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• How to define generic super type for static factory method?

  - by Esko

  If this has already been asked, please link and close this one. I'm currently prototyping a design for a simplified API of a certain another API that's a lot more complex (and potentially dangerous) to use. Considering the related somewhat complex object creation I decided to use static factory methods to simplify the API and I currently have the following which works as expected: public class Glue<T> { private List<Type<T>> types; private Glue() { types = new ArrayList<Type<T>>(); } private static class Type<T> { private T value; /* some other properties, omitted for simplicity */ public Type(T value) { this.value = value; } } public static <T> Glue<T> glueFactory(String name, T first, T second) { Glue<T> g = new Glue<T>(); Type<T> firstType = new Glue.Type<T>(first); Type<T> secondType = new Glue.Type<T>(second); g.types.add(firstType); g.types.add(secondType); /* omitted complex stuff */ return g; } } As said, this works as intended. When the API user (=another developer) types Glue<Horse> strongGlue = Glue.glueFactory("2HP", new Horse(), new Horse()); he gets exactly what he wanted. What I'm missing is that how do I enforce that Horse - or whatever is put into the factory method - always implements both Serializable and Comparable? Simply adding them to factory method's signature using <T extends Comparable<T> & Serializable> doesn't necessarily enforce this rule in all cases, only when this simplified API is used. That's why I'd like to add them to the class' definition and then modify the factory method accordingly. PS: No horses (and definitely no ponies!) were harmed in writing of this question.

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• Perl LWP::UserAgent mishandling UTF-8 response

  - by RedGrittyBrick

  When I use LWP::UserAgent to retrieve content encoded in UTF-8 it seems LWP::UserAgent doesn't handle the encoding correctly. Here's the output after setting the Command Prompt window to Unicode by the command chcp 65001 Note that this initially gives the appearance that all is well, but I think it's just the shell reassembling bytes and decoding UTF-8, From the other output you can see that perl itself is not handling wide characters correctly. C:\perl getutf8.pl ====================================================================== HTTP/1.1 200 OK Connection: close Date: Fri, 31 Dec 2010 19:24:04 GMT Accept-Ranges: bytes Server: Apache/2.2.8 (Win32) PHP/5.2.6 Content-Length: 75 Content-Type: application/xml; charset=utf-8 Last-Modified: Fri, 31 Dec 2010 19:20:18 GMT Client-Date: Fri, 31 Dec 2010 19:24:04 GMT Client-Peer: 127.0.0.1:80 Client-Response-Num: 1 <?xml version="1.0" encoding="UTF-8"? <nameBudejovický Budvar</name ====================================================================== response content length is 33 ....v....1....v....2....v....3....v....4 <nameBudejovický Budvar</name . . . . v . . . . 1 . . . . v . . . . 2 . . . . v . . . . 3 . . . . 3c6e616d653e427564c49b6a6f7669636bc3bd204275647661723c2f6e616d653e < n a m e B u d ? ? j o v i c k ? ? B u d v a r < / n a m e Above you can see the payload length is 31 characters but Perl thinks it is 33. For confirmation, in the hex, we can see that the UTF-8 sequences c49b and c3bd are being interpreted as four separate characters and not as two Unicode characters. Here's the code #!perl use strict; use warnings; use LWP::UserAgent; my $ua = LWP::UserAgent-new(); my $response = $ua-get('http://localhost/Bud.xml'); if (! $response-is_success) { die $response-status_line; } print '='x70,"\n",$response-as_string(), '='x70,"\n"; my $r = $response-decoded_content((charset = 'UTF-8')); $/ = "\x0d\x0a"; # seems to be \x0a otherwise! chomp($r); # Remove any xml prologue $r =~ s/^<\?.*\?\x0d\x0a//; print "Response content length is ", length($r), "\n\n"; print "....v....1....v....2....v....3....v....4\n"; print $r,"\n"; print ". . . . v . . . . 1 . . . . v . . . . 2 . . . . v . . . . 3 . . . . \n"; print unpack("H*", $r), "\n"; print join(" ", split("", $r)), "\n"; Note that Bud.xml is UTF-8 encoded without a BOM. How can I persuade LWP::UserAgent to do the right thing? P.S. Ultimately I want to translate the Unicode data into an ASCII encoding, even if it means replacing each non-ASCII character with one question mark or other marker. I have accepted Ysth's "upgrade" answer - because I know it is the right thing to do when possible. However I am going to use a work-around (which may depress Tom further): $r = encode("cp437", decode("utf8", $r));

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• Hide a base class method from derived class, but still visible outside of assembly

  - by clintp

  This is a question about tidyness. The project is already working, I'm satisfied with the design but I have a couple of loose ends that I'd like to tie up. My project has a plugin architecture. The main body of the program dispatches work to the plugins that each reside in their own AppDomain. The plugins are described with an interface, which is used by the main program (to get the signature for invoking DispatchTaskToPlugin) and by the plugins themselves as an API contract: namespace AppServer.Plugin.Common { public interface IAppServerPlugin { void Register(); void DispatchTaskToPlugin(Task t); // Other methods omitted } } In the main body of the program Register() is called so that the plugin can register its callback methods with the base class, and then later DispatchTaskToPlugin() is called to get the plugin running. The plugins themselves are in two parts. There's a base class that implements the framework for the plugin (setup, housekeeping, teardown, etc..). This is where DispatchTaskToPlugin is actually defined: namespace AppServer.Plugin { abstract public class BasePlugin : MarshalByRefObject, AppServer.Plugin.Common.IAppServerPlugin { public void DispatchTaskToPlugin(Task t) { // ... // Eventual call to actual plugin code // } // Other methods omitted } } The actual plugins themselves only need to implement a Register() method (to give the base class the delegates to call eventually) and then their business logic. namespace AppServer.Plugin { public class Plugin : BasePlugin { override public void Register() { // Calls a method in the base class to register itself. } // Various callback methods, business logic, etc... } } Now in the base class (BasePlugin) I've implemented all kinds of convenience methods, collected data, etc.. for the plugins to use. Everything's kosher except for that lingering method DispatchTaskToPlugin(). It's not supposed to be callable from the Plugin class implementations -- they have no use for it. It's only needed by the dispatcher in the main body of the program. How can I prevent the derived classes (Plugin) from seeing the method in the base class (BasePlugin/DispatchTaskToPlugin) but still have it visible from outside of the assembly? I can split hairs and have DispatchTaskToPlugin() throw an exception if it's called from the derived classes, but that's closing the barn door a little late. I'd like to keep it out of Intellisense or possibly have the compiler take care of this for me. Suggestions?

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• Getting RGB values for each pixel from a 24bpp Bitmap in C

  - by seven

  Hello, i want to read the RGB values for each pixel from a .bmp file , so i can convert the bmp into a format suitable for gba . so i need to get just the RGB for each pixel and then write this information to a file. i am trying to use the windows.h structures : typedef struct { char signature[2]; unsigned int fileSize; unsigned int reserved; unsigned int offset; }BmpHeader; typedef struct { unsigned int headerSize; unsigned int width; unsigned int height; unsigned short planeCount; unsigned short bitDepth; unsigned int compression; unsigned int compressedImageSize; unsigned int horizontalResolution; unsigned int verticalResolution; unsigned int numColors; unsigned int importantColors; }BmpImageInfo; typedef struct { unsigned char blue; unsigned char green; unsigned char red; unsigned char reserved; }Rgb; typedef struct { BmpHeader header; BmpImageInfo info; Rgb colors[256]; unsigned short image[1]; }BmpFile; but i only need RGB struct. So lets say i read "in.bmp": FILE *inFile, *outFile; inFile = fopen("C://in.bmp", "rb"); Rgb Palette[256]; for(i=0;i<256;i++) { fread(&Palette[i],sizeof(Rgb),1,inFile); } fclose(inFile); is this correct ? how do i write only the RGB information to a file ? can anyone please give me some information please . Thank you.

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• What to name 2 methods with same signatures

  - by coffeeaddict

  Initially I had a method in our DL that would take in the object it's updating like so: internal void UpdateCash(Cash Cash) { using (OurCustomDbConnection conn = CreateConnection("UpdateCash")) { conn.CommandText = @"update Cash set captureID = @captureID, ac_code = @acCode, captureDate = @captureDate, errmsg = @errorMessage, isDebit = @isDebit, SourceInfoID = @sourceInfoID, PayPalTransactionInfoID = @payPalTransactionInfoID, CreditCardTransactionInfoID = @CreditCardTransactionInfoID where id = @cashID"; conn.AddParam("@captureID", cash.CaptureID); conn.AddParam("@acCode", cash.ActionCode); conn.AddParam("@captureDate", cash.CaptureDate); conn.AddParam("@errorMessage", cash.ErrorMessage); conn.AddParam("@isDebit", cyberCash.IsDebit); conn.AddParam("@PayPalTransactionInfoID", cash.PayPalTransactionInfoID); conn.AddParam("@CreditCardTransactionInfoID", cash.CreditCardTransactionInfoID); conn.AddParam("@sourceInfoID", cash.SourceInfoID); conn.AddParam("@cashID", cash.Id); conn.ExecuteNonQuery(); } } My boss felt that creating an object every time just to update one or two fields is overkill. But I had a couple places in code using this. He recommended using just UpdateCash and sending in the ID for CAsh and field I want to update. Well the problem is I have 2 places in code using my original method. And those 2 places are updating 2 completely different fields in the Cash table. Before I was just able to get the existing Cash record and shove it into a Cash object, then update the properties I wanted to be updated in the DB, then send back the cash object to my method above. I need some advice on what to do here. I have 2 methods and they have the same signature. I'm not quite sure what to rename these because both are updating 2 completely different fields in the Cash table: internal void UpdateCash(int cashID, int paypalCaptureID) { using (OurCustomDbConnection conn = CreateConnection("UpdateCash")) { conn.CommandText = @"update Cash set CaptureID = @paypalCaptureID where id = @cashID"; conn.AddParam("@captureID", paypalCaptureID); conn.ExecuteNonQuery(); } } internal void UpdateCash(int cashID, int PayPalTransactionInfoID) { using (OurCustomDbConnection conn = CreateConnection("UpdateCash")) { conn.CommandText = @"update Cash set PaymentSourceID = @PayPalTransactionInfoID where id = @cashID"; conn.AddParam("@PayPalTransactionInfoID", PayPalTransactionInfoID); conn.ExecuteNonQuery(); } } So I thought hmm, maybe change the names to these so that they are now unique and somewhat explain what field its updating: UpdateCashOrderID UpdateCashTransactionInfoID ok but that's not really very good names. And I can't go too generic, for example: UpdateCashTransaction(int cashID, paypalTransactionID) What if we have different types of transactionIDs that the cash record holds besides just the paypalTransactionInfoID? such as the creditCardInfoID? Then what? Transaction doesn't tell me what kind. And furthermore what if you're updating 2 fields so you have 2 params next to the cashID param: UpdateCashTransaction(int cashID, paypalTransactionID, someOtherFieldIWantToUpdate) see my frustration? what's the best way to handle this is my boss doesn't like my first route?

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• Self updating app, wont overwrite existing app, using Android packagemanager?

