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• Output on namespaced xpath in java

  - by user347928

  I have the following code and have had some trouble with a specific field and it's output. The namespace is connected but doesn't seem to be outputting on the required field. Any info on this would be great. import org.w3c.dom.Document; import org.xml.sax.SAXException; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.ParserConfigurationException; import javax.xml.xpath.XPathFactory; import javax.xml.xpath.XPath; import javax.xml.xpath.XPathExpressionException; import java.io.ByteArrayInputStream; import java.io.IOException; public class test { public static void main(String args[]) { String xmlStr = "<aws:UrlInfoResponse xmlns:aws=\"http://alexa.amazonaws.com/doc/2005-10-05/\">\n" + " <aws:Response xmlns:aws=\"http://awis.amazonaws.com/doc/2005-07-11\">\n" + " <aws:OperationRequest>\n" + " <aws:RequestId>blah</aws:RequestId>\n" + " </aws:OperationRequest>\n" + " <aws:UrlInfoResult>\n" + " <aws:Alexa>\n" + " <aws:TrafficData>\n" + " <aws:DataUrl type=\"canonical\">harvard.edu/</aws:DataUrl>\n" + " <aws:Rank>1635</aws:Rank>\n" + " </aws:TrafficData>\n" + " </aws:Alexa>\n" + " </aws:UrlInfoResult>\n" + " <aws:ResponseStatus xmlns:aws=\"http://alexa.amazonaws.com/doc/2005-10-05/\">\n" + " <aws:StatusCode>Success</aws:StatusCode>\n" + " </aws:ResponseStatus>\n" + " </aws:Response>\n" + "</aws:UrlInfoResponse>"; DocumentBuilderFactory xmlFact = DocumentBuilderFactory.newInstance(); xmlFact.setNamespaceAware(true); DocumentBuilder builder = null; try { builder = xmlFact.newDocumentBuilder(); } catch (ParserConfigurationException e) { e.printStackTrace(); } Document doc = null; try { doc = builder.parse( new ByteArrayInputStream( xmlStr.getBytes())); } catch (SAXException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } System.out.println(doc.getDocumentElement().getNamespaceURI()); System.out.println(xmlFact.isNamespaceAware()); String xpathStr = "//aws:OperationRequest"; XPathFactory xpathFact = XPathFactory.newInstance(); XPath xpath = xpathFact.newXPath(); String result = null; try { result = xpath.evaluate(xpathStr, doc); } catch (XPathExpressionException e) { e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates. } System.out.println("XPath result is \"" + result + "\""); } }

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• Segfault (possibly due to casting)

  - by BSchlinker

  I don't normally go to stackoverflow for sigsegv errors, but I have done all I can with my debugger at the moment. The segmentation fault error is thrown following the completion of the function. Any ideas what I'm overlooking? I suspect that it is due to the casting of the sockaddr to the sockaddr_in, but I am unable to find any mistakes there. (Removing that line gets rid of the seg fault -- but I know that may not be the root cause here). // basic setup int sockfd; char str[INET_ADDRSTRLEN]; sockaddr* sa; socklen_t* sl; struct addrinfo hints, *servinfo, *p; int rv; memset(&hints, 0, sizeof hints); hints.ai_family = AF_UNSPEC; hints.ai_socktype = SOCK_DGRAM; // return string string foundIP; // setup the struct for a connection with selected IP if ((rv = getaddrinfo("4.2.2.1", NULL, &hints, &servinfo)) != 0) { fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv)); return "1"; } // loop through all the results and make a socket for(p = servinfo; p != NULL; p = p->ai_next) { if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) { perror("talker: socket"); continue; } break; } if (p == NULL) { fprintf(stderr, "talker: failed to bind socket\n"); return "2"; } // connect the UDP socket to something connect(sockfd, p->ai_addr, p->ai_addrlen); // we need to connect to get the systems local IP // get information on the local IP from the socket we created getsockname(sockfd, sa, sl); // convert the sockaddr to a sockaddr_in via casting struct sockaddr_in *sa_ipv4 = (struct sockaddr_in *)sa; // get the IP from the sockaddr_in and print it inet_ntop(AF_INET, &(sa_ipv4->sin_addr), str, INET_ADDRSTRLEN); printf("%s\n", str); // return the IP return foundIP; }

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• How can I make these images download on a seperate thread?

