <script> function setRedViaDOM() { replaceStyleViaDOM("\n.myStyle { color : #FF0000 ; }\n") } function setRedViaInnerHTML() { replaceStyleViaInnerHTML("\n.myStyle { color : #FF0000 ; }\n") } function setBlueViaDOM() { replaceStyleViaDOM("\n.myStyle { color : #0000FF ; }\n") } function setBlueViaInnerHTML() { replaceStyleViaInnerHTML("\n.myStyle { color : #0000FF ; }\n") } function alertStyle() { alert("*******************\n" + document.getElementById("ID_Style").innerHTML + "\n*******************") ; } </script> </head> <body> <div> <button type="button" onclick="alertStyle()">alert Style</button> <br /> <button type="button" onclick="setRedViaDOM()">set Red via DOM</button> <button type="button" onclick="setRedViaDOM()">set Red via InnerHTML</button> <br /> <button type="button" onclick="setBlueViaDOM()">set Blue via DOM</button> <button type="button" onclick="setBlueViaInnerHTML()">set Blue via InnerHTML</button> </div> <p class="myStyle"> Hello World ! </p> </body> </html> Thanks !

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  • window.requestFileSystem fails/events firing multiple times in PhoneGap Cordova 3

    - by ezycheez
    cordova 3.1.0-0.2.0 Droid Razr M Android 4.1.2 Windows 7 New to PhoneGap/Cordova. Running one of the filesystem demos from http://docs.phonegap.com/en/3.1.0/cordova_file_file.md.html#File. Using "cordova run android" to compile the code and run it on the phone attached via USB. Problem #1: When the app first starts I get alert("1") twice and then nothing else. Problem #2: When I kick of the code via the button onclick I get the following alert pattern: 1, 2, 2, 3, 3, 4, 6, 5, 7, 4, 6, 5, 7. Some of that makes sense based on the code flow but most of them are firing twice. I'm suspecting problem #2 is being caused by some asynchronous calls hanging out from the first attempt but no matter how long I wait those events don't fire until I kick of the code via the button. So why is the requestFileSystem call failing even though it is waiting for deviceready and why is the other code getting intermingled? Any thoughts are appreciated. <!DOCTYPE html> <html> <head> <title>FileReader Example</title> <script type="text/javascript" charset="utf-8" src="cordova.js"></script> <script type="text/javascript" charset="utf-8"> // Wait for device API libraries to load // document.addEventListener("deviceready", onDeviceReady, false); // device APIs are available // function onDeviceReady() { alert("1"); window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, gotFS, fail); } function gotFS(fileSystem) { alert("2"); fileSystem.root.getFile("readme.txt", null, gotFileEntry, fail); } function gotFileEntry(fileEntry) { alert("3"); fileEntry.file(gotFile, fail); } function gotFile(file) { alert("4"); readDataUrl(file); alert("5"); readAsText(file); } function readDataUrl(file) { alert("6"); var reader = new FileReader(); reader.onloadend = function (evt) { console.log("Read as data URL"); console.log(evt.target.result); }; reader.readAsDataURL(file); } function readAsText(file) { alert("7"); var reader = new FileReader(); reader.onloadend = function (evt) { console.log("Read as text"); console.log(evt.target.result); }; reader.readAsText(file); } function fail(error) { alert("8"); console.log(error.code); } </script> </head> <body> <h1>Example</h1> <p>Read File</p> <button onclick="onDeviceReady();">Read File</button> </body> </html>

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  • Entity Framework RC1 DbContext query issue

    - by Steve
    I'm trying to implement the repository pattern using entity framework code first rc 1. The problem I am running into is with creating the DbContext. I have an ioc container resolving the IRepository and it has a contextprovider which just news up a new DbContext with a connection string in a windsor.config file. With linq2sql this part was no problem but EF seems to be choking. I'll describe the problem below with an example. I've pulled out the code to simplify things a bit so that is why you don't see any repository pattern stuff here. just sorta what is happening without all the extra code and classes. using (var context = new PlssContext()) { var x = context.Set<User>(); var y = x.Where(u => u.UserName == LogOnModel.UserName).FirstOrDefault(); } using (var context2 = new DbContext(@"Data Source=.\SQLEXPRESS;Initial Catalog=PLSS.Models.PlssContext;Integrated Security=True;MultipleActiveResultSets=True")) { var x = context2.Set<User>(); var y = x.Where(u => u.UserName == LogOnModel.UserName).FirstOrDefault(); } PlssContext is where I am creating my DbContext class. The repository pattern doesn't know anything about PlssContext. The best I thought I could do was create a DbContext with the connection string to the sqlexpress database and query the data that way. The connection string in the var context2 was grabbed from the context after newing up the PlssContext object. So they are pointing at the same sqlexpress database. The first query works. The second query fails miserably with this error: The model backing the 'DbContext' context has changed since the database was created. Either manually delete/update the database, or call Database.SetInitializer with an IDatabaseInitializer instance. For example, the DropCreateDatabaseIfModelChanges strategy will automatically delete and recreate the database, and optionally seed it with new data. on this line var y = x.Where(u => u.UserName == LogOnModel.UserName).FirstOrDefault(); Here is my DbContext namespace PLSS.Models { public class PlssContext : DbContext { public DbSet<User> Users { get; set; } public DbSet<Corner> Corners { get; set; } public DbSet<Lookup_County> Lookup_County { get; set; } public DbSet<Lookup_Accuracy> Lookup_Accuracy { get; set; } public DbSet<Lookup_MonumentStatus> Lookup_MonumentStatus { get; set; } public DbSet<Lookup_CoordinateSystem> Lookup_CoordinateSystem { get; set; } public class Initializer : DropCreateDatabaseAlways<PlssContext> { protected override void Seed(PlssContext context) { I've tried all of the Initializer strategies with the same errors. I don't think the database is changing. If I remove the modelBuilder.Conventions.Remove<IncludeMetadataConvention>(); Then the error returns is The entity type User is not part of the model for the current context. Which sort of makes sense. But how do you bring this all together?