  - by LokiSinclair

  I know there are plenty of questions about this on here, but I've tried everything (but the correct 'thing', obviously!) and nothing seems to shine any light on the problem I'm having. I've written an app (for a customer), which is designed to be hosted on their own server. The app references a simple text file with the latest version code in it and checks it against it's own version. If it's out of date it goes off and downloads the update. Everything is working as intended up to this point. I use the: Intent i = new Intent(Intent.ACTION_VIEW); i.setDataAndType(Uri.fromFile(outputFile), "application/vnd.android.package-archive"); i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); startActivity(i); ...code to start the install process of the newly downloaded .apk file. And that all starts as I would expect. I click on "Install" - when I'm prompted to confirm the overwriting of the current app, with the new. It starts, and then displays: App not installed. And existing package by the same name with a conflicting signature is already installed. Now I'm aware that Android can't have multiple applications sharing the same package name, which is fine, but nothing comes up in LogCat and I can only assume that the OS is annoyed at me attempting to 'update' my app, even though I'm going through all the correct channels and using the inbuilt package manager to do it for me! Can anyone tell me what the OS is moaning about? I'm not attempting to install two apps side by side, I want it to update it, which it starts to do, and then gets really confused. Is it something to do with me using the same keystore for signing the packages? I highly doubt it as I've used the same keystores previously to handle updates to games and the like, but I just can't figure out what it's complaining about. Hopefully someone out there has had this issue and solved it, and can point me in the right direction. I'm flying a bit blind with the limited information it's giving me :( Cheers.

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• How to verify if the private key matches with the certificate..?

  - by surendhar_s

  I have the private key stored as .key file.. -----BEGIN RSA PRIVATE KEY----- MIICXAIBAAKBgQD5YBS6V3APdgqaWAkijIUHRK4KQ6eChSaRWaw9L/4u8o3T1s8J rUFHQhcIo5LPaQ4BrIuzHS8yzZf0m3viCTdZAiDn1ZjC2koquJ53rfDzqYxZFrId 7a4QYUCvM0gqx5nQ+lw1KoY/CDAoZN+sO7IJ4WkMg5XbgTWlSLBeBg0gMwIDAQAB AoGASKDKCKdUlLwtRFxldLF2QPKouYaQr7u1ytlSB5QFtIih89N5Avl5rJY7/SEe rdeL48LsAON8DpDAM9Zg0ykZ+/gsYI/C8b5Ch3QVgU9m50j9q8pVT04EOCYmsFi0 DBnwNBRLDESvm1p6NqKEc7zO9zjABgBvwL+loEVa1JFcp5ECQQD9/sekGTzzvKa5 SSVQOZmbwttPBjD44KRKi6LC7rQahM1PDqmCwPFgMVpRZL6dViBzYyWeWxN08Fuv p+sIwwLrAkEA+1f3VnSgIduzF9McMfZoNIkkZongcDAzjQ8sIHXwwTklkZcCqn69 qTVPmhyEDA/dJeAK3GhalcSqOFRFEC812QJAXStgQCmh2iaRYdYbAdqfJivMFqjG vgRpP48JHUhCeJfOV/mg5H2yDP8Nil3SLhSxwqHT4sq10Gd6umx2IrimEQJAFNA1 ACjKNeOOkhN+SzjfajJNHFyghEnJiw3NlqaNmEKWNNcvdlTmecObYuSnnqQVqRRD cfsGPU661c1MpslyCQJBAPqN0VXRMwfU29a3Ve0TF4Aiu1iq88aIPHsT3GKVURpO XNatMFINBW8ywN5euu8oYaeeKdrVSMW415a5+XEzEBY= -----END RSA PRIVATE KEY----- And i extracted public key from ssl certificate file.. Below is the code i tried to verify if private key matches with ssl certificate or not.. I used the modulus[i.e. private key get modulus==public key get modulus] to check if they are matching.. And this seems to hold only for RSAKEYS.. But i want to check for other keys as well.. Is there any other alternative to do the same..?? private static boolean verifySignature(File serverCertificateFile, File serverCertificateKey) { try { byte[] certificateBytes = FileUtils.readFileToByteArray(serverCertificateFile); //byte[] keyBytes = FileUtils.readFileToByteArray(serverCertificateKey); RandomAccessFile raf = new RandomAccessFile(serverCertificateKey, "r"); byte[] buf = new byte[(int) raf.length()]; raf.readFully(buf); raf.close(); PKCS8EncodedKeySpec kspec = new PKCS8EncodedKeySpec(buf); KeyFactory kf; try { kf = KeyFactory.getInstance("RSA"); RSAPrivateKey privKey = (RSAPrivateKey) kf.generatePrivate(kspec); CertificateFactory certFactory = CertificateFactory.getInstance("X.509"); InputStream in = new ByteArrayInputStream(certificateBytes); //Generate Certificate in X509 Format X509Certificate cert = (X509Certificate) certFactory.generateCertificate(in); RSAPublicKey publicKey = (RSAPublicKey) cert.getPublicKey(); in.close(); return privKey.getModulus() == publicKey.getModulus(); } catch (NoSuchAlgorithmException ex) { logger.log(Level.SEVERE, "Such algorithm is not found", ex); } catch (CertificateException ex) { logger.log(Level.SEVERE, "certificate exception", ex); } catch (InvalidKeySpecException ex) { Logger.getLogger(CertificateConversion.class.getName()).log(Level.SEVERE, null, ex); } } catch (IOException ex) { logger.log(Level.SEVERE, "Signature verification failed.. This could be because the file is in use", ex); } return false; } And the code isn't working either.. throws invalidkeyspec exception

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• Supporting multiple instances of a plugin DLL with global data

  - by Bruno De Fraine

  Context: I converted a legacy standalone engine into a plugin component for a composition tool. Technically, this means that I compiled the engine code base to a C DLL which I invoke from a .NET wrapper using P/Invoke; the wrapper implements an interface defined by the composition tool. This works quite well, but now I receive the request to load multiple instances of the engine, for different projects. Since the engine keeps the project data in a set of global variables, and since the DLL with the engine code base is loaded only once, loading multiple projects means that the project data is overwritten. I can see a number of solutions, but they all have some disadvantages: You can create multiple DLLs with the same code, which are seen as different DLLs by Windows, so their code is not shared. Probably this already works if you have multiple copies of the engine DLL with different names. However, the engine is invoked from the wrapper using DllImport attributes and I think the name of the engine DLL needs to be known when compiling the wrapper. Obviously, if I have to compile different versions of the wrapper for each project, this is quite cumbersome. The engine could run as a separate process. This means that the wrapper would launch a separate process for the engine when it loads a project, and it would use some form of IPC to communicate with this process. While this is a relatively clean solution, it requires some effort to get working, I don't now which IPC technology would be best to set-up this kind of construction. There may also be a significant overhead of the communication: the engine needs to frequently exchange arrays of floating-point numbers. The engine could be adapted to support multiple projects. This means that the global variables should be put into a project structure, and every reference to the globals should be converted to a corresponding reference that is relative to a particular project. There are about 20-30 global variables, but as you can imagine, these global variables are referenced from all over the code base, so this conversion would need to be done in some automatic manner. A related problem is that you should be able to reference the "current" project structure in all places, but passing this along as an extra argument in each and every function signature is also cumbersome. Does there exist a technique (in C) to consider the current call stack and find the nearest enclosing instance of a relevant data value there? Can the stackoverflow community give some advice on these (or other) solutions?

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• asp:Button is not calling server-side function

  - by Richard Neil Ilagan

  Hi guys, I know that there has been much discussion here about this topic, but none of the threads I got across helped me solve this problem. I'm hoping that mine is somewhat unique, and may actually merit a different solution. I'm instantiating an asp:Button inside a data-bound asp:GridView through template fields. Some of the buttons are supposed to call a server-side function, but for some weird reason, it doesn't. All the buttons do when you click them is fire a postback to the current page, doing nothing, effectively just reloading the page. Below is a fragment of the code: <asp:GridView ID="gv" runat="server" AutoGenerateColumns="false" CssClass="l2 submissions" ShowHeader="false"> <Columns> <asp:TemplateField> <ItemTemplate><asp:Panel ID="swatchpanel" CssClass='<%# Bind("status") %>' runat="server"></asp:Panel></ItemTemplate> <ItemStyle Width="50px" CssClass="sw" /> </asp:TemplateField> <asp:BoundField DataField="description" ReadOnly="true"> </asp:BoundField> <asp:BoundField DataField="owner" ReadOnly="true"> <ItemStyle Font-Italic="true" /> </asp:BoundField> <asp:BoundField DataField="last-modified" ReadOnly="true"> <ItemStyle Width="100px" /> </asp:BoundField> <asp:TemplateField> <ItemTemplate> <asp:Button ID="viewBtn" cssclass='<%# Bind("sid") %>' runat="server" Text="View" OnClick="viewBtnClick" /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> The viewBtn above should call the viewBtnClick() function on server-side. I do have that function defined, along with a proper signature (object,EventArgs). One thing that may be of note is that this code is actually inside an ASCX, which is loaded in another ASCX, finally loaded into an ASPX. Any help or insight into the matter will be SO appreciated. Thanks! (oh, and please don't mind my trashy HTML/CSS semantics - this is still in a very,very early stage :p)

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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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• Avoiding explicit recursion in Haskell

  - by Travis Brown

  The following simple function applies a given monadic function iteratively until it hits a Nothing, at which point it returns the last non-Nothing value. It does what I need, and I understand how it works. lastJustM :: (Monad m) => (a -> m (Maybe a)) -> a -> m a lastJustM g x = g x >>= maybe (return x) (lastJustM g) As part of my self-education in Haskell I'm trying to avoid explicit recursion (or at least understand how to) whenever I can. It seems like there should be a simple non-explicitly recursive solution in this case, but I'm having trouble figuring it out. I don't want something like a monadic version of takeWhile, since it could be expensive to collect all the pre-Nothing values, and I don't care about them anyway. I checked Hoogle for the signature and nothing shows up. The m (Maybe a) bit makes me think a monad transformer might be useful here, but I don't really have the intuitions I'd need to come up with the details (yet). It's probably either embarrassingly easy to do this or embarrassingly easy to see why it can't or shouldn't be done, but this wouldn't be the first time I've used self-embarrassment as a pedagogical strategy. Background: Here's a simplified working example for context: suppose we're interested in random walks in the unit square, but we only care about points of exit. We have the following step function: randomStep :: (Floating a, Ord a, Random a) => a -> (a, a) -> State StdGen (Maybe (a, a)) randomStep s (x, y) = do (a, gen') <- randomR (0, 2 * pi) <$> get put gen' let (x', y') = (x + s * cos a, y + s * sin a) if x' < 0 || x' > 1 || y' < 0 || y' > 1 then return Nothing else return $ Just (x', y') Something like evalState (lastJustM (randomStep 0.01) (0.5, 0.5)) <$> newStdGen will give us a new data point.

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• What the best approach to iterate and "store" files over a directory in C (Linux) ?

  - by Andrei Ciobanu

  I have written a function that checks if to files are duplicates or not. This function signature is: int check_dup_memmap(char *f1_name, char *f2_name) It returns: (-1) - If something went wrong; (0) - If the two files are similar; (+1) - If the two files are different; The next step is to write a function that iterates through all the files in a certain directory,apply the previous function, and gives a report on every existing duplicates. Initially I've thought to write a function that generates a file with all the filenames in a certain directory and then, read that file again and gain and compare every two files. Here is that version of the function, that gets all the filenames in a certain directory. void *build_dir_tree(char *dirname, FILE *f) { DIR *cdir = NULL; struct dirent *ent = NULL; struct stat buf; if(f == NULL){ fprintf(stderr, "NULL file submitted. [build_dir_tree].\n"); exit(-1); } if(dirname == NULL){ fprintf(stderr, "NULL dirname submitted. [build_dir_tree].\n"); exit(-1); } if((cdir = opendir(dirname)) == NULL){ char emsg[MFILE_LEN]; sprintf(emsg, "Cannot open dir: %s [build_dir_tree]\t",dirname); perror(emsg); } chdir(dirname); while ((ent = readdir(cdir)) != NULL) { lstat(ent->d_name, &buf); if (S_ISDIR(buf.st_mode)) { if (strcmp(".", ent->d_name) == 0 || strcmp("..", ent->d_name) == 0) { continue; } build_dir_tree(ent->d_name, f); } else{ fprintf(f, "/%s/%s\n",util_get_cwd(),ent->d_name); } } chdir(".."); closedir(cdir); } Still I consider this approach a little inefficient, as I have to parse the file again and again. In your opinion what are other approaches should I follow: Write a datastructure and hold the files instead of writing them in the file ? I think for a directory with a lot of files, the memory will become very fragmented. Hold all the filenames in auto-expanding array, so that I can easy access every file by their index, because they will in a contiguous memory location. Map this file in memory using mmap() ? But mmap may fail, as the file gets to big. Any opinions on this. I want to choose the most efficient path, and access as few resources as possible. This is the requirement of the program... EDIT: Is there a way to get the numbers of files in a certain directory, without iterating through it ?