  - by Andy Barlow

  Hello!! I have the following code running on my Android device. It works great and displays my list items wonderfully. It's also clever in the fact it only downloads the data when it's needed by the ArrayAdapter. However, whilst the download of the thumbnail is occurring, the entire list stalls and you cannot scroll until it's finished downloading. Is there any way of threading this so it'll still scroll happily, maybe show a place holder for the downloading image, finish the download, and then show? Any help with this would be really apreciated. Thank-you kindly. Andy Barlow private class CatalogAdapter extends ArrayAdapter { private ArrayList<SingleQueueResult> items; //Must research what this actually does! public CatalogAdapter(Context context, int textViewResourceId, ArrayList<SingleQueueResult> items) { super(context, textViewResourceId, items); this.items = items; } /** This overrides the getview of the ArrayAdapter. It should send back our new custom rows for the list */ @Override public View getView(int position, View convertView, ViewGroup parent) { View v = convertView; if (v == null) { LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE); v = vi.inflate(R.layout.mylists_rows, null); } final SingleQueueResult result = items.get(position); // Sets the text inside the rows as they are scrolled by! if (result != null) { TextView title = (TextView)v.findViewById(R.id.mylist_title); TextView format = (TextView)v.findViewById(R.id.mylist_format); title.setText(result.getTitle()); format.setText(result.getThumbnail()); // Download Images ImageView myImageView = (ImageView)v.findViewById(R.id.mylist_thumbnail); downloadImage(result.getThumbnail(), myImageView); } return v; } } // This should run in a seperate thread public void downloadImage(String imageUrl, ImageView myImageView) { try { url = new URL(imageUrl); URLConnection conn = url.openConnection(); conn.connect(); InputStream is = conn.getInputStream(); BufferedInputStream bis = new BufferedInputStream(is); Bitmap bm = BitmapFactory.decodeStream(bis); bis.close(); is.close(); myImageView.setImageBitmap(bm); } catch (IOException e) { /* Reset to Default image on any error. */ //this.myImageView.setImageDrawable(getResources().getDrawable(R.drawable.default)); } }

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• Unable to make 2 parallel TCP requests to the same TCP Client

  - by soldieraman

  Error: Unable to read data from the transport connection: A blocking operation was interrupted by a call to WSACancelBlockingCall Situation There is a TCP Server My web application connects to this TCP Server Using the below code: TcpClientInfo = new TcpClient(); _result = TcpClientInfo.BeginConnect(<serverAddress>,<portNumber>, null, null); bool success = _result.AsyncWaitHandle.WaitOne(20000, true); if (!success) { TcpClientInfo.Close(); throw new Exception("Connection Timeout: Failed to establish connection."); } NetworkStreamInfo = TcpClientInfo.GetStream(); NetworkStreamInfo.ReadTimeout = 20000; 2 Users use the same application from two different location to access information from this server at the SAME TIME Server takes around 2sec to reply Both Connect But One of the user gets above error "Unable to read data from the transport connection: A blocking operation was interrupted by a call to WSACancelBlockingCall" when trying to read data from stream How can I resolve this issue? Use a better way of connecting to the server Can't because it's a server issue if a server issue, how should the server handle request to avoid this problem

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• Is Java assert broken?

  - by BlairHippo

  While poking around the questions, I recently discovered the assert keyword in Java. At first, I was excited. Something useful I didn't already know! A more efficient way for me to check the validity of input parameters! Yay learning! But then I took a closer look, and my enthusiasm was not so much "tempered" as "snuffed-out completely" by one simple fact: you can turn assertions off.* This sounds like a nightmare. If I'm asserting that I don't want the code to keep going if the input listOfStuff is null, why on earth would I want that assertion ignored? It sounds like if I'm debugging a piece of production code and suspect that listOfStuff may have been erroneously passed a null but don't see any logfile evidence of that assertion being triggered, I can't trust that listOfStuff actually got sent a valid value; I also have to account for the possibility that assertions may have been turned off entirely. And this assumes that I'm the one debugging the code. Somebody unfamiliar with assertions might see that and assume (quite reasonably) that if the assertion message doesn't appear in the log, listOfStuff couldn't be the problem. If your first encounter with assert was in the wild, would it even occur to you that it could be turned-off entirely? It's not like there's a command-line option that lets you disable try/catch blocks, after all. All of which brings me to my question (and this is a question, not an excuse for a rant! I promise!): What am I missing? Is there some nuance that renders Java's implementation of assert far more useful than I'm giving it credit for? Is the ability to enable/disable it from the command line actually incredibly valuable in some contexts? Am I misconceptualizing it somehow when I envision using it in production code in lieu of statements like if (listOfStuff == null) barf();? I just feel like there's something important here that I'm not getting. *Okay, technically speaking, they're actually off by default; you have to go out of your way to turn them on. But still, you can knock them out entirely.