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  • RackSpace Cloud Strips $_SESSION if URL Has Certain File Extensions

    - by macinjosh
    The Situation I am creating a video training site for a client on the RackSpace Cloud using the traditional LAMP stack (RackSpace's cloud has both Windows and LAMP stacks). The videos and other media files I'm serving on this site need to be protected as my client charges money for access to them. There is no DRM or funny business like that, essentially we store the files outside of the web root and use PHP to authenticate user's before they are able to access the files by using mod_rewrite to run the request through PHP. So let's say the user requests a file at this URL: http://www.example.com/uploads/preview_image/29.jpg I am using mod_rewrite to rewrite that url to: http://www.example.com/files.php?path=%2Fuploads%2Fpreview_image%2F29.jpg Here is a simplified version of the files.php script: <?php // Setups the environment and sets $logged_in // This part requires $_SESSION require_once('../../includes/user_config.php'); if (!$logged_in) { // Redirect non-authenticated users header('Location: login.php'); } // This user is authenticated, continue $content_type = "image/jpeg"; // getAbsolutePathForRequestedResource() takes // a Query Parameter called path and uses DB // lookups and some string manipulation to get // an absolute path. This part doesn't have // any bearing on the problem at hand $file_path = getAbsolutePathForRequestedResource($_GET['path']); // At this point $file_path looks something like // this: "/path/to/a/place/outside/the/webroot" if (file_exists($file_path) && !is_dir($file_path)) { header("Content-Type: $content_type"); header('Content-Length: ' . filesize($file_path)); echo file_get_contents($file_path); } else { header('HTTP/1.0 404 Not Found'); header('Status: 404 Not Found'); echo '404 Not Found'; } exit(); ?> The Problem Let me start by saying this works perfectly for me. On local test machines it works like a charm. However once deployed to the cloud it stops working. After some debugging it turns out that if a request to the cloud has certain file extensions like .JPG, .PNG, or .SWF (i.e. extensions of typically static media files.) the request is routed to a cache system called Varnish. The end result of this routing is that by the time this whole process makes it to my PHP script the session is not present. If I change the extension in the URL to .PHP or if I even add a query parameter Varnish is bypassed and the PHP script can get the session. No problem right? I'll just add a meaningless query parameter to my requests! Here is the rub: The media files I am serving through this system are being requested through compiled SWF files that I have zero control over. They are generated by third-party software and I have no hope of adding or changing the URLs that they request. Are there any other options I have on this? Update: I should note that I have verified this behavior with RackSpace support and they have said there is nothing they can do about it.

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  • Recommended integration mechanism for bi-directional, authenticated, encrypted connection in C clien

    - by rcampbell
    Let me first give an example. Imagine you have a single server running a JVM application. This server keeps a collection of N equations, once for each client: Client #1: 2x Client #2: 1 + y Client #3: z/4 This server includes an HTTP interface so that random visitors can type https://www.acme.com/client/3 int their browsers and see the latest evaluated result of z/4. The tricky part is that either the client or the server may change the variable value at any time, informing the other party immediately. More specifically, Client #3 - a C app - can initially tell the server that z = 20. An hour later that same client informs the server that z = 23. Likewise the server can later inform the client that z = 28. As caf pointed out in the comments, there can be a race condition when values are changed by the client and server simultaneously. The solution would be for both client and server to send the operation performed in their message, which would need to be executed by the other party. To keep things simple, let's limit the operations to (commutative) addition, allowing us to disregard message ordering. For example, the client seeds the server with z = 20: server:z=20, client:z=20 server sends {+3} message (so z=23 locally) & client sends {-2} message (so z=18 locally) at the exact same time server receives {-2} message at some point, adds to his local copy so z=21 client receives {+3} message at some point, adds to his local copy so z=21 As long as all messages are eventually evaluated by both parties, the correct answer will eventually be given to the users of the client and server since we limited ourselves to commutative operations (addition of 3 and -2). This does mean that both client and server can be returning incorrect answers in the time it takes for messages to be exchanged and processed. While undesirable, I believe this is unavoidable. Some possible implementations of this idea include: Open an encrypted, always on TCP socket connection for communication Pros: no additional infrastructure needed, client and server know immediately if there is a problem (disconnect) with the other party, fairly straightforward (except the the encryption), native support from both JVM and C platforms Cons: pretty low-level so you end up writing a lot yourself (protocol, delivery verification, retry-on-failure logic), probably have a lot of firewall headaches during client app installation Asynchronous messaging (ex: ActiveMQ) Pros: transactional, both C & Java integration, free up the client and server apps from needing retry logic or delivery verification, pretty straightforward encryption, easy extensibility via message filters/routers/etc Cons: need additional infrastructure (message server) which must never fail, Database or file system as asynchronous integration point Same pros/cons as above but messier RESTful Web Service Pros: simple, possible reuse of the server's existing REST API, SSL figures out the encryption problem for you (maybe use RSA key a la GitHub for authentication?) Cons: Client now needs to run a C HTTP REST server w/SSL, client and server need retry logic. Axis2 has both a Java and C version, but you may be limited to SOAP. What other techniques should I be evaluating? What real world experiences have you had with these mechanisms? Which do you recommend for this problem and why?

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  • PHP Mail Not Sending Messages

    - by Kenton de Jong
    I realize this question title is pretty overused, but I couldn't find an answer to my problem. This could be because either I'm not too good with PHP and I don't understand the problem, or because I have a different issue, but I thought I would post it and see if somebody can help me. I developed a website for a local church in my city and I made the site on my computer, put it onto my website as a sub directory and tested it all. It worked great. One of the things the client wanted was there to be an email form that can send emails. I made it and all was good. I then uploaded it onto the church server and thought it went good too. But then we decided to try the email form out, and for some reason it didn't work. I made the email form by having the user select a recipient (pastor, office manager, etc.) with a radio button, and that would change the action of the email form. I just did something like this: if (recipent == "pastor") { document.forms[0].action = "../scripts/php/pastor_contact.php"; } else if (recipent == "pastoralAssist") { document.forms[0].action = "../scripts/php/pastoral_assist_contact.php"; } else if (recipent == "famMinistry") { document.forms[0].action = "../scripts/php/sacra_assist_contact.php"; } else if (recipent == "sacraAssist") { document.forms[0].action = "../scripts/php/fam_ministry_contact.php"; } I know this isn't the cleanest, but it works great. The php files then, all look very similar to this (just a different email)" <?php $name = $_POST['name']; $email = $_POST['email']; $phone = $_POST['phone']; $message = $_POST['message']; $formcontent="From: $name \n Email: $email \n Phone Number: $phone \n Message: $message"; $recipient = "[email protected]"; $subject = $_POST['subject']; $mailheader = "$subject \r\n"; mail($recipient, $subject, $formcontent, $mailheader) or die("There seems to be an error with this form. Sorry about the inconveince. We are working to get this fixed."); header('Location: ../../quickylinks/message_sent.html') ; ?> What this does, briefly, is collect the information from the email form, submit it as an email and then redirect the user to a "Message Sent" page. This works on my server, but not theirs so I believe it's something to do with their server. You can see their server information here and mine here. When the user sends the message, they get "There seems to be an error with this form. Sorry about the inconveince. We are working to get this fixed." and the email doesn't go through, although the code is the same on my server and it works fine there. My initial thought was that PHP wasn't installed on their server (rare, but it does happen). But it was. So then I thought maybe it was installed, but the "mail" function was disabled. So I tried the following php code: <?php if (function_exists('mail')) { echo 'mail() is available'; } else { echo 'mail() has been disabled'; } ?> And it came back with "mail() is available". So now I'm stuck and I don't know the problem could be. As I said, I'm not very good at PHP yet so if somebody could give a detailed answer, I would be really really thankful! Thank you so much!