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• Can I write a test that succeeds if and only if a statement does not compile?

  - by Billy ONeal

  I'd like to prevent clients of my class from doing something stupid. To that end, I have used the type system, and made my class only accept specific types as input. Consider the following example (Not real code, I've left off things like virtual destructors for the sake of example): class MyDataChunk { //Look Ma! Implementation! }; class Sink; class Source { virtual void Run() = 0; Sink *next_; void SetNext(Sink *next) { next_ = next; } }; class Sink { virtual void GiveMeAChunk(const MyDataChunk& data) { //Impl }; }; class In { virtual void Run { //Impl } }; class Out { }; //Note how filter and sorter have the same declaration. Concrete classes //will inherit from them. The seperate names are there to ensure only //that some idiot doesn't go in and put in a filter where someone expects //a sorter, etc. class Filter : public Source, public Sink { //Drop objects from the chain-of-command pattern that don't match a particular //criterion. }; class Sorter : public Source, public Sink { //Sorts inputs to outputs. There are different sorters because someone might //want to sort by filename, size, date, etc... }; class MyClass { In i; Out o; Filter f; Sorter s; public: //Functions to set i, o, f, and s void Execute() { i.SetNext(f); f.SetNext(s); s.SetNext(o); i.Run(); } }; What I don't want is for somebody to come back later and go, "Hey, look! Sorter and Filter have the same signature. I can make a common one that does both!", thus breaking the semantic difference MyClass requires. Is this a common kind of requirement, and if so, how might I implement a test for it?

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• Marshalling non-Blittable Structs from C# to C++

  - by Greggo

  I'm in the process of rewriting an overengineered and unmaintainable chunk of my company's library code that interfaces between C# and C++. I've started looking into P/Invoke, but it seems like there's not much in the way of accessible help. We're passing a struct that contains various parameters and settings down to unmanaged codes, so we're defining identical structs. We don't need to change any of those parameters on the C++ side, but we do need to access them after the P/Invoked function has returned. My questions are: What is the best way to pass strings? Some are short (device id's which can be set by us), and some are file paths (which may contain Asian characters) Should I pass an IntPtr to the C# struct or should I just let the Marshaller take care of it by putting the struct type in the function signature? Should I be worried about any non-pointer datatypes like bools or enums (in other, related structs)? We have the treat warnings as errors flag set in C++ so we can't use the Microsoft extension for enums to force a datatype. Is P/Invoke actually the way to go? There was some Microsoft documentation about Implicit P/Invoke that said it was more type-safe and performant. For reference, here is one of the pairs of structs I've written so far: C++ /** Struct used for marshalling Scan parameters from managed to unmanaged code. */ struct ScanParameters { LPSTR deviceID; LPSTR spdClock; LPSTR spdStartTrigger; double spinRpm; double startRadius; double endRadius; double trackSpacing; UINT64 numTracks; UINT32 nominalSampleCount; double gainLimit; double sampleRate; double scanHeight; LPWSTR qmoPath; //includes filename LPWSTR qzpPath; //includes filename }; C# /// <summary> /// Struct used for marshalling scan parameters between managed and unmanaged code. /// </summary> [StructLayout(LayoutKind.Sequential)] public struct ScanParameters { [MarshalAs(UnmanagedType.LPStr)] public string deviceID; [MarshalAs(UnmanagedType.LPStr)] public string spdClock; [MarshalAs(UnmanagedType.LPStr)] public string spdStartTrigger; public Double spinRpm; public Double startRadius; public Double endRadius; public Double trackSpacing; public UInt64 numTracks; public UInt32 nominalSampleCount; public Double gainLimit; public Double sampleRate; public Double scanHeight; [MarshalAs(UnmanagedType.LPWStr)] public string qmoPath; [MarshalAs(UnmanagedType.LPWStr)] public string qzpPath; }

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• Entity Framework: An object with the same key already exists in the objectstatemanager

  - by NealR

  I see that this question has been asked a lot, however I haven't found anything yet that solves the problem I'm having. Obviously i'm using the Entity Framework to perform an update to a record. Once the updates are complete, however, whenever I try to save I get the following error message: An object with the same key already exists in the objectstatemanager At first I was passing in a collection object from the view that contained a copy of the the ZipCodeTerritory model object zipToUpdate. I changed the code by pulling this object out and just sending in the relevant fields instead. However, I'm still getting the same error. What's also weird is the first time I run this code, it works fine. Any attempt after that I get the error. Controller Here is the code from the method calling the edit function public static string DescriptionOnly(ZipCodeIndex updateZip) { if (!string.IsNullOrWhiteSpace(updateZip.newEffectiveDate) || !string.IsNullOrWhiteSpace(updateZip.newEndDate)) { return "Neither effective or end date can be present if updating Territory Code only; "; } _updated = 0; foreach (var zipCode in updateZip.displayForPaging.Where(x => x.Update)) { ProcessAllChanges(zipCode, updateZip.newTerritory, updateZip.newStateCode, updateZip.newDescription, updateZip.newChannelCode); } _msg += _updated + " record(s) updated; "; return _msg; } And here is the method that actually does the updating. private static void ProcessAllChanges(ZipCodeTerritory zipToUpdate, string newTerritory, string newStateCode, string newDescription, string newChannelCode) { try { if (!string.IsNullOrWhiteSpace(newTerritory)) zipToUpdate.IndDistrnId = newTerritory; if (!string.IsNullOrWhiteSpace(newStateCode)) zipToUpdate.StateCode = newStateCode; if (!string.IsNullOrWhiteSpace(newDescription)) zipToUpdate.DrmTerrDesc = newDescription; if (!string.IsNullOrWhiteSpace(newChannelCode)) zipToUpdate.ChannelCode = newChannelCode; if (zipToUpdate.EndDate == DateTime.MinValue) zipToUpdate.EndDate = DateTime.MaxValue; _db.Entry(zipToUpdate).State = EntityState.Modified; _db.SaveChanges(); _updated++; } catch (DbEntityValidationException dbEx) { _msg += "Error during update; "; EventLog.WriteEntry("Monet", "Error during ProcessAllChanges: " + zipToUpdate.ToString() + " |EX| " + dbEx.Message); } catch (Exception ex) { _msg += "Error during update; "; EventLog.WriteEntry("Monet", "Error during ProcessAllChanges: " + zipToUpdate.ToString() + " |MESSAGE| " + ex.Message); } } EDIT The ZipCodeIndex object contains a list of ZipCodeTerritory model objects. These aren't being pulled from a linq query, but instead simply passed back to the controller from the view. Here is the signature of the controller method that starts the process: [HttpPost] public ActionResult Update(ZipCodeIndex updateZip, string button)

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• The dynamic Type in C# Simplifies COM Member Access from Visual FoxPro

  - by Rick Strahl

  I’ve written quite a bit about Visual FoxPro interoperating with .NET in the past both for ASP.NET interacting with Visual FoxPro COM objects as well as Visual FoxPro calling into .NET code via COM Interop. COM Interop with Visual FoxPro has a number of problems but one of them at least got a lot easier with the introduction of dynamic type support in .NET. One of the biggest problems with COM interop has been that it’s been really difficult to pass dynamic objects from FoxPro to .NET and get them properly typed. The only way that any strong typing can occur in .NET for FoxPro components is via COM type library exports of Visual FoxPro components. Due to limitations in Visual FoxPro’s type library support as well as the dynamic nature of the Visual FoxPro language where few things are or can be described in the form of a COM type library, a lot of useful interaction between FoxPro and .NET required the use of messy Reflection code in .NET. Reflection is .NET’s base interface to runtime type discovery and dynamic execution of code without requiring strong typing. In FoxPro terms it’s similar to EVALUATE() functionality albeit with a much more complex API and corresponiding syntax. The Reflection APIs are fairly powerful, but they are rather awkward to use and require a lot of code. Even with the creation of wrapper utility classes for common EVAL() style Reflection functionality dynamically access COM objects passed to .NET often is pretty tedious and ugly. Let’s look at a simple example. In the following code I use some FoxPro code to dynamically create an object in code and then pass this object to .NET. An alternative to this might also be to create a new object on the fly by using SCATTER NAME on a database record. How the object is created is inconsequential, other than the fact that it’s not defined as a COM object – it’s a pure FoxPro object that is passed to .NET. Here’s the code: *** Create .NET COM InstanceloNet = CREATEOBJECT('DotNetCom.DotNetComPublisher') *** Create a Customer Object Instance (factory method) loCustomer = GetCustomer() loCustomer.Name = "Rick Strahl" loCustomer.Company = "West Wind Technologies" loCustomer.creditLimit = 9999999999.99 loCustomer.Address.StreetAddress = "32 Kaiea Place" loCustomer.Address.Phone = "808 579-8342" loCustomer.Address.Email = "[email protected]" *** Pass Fox Object and echo back values ? loNet.PassRecordObject(loObject) RETURN FUNCTION GetCustomer LOCAL loCustomer, loAddress loCustomer = CREATEOBJECT("EMPTY") ADDPROPERTY(loCustomer,"Name","") ADDPROPERTY(loCustomer,"Company","") ADDPROPERTY(loCUstomer,"CreditLimit",0.00) ADDPROPERTY(loCustomer,"Entered",DATETIME()) loAddress = CREATEOBJECT("Empty") ADDPROPERTY(loAddress,"StreetAddress","") ADDPROPERTY(loAddress,"Phone","") ADDPROPERTY(loAddress,"Email","") ADDPROPERTY(loCustomer,"Address",loAddress) RETURN loCustomer ENDFUNC Now prior to .NET 4.0 you’d have to access this object passed to .NET via Reflection and the method code to do this would looks something like this in the .NET component: public string PassRecordObject(object FoxObject) { // *** using raw Reflection string Company = (string) FoxObject.GetType().InvokeMember( "Company", BindingFlags.GetProperty,null, FoxObject,null); // using the easier ComUtils wrappers string Name = (string) ComUtils.GetProperty(FoxObject,"Name"); // Getting Address object – then getting child properties object Address = ComUtils.GetProperty(FoxObject,"Address");    string Street = (string) ComUtils.GetProperty(FoxObject,"StreetAddress"); // using ComUtils 'Ex' functions you can use . Syntax     string StreetAddress = (string) ComUtils.GetPropertyEx(FoxObject,"AddressStreetAddress"); return Name + Environment.NewLine + Company + Environment.NewLine + StreetAddress + Environment.NewLine + " FOX"; } Note that the FoxObject is passed in as type object which has no specific type. Since the object doesn’t exist in .NET as a type signature the object is passed without any specific type information as plain non-descript object. To retrieve a property the Reflection APIs like Type.InvokeMember or Type.GetProperty().GetValue() etc. need to be used. I made this code a little simpler by using the Reflection Wrappers I mentioned earlier but even with those ComUtils calls the code is pretty ugly requiring passing the objects for each call and casting each element. Using .NET 4.0 Dynamic Typing makes this Code a lot cleaner Enter .NET 4.0 and the dynamic type. Replacing the input parameter to the .NET method from type object to dynamic makes the code to access the FoxPro component inside of .NET much more natural: public string PassRecordObjectDynamic(dynamic FoxObject) { // *** using raw Reflection string Company = FoxObject.Company; // *** using the easier ComUtils class string Name = FoxObject.Name; // *** using ComUtils 'ex' functions to use . Syntax string Address = FoxObject.Address.StreetAddress; return Name + Environment.NewLine + Company + Environment.NewLine + Address + Environment.NewLine + " FOX"; } As you can see the parameter is of type dynamic which as the name implies performs Reflection lookups and evaluation on the fly so all the Reflection code in the last example goes away. The code can use regular object ‘.’ syntax to reference each of the members of the object. You can access properties and call methods this way using natural object language. Also note that all the type casts that were required in the Reflection code go away – dynamic types like var can infer the type to cast to based on the target assignment. As long as the type can be inferred by the compiler at compile time (ie. the left side of the expression is strongly typed) no explicit casts are required. Note that although you get to use plain object syntax in the code above you don’t get Intellisense in Visual Studio because the type is dynamic and thus has no hard type definition in .NET . The above example calls a .NET Component from VFP, but it also works the other way around. Another frequent scenario is an .NET code calling into a FoxPro COM object that returns a dynamic result. Assume you have a FoxPro COM object returns a FoxPro Cursor Record as an object: DEFINE CLASS FoxData AS SESSION OlePublic cAppStartPath = "" FUNCTION INIT THIS.cAppStartPath = ADDBS( JustPath(Application.ServerName) ) SET PATH TO ( THIS.cAppStartpath ) ENDFUNC FUNCTION GetRecord(lnPk) LOCAL loCustomer SELECT * FROM tt_Cust WHERE pk = lnPk ; INTO CURSOR TCustomer IF _TALLY < 1 RETURN NULL ENDIF SCATTER NAME loCustomer MEMO RETURN loCustomer ENDFUNC ENDDEFINE If you call this from a .NET application you can now retrieve this data via COM Interop and cast the result as dynamic to simplify the data access of the dynamic FoxPro type that was created on the fly: int pk = 0; int.TryParse(Request.QueryString["id"],out pk); // Create Fox COM Object with Com Callable Wrapper FoxData foxData = new FoxData(); dynamic foxRecord = foxData.GetRecord(pk); string company = foxRecord.Company; DateTime entered = foxRecord.Entered; This code looks simple and natural as it should be – heck you could write code like this in days long gone by in scripting languages like ASP classic for example. Compared to the Reflection code that previously was necessary to run similar code this is much easier to write, understand and maintain. For COM interop and Visual FoxPro operation dynamic type support in .NET 4.0 is a huge improvement and certainly makes it much easier to deal with FoxPro code that calls into .NET. Regardless of whether you’re using COM for calling Visual FoxPro objects from .NET (ASP.NET calling a COM component and getting a dynamic result returned) or whether FoxPro code is calling into a .NET COM component from a FoxPro desktop application. At one point or another FoxPro likely ends up passing complex dynamic data to .NET and for this the dynamic typing makes coding much cleaner and more readable without having to create custom Reflection wrappers. As a bonus the dynamic runtime that underlies the dynamic type is fairly efficient in terms of making Reflection calls especially if members are repeatedly accessed. © Rick Strahl, West Wind Technologies, 2005-2010Posted in COM  FoxPro  .NET  CSharp  

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• Week in Geek: LastPass Rescues Xmarks Edition

  - by Asian Angel

  This week we learned how to breathe new life into an aging Windows Mobile 6.x device, use filters in Photoshop, backup and move VirtualBox machines, use the BitDefender Rescue CD to clean an infected PC, and had fun setting up a pirates theme on our computers. Photo by _nash. Weekly Feature Do you love using the Faenza icon set on your Ubuntu system but feel that there are a few much needed icons missing (or you desire a different version of a particular icon)? Then you may want to take a look at the Faenza Variants icon pack. The icons are available in the following sizes: 16px, 22px, 32px, 48px and scalable sizes. Photo by Asian Angel. Faenza Variants Random Geek Links Another week with extra link goodness to help keep you on top of the news. Photo by Asian Angel. LastPass acquires Xmarks, premium service announced Xmarks announced that it has been acquired by LastPass, a cross-platform password management service. This also means that Xmarks is now in transition from a “free” to a “freemium” business model. WikiLeaks reappears on European Net domains WikiLeaks has re-emerged on a Swiss Internet domain followed by domains in Germany, Finland, and the Netherlands, sidestepping a move that had in effect taken the controversial site off the Internet. Iran: Yes, Stuxnet hurt our nuclear program The Stuxnet worm got some big play from Iranian President Mahmoud Ahmadinejad, who acknowledged that the malware dinged his nuclear program. More Windows Rogues than Just AV – Fake Defragmenter Check Disk Don’t think for a second that rogues are limited to scareware, because as so-called products such as “System Defragmenter”, “Scan Disk” “Check Disk” prove, they’re not. Internet Explorer’s Protected Mode can be bypassed Researchers from Verizon Business have now described a way of bypassing Protected Mode in IE 7 and 8 in order to gain access to user accounts. Can you really see who viewed your Facebook profile? Rogue application spreads virally Once again, a rogue application is spreading virally between Facebook users pretending to offer you a way of seeing who has viewed your profile. More holes in Palm’s WebOS Researchers Orlando Barrera and Daniel Herrera, who both work for security firm SecTheory, have discovered a gaping security hole in Palm’s WebOS smartphone operating system. Next-gen banking Trojans hit APAC With the proliferation of banking Trojans, Web and smartphone users of online banking services have to be on constant alert to avoid falling prey to fraud schemes, warned Etay Maor, project manager for RSA Fraud Action. AVG update cripples 64-bit computers A signature update automatically deployed by the AVG virus scanner Thursday has crippled numerous computers. Article includes link to forums to fix computers affected after a restart. Congress moves to outlaw ‘mystery charges’ for Web shoppers Legislation that makes it illegal for Web merchants and so-called post-transaction marketers to charge credit cards without the card owners’ say-so came closer to becoming law this week. Ballmer Set to “Look Into” Windows Home Server Drive Extender Fiasco Tuesday’s announcement from Microsoft regarding the removal of Drive Extender from Windows Home Server has sent shock waves across the web. Google tweaks search recipe to ding scam artists Google has changed its search algorithm to penalize sites deemed to provide an “extremely poor user experience” following a New York Times story on a merchant who justified abusive behavior towards customers as a search-engine optimization tactic. Geek Video of the Week Watch as our two friends debate back and forth about the early adoption of new technology through multiple time periods (Stone Age to the far future). Will our reluctant friend finally succumb to the temptation? Photo by CollegeHumor. Early Adopters Through History Random TinyHacker Links Fix Issues in Windows 7 Using Reliability Monitor Learn how to analyze Windows 7 errors and then fix them using the built-in reliability monitor. Learn About IE Tab Groups Tab groups is a useful feature in IE 8. Here’s a detailed guide to what it is all about. Google’s Book Helps You Learn About Browsers and Web A cool new online book by the Google Chrome team on browsers and the web. TrustPort Internet Security 2011 – Good Security from a Less Known Provider TrustPort is not exactly a well-known provider of security solutions. At least not in the consumer space. This review tests in detail their latest offering. How the World is Using Cell phones An infographic showing the shocking demographics of cell phone use. Super User Questions See the great answers to these questions from Super User. I am unable to access my C drive. It says it is unable to display current owner. List of Windows special directories/shortcuts like ‘%TEMP%’ Is using multiple passes for wiping a disk really necessary? How can I view two files side by side in Notepad++ Is there any tool that automatically puts screenshots to my Dropbox? How-To Geek Weekly Article Recap Look through our hottest articles from this past week at How-To Geek. How to Create a Software RAID Array in Windows 7 9 Alternatives for Windows Home Server’s Drive Extender Why Doesn’t Disk Cleanup Delete Everything from the Temp Folder? Ask the Readers: How Much Do You Customize Your Operating System? How to Upload Really Large Files to SkyDrive, Dropbox, or Email One Year Ago on How-To Geek Enjoy reading through these awesome articles from one year ago. How To Upgrade from Vista to Windows 7 Home Premium Edition How To Fix No Aero Transparency in Windows 7 Troubleshoot Startup Problems with Startup Repair Tool in Windows 7 & Vista Rename the Guest Account in Windows 7 for Enhanced Security Disable Error Reporting in XP, Vista, and Windows 7 The Geek Note That wraps things up here for this week. Regardless of the weather wherever you may be, we hope that you have an opportunity to get outside and have some fun! Remember to keep sending those great tips in to us at [email protected]. Photo by Tony the Misfit. Latest Features How-To Geek ETC The How-To Geek Guide to Learning Photoshop, Part 8: Filters Get the Complete Android Guide eBook for Only 99 Cents [Update: Expired] Improve Digital Photography by Calibrating Your Monitor The How-To Geek Guide to Learning Photoshop, Part 7: Design and Typography How to Choose What to Back Up on Your Linux Home Server How To Harmonize Your Dual-Boot Setup for Windows and Ubuntu Hang in There Scrat! – Ice Age Wallpaper How Do You Know When You’ve Passed Geek and Headed to Nerd? On The Tip – A Lamborghini Theme for Chrome and Iron What if Wile E. Coyote and the Road Runner were Human? [Video] Peaceful Winter Cabin Wallpaper Store Tabs for Later Viewing in Opera with Tab Vault

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• Update information outdated