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  • Conflict between some JavaScript and jQuery on same page

    - by hollyb
    I am using a JavaScript function and some jQuery to perform two actions on a page. The first is a simple JS function to hide/show divs and change the active state of a tab: This is the JS that show/hides divs and changes the active state on some tabs: var ids=new Array('section1','section2','section3'); function switchid(id, el){ hideallids(); showdiv(id); var li = el.parentNode.parentNode.childNodes[0]; while (li) { if (!li.tagName || li.tagName.toLowerCase() != "li") li = li.nextSibling; // skip the text node if (li) { li.className = ""; li = li.nextSibling; } } el.parentNode.className = "active"; } function hideallids(){ //loop through the array and hide each element by id for (var i=0;i<ids.length;i++){ hidediv(ids[i]); } } function hidediv(id) { //safe function to hide an element with a specified id document.getElementById(id).style.display = 'none'; } function showdiv(id) { //safe function to show an element with a specified id document.getElementById(id).style.display = 'block'; } The html: <ul> <li class="active"><a onclick="switchid('section1', this);return false;">ONE</a></li> <li><a onclick="switchid('section2', this);return false;">TWO</a></li> <li><a onclick="switchid('section3', this);return false;">THREE</a></li> </ul> <div id="section1" style="display:block;">TEST</div> <div id="section2" style="display:none;">TEST 2</div> <div id="section3" style="display:none;">TEST 3</div> Now the problem.... I've added the jQuery image gallery called galleria to one of the tabs. The gallery works great when it resides in the div that is intially set to display:block. However, when it is in one of the divs that is set to display: none; part of the gallery doesn't work when the div is toggled to be visible. Specifically, the following css ceases to be written (this is created by galleria jQuery): element.style { display:block; height:50px; margin-left:-17px; width:auto; } For the life of me, I can't figure out why the gallery fails when it's div is set to display: none. Since this declaration is overwritten when a tab is clicked (via the Javascript functions above), why would this cause a problem? As I mentioned, it works perfectly when it lives the in display: block; div. Any ideas? I don't expect anybody to be familiar with the jQuery galleria image gallery... but perhaps an idea of how one might repair this problem? Thanks!

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  • Help with Silverlight Sockets and Message delivery

    - by pixel3cs
    There are 4 months since I stopped developing my Silverlight Multiplayer Chess game. The problem was a bug wich I couldn't reproduce. Sice I got some free time this week I managed to discover the problem and I am now able to reproduce the bug. It seems that if I send 10 messages from client, one after another, with no delay between them, just like in the below example // when I press Enter, the client will 10 messages with no delay between them private void textBox_KeyDown(object sender, KeyEventArgs e) { if (e.Key == Key.Enter && textBox.Text.Length > 0) { for (int i = 0; i < 10; i++) { MessageBuilder mb = new MessageBuilder(); mb.Writer.Write((byte)GameCommands.NewChatMessageInTable); mb.Writer.Write(string.Format("{0}{2}: {1}", ClientVars.PlayerNickname, textBox.Text, i)); SendChatMessageEvent(mb.GetMessage()); //System.Threading.Thread.Sleep(100); } textBox.Text = string.Empty; } } // the method used by client to send a message to server public void SendData(Message message) { if (socket.Connected) { SocketAsyncEventArgs myMsg = new SocketAsyncEventArgs(); myMsg.RemoteEndPoint = socket.RemoteEndPoint; byte[] buffer = message.Buffer; myMsg.SetBuffer(buffer, 0, buffer.Length); socket.SendAsync(myMsg); } else { string err = "Server does not respond. You are disconnected."; socket.Close(); uiContext.Post(this.uiClient.ProcessOnErrorData, err); } } // the method used by server to receive data from client private void OnDataReceived(IAsyncResult async) { ClientSocketPacket client = async.AsyncState as ClientSocketPacket; int count = 0; try { if (client.Socket.Connected) count = client.Socket.EndReceive(async); // THE PROBLEM IS HERE // IF SERVER WAS RECEIVE ALL MESSAGES SEPARATELY, ONE BY ONE, THE COUNT // WAS ALWAYS 15, BUT BECAUSE THE SERVER RECEIVE 3 MESSAGES IN 1, THE COUNT // IS SOMETIME 45 } catch { HandleException(client); } client.MessageStream.Write(client.Buffer, 0, count); Message message; while (client.MessageStream.Read(out message)) { message.Tag = client; ThreadPool.QueueUserWorkItem(new WaitCallback(this.processingThreadEvent.ServerGotData), message); totalReceivedBytes += message.Buffer.Length; } try { if (client.Socket.Connected) client.Socket.BeginReceive(client.Buffer, 0, client.Buffer.Length, 0, new AsyncCallback(OnDataReceived), client); } catch { HandleException(client); } } there are sent only 3 big messages, and every big message contain 3 or 4 small messages. This is not the behavior I want. If I put a 100 milliseconds delay between message delivery, everything is work fine, but in a real world scenario users can send messages to server even at 1 millisecond between them. Are there any settings to be done in order to make the client send only one message at a time, or Even if I receive 3 messages in 1, are they full messages all the time (I dont't want to receive 2.5 messages in one big message) ? because if they are, I can read them and treat this new situation

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  • auth.getSession not working

    - by dC
    hi all, i am having troubles with calling auth.getSession in my proxy. It is being called from a iPhone connect client. When the proxy URL is invocated from the iphone, FB returns a 100 invalid parameter error to the proxy. However the 2nd attempt from iPhone yields success. Both times the proxy is doing the same code, only the auth_token is different. Doing a good search, shows that this is a problematic method. I have tried everything in code and even called in a iPhone expert to see if the problem is on the iPhone client. I have concentrated my efforts on the java api being the problem, however i believe the problem lies else where. I have done the following checked and tested java code checked and test iphone code checked FB application settings. any help is most appreciated. ------Here is my java code.--------- String api_secret = FacebookProperty.getString(FacebookConstants.PROPERTY_API_SECRET); String api_key = FacebookProperty.getString(FacebookConstants.PROPERTY_API_KEY); String call_back_url = FacebookProperty.getString(FacebookConstants.PROPERTY_CALLBACK_URL); int connectTimeout = 200000; //use the xml helper // Make sure the user is logged in to Facebook String authToken = request.getParameter("auth_token"); log.info( "FACEBOOK: auth_token?: " + authToken ); Map<String, Object> model = new HashMap<String, Object>(); model.put(FacebookConstants.MODEL_WELCOME_SELECTED, true); FacebookXmlRestClient facebookRestClient = new FacebookXmlRestClient(api_key, api_secret); boolean generateSessionSecret = true; //always true of connect client try{ facebookRestClient.setConnectTimeout(connectTimeout ); String authSessionKey = facebookRestClient.auth_getSession(authToken, true); } catch (Exception e) { log.log( Level.SEVERE, e.toString()); log.log( Level.SEVERE, e.getMessage()); } String rawResponse = facebookRestClient.getRawResponse(); log.info( rawResponse ); -------the iphone code is ----------- session = [FBSession sessionForApplication:myApiKey getSessionProxy:myURL delegate:self]; -----------the error is -------------- <error_response xmlns="http://api.facebook.com/1.0/" xmlns:xsi="http:// www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http:// api.facebook.com/1.0/ http://api.facebook.com/1.0/facebook.xsd"> <error_code>100</error_code> <error_msg>Invalid parameter</error_msg> <request_args list="true"> <arg> <key>api_key</key> <value>bf22a0512c8558a1656d73160507460b</value> </arg> <arg> <key>auth_token</key> <value>fcd1e597aca5c9ba43875cdd01221be5</value> </arg> <arg> <key>call_id</key> <value>1269066988055</value> </arg> <arg> <key>format</key> <value>xml</value> </arg> <arg> <key>generate_session_secret</key> <value>true</value> </arg> <arg> <key>method</key> <value>facebook.auth.getSession</value> </arg> <arg> <key>sig</key> <value>e9f477fd72adf74cd2de72528fd9aa72</value> </arg> <arg> <key>v</key> <value>1.0</value> </arg> </request_args> </error_response>