  - by Achim Krause

  I have a warning triangle that my update information is outdated, the last update was 12 days ago. I use Ubuntu 11.10. A run of sudo apt-get update produces the following output: Ign http://ppa.launchpad.net oneiric InRelease Ign http://de.archive.ubuntu.com oneiric InRelease Ign http://de.archive.ubuntu.com oneiric-updates InRelease Ign http://de.archive.ubuntu.com oneiric-backports InRelease Ign http://security.ubuntu.com oneiric-security InRelease Ign http://extras.ubuntu.com oneiric InRelease Hit http://ppa.launchpad.net oneiric Release.gpg Get:1 http://de.archive.ubuntu.com oneiric Release.gpg [198 B] Hit http://security.ubuntu.com oneiric-security Release.gpg Get:2 http://extras.ubuntu.com oneiric Release.gpg [72 B] Hit http://ppa.launchpad.net oneiric Release Hit http://de.archive.ubuntu.com oneiric-updates Release.gpg Hit http://security.ubuntu.com oneiric-security Release Hit http://extras.ubuntu.com oneiric Release Err http://extras.ubuntu.com oneiric Release Hit http://ppa.launchpad.net oneiric/main Sources Hit http://de.archive.ubuntu.com oneiric-backports Release.gpg Hit http://security.ubuntu.com oneiric-security/main Sources Hit http://ppa.launchpad.net oneiric/main i386 Packages Ign http://ppa.launchpad.net oneiric/main TranslationIndex Ign http://linux.dropbox.com oneiric InRelease Hit http://security.ubuntu.com oneiric-security/restricted Sources Hit http://security.ubuntu.com oneiric-security/universe Sources Hit http://security.ubuntu.com oneiric-security/multiverse Sources Hit http://security.ubuntu.com oneiric-security/main i386 Packages Hit http://security.ubuntu.com oneiric-security/restricted i386 Packages Hit http://security.ubuntu.com oneiric-security/universe i386 Packages Hit http://security.ubuntu.com oneiric-security/multiverse i386 Packages Hit http://security.ubuntu.com oneiric-security/main TranslationIndex Hit http://security.ubuntu.com oneiric-security/multiverse TranslationIndex Hit http://security.ubuntu.com oneiric-security/restricted TranslationIndex Hit http://security.ubuntu.com oneiric-security/universe TranslationIndex Hit http://de.archive.ubuntu.com oneiric Release Hit http://de.archive.ubuntu.com oneiric-updates Release Ign http://de.archive.ubuntu.com oneiric Release Hit http://security.ubuntu.com oneiric-security/main Translation-en Hit http://security.ubuntu.com oneiric-security/multiverse Translation-en Hit http://linux.dropbox.com oneiric Release.gpg Hit http://security.ubuntu.com oneiric-security/restricted Translation-en Hit http://de.archive.ubuntu.com oneiric-backports Release Hit http://security.ubuntu.com oneiric-security/universe Translation-en Ign http://de.archive.ubuntu.com oneiric/main Sources/DiffIndex Ign http://de.archive.ubuntu.com oneiric/restricted Sources/DiffIndex Ign http://de.archive.ubuntu.com oneiric/universe Sources/DiffIndex Ign http://de.archive.ubuntu.com oneiric/multiverse Sources/DiffIndex Ign http://de.archive.ubuntu.com oneiric/main i386 Packages/DiffIndex Ign http://de.archive.ubuntu.com oneiric/restricted i386 Packages/DiffIndex Ign http://de.archive.ubuntu.com oneiric/universe i386 Packages/DiffIndex Ign http://de.archive.ubuntu.com oneiric/multiverse i386 Packages/DiffIndex Hit http://linux.dropbox.com oneiric Release Get:3 http://de.archive.ubuntu.com oneiric/main TranslationIndex [3,289 B] Get:4 http://de.archive.ubuntu.com oneiric/multiverse TranslationIndex [2,265 B] Hit http://de.archive.ubuntu.com oneiric/restricted TranslationIndex Get:5 http://de.archive.ubuntu.com oneiric/universe TranslationIndex [2,640 B] Hit http://de.archive.ubuntu.com oneiric-updates/restricted i386 Packages Hit http://de.archive.ubuntu.com oneiric-updates/universe i386 Packages Hit http://de.archive.ubuntu.com oneiric-updates/multiverse i386 Packages Hit http://de.archive.ubuntu.com oneiric-updates/main TranslationIndex Hit http://de.archive.ubuntu.com oneiric-updates/multiverse TranslationIndex Hit http://de.archive.ubuntu.com oneiric-updates/restricted TranslationIndex Hit http://de.archive.ubuntu.com oneiric-updates/universe TranslationIndex Hit http://de.archive.ubuntu.com oneiric-backports/main Sources Hit http://linux.dropbox.com oneiric/main i386 Packages Ign http://ppa.launchpad.net oneiric/main Translation-en_US Ign http://ppa.launchpad.net oneiric/main Translation-en Ign http://linux.dropbox.com oneiric/main TranslationIndex Hit http://de.archive.ubuntu.com oneiric-backports/restricted Sources Hit http://de.archive.ubuntu.com oneiric-backports/universe Sources Hit http://de.archive.ubuntu.com oneiric-backports/multiverse Sources Hit http://de.archive.ubuntu.com oneiric-backports/main i386 Packages Hit http://de.archive.ubuntu.com oneiric-backports/restricted i386 Packages Hit http://de.archive.ubuntu.com oneiric-backports/universe i386 Packages Hit http://de.archive.ubuntu.com oneiric-backports/multiverse i386 Packages Hit http://de.archive.ubuntu.com oneiric-backports/main TranslationIndex Hit http://de.archive.ubuntu.com oneiric-backports/multiverse TranslationIndex Hit http://de.archive.ubuntu.com oneiric-backports/restricted TranslationIndex Hit http://de.archive.ubuntu.com oneiric-backports/universe TranslationIndex Hit http://de.archive.ubuntu.com oneiric/main Sources Hit http://de.archive.ubuntu.com oneiric/restricted Sources Hit http://de.archive.ubuntu.com oneiric/universe Sources Hit http://de.archive.ubuntu.com oneiric/multiverse Sources Hit http://de.archive.ubuntu.com oneiric/main i386 Packages Hit http://de.archive.ubuntu.com oneiric/restricted i386 Packages Hit http://de.archive.ubuntu.com oneiric/universe i386 Packages Hit http://de.archive.ubuntu.com oneiric/multiverse i386 Packages Hit http://de.archive.ubuntu.com oneiric/restricted Translation-en Hit http://de.archive.ubuntu.com oneiric-updates/main Translation-en Hit http://de.archive.ubuntu.com oneiric-updates/multiverse Translation-en Hit http://de.archive.ubuntu.com oneiric-updates/restricted Translation-en Hit http://de.archive.ubuntu.com oneiric-updates/universe Translation-en Hit http://de.archive.ubuntu.com oneiric-backports/main Translation-en Hit http://de.archive.ubuntu.com oneiric-backports/multiverse Translation-en Hit http://de.archive.ubuntu.com oneiric-backports/restricted Translation-en Hit http://de.archive.ubuntu.com oneiric-backports/universe Translation-en Err http://de.archive.ubuntu.com oneiric-updates/main Sources 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] Err http://de.archive.ubuntu.com oneiric-updates/restricted Sources 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] Err http://de.archive.ubuntu.com oneiric-updates/universe Sources 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] Err http://de.archive.ubuntu.com oneiric-updates/multiverse Sources 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] Err http://de.archive.ubuntu.com oneiric-updates/main i386 Packages 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] Ign http://linux.dropbox.com oneiric/main Translation-en_US Ign http://linux.dropbox.com oneiric/main Translation-en Fetched 273 B in 2s (91 B/s) Reading package lists... Done W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://extras.ubuntu.com oneiric Release: The following signatures were invalid: BADSIG 16126D3A3E5C1192 Ubuntu Extras Archive Automatic Signing Key <[email protected]> W: GPG error: http://de.archive.ubuntu.com oneiric Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key <[email protected]> W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/oneiric/Release W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric/main/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/de.archive.ubuntu.com_ubuntu_dists_oneiric_main_i18n_Index W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric/multiverse/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/de.archive.ubuntu.com_ubuntu_dists_oneiric_multiverse_i18n_Index W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric/universe/i18n/Index No Hash entry in Release file /var/lib/apt/lists/partial/de.archive.ubuntu.com_ubuntu_dists_oneiric_universe_i18n_Index W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric-updates/main/source/Sources 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric-updates/restricted/source/Sources 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric-updates/universe/source/Sources 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric-updates/multiverse/source/Sources 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric-updates/main/binary-i386/Packages 416 Requested Range Not Satisfiable [IP: 141.30.13.30 80] W: Some index files failed to download. They have been ignored, or old ones used instead. There are some questions with similar problems, but no one seems to get these "Range Not Satisfiable" errors. I do not use a proxy, and the network configuration should not have changed since it worked the last time.

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• How to subscribe to the free Oracle Linux errata yum repositories

  - by Lenz Grimmer

  Now that updates and errata for Oracle Linux are available for free (both as in beer and freedom), here's a quick HOWTO on how to subscribe your Oracle Linux system to the newly added yum repositories on our public yum server, assuming that you just installed Oracle Linux from scratch, e.g. by using the installation media (ISO images) available from the Oracle Software Delivery Cloud You need to download the appropriate yum repository configuration file from the public yum server and install it in the yum repository directory. For Oracle Linux 6, the process would look as follows: as the root user, run the following command: [root@oraclelinux62 ~]# wget http://public-yum.oracle.com/public-yum-ol6.repo \ -P /etc/yum.repos.d/ --2012-03-23 00:18:25-- http://public-yum.oracle.com/public-yum-ol6.repo Resolving public-yum.oracle.com... 141.146.44.34 Connecting to public-yum.oracle.com|141.146.44.34|:80... connected. HTTP request sent, awaiting response... 200 OK Length: 1461 (1.4K) [text/plain] Saving to: “/etc/yum.repos.d/public-yum-ol6.repo” 100%[=================================================>] 1,461 --.-K/s in 0s 2012-03-23 00:18:26 (37.1 MB/s) - “/etc/yum.repos.d/public-yum-ol6.repo” saved [1461/1461] For Oracle Linux 5, the file name would be public-yum-ol5.repo in the URL above instead. The "_latest" repositories that contain the errata packages are already enabled by default — you can simply pull in all available updates by running "yum update" next: [root@oraclelinux62 ~]# yum update Loaded plugins: refresh-packagekit, security ol6_latest | 1.1 kB 00:00 ol6_latest/primary | 15 MB 00:42 ol6_latest 14643/14643 Setting up Update Process Resolving Dependencies --> Running transaction check ---> Package at.x86_64 0:3.1.10-43.el6 will be updated ---> Package at.x86_64 0:3.1.10-43.el6_2.1 will be an update ---> Package autofs.x86_64 1:5.0.5-39.el6 will be updated ---> Package autofs.x86_64 1:5.0.5-39.el6_2.1 will be an update ---> Package bind-libs.x86_64 32:9.7.3-8.P3.el6 will be updated ---> Package bind-libs.x86_64 32:9.7.3-8.P3.el6_2.2 will be an update ---> Package bind-utils.x86_64 32:9.7.3-8.P3.el6 will be updated ---> Package bind-utils.x86_64 32:9.7.3-8.P3.el6_2.2 will be an update ---> Package cvs.x86_64 0:1.11.23-11.el6_0.1 will be updated ---> Package cvs.x86_64 0:1.11.23-11.el6_2.1 will be an update [...] ---> Package yum.noarch 0:3.2.29-22.0.1.el6 will be updated ---> Package yum.noarch 0:3.2.29-22.0.2.el6_2.2 will be an update ---> Package yum-plugin-security.noarch 0:1.1.30-10.el6 will be updated ---> Package yum-plugin-security.noarch 0:1.1.30-10.0.1.el6 will be an update ---> Package yum-utils.noarch 0:1.1.30-10.el6 will be updated ---> Package yum-utils.noarch 0:1.1.30-10.0.1.el6 will be an update --> Finished Dependency Resolution Dependencies Resolved ===================================================================================== Package Arch Version Repository Size ===================================================================================== Installing: kernel x86_64 2.6.32-220.7.1.el6 ol6_latest 24 M kernel-uek x86_64 2.6.32-300.11.1.el6uek ol6_latest 21 M kernel-uek-devel x86_64 2.6.32-300.11.1.el6uek ol6_latest 6.3 M Updating: at x86_64 3.1.10-43.el6_2.1 ol6_latest 60 k autofs x86_64 1:5.0.5-39.el6_2.1 ol6_latest 470 k bind-libs x86_64 32:9.7.3-8.P3.el6_2.2 ol6_latest 839 k bind-utils x86_64 32:9.7.3-8.P3.el6_2.2 ol6_latest 178 k cvs x86_64 1.11.23-11.el6_2.1 ol6_latest 711 k [...] xulrunner x86_64 10.0.3-1.0.1.el6_2 ol6_latest 12 M yelp x86_64 2.28.1-13.el6_2 ol6_latest 778 k yum noarch 3.2.29-22.0.2.el6_2.2 ol6_latest 987 k yum-plugin-security noarch 1.1.30-10.0.1.el6 ol6_latest 36 k yum-utils noarch 1.1.30-10.0.1.el6 ol6_latest 94 k Transaction Summary ===================================================================================== Install 3 Package(s) Upgrade 96 Package(s) Total download size: 173 M Is this ok [y/N]: y Downloading Packages: (1/99): at-3.1.10-43.el6_2.1.x86_64.rpm | 60 kB 00:00 (2/99): autofs-5.0.5-39.el6_2.1.x86_64.rpm | 470 kB 00:01 (3/99): bind-libs-9.7.3-8.P3.el6_2.2.x86_64.rpm | 839 kB 00:02 (4/99): bind-utils-9.7.3-8.P3.el6_2.2.x86_64.rpm | 178 kB 00:00 [...] (96/99): yelp-2.28.1-13.el6_2.x86_64.rpm | 778 kB 00:02 (97/99): yum-3.2.29-22.0.2.el6_2.2.noarch.rpm | 987 kB 00:03 (98/99): yum-plugin-security-1.1.30-10.0.1.el6.noarch.rpm | 36 kB 00:00 (99/99): yum-utils-1.1.30-10.0.1.el6.noarch.rpm | 94 kB 00:00 ------------------------------------------------------------------------------------- Total 306 kB/s | 173 MB 09:38 warning: rpmts_HdrFromFdno: Header V3 RSA/SHA256 Signature, key ID ec551f03: NOKEY Retrieving key from http://public-yum.oracle.com/RPM-GPG-KEY-oracle-ol6 Importing GPG key 0xEC551F03: Userid: "Oracle OSS group (Open Source Software group) " From : http://public-yum.oracle.com/RPM-GPG-KEY-oracle-ol6 Is this ok [y/N]: y Running rpm_check_debug Running Transaction Test Transaction Test Succeeded Running Transaction Updating : yum-3.2.29-22.0.2.el6_2.2.noarch 1/195 Updating : xorg-x11-server-common-1.10.4-6.el6_2.3.x86_64 2/195 Updating : kernel-uek-headers-2.6.32-300.11.1.el6uek.x86_64 3/195 Updating : 12:dhcp-common-4.1.1-25.P1.el6_2.1.x86_64 4/195 Updating : tzdata-java-2011n-2.el6.noarch 5/195 Updating : tzdata-2011n-2.el6.noarch 6/195 Updating : glibc-common-2.12-1.47.el6_2.9.x86_64 7/195 Updating : glibc-2.12-1.47.el6_2.9.x86_64 8/195 [...] Cleanup : kernel-firmware-2.6.32-220.el6.noarch 191/195 Cleanup : kernel-uek-firmware-2.6.32-300.3.1.el6uek.noarch 192/195 Cleanup : glibc-common-2.12-1.47.el6.x86_64 193/195 Cleanup : glibc-2.12-1.47.el6.x86_64 194/195 Cleanup : tzdata-2011l-4.el6.noarch 195/195 Installed: kernel.x86_64 0:2.6.32-220.7.1.el6 kernel-uek.x86_64 0:2.6.32-300.11.1.el6uek kernel-uek-devel.x86_64 0:2.6.32-300.11.1.el6uek Updated: at.x86_64 0:3.1.10-43.el6_2.1 autofs.x86_64 1:5.0.5-39.el6_2.1 bind-libs.x86_64 32:9.7.3-8.P3.el6_2.2 bind-utils.x86_64 32:9.7.3-8.P3.el6_2.2 cvs.x86_64 0:1.11.23-11.el6_2.1 dhclient.x86_64 12:4.1.1-25.P1.el6_2.1 [...] xorg-x11-server-common.x86_64 0:1.10.4-6.el6_2.3 xulrunner.x86_64 0:10.0.3-1.0.1.el6_2 yelp.x86_64 0:2.28.1-13.el6_2 yum.noarch 0:3.2.29-22.0.2.el6_2.2 yum-plugin-security.noarch 0:1.1.30-10.0.1.el6 yum-utils.noarch 0:1.1.30-10.0.1.el6 Complete! At this point, your system is fully up to date. As the kernel was updated as well, a reboot is the recommended next action. If you want to install the latest release of the Unbreakable Enterprise Kernel Release 2 as well, you need to edit the .repo file and enable the respective yum repository (e.g. "ol6_UEK_latest" for Oracle Linux 6 and "ol5_UEK_latest" for Oracle Linux 5) manually, by setting enabled to "1". The next yum update run will download and install the second release of the Unbreakable Enterprise Kernel, which will be enabled after the next reboot. -Lenz