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  • Simple Detached pThread does not cancel! (cout blocks and interleaves even if mutexed)

    - by Gabriel
    I have a hard problem here, which I can not solve and do not find the right answer on the net: I have created a detached thread with a clean up routing, the problem is that on my Imac and Ubuntu 9.1 (Dual Core). I am not able to correctly cancel the detached thread in the fallowing code: #include <iostream> #include <pthread.h> #include <sched.h> #include <signal.h> #include <time.h> pthread_mutex_t mutex_t; using namespace std; static void cleanup(void *arg){ pthread_mutex_lock(&mutex_t); cout << " doing clean up"<<endl; pthread_mutex_unlock(&mutex_t); } static void *thread(void *aArgument) { pthread_setcancelstate(PTHREAD_CANCEL_ENABLE,NULL); pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED,NULL); pthread_cleanup_push(&cleanup,NULL); int n=0; while(1){ pthread_testcancel(); sched_yield(); n++; pthread_mutex_lock(&mutex_t); cout << " Thread 2: "<< n<<endl; pthread_mutex_unlock(&mutex_t); } pthread_cleanup_pop(0); return NULL; } int main() { pthread_t thread_id; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED); int error; if (pthread_mutex_init(&mutex_t,NULL) != 0) return 1; if (pthread_create(&thread_id, &attr, &(thread) , NULL) != 0) return 1; pthread_mutex_lock(&mutex_t); cout << "waiting 1s for thread...\n" <<endl; pthread_mutex_unlock(&mutex_t); int n =0; while(n<1E3){ pthread_testcancel(); sched_yield(); n++; pthread_mutex_lock(&mutex_t); cout << " Thread 1: "<< n<<endl; pthread_mutex_unlock(&mutex_t); } pthread_mutex_lock(&mutex_t); cout << "canceling thread...\n" <<endl; pthread_mutex_unlock(&mutex_t); if (pthread_cancel(thread_id) == 0) { //This doesn't wait for the thread to exit pthread_mutex_lock(&mutex_t); cout << "detaching thread...\n"<<endl; pthread_mutex_unlock(&mutex_t); pthread_detach(thread_id); while (pthread_kill(thread_id,0)==0) { sched_yield(); } pthread_mutex_lock(&mutex_t); cout << "thread is canceled"; pthread_mutex_unlock(&mutex_t); } pthread_mutex_lock(&mutex_t); cout << "exit"<<endl; pthread_mutex_unlock(&mutex_t); return 0; } When I replace the Cout with printf() i workes to the end "exit" , but with the cout (even locked) the executable hangs after outputting "detaching thread... It would be very cool to know from a Pro, what the problem here is?. Why does this not work even when cout is locked by a mutex!? Thanks a lot for your support!!

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  • How to kill android application using android code?

    - by Natarajan M
    I am develoing small android application in eclipse. In that project i kill the running process in android, i got the Permission Denial error. how can i solve this problem in android. Anybody help for this problem.... THIS IS MY CODE package com.example.nuts; import java.util.Iterator; import java.util.List; import android.app.Activity; import android.app.ActivityManager; import android.app.ActivityManager.RunningAppProcessInfo; import android.content.Context; import android.content.pm.PackageManager; import android.os.Bundle; import android.telephony.SmsManager; import android.widget.Toast; import android.*; public class killprocess extends Activity { SmsManager smsManager = SmsManager.getDefault(); Recivesms rms=new Recivesms(); String Number=""; int pid=0; String appname=""; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); try { Number=Recivesms.senderNum; pid=Integer.parseInt(Recivesms.struid); appname=getAppName(pid); Toast.makeText(getBaseContext(),"App Name is "+appname, Toast.LENGTH_LONG).show(); ActivityManager am = (ActivityManager) getSystemService(Activity.ACTIVITY_SERVICE); List<RunningAppProcessInfo> processes = am.getRunningAppProcesses(); if (processes != null){ for (int i=0; i<processes.size(); i++){ RunningAppProcessInfo temp = processes.get(i); String pName = temp.processName; if (pName.equals(appname)) { Toast.makeText(getBaseContext(),"App Name is matched "+appname+" "+pName, Toast.LENGTH_LONG).show(); int pid1 = android.os.Process.getUidForName(pName); //android.os.Process.killProcess(pid1); am.killBackgroundProcesses(pName); Toast.makeText(getBaseContext(), "Killed successfully....", Toast.LENGTH_LONG).show(); } } } smsManager.sendTextMessage(Number, null,"Your process Successfully killed..." , null,null); }catch(Exception e) { Toast.makeText(getBaseContext(),e.getMessage(), Toast.LENGTH_LONG).show(); } } private String getAppName(int Pid) { String processName = ""; ActivityManager am = (ActivityManager)this.getSystemService(ACTIVITY_SERVICE); List l = am.getRunningAppProcesses(); Iterator i = l.iterator(); PackageManager pm = this.getPackageManager(); while(i.hasNext()) { ActivityManager.RunningAppProcessInfo info = (ActivityManager.RunningAppProcessInfo)(i.next()); try { if(info.pid == Pid) { CharSequence c = pm.getApplicationLabel(pm.getApplicationInfo(info.processName, PackageManager.GET_META_DATA)); //Log.d("Process", "Id: "+ info.pid +" ProcessName: "+ info.processName +" Label: "+c.toString()); //processName = c.toString(); processName = info.processName; } } catch(Exception e) { //Log.d("Process", "Error>> :"+ e.toString()); } } return processName; } } After executing the code. i got the following error... Permission Denial: killBackgroundProcess() from pid=894, uid=10052 requires android.permission.KILL_BACKGROUND_PROCESSES Also i put the following line on manifest file <uses-permission android:name="android.permission.KILL_BACKGROUND_PROCESS" /> Anybody help for how to solve this problem... Thanking you....

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  • Lock free multiple readers single writer

    - by dummzeuch
    I have got an in memory data structure that is read by multiple threads and written by only one thread. Currently I am using a critical section to make this access threadsafe. Unfortunately this has the effect of blocking readers even though only another reader is accessing it. There are two options to remedy this: use TMultiReadExclusiveWriteSynchronizer do away with any blocking by using a lock free approach For 2. I have got the following so far (any code that doesn't matter has been left out): type TDataManager = class private FAccessCount: integer; FData: TDataClass; public procedure Read(out _Some: integer; out _Data: double); procedure Write(_Some: integer; _Data: double); end; procedure TDataManager.Read(out _Some: integer; out _Data: double); var Data: TDAtaClass; begin InterlockedIncrement(FAccessCount); try // make sure we get both values from the same TDataClass instance Data := FData; // read the actual data _Some := Data.Some; _Data := Data.Data; finally InterlockedDecrement(FAccessCount); end; end; procedure TDataManager.Write(_Some: integer; _Data: double); var NewData: TDataClass; OldData: TDataClass; ReaderCount: integer; begin NewData := TDataClass.Create(_Some, _Data); InterlockedIncrement(FAccessCount); OldData := TDataClass(InterlockedExchange(integer(FData), integer(NewData)); // now FData points to the new instance but there might still be // readers that got the old one before we exchanged it. ReaderCount := InterlockedDecrement(FAccessCount); if ReaderCount = 0 then // no active readers, so we can safely free the old instance FreeAndNil(OldData) else begin /// here is the problem end; end; Unfortunately there is the small problem of getting rid of the OldData instance after it has been replaced. If no other thread is currently within the Read method (ReaderCount=0), it can safely be disposed and that's it. But what can I do if that's not the case? I could just store it until the next call and dispose it there, but Windows scheduling could in theory let a reader thread sleep while it is within the Read method and still has got a reference to OldData. If you see any other problem with the above code, please tell me about it. This is to be run on computers with multiple cores and the above methods are to be called very frequently. In case this matters: I am using Delphi 2007 with the builtin memory manager. I am aware that the memory manager probably enforces some lock anyway when creating a new class but I want to ignore that for the moment. Edit: It may not have been clear from the above: For the full lifetime of the TDataManager object there is only one thread that writes to the data, not several that might compete for write access. So this is a special case of MREW.

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  • Explicit method tables in C# instead of OO - good? bad?

    - by FunctorSalad
    Hi! I hope the title doesn't sound too subjective; I absolutely do not mean to start a debate on OO in general. I'd merely like to discuss the basic pros and cons for different ways of solving the following sort of problem. Let's take this minimal example: you want to express an abstract datatype T with functions that may take T as input, output, or both: f1 : Takes a T, returns an int f2 : Takes a string, returns a T f3 : Takes a T and a double, returns another T I'd like to avoid downcasting and any other dynamic typing. I'd also like to avoid mutation whenever possible. 1: Abstract-class-based attempt abstract class T { abstract int f1(); // We can't have abstract constructors, so the best we can do, as I see it, is: abstract void f2(string s); // The convention would be that you'd replace calls to the original f2 by invocation of the nullary constructor of the implementing type, followed by invocation of f2. f2 would need to have side-effects to be of any use. // f3 is a problem too: abstract T f3(double d); // This doesn't express that the return value is of the *same* type as the object whose method is invoked; it just expresses that the return value is *some* T. } 2: Parametric polymorphism and an auxilliary class (all implementing classes of TImpl will be singleton classes): abstract class TImpl<T> { abstract int f1(T t); abstract T f2(string s); abstract T f3(T t, double d); } We no longer express that some concrete type actually implements our original spec -- an implementation is simply a type Foo for which we happen to have an instance of TImpl. This doesn't seem to be a problem: If you want a function that works on arbitrary implementations, you just do something like: // Say we want to return a Bar given an arbitrary implementation of our abstract type Bar bar<T>(TImpl<T> ti, T t); At this point, one might as well skip inheritance and singletons altogether and use a 3 First-class function table class /* or struct, even */ TDictT<T> { readonly Func<T,int> f1; readonly Func<string,T> f2; readonly Func<T,double,T> f3; TDict( ... ) { this.f1 = f1; this.f2 = f2; this.f3 = f3; } } Bar bar<T>(TDict<T> td; T t); Though I don't see much practical difference between #2 and #3. Example Implementation class MyT { /* raw data structure goes here; this class needn't have any methods */ } // It doesn't matter where we put the following; could be a static method of MyT, or some static class collecting dictionaries static readonly TDict<MyT> MyTDict = new TDict<MyT>( (t) => /* body of f1 goes here */ , // f2 (s) => /* body of f2 goes here */, // f3 (t,d) => /* body of f3 goes here */ ); Thoughts? #3 is unidiomatic, but it seems rather safe and clean. One question is whether there are any performance concerns with it. I don't usually need dynamic dispatch, and I'd prefer if these function bodies get statically inlined in places where the concrete implementing type is known statically. Is #2 better in that regard?

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  • Using resize to getScript if above x pixels (jQuery)

    - by user1065573
    So I have an issue with this script. It basically is loading the script on any resize event. I have it working if lets say... - User has window size above 768 (getScipt() and content by .load() in that script) - Script will load (and content) - User for some reason window size goes below 768 (css hides #div) - User re-sizes again above 768, And does not load the script again! (css displays the div) Great. Works right. Now.. (for some cray reason) - User has window size below 768 (Does NOT getScript() or nothing) - User re-sizes above 768 and stops at any px (getScript and content) - User re-sizes again anything above 768 (It getScript AGAIN) I need it to only get script once. Ive used some code from here jQuery: How to detect window width on the fly? (edit - i found this, which he has the same issue of loading a script once.) Problem with function within $(window).resize - using jQuery And others i lost the links to :/ When i first found this problem I was using something like this, then i added the allcheckWidth() to solve problem. But it does not. var $window = $(window); function checkWidth() { var windowsize = $window.width(); ////// LETS GET SOME THINGS IF IS DESKTOP var $desktop_load = 0; if (windowsize >= 768) { if (!$desktop_load) { // GET DESKTOP SCRIPT TO KEEP THINGS QUICK $.getScript("js/desktop.js", function() { $desktop_load = 1; }); } else { } } ////// LETS GET SOME THINGS IF IS MOBILE if (windowsize < 768) { } } checkWidth(); function allcheckWidth () { var windowsize = $window.width(); //// IF WINDOW SIZE LOADS < 768 THEN CHANGES >= 768 LOAD ONCE var $desktop_load = 0; if (!$desktop_load) { if (windowsize < 768) { if ( $(window).width() >= 768) { $.getScript("js/desktop.js", function() { $desktop_load = 1; }); } } } } $(window).resize(allcheckWidth); Now im using something like this which makes more sense? $(function() { $(window).resize(function() { var $desktop_load = 0; //Dekstop if (window.innerWidth >= 768) { if (!$desktop_load) { // GET DESKTOP SCRIPT TO KEEP THINGS QUICK $.getScript("js/desktop.js", function() { $desktop_load + 1; }); } else { } } if (window.innerWidth < 768) { if (window.innerWidth >= 768) { if (!$desktop_load) { // GET DESKTOP SCRIPT TO KEEP THINGS QUICK $.getScript("js/desktop.js", function() { $desktop_load + 1; }); } else { } } } }) .resize(); // trigger resize event }) Ty for future response. Edit - To give an example, in desktop.js i have a gif that loads before "abc" content, that gets inserted by .load(). On resize this gif will show up and the .load() in desktop.js will fire again. So if getScript was only being called once, it should not be doing anything again in desktop.js. Confusing?