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• Replacing jQuery.live() with jQuery.on()

  - by Rick Strahl

  jQuery 1.9 and 1.10 have introduced a host of changes, but for the most part these changes are mostly transparent to existing application usage of jQuery. After spending some time last week with a few of my projects and going through them with a specific eye for jQuery failures I found that for the most part there wasn't a big issue. The vast majority of code continues to run just fine with either 1.9 or 1.10 (which are supposed to be in sync but with 1.10 removing support for legacy Internet Explorer pre-9.0 versions). However, one particular change in the new versions has caused me quite a bit of update trouble, is the removal of the jQuery.live() function. This is my own fault I suppose - .live() has been deprecated for a while, but with 1.9 and later it was finally removed altogether from jQuery. In the past I had quite a bit of jQuery code that used .live() and it's one of the things that's holding back my upgrade process, although I'm slowly cleaning up my code and switching to the .on() function as the replacement. jQuery.live() jQuery.live() was introduced a long time ago to simplify handling events on matched elements that exist currently on the document and those that are are added in the future and also match the selector. jQuery uses event bubbling, special event binding, plus some magic using meta data attached to a parent level element to check and see if the original target event element matches the selected selected elements (for more info see Elijah Manor's comment below). An Example Assume a list of items like the following in HTML for example and further assume that the items in this list can be appended to at a later point. In this app there's a smallish initial list that loads to start, and as the user scrolls towards the end of the initial small list more items are loaded dynamically and added to the list.<div id="PostItemContainer" class="scrollbox"> <div class="postitem" data-id="4z6qhomm"> <div class="post-icon"></div> <div class="postitemheader"><a href="show/4z6qhomm" target="Content">1999 Buick Century For Sale!</a></div> <div class="postitemprice rightalign">$ 3,500 O.B.O.</div> <div class="smalltext leftalign">Jun. 07 @ 1:06am</div> <div class="post-byline">- Vehicles - Automobiles</div> </div> <div class="postitem" data-id="2jtvuu17"> <div class="postitemheader"><a href="show/2jtvuu17" target="Content">Toyota VAN 1987</a></div> <div class="postitemprice rightalign">$950</div> <div class="smalltext leftalign">Jun. 07 @ 12:29am</div> <div class="post-byline">- Vehicles - Automobiles</div> </div> … </div> With the jQuery.live() function you could easily select elements and hook up a click handler like this:$(".postitem").live("click", function() {...}); Simple and perfectly readable. The behavior of the .live handler generally was the same as the corresponding simple event handlers like .click(), except that you have to explicitly name the event instead of using one of the methods. Re-writing with jQuery.on() With .live() removed in 1.9 and later we have to re-write .live() code above with an alternative. The jQuery documentation points you at the .on() or .delegate() functions to update your code. jQuery.on() is a more generic event handler function, and it's what jQuery uses internally to map the high level event functions like .click(),.change() etc. that jQuery exposes. Using jQuery.on() however is not a one to one replacement of the .live() function. While .on() can handle events directly and use the same syntax as .live() did, you'll find if you simply switch out .live() with .on() that events on not-yet existing elements will not fire. IOW, the key feature of .live() is not working. You can use .on() to get the desired effect however, but you have to change the syntax to explicitly handle the event you're interested in on the container and then provide a filter selector to specify which elements you are actually interested in for handling the event for. Sounds more complicated than it is and it's easier to see with an example. For the list above hooking .postitem clicks, using jQuery.on() looks like this:$("#PostItemContainer").on("click", ".postitem", function() {...}); You specify a container that can handle the .click event and then provide a filter selector to find the child elements that trigger the  the actual event. So here #PostItemContainer contains many .postitems, whose click events I want to handle. Any container will do including document, but I tend to use the container closest to the elements I actually want to handle the events on to minimize the event bubbling that occurs to capture the event. With this code I get the same behavior as with .live() and now as new .postitem elements are added the click events are always available. Sweet. Here's the full event signature for the .on() function: .on( events [, selector ] [, data ], handler(eventObject) ) Note that the selector is optional - if you omit it you essentially create a simple event handler that handles the event directly on the selected object. The filter/child selector required if you want life-like - uh, .live() like behavior to happen. While it's a bit more verbose than what .live() did, .on() provides the same functionality by being more explicit on what your parent container for trapping events is. .on() is good Practice even for ordinary static Element Lists As a side note, it's a good practice to use jQuery.on() or jQuery.delegate() for events in most cases anyway, using this 'container event trapping' syntax. That's because rather than requiring lots of event handlers on each of the child elements (.postitem in the sample above), there's just one event handler on the container, and only when clicked does jQuery drill down to find the matching filter element and tries to match it to the originating element. In the early days of jQuery I used manually build handlers that did this and manually drilled from the event object into the originalTarget to determine if it's a matching element. With later versions of jQuery the various event functions in jQuery essentially provide this functionality out of the box with functions like .on() and .delegate(). All of this is nothing new, but I thought I'd write this up because I have on a few occasions forgotten what exactly was needed to replace the many .live() function calls that litter my code - especially older code. This will be a nice reminder next time I have a memory blank on this topic. And maybe along the way I've helped one or two of you as well to clean up your .live() code…© Rick Strahl, West Wind Technologies, 2005-2013Posted in jQuery   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• SSL certificates and types for securing your websites and applications

  - by Mit Naik

  Need to share few information regarding SSL certificates and there types, which SSL certificates are widely used etc. There are several SSL certificates available in the market today inorder to secure your domains, multiple subdomains, your applications and code too. Few of the details are mentioned below. CheapSSL certificates available today are Standard Rapidssl certificate, Thwate SSL 123 etc certificates which are basic level certificates. Most of these cheap SSL certificates are domain-validated only and don't provide the greatest trust for your customers. This means you shouldn't use cheap SSL certificates on e-commerce stores or other public-facing sites that require people to trust the site. EV certificates I found Geotrust Truebusinessid with EV certificate which is one of the cheapest certificate available in market today, you can also find Thwate, Versign EV version of certificates. Its designed to prevent phishing attacks better than normal SSL certificates. What makes an EV Certificate so special? An SSL Certificate Provider has to do some extensive validation to give you one including: Verifying that your organization is legally registered and active, Verifying the address and phone number of your organization, Verifying that your organization has exclusive right to use the domain specified in the EV Certificate, Verifying that the person ordering the certificate has been authorized by the organization, Verifying that your organization is not on any government blacklists. SSL WILDCARD CERTIFICATES, SSL Wildcard Certificates are big money-savers. An SSL Wildcard Certificate allows you to secure an unlimited number of first-level sub-domains on a single domain name. For example, if you need to secure the following websites: * www.yourdomain.com * secure.yourdomain.com * product.yourdomain.com * info.yourdomain.com * download.yourdomain.com * anything.yourdomain.com and all of these websites are hosted on the multiple server box, you can purchase and install one Wildcard certificate issued to *.yourdomain.com to secure all these sites. SAN CERTIFICATES, are interesting certificates and are helpfull if you want to secure multiple domains by generating single CSR and can install the same certificate on your additional sites without generating new CSRs for all the additional domains. CODE SIGNING CERTIFICATES, A code signing certificate is a file containing a digital signature that can be used to sign executables and scripts in order to verify your identity and ensure that your code has not been tampered with since it was signed. This helps your users to determine whether your software can be trusted. Scroll to the chart below to compare cheap code signing certificates. A code signing certificate allows you to sign code using a private and public key system similar to how an SSL certificate secures a website. When you request a code signing certificate, a public/private key pair is generated. The certificate authority will then issue a code signing certificate that contains the public key. A certificate for code signing needs to be signed by a trusted certificate authority so that the operating system knows that your identity has been validated. You could still use the code signing certificate to sign and distribute malicious software but you will be held legally accountable for it. You can sign many different types of code. The most common types include Windows applications such as .exe, .cab, .dll, .ocx, and .xpi files (using an Authenticode certificate), Apple applications (using an Apple code signing certificate), Microsoft Office VBA objects and macros (using a VBA code signing certificate), .jar files (using a Java code signing certificate), .air or .airi files (using an Adobe AIR certificate), and Windows Vista drivers and other kernel-mode software (using a Vista code certificate). In reality, a code signing certificate can sign almost all types of code as long as you convert the certificate to the correct format first. Also I found the below URL which provides you good suggestion regarding purchasing best SSL certificates for securing your site, as per the Financial institution, Bank, Hosting providers, ISP, Retail Merchants etc. Please vote and provide comments or any additional suggestions regarding SSL certificates.

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• Sign an OpenSSL .CSR with Microsoft Certificate Authority

  - by kce

  I'm in the process of building a Debian FreeRadius server that does 802.1x authentication for domain members. I would like to sign my radius server's SSL certificate (used for EAP-TLS) and leverage the domain's existing PKI. The radius server is joined to domain via Samba and has a machine account as displayed in Active Directory Users and Computers. The domain controller I'm trying to sign my radius server's key against does not have IIS installed so I can't use the preferred Certsrv webpage to generate the certificate. The MMC tools won't work as it can't access the certificate stores on the radius server because they don't exist. This leaves the certreq.exe utility. I'm generating my .CSR with the following command: openssl req -nodes -newkey rsa:1024 -keyout server.key -out server.csr The resulting .CSR: ******@mis-ke-lnx:~/G$ openssl req -text -noout -in mis-radius-lnx.csr Certificate Request: Data: Version: 0 (0x0) Subject: C=US, ST=Alaska, L=CITY, O=ORG, OU=DEPT, CN=ME/emailAddress=MYEMAIL Subject Public Key Info: Public Key Algorithm: rsaEncryption RSA Public Key: (1024 bit) Modulus (1024 bit): 00:a8:b3:0d:4b:3f:fa:a4:5f:78:0c:24:24:23:ac: cf:c5:28:af:af:a2:9b:07:23:67:4c:77:b5:e8:8a: 08:2e:c5:a3:37:e1:05:53:41:f3:4b:e1:56:44:d2: 27:c6:90:df:ae:3b:79:e4:20:c2:e4:d1:3e:22:df: 03:60:08:b7:f0:6b:39:4d:b4:5e:15:f7:1d:90:e8: 46:10:28:38:6a:62:c2:39:80:5a:92:73:37:85:37: d3:3e:57:55:b8:93:a3:43:ac:2b:de:0f:f8:ab:44: 13:8e:48:29:d7:8d:ce:e2:1d:2a:b7:2b:9d:88:ea: 79:64:3f:9a:7b:90:13:87:63 Exponent: 65537 (0x10001) Attributes: a0:00 Signature Algorithm: sha1WithRSAEncryption 35:57:3a:ec:82:fc:0a:8b:90:9a:11:6b:56:e7:a8:e4:91:df: 73:1a:59:d6:5f:90:07:83:46:aa:55:54:1c:f9:28:3e:a6:42: 48:0d:6b:da:58:e4:f5:7f:81:ee:e2:66:71:78:85:bd:7f:6d: 02:b6:9c:32:ad:fa:1f:53:0a:b4:38:25:65:c2:e4:37:00:16: 53:d2:da:f2:ad:cb:92:2b:58:15:f4:ea:02:1c:a3:1c:1f:59: 4b:0f:6c:53:70:ef:47:60:b6:87:c7:2c:39:85:d8:54:84:a1: b4:67:f0:d3:32:f4:8e:b3:76:04:a8:65:48:58:ad:3a:d2:c9: 3d:63 I'm trying to submit my certificate using the following certreq.exe command: certreq -submit -attrib "CertificateTemplate:Machine" server.csr I receive the following error upon doing so: RequestId: 601 Certificate not issued (Denied) Denied by Policy Module The DNS name is unavailable and cannot be added to the Subject Alternate name. 0x8009480f (-2146875377) Certificate Request Processor: The DNS name is unavailable and cannot be added to the Subject Alternate name. 0x8009480f (-2146875377) Denied by Policy Module My certificate authority has the following certificate templates available. If I try to submit by certreq.exe using "CertificiateTemplate:Computer" instead of "CertificateTemplate:Machine" I get an error reporting that "the requested certificate template is not supported by this CA." My google-foo has failed me so far on trying to understand this error... I feel like this should be a relatively simple task as X.509 is X.509 and OpenSSL generates the .CSRs in the required PKCS10 format. I can't be only one out there trying to sign a OpenSSL generated key on a Linux box with a Windows Certificate Authority, so how do I do this (perferably using the off-line certreq.exe tool)?

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• ASP.NET Controls – CommunityServer Captcha ControlAdapter, a practical case

  - by nmgomes

  The ControlAdapter is available since .NET framework version 2.0 and his main goal is to adapt and customize a control render in order to achieve a specific behavior or layout. This customization is done without changing the base control. A ControlAdapter is commonly used to custom render for specific platforms like Mobile. In this particular case the ControlAdapter was used to add a specific behavior to a Control. In this  post I will use one adapter to add a Captcha to all WeblogPostCommentForm controls within pontonetpt.com CommunityServer instance. The Challenge The ControlAdapter complexity is usually associated with the complexity/structure of is base control. This case is precisely one of those since base control dynamically load his content (controls) thru several ITemplate. Those of you who already played with ITemplate knows that while it is an excellent option for control composition it also brings to the table a big issue: “Controls defined within a template are not available for manipulation until they are instantiated inside another control.” While analyzing the WeblogPostCommentForm control I found that he uses the ITemplate technique to compose it’s layout and unfortunately I also found that the template content vary from theme to theme. This could have been a problem but luckily WeblogPostCommentForm control template content always contains a submit button with a well known ID (at least I can assume that there are a well known set of IDs). Using this submit button as anchor it’s possible to add the Captcha controls in the correct place. Another important finding was that WeblogPostCommentForm control inherits from the WrappedFormBase control which is the base control for all CommunityServer input forms. Knowing this inheritance link the main goal has changed to became the creation of a base ControlAdapter that  could be extended and customized to allow adding Captcha to: post comments form contact form user creation form. And, with this mind set, I decided to used the following ControlAdapter base class signature :public abstract class WrappedFormBaseCaptchaAdapter<T> : ControlAdapter where T : WrappedFormBase { }Great, but there are still many to do … Captcha The Captcha will be assembled with: A dynamically generated image with a set of random numbers A TextBox control where the image number will be inserted A Validator control to validate whether TextBox numbers match the image numbers This is a common Captcha implementation, is not rocket science and don’t bring any additional problem. The main problem, as told before, is to find the correct anchor control to ensure a correct Captcha control injection. The anchor control can vary by: target control  theme Implementation To support this dynamic scenario I choose to use the following implementation:private List<string> _validAnchorIds = null; protected virtual List<string> ValidAnchorIds { get { if (this._validAnchorIds == null) { this._validAnchorIds = new List<string>(); this._validAnchorIds.Add("btnSubmit"); } return this._validAnchorIds; } } private Control GetAnchorControl(T wrapper) { if (this.ValidAnchorIds == null || this.ValidAnchorIds.Count == 0) { throw new ArgumentException("Cannot be null or empty", "validAnchorNames"); } var q = from anchorId in this.ValidAnchorIds let anchorControl = CSControlUtility.Instance().FindControl(wrapper, anchorId) where anchorControl != null select anchorControl; return q.FirstOrDefault(); } I can now, using the ValidAnchorIds property, configure a set of valid anchor control  Ids. The GetAnchorControl method searches for a valid anchor control within the set of valid control Ids. Here, some of you may question why to use a LINQ To Objects expression, but the important here is to notice the usage of CSControlUtility.Instance().FindControl CommunityServer method. I want to build on top of CommunityServer not to reinvent the wheel. Assuming that an anchor control was found, it’s now possible to inject the Captcha at the correct place. This not something new, we do this all the time when creating server controls or adding dynamic controls:protected sealed override void CreateChildControls() { base.CreateChildControls(); if (this.IsCaptchaRequired) { T wrapper = base.Control as T; if (wrapper != null) { Control anchorControl = GetAnchorControl(wrapper); if (anchorControl != null) { Panel phCaptcha = new Panel {CssClass = "CommonFormField", ID = "Captcha"}; int index = anchorControl.Parent.Controls.IndexOf(anchorControl); anchorControl.Parent.Controls.AddAt(index, phCaptcha); CaptchaConfiguration.DefaultProvider.AddCaptchaControls( phCaptcha, GetValidationGroup(wrapper, anchorControl)); } } } } Here you can see a new entity in action: a provider. This is a CaptchaProvider class instance and is only goal is to create the Captcha itself and do everything else is needed to ensure is correct operation.public abstract class CaptchaProvider : ProviderBase { public abstract void AddCaptchaControls(Panel captchaPanel, string validationGroup); } You can create your own specific CaptchaProvider class to use different Captcha strategies including the use of existing Captcha services  like ReCaptcha. Once the generic ControlAdapter was created became extremely easy to created a specific one. Here is the specific ControlAdapter for the WeblogPostCommentForm control:public class WeblogPostCommentFormCaptchaAdapter : WrappedFormBaseCaptchaAdapter<WrappedFormBase> { #region Overriden Methods protected override List<string> ValidAnchorIds { get { List<string> validAnchorNames = base.ValidAnchorIds; validAnchorNames.Add("CommentSubmit"); return validAnchorNames; } } protected override string DefaultValidationGroup { get { return "CreateCommentForm"; } } #endregion Overriden Methods } Configuration This is the magic step. Without changing the original pages and keeping the application original assemblies untouched we are going to add a new behavior to the CommunityServer application. To glue everything together you must follow this steps: Add the following configuration to default.browser file:<?xml version='1.0' encoding='utf-8'?> <browsers> <browser refID="Default"> <controlAdapters> <!-- Adapter for the WeblogPostCommentForm control in order to add the Captcha and prevent SPAM comments --> <adapter controlType="CommunityServer.Blogs.Controls.WeblogPostCommentForm" adapterType="NunoGomes.CommunityServer.Components.WeblogPostCommentFormCaptchaAdapter, NunoGomes.CommunityServer" /> </controlAdapters> </browser> </browsers> Add the following configuration to web.config file:<configuration> <configSections> <!-- New section for Captcha providers configuration --> <section name="communityServer.Captcha" type="NunoGomes.CommunityServer.Captcha.Configuration.CaptchaSection" /> </configSections> <!-- Configuring a simple Captcha provider --> <communityServer.Captcha defaultProvider="simpleCaptcha"> <providers> <add name="simpleCaptcha" type="NunoGomes.CommunityServer.Captcha.Providers.SimpleCaptchaProvider, NunoGomes.CommunityServer" imageUrl="~/captcha.ashx" enabled="true" passPhrase="_YourPassPhrase_" saltValue="_YourSaltValue_" hashAlgorithm="SHA1" passwordIterations="3" keySize="256" initVector="_YourInitVectorWithExactly_16_Bytes_" /> </providers> </communityServer.Captcha> <system.web> <httpHandlers> <!-- The Captcha Image handler used by the simple Captcha provider --> <add verb="GET" path="captcha.ashx" type="NunoGomes.CommunityServer.Captcha.Providers.SimpleCaptchaProviderImageHandler, NunoGomes.CommunityServer" /> </httpHandlers> </system.web> <system.webServer> <handlers accessPolicy="Read, Write, Script, Execute"> <!-- The Captcha Image handler used by the simple Captcha provider --> <add verb="GET" name="captcha" path="captcha.ashx" type="NunoGomes.CommunityServer.Captcha.Providers.SimpleCaptchaProviderImageHandler, NunoGomes.CommunityServer" /> </handlers> </system.webServer> </configuration> Conclusion Building a ControlAdapter can be complex but the reward is his ability to allows us, thru configuration changes, to modify an application render and/or behavior. You can see this ControlAdapter in action here and here (anonymous required). A complete solution is available in “CommunityServer Extensions” Codeplex project.