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  • Reconciling a new BindingList into a master BindingList using LINQ

    - by Neo
    I have a seemingly simple problem whereby I wish to reconcile two lists so that an 'old' master list is updated by a 'new' list containing updated elements. Elements are denoted by a key property. These are my requirements: All elements in either list that have the same key results in an assignment of that element from the 'new' list over the original element in the 'old' list only if any properties have changed. Any elements in the 'new' list that have keys not in the 'old' list will be added to the 'old' list. Any elements in the 'old' list that have keys not in the 'new' list will be removed from the 'old' list. I found an equivalent problem here - http://stackoverflow.com/questions/161432/ - but it hasn't really been answered properly. So, I came up with an algorithm to iterate through the old and new lists and perform the reconciliation as per the above. Before anyone asks why I'm not just replacing the old list object with the new list object in its entirety, it's for presentation purposes - this is a BindingList bound to a grid on a GUI and I need to prevent refresh artifacts such as blinking, scrollbars moving, etc. So the list object must remain the same, only its updated elements changed. Another thing to note is that the objects in the 'new' list, even if the key is the same and all the properties are the same, are completely different instances to the equivalent objects in the 'old' list, so copying references is not an option. Below is what I've come up with so far - it's a generic extension method for a BindingList. I've put comments in to demonstrate what I'm trying to do. public static class BindingListExtension { public static void Reconcile<T>(this BindingList<T> left, BindingList<T> right, string key) { PropertyInfo piKey = typeof(T).GetProperty(key); // Go through each item in the new list in order to find all updated and new elements foreach (T newObj in right) { // First, find an object in the new list that shares its key with an object in the old list T oldObj = left.First(call => piKey.GetValue(call, null).Equals(piKey.GetValue(newObj, null))); if (oldObj != null) { // An object in each list was found with the same key, so now check to see if any properties have changed and // if any have, then assign the object from the new list over the top of the equivalent element in the old list foreach (PropertyInfo pi in typeof(T).GetProperties()) { if (!pi.GetValue(oldObj, null).Equals(pi.GetValue(newObj, null))) { left[left.IndexOf(oldObj)] = newObj; break; } } } else { // The object in the new list is brand new (has a new key), so add it to the old list left.Add(newObj); } } // Now, go through each item in the old list to find all elements with keys no longer in the new list foreach (T oldObj in left) { // Look for an element in the new list with a key matching an element in the old list if (right.First(call => piKey.GetValue(call, null).Equals(piKey.GetValue(oldObj, null))) == null) { // A matching element cannot be found in the new list, so remove the item from the old list left.Remove(oldObj); } } } } It can be called like this: _oldBindingList.Reconcile(newBindingList, "MyKey") However, I'm looking for perhaps a method of doing the same using LINQ type methods such as GroupJoin<, Join<, Select<, SelectMany<, Intersect<, etc. So far, the problem I've had is that each of these LINQ type methods result in brand new intermediary lists (as a return value) and really, I only want to modify the existing list for all the above reasons. If anyone can help with this, would be most appreciated. If not, no worries, the above method (as it were) will suffice for now. Thanks, Jason

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  • Create / build / generate a web form that can be on my server and has modern looks and could be impl

    - by Luay
    I have a small web site and would like to add a 'contact us' form and a 'feedback' form. i would like the forms to satisfy the following: 1- be modern looking (with beautiful css effects) 2- the form fields are validated properly and 'inline'. What I mean is once a user skips a required field or enters an email address incorrectly some kind of tooltip or icon is displayed to ask him to cerrect the error (as opposed to a message box that appears after the user clicks 'submit') 3- once the submit button is clicked the form contents are emailed to me. 4- the whole thing can be setup by a noob like myself. 5- no ads on the form I have been searching for at least 5 days for a solution but I can't seem to find anything the would satisfy the above 5 conditions. I don't mind paying for a solution as long as it is hosted on my site and it is a one off payment and not a monthly payment. So far my search has lead me to the following: 1 wufoo. The good: the generated forms seem to look okay but not the best there is. The bad: the free service is limited to 100 submissions. ads on the form. it is not hosted on my server. Paid service requires monthly payments 2- emailmeform: almost same as above except the generated form looks old. They do have an offer where you pay only $4 to get the form and set it up on your own site but that doesn't solve the fact that the forms look old. 3- formAssembly: same as above with minor variations (the generated form looks better) 4- formchamp, formthis, kontaktr,... And other similar online services: the same problem. either the form generated looks outdated or require monthly payments or they put ads...they don't satisfy my conditions. 5- coffeecup form builder. a desktop software. The problem is the generated forms look too old and use flash. 6- simfatic. Another software. Much better than coffeecup. almost satisfies my conditions but the forms not as good as I like. 7- many, many php scripts or html templates that look so outdated or fail when tested (probably because they are too old). Seriously guys, how hard is this. At least 90%+ of website contain at least a 'contact us' form. Why aren't there better solutions? if there is I can't seem to find them. In terms of looks I want something similar to this: http://web-kreation.com/articles/lightform-free-ajaxphp-contact-form/ It is called lightform. And this is a perfect example of what I mean by 'inline' validation. the only problem: there is no script to handle sending the mail. Even if I find one, I don't know how to modify it for my needs. So could you please help me out. I really can't search anymore. I reached rock bottom with this issue. I need a complete solution. If nothing exists then at least a: 1- form template (html) that looks nice and can easily be modified 2- a validation script that does 'inline' validation like the example above (or similar to it) and can be easily implemented by a noob like me to work with the html form. 3- a php script that will handle sending the email and can be easily implemented (all three working in harmony). I hope there is a complete solution but am I asking for too much? Pretty please...help...

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  • BFS Shortest Path: Edge weight either 1 or 2

    - by Hackster
    I am trying to implement a shortest path algorithm using BFS. That is I am trying to find the shortest path from a specified vertex to every other vertex. However, its a special case where all edge weights are either 1 or 2. I know it could be done with Dijkstra's algorithm but I must use Breadth First Search. So far I have a working version of BFS that searches first for a vertex connected with an edge of weight 1. If it cannot find it, then returns a vertex connected with an edge of weight 2. After thinking about it, this is not the correct way to find the shortest path. The problem is I cannot think of any reasoning why BFS would work with weights 1 or 2, as opposed to any weight. Here is the code: public void addEdge(int start, int end, int weight) { adjMat[start][end] = 1; adjMat[end][start] = 1; edge_weight[start][end] = weight; edge_weight[end][start] = weight; } // ------------------------------------------------------------- public void bfs() // breadth-first search { // begin at vertex 0 vertexList[0].wasVisited = true; // mark it displayVertex(0); // display it theQueue.insert(0); // insert at tail int v2; while( !theQueue.isEmpty() ) // until queue empty, { int v1 = theQueue.remove(); // remove vertex at head // until it has no unvisited neighbors while( (v2=getAdjUnvisitedVertex(v1)) != -1 ){// get one, vertexList[v2].wasVisited = true; // mark it displayVertex(v2); // display it theQueue.insert(v2); // insert it } } // end while(queue not empty) // queue is empty, so we're done for(int j=0; j<nVerts; j++) // reset flags vertexList[j].wasVisited = false; } // end bfs() // ------------------------------------------------------------- // returns an unvisited vertex adj to v -- ****WITH WEIGHT 1**** public int getAdjUnvisitedVertex(int v) { for (int j = 0; j < nVerts; j++) if (adjMat[v][j] == 1 && vertexList[j].wasVisited == false && edge_weight[v][j] == 1){ //System.out.println("Vertex found with 1:"+ vertexList[j].label); return j; } for (int k = 0; k < nVerts; k++) if (adjMat[v][k] == 1 && vertexList[k].wasVisited == false && edge_weight[v][k] == 2){ //System.out.println("Vertex found with 2:"+vertexList[k].label); return k; } return -1; } // end getAdjUnvisitedVertex() // ------------------------------------------------------------- } //////////////////////////////////////////////////////////////// public class BFS{ public static void main(String[] args) { Graph theGraph = new Graph(); theGraph.addVertex('A'); // 0 (start for bfs) theGraph.addVertex('B'); // 1 theGraph.addVertex('C'); // 2 theGraph.addEdge(0, 1,2); // AB theGraph.addEdge(1, 2,1); // BC theGraph.addEdge(2, 0,1); // AD System.out.print("Visits: "); theGraph.bfs(); // breadth-first search System.out.println(); } // end main() } The problem then is, that I don't know why BFS can work for the shortest path problem with edges of weight 1 or 2 as opposed to any edges of any weight. Any help is appreciated. Thanks!

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  • New cast exception with VS2010/.Net 4

    - by Trevor
    [ Updated 25 May 2010 ] I've recently upgraded from VS2008 to VS2010, and at the same time upgraded to .Net 4. I've recompiled an existing solution of mine and I'm encountering a Cast exception I did not have before. The structure of the code is simple (although the actual implementation somewhat more complicated). Basically I have: public class SomeClass : ISomeClass { // Stuff } public static class ClassFactory { public static IInterface GetClassInstance<IInterface>(Type classType) { return (IInterface)Activator.CreateInstance(classType); // This throws a cast exception } } // Call the factory with: ISomeClass anInstance = ClassFactory.GetClassInstance<ISomeClass>(typeof(SomeClass)); Ignore the 'sensibleness' of the above - its provides just a representation of the issue rather than the specifics of what I'm doing (e.g. constructor parameters have been removed). The marked line throws the exception: Unable to cast object of type 'Namespace.SomeClass' to type 'Namespace.ISomeClass'. I suspect it may have something to do with the additional DotNet security (and in particular, explicit loading of assemblies, as this is something my app does). The reason I suspect this is that I have had to add to the config file the setting: <runtime> <loadFromRemoteSources enabled="true" /> </runtime> .. but I'm unsure if this is related. Update I see (from comments) that my basic code does not reproduce the issue by itself. Not surprising I suppose. It's going to be tricky to identify which part of a largish 3-tier CQS system is relevant to this problem. One issue might be that there are multiple assemblies involved. My static class is actually a factory provider, and the 'SomeClass' is a class factory (relevant in that the factories are 'registered' within the app via explicit assembly/type loading - see below) . Upfront I use reflection to 'register' all factories (i.e. classes that implement a particular interface) and that I do this when the app starts by identifying the relevant assemblies, loading them and adding them to a cache using (in essence): Loop over (file in files) { Assembly assembly = Assembly.LoadFile(file); baseAssemblyList.Add(assembly); } Then I cache the available types in these assemblies with: foreach (Assembly assembly in _loadedAssemblyList) { Type[] assemblyTypes = assembly.GetTypes(); _loadedTypesCache.AddRange(assemblyTypes); } And then I use this cache to do a variety of reflection operations, including 'registering' of factories, which involves looping through all loaded (cached) types and finding those that implement the (base) Factory interface. I've experienced what may be a similar problem in the past (.Net 3.5, so not exactly the same) with an architecture that involved dynamically creating classes on the server and streaming the compiled binary of those classes to the client app. The problem came when trying to deserialize an instance of the dynamic class on the client from a remote call: the exception said the class type was not know, even though the source and destination types were exactly the same name (including namespace). Basically the cross boundry versions of the class were not recognised as being the same. I solved that by intercepting the deserialization process and explicitly defining the deseriazation class type in the context of the local assemblies. This experience is what makes me think the types are considered mismatched because (somehow) the interface of the actual SomeClass object, and the interface of passed into the Generic method are not considered the same type. So (possibly) my question for those more knowledgable about C#/DotNet is: How does the class loading work that somehow my app thinks there are two versions/types of the interface type and how can I fit that? [ whew ... anyone who got here is quite patient .. thanks ]

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  • What's the best-practice way to update an Adapter's underlying data?