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• SSH new connection begins to hang (not reject or terminate) after a day or so on Ubuntu 13.04 server

  - by kross

  Recently we upgraded the server from 12.04 LTS server to 13.04. All was well, including after a reboot. With all packages updated we began to see a strange issue, ssh works for a day or so (unclear on timing) then a later request for SSH hangs (cannot ctrl+c, nothing). It is up and serving webserver traffic etc. Port 22 is open (ips etc altered slightly for posting): nmap -T4 -A x.acme.com Starting Nmap 6.40 ( http://nmap.org ) at 2013-09-12 16:01 CDT Nmap scan report for x.acme.com (69.137.56.18) Host is up (0.026s latency). rDNS record for 69.137.56.18: c-69-137-56-18.hsd1.tn.provider.net Not shown: 998 filtered ports PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 6.1p1 Debian 4 (protocol 2.0) | ssh-hostkey: 1024 54:d3:e3:38:44:f4:20:a4:e7:42:49:d0:a7:f1:3e:21 (DSA) | 2048 dc:21:77:3b:f4:4e:74:d0:87:33:14:40:04:68:33:a6 (RSA) |_256 45:69:10:79:5a:9f:0b:f0:66:15:39:87:b9:a1:37:f7 (ECDSA) 80/tcp open http Jetty 7.6.2.v20120308 | http-title: Log in as a Bamboo user - Atlassian Bamboo |_Requested resource was http://x.acme.com/userlogin!default.action;jsessionid=19v135zn8cl1tgso28fse4d50?os_destination=%2Fstart.action Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel Service detection performed. Please report any incorrect results at http://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 12.89 seconds Here is the ssh -vvv: ssh -vvv x.acme.com OpenSSH_5.9p1, OpenSSL 0.9.8x 10 May 2012 debug1: Reading configuration data /Users/tfergeson/.ssh/config debug1: Reading configuration data /etc/ssh_config debug1: /etc/ssh_config line 20: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to x.acme.com [69.137.56.18] port 22. debug1: Connection established. debug3: Incorrect RSA1 identifier debug3: Could not load "/Users/tfergeson/.ssh/id_rsa" as a RSA1 public key debug1: identity file /Users/tfergeson/.ssh/id_rsa type 1 debug1: identity file /Users/tfergeson/.ssh/id_rsa-cert type -1 debug1: identity file /Users/tfergeson/.ssh/id_dsa type -1 debug1: identity file /Users/tfergeson/.ssh/id_dsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_6.1p1 Debian-4 debug1: match: OpenSSH_6.1p1 Debian-4 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.9 debug2: fd 3 setting O_NONBLOCK debug3: load_hostkeys: loading entries for host "x.acme.com" from file "/Users/tfergeson/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /Users/tfergeson/.ssh/known_hosts:10 debug3: load_hostkeys: loaded 1 keys debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],ssh-rsa debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: [email protected],[email protected],ssh-rsa,[email protected],[email protected],ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256 debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 130/256 debug2: bits set: 503/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA dc:21:77:3b:f4:4e:74:d0:87:33:14:40:04:68:33:a6 debug3: load_hostkeys: loading entries for host "x.acme.com" from file "/Users/tfergeson/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /Users/tfergeson/.ssh/known_hosts:10 debug3: load_hostkeys: loaded 1 keys debug3: load_hostkeys: loading entries for host "69.137.56.18" from file "/Users/tfergeson/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /Users/tfergeson/.ssh/known_hosts:6 debug3: load_hostkeys: loaded 1 keys debug1: Host 'x.acme.com' is known and matches the RSA host key. debug1: Found key in /Users/tfergeson/.ssh/known_hosts:10 debug2: bits set: 493/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /Users/tfergeson/.ssh/id_rsa (0x7ff189c1d7d0) debug2: key: /Users/tfergeson/.ssh/id_dsa (0x0) debug1: Authentications that can continue: publickey debug3: start over, passed a different list publickey debug3: preferred publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: /Users/tfergeson/.ssh/id_rsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Server accepts key: pkalg ssh-rsa blen 277 debug2: input_userauth_pk_ok: fp 3c:e5:29:6c:9d:27:d1:7d:e8:09:a2:e8:8e:6e:af:6f debug3: sign_and_send_pubkey: RSA 3c:e5:29:6c:9d:27:d1:7d:e8:09:a2:e8:8e:6e:af:6f debug1: read PEM private key done: type RSA debug1: Authentication succeeded (publickey). Authenticated to x.acme.com ([69.137.56.18]:22). debug1: channel 0: new [client-session] debug3: ssh_session2_open: channel_new: 0 debug2: channel 0: send open debug1: Requesting [email protected] debug1: Entering interactive session. debug2: callback start debug2: client_session2_setup: id 0 debug2: fd 3 setting TCP_NODELAY debug2: channel 0: request pty-req confirm 1 debug1: Sending environment. debug3: Ignored env ATLAS_OPTS debug3: Ignored env rvm_bin_path debug3: Ignored env TERM_PROGRAM debug3: Ignored env GEM_HOME debug3: Ignored env SHELL debug3: Ignored env TERM debug3: Ignored env CLICOLOR debug3: Ignored env IRBRC debug3: Ignored env TMPDIR debug3: Ignored env Apple_PubSub_Socket_Render debug3: Ignored env TERM_PROGRAM_VERSION debug3: Ignored env MY_RUBY_HOME debug3: Ignored env TERM_SESSION_ID debug3: Ignored env USER debug3: Ignored env COMMAND_MODE debug3: Ignored env rvm_path debug3: Ignored env COM_GOOGLE_CHROME_FRAMEWORK_SERVICE_PROCESS/USERS/tfergeson/LIBRARY/APPLICATION_SUPPORT/GOOGLE/CHROME_SOCKET debug3: Ignored env JPDA_ADDRESS debug3: Ignored env APDK_HOME debug3: Ignored env SSH_AUTH_SOCK debug3: Ignored env Apple_Ubiquity_Message debug3: Ignored env __CF_USER_TEXT_ENCODING debug3: Ignored env rvm_sticky_flag debug3: Ignored env MAVEN_OPTS debug3: Ignored env LSCOLORS debug3: Ignored env rvm_prefix debug3: Ignored env PATH debug3: Ignored env PWD debug3: Ignored env JAVA_HOME debug1: Sending env LANG = en_US.UTF-8 debug2: channel 0: request env confirm 0 debug3: Ignored env JPDA_TRANSPORT debug3: Ignored env rvm_version debug3: Ignored env M2_HOME debug3: Ignored env HOME debug3: Ignored env SHLVL debug3: Ignored env rvm_ruby_string debug3: Ignored env LOGNAME debug3: Ignored env M2_REPO debug3: Ignored env GEM_PATH debug3: Ignored env AWS_RDS_HOME debug3: Ignored env rvm_delete_flag debug3: Ignored env EC2_PRIVATE_KEY debug3: Ignored env RUBY_VERSION debug3: Ignored env SECURITYSESSIONID debug3: Ignored env EC2_CERT debug3: Ignored env _ debug2: channel 0: request shell confirm 1 debug2: callback done debug2: channel 0: open confirm rwindow 0 rmax 32768 I can hard reboot (only mac monitors at that location) and it will again be accessible. This now happens every single time. It is imperative that I get it sorted. The strange thing is that it behaves initially then starts to hang after several hours. I perused logs previously and nothing stood out. From the auth.log, I can see that it has allowed me in, but still I get nothing back on the client side: Sep 20 12:47:50 cbear sshd[25376]: Accepted publickey for tfergeson from 10.1.10.14 port 54631 ssh2 Sep 20 12:47:50 cbear sshd[25376]: pam_unix(sshd:session): session opened for user tfergeson by (uid=0) UPDATES: Still occurring even after setting UseDNS no and commenting out #session optional pam_mail.so standard noenv This does not appear to be a network/dns related issue, as all services running on the machine are as responsive and accessible as ever, with the exception of sshd. Any thoughts on where to start?

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• Using delegates in C# (Part 2)

  - by rajbk

  Part 1 of this post can be read here. We are now about to see the different syntaxes for invoking a delegate and some c# syntactic sugar which allows you to code faster. We have the following console application. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Operation op1 = new Operation(Division); 9: double result = op1.Invoke(10, 5); 10: 11: Console.WriteLine(result); 12: Console.ReadLine(); 13: } 14: 15: static double Division(double x, double y) { 16: return x / y; 17: } 18: } Line 1 defines a delegate type called Operation with input parameters (double x, double y) and a return type of double. On Line 8, we create an instance of this delegate and set the target to be a static method called Division (Line 15) On Line 9, we invoke the delegate (one entry in the invocation list). The program outputs 5 when run. The language provides shortcuts for creating a delegate and invoking it (see line 9 and 11). Line 9 is a syntactical shortcut for creating an instance of the Delegate. The C# compiler will infer on its own what the delegate type is and produces intermediate language that creates a new instance of that delegate. Line 11 uses a a syntactical shortcut for invoking the delegate by removing the Invoke method. The compiler sees the line and generates intermediate language which invokes the delegate. When this code is compiled, the generated IL will look exactly like the IL of the compiled code above. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //shortcut constructor syntax 9: Operation op1 = Division; 10: //shortcut invoke syntax 11: double result = op1(10, 2); 12: 13: Console.WriteLine(result); 14: Console.ReadLine(); 15: } 16: 17: static double Division(double x, double y) { 18: return x / y; 19: } 20: } C# 2.0 introduced Anonymous Methods. Anonymous methods avoid the need to create a separate method that contains the same signature as the delegate type. Instead you write the method body in-line. There is an interesting fact about Anonymous methods and closures which won’t be covered here. Use your favorite search engine ;-)We rewrite our code to use anonymous methods (see line 9): 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //Anonymous method 9: Operation op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } We could rewrite our delegate to be of a generic type like so (see line 2 and line 9). You will see why soon. 1: //Generic delegate 2: public delegate T Operation<T>(T x, T y); 3:  4: public class Program 5: { 6: [STAThread] 7: static void Main(string[] args) 8: { 9: Operation<double> op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } The .NET 3.5 framework introduced a whole set of predefined delegates for us including public delegate TResult Func<T1, T2, TResult>(T1 arg1, T2 arg2); Our code can be modified to use this delegate instead of the one we declared. Our delegate declaration has been removed and line 7 has been changed to use the Func delegate type. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //Func is a delegate defined in the .NET 3.5 framework 7: Func<double, double, double> op1 = delegate (double x, double y) { 8: return x / y; 9: }; 10: double result = op1(10, 2); 11: 12: Console.WriteLine(result); 13: Console.ReadLine(); 14: } 15: 16: static double Division(double x, double y) { 17: return x / y; 18: } 19: } .NET 3.5 also introduced lambda expressions. A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types. We change our code to use lambda expressions. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //lambda expression 7: Func<double, double, double> op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } C# 3.0 introduced the keyword var (implicitly typed local variable) where the type of the variable is inferred based on the type of the associated initializer expression. We can rewrite our code to use var as shown below (line 7).  The implicitly typed local variable op1 is inferred to be a delegate of type Func<double, double, double> at compile time. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //implicitly typed local variable 7: var op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } You have seen how we can write code in fewer lines by using a combination of the Func delegate type, implicitly typed local variables and lambda expressions.

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