    - by skyler
    I'm running into an IllegalStateException updating an underlying List to an Adapter (might be an ArrayAdapter or an extension of BaseAdapter, I don't remember). I do not have or remember the text of the exception at the moment, but it says something to the effect of the List's content changing without the Adapter having been notified of the change. This List /may/ be updated from another thread other than the UI thread (main). After I update this list (adding an item), I call notifyDataSetChanged. The issue seems to be that the Adapter, or ListView attached to the Adapter attempts to update itself before this method is invoked. When this happens, the IllegalStateException is thrown. If I set the ListView's visibility to GONE before the update, then VISIBLE again, no error occurs. But this isn't always practical. I read somewhere that you cannot modify the underlying this from another thread--this would seem to limit an MVC pattern, as with this particular List, I want to add items from different threads. I assumed that as long as I called notifyDataSetChanged() I'd be safe--that the Adapter didn't revisit the underlying List until this method was invoked but this doesn't seem to be the case. I suppose what I'm asking is, can it be safe to update the underlying List from threads other than the UI? Additionally, if I want to modify the data within an Adapter, do I modify the underlying List or the Adapter itself (via its add(), etc. methods). Modifying the data through the Adapter seems wrong. I came across a thread on another site from someone who seems to be having a similar problem to mine: http://osdir.com/ml/Android-Developers/2010-04/msg01199.html (this is from where I grabbed the Visibility.GONE and .VISIBLE idea). To give you a better idea of my particular problem, I'll describe a bit of how my List, Adapter, etc. are set up. I've an object named Queue that contains a LinkedList. Queue extends Observable, and when things are added to its internal list through its methods, I call setChanged() and notifyListeners(). This Queue object can have items added or removed from any number of threads. I have a single "queue view" Activity that contains an Adapter. This Activity, in its onCreate() method, registers an Observer listener to my Queue object. In the Observer's update() method I call notifyDataSetChanged() on the Adapter. I added a lot of log output and determined that when this IllegalStateExcption occurs that my Observer callback was never invoked. So it's as if the Adapter noticed the List's change before the Observer had a chance to notify its Observers, and call my method to notify the Adapter that the contents had changed. So I suppose what I'm asking is, is this a good way to rig-up an Adapter? Is this a problem because I'm updating the Adapter's contents from a thread other than the UI thread? If this is the case, I may have a solution in mind (give the Queue object a Handler to the UI thread when it's created, and make all List modifications using that Handler, but this seems improper). I realize that this is a very open-ended post, but I'm a bit lost on this and would appreciate any comments on what I've written.

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  • Getting 404 in Android app while trying to get xml from localhost

    - by Patrick
    This must be something really stupid, trying to solve this issue for a couple of days now and it's really not working. I searched everywhere and there probably is someone with the same problem, but I can't seem to find it. I'm working on an Android app and this app pulls some xml from a website. Since this website is down a lot, I decided to save it and run it locally. Now what I did; - I downloaded the kWs app for hosting the downloaded xml file - I put the file in the right directory and could access it through the mobile browser, but not with my app (same code as I used with pulling it from some other website, not hosted by me, only difference was the URL obviously) So I tried to host it on my PC and access it with my app from there. Again the same results, the mobile browsers had no problem finding it, but the app kept saying 404 Not Found: "The requested URL /test.xml&parama=Someone&paramb= was not found on this server." Note: Don't mind the 2 parameters I am sending, I needed that to get the right stuff from the website that wasn't hosted by me. My code: public String getStuff(String name){ String URL = "http://10.0.0.8/test.xml"; ArrayList<NameValuePair> params = new ArrayList<NameValuePair>(2); params.add(new BasicNameValuePair("parama", name)); params.add(new BasicNameValuePair("paramb", "")); APIRequest request = new APIRequest(URL, params); try { RequestXML rxml = new RequestXML(); AsyncTask<APIRequest, Void, String> a = rxml.execute(request); ... } catch(Exception e) { e.printStackTrace(); } return null; } That should be working correctly. Now the RequestXML class part: class RequestXML extends AsyncTask<APIRequest, Void, String>{ @Override protected String doInBackground(APIRequest... uri) { HttpClient httpclient = new DefaultHttpClient(); String completeUrl = uri[0].url; // ... Add parameters to URL ... HttpGet request = null; try { request = new HttpGet(new URI(completeUrl)); } catch (URISyntaxException e1) { e1.printStackTrace(); } HttpResponse response; String responseString = ""; try { response = httpclient.execute(request); StatusLine statusLine = response.getStatusLine(); if(statusLine.getStatusCode() == HttpStatus.SC_OK){ // .. It crashes here, because statusLine.getStatusCode() returns a 404 instead of a 200. The xml is just plain xml, nothing special about it. I changed the contents of the .htaccess file into "ALLOW FROM ALL" (works, cause the browser on my mobile device can access it and shows the correct xml). I am running Android 4.0.4 and I am using the default browser AND chrome on my mobile device. I am using MoWeS to host the website on my PC. Any help would be appreciated and if you need to know anything before you can find an answer to this problem, I'll be more than happy to give you that info. Thank you for you time! Cheers.

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  • How do I learn algorithms?

    - by Panthe
    Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be lear ning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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  • Linq To Xml problems using XElement's method Elements(XName)

    - by Dorian McHensie
    Hello everyone. I have a problem using Linq To Xml. A simple code. I have this XML: <?xml version="1.0" encoding="utf-8" ?> <data xmlns="http://www.xxx.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xxx.com/directory file.xsd"> <contact> <name>aaa</name> <email>[email protected]</email> <birthdate>2002-09-22</birthdate> <telephone>000:000000</telephone> <description>Description for this contact</description> </contact> <contact> <name>sss</name> <email>[email protected]</email> <birthdate>2002-09-22</birthdate> <telephone>000:000000</telephone> <description>Description for this contact</description> </contact> <contact> <name>bbb</name> <email>[email protected]</email> <birthdate>2002-09-22</birthdate> <telephone>000:000000</telephone> <description>Description for this contact</description> </contact> <contact> <name>ccc</name> <email>[email protected]</email> <birthdate>2002-09-22</birthdate> <telephone>000:000000</telephone> <description>Description for this contact</description> </contact> I want to get every contact mapping it on an object Contact. To do this I use this fragment of code: XDocument XDoc = XDocument.Load(System.Web.HttpRuntime.AppDomainAppPath + this.filesource); XElement XRoot = XDoc.Root; //XElement XEl = XElement.Load(this.filesource); var results = from e in XRoot.Elements("contact") select new Contact((string)e.Element("name"), (string)e.Element("email"), "1-1-1", null, null); List<Contact> cntcts = new List<Contact>(); foreach (Contact cntct in results) { cntcts.Add(cntct); } Contact[] c = cntcts.ToArray(); // Encapsulating element Elements<Contact> final = new Elements<Contact>(c); Ok just don't mind that all: focus on this: When I get the root node, it is all right, I get it correctly. When I use the select directive I try to get every node saying: from e in XRoot.Elements("contact") OK here's the problem: if I use: from e in XRoot.Elements() I get all contact nodes, but if I use: from e in XRoot.Elements("contact") I GET NOTHING: Empty SET. OK you tell me: Use the other one: OK I DO SO, let's use: from e in XRoot.Elements(), I get all nodes anyway, THAT's RIGHT BUT HERE COMES THE OTHER PROBLEM: When Saying: select new Contact((string)e.Element("name"), (string)e.Element("email"), "1-1-1", null, null); I Try to access <name>, <email>... I HAVE TO USE .Element("name") AND IT DOES NOT WORK TOO!!!!!!!!WHAT THE HELL IS THIS????????????? IT SEEMS THAT I DOES NOT MATCH THE NAME I PASS But how is it possible. I know that Elements() function takes, overloaded, one argument that is an XName which is mapped onto a string. Please consider that the code I wrote come from an example, It should work. Please somebody help me. THANKS IN ADVANCE

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