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• mx:Tree not dispatching "itemClick" event when click on icon

  - by Xshare

  I have a flex tree that worked perfectly fine when we set the defaultLeafIcon={null} and the folderClosedIcon and folderOpenIcon to {null}. We decided to put the icons back in and took out the nulls. Now they show up fine, but if you click on the icon instead of the label or the rest of the row, it seems to change the selected item, shows the highlight around the new item, but doesn't dispatch the ItemClick event. This makes it really hard to know that the tree's selected item has changed! The weird part is that once you have clicked on the icon once and it looked like the selectedItem changed (or at least it applied that style), if you click the same icon again, it will actually fire the itemClick event. if you click any other icon, it does the same thing again, switching the selectedItem and styling that row, but not firing the itemClick event. Any ideas? Thanks. (This is in flex 4 btw)

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• How to validate Data Annotations with a MetaData class

  - by Micah

  I'm trying to validate a class using Data Annotations but with a metadata class. [MetadataType(typeof(TestMetaData))] public class Test { public string Prop { get; set; } internal class TestMetaData { [Required] public string Prop { get; set; } } } [Test] [ExpectedException(typeof(ValidationException))] public void TestIt() { var invalidObject = new Test(); var context = new ValidationContext(invalidObject, null, null); context.MemberName = "Prop"; Validator.ValidateProperty(invalidObject.Prop, context); } The test fails. If I ditch the metadata class and just decorated the property on the actual class it works fine. WTH am I doing wrong? This is putting me on the verge of insanity. Please help.

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• XDocument holding onto Memory?

  - by Jon

  I have an appplication that does a XDocument.Load from a 20mb file and then gets passed to a form to view its contents: openFileDialog1.FileName = ""; if (openFileDialog1.ShowDialog() == DialogResult.OK) { AuditFile = XDocument.Load(openFileDialog1.FileName); fmAuditLogViewer AuditViewer = new fmAuditLogViewer(); AuditViewer.ReportDocument = AuditFile; AuditViewer.Init(); AuditViewer.ShowDialog(); AuditViewer.Dispose(); AuditFile.RemoveNodes(); AuditFile = null; } In Task Manager I can see the memory being used by my application shoot up when I open this file. When I have finished viewing this file in my application I call : myXDocument.RemoveNodes(); myXDocument = null; However the memory use in Task Manager is still pretty high against my app. Is the XDocument still being held in memory and can I decrease the memory usage by my app?

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• C# assign char and char array to string?

  - by Bopha

  char character = 'c'; string str = null; str = character.ToString();//this is ok char[] arrayChar = { 'a', 'b', 'c', 'd' }; string str2 = null; str2 = string.Copy(arrayChar.ToString());//this is not ok str2 = arrayChar.ToString();//this is not ok. I'm trying to converting char array to string, but the last two attempts don't work. Other source I found and they have to create new string type, but I don't know why. Can someone give me little explaination, thanks.

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• Django: query with ManyToManyField count?

  - by AP257

  In Django, how do I construct a COUNT query for a ManyToManyField? My models are as follows, and I want to get all the people whose name starts with A and who are the lord or overlord of at least one Place, and order the results by name. class Manor(models.Model): lord = models.ManyToManyField(Person, null=True, related_name="lord") overlord = models.ManyToManyField(Person, null=True, related_name="overlord") class Person(models.Model): name = models.CharField(max_length=100) So my query should look something like this... but how do I construct the third line? people = Person.objects.filter( Q(name__istartswith='a'), Q(lord.count > 0) | Q(overlord.count > 0) # pseudocode ).order_by('name'))

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• DataContractJsonSerializer set value extension point

  - by svinto

  using System.IO; using System.Runtime.Serialization; using System.Runtime.Serialization.Json; using System.Text; namespace ConsoleApplication1 { internal class Program { private static void Main(string[] args) { var pony = new Pony(); var serializer = new DataContractJsonSerializer(pony.GetType()); var example = @"{""Foo"":null}"; var stream = new MemoryStream(Encoding.UTF8.GetBytes(example.ToCharArray())); stream.Position = 0; pony = (Pony) serializer.ReadObject(stream); // The previous line throws an exception. } } [DataContract] public class Pony { [DataMember] private int Foo { get; set; } } } Sometimes the serialization throws a casting error on Int32s being set to null. Is there any way to hook into the Json-serializer?

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• Error : while creating a file.

  - by Harikrishna

  I am storing records of datatable to csv file with the help of the following code : // we'll use these to check for rows with nulls var columns = yourTable.Columns .Cast<DataColumn>(); using (var writer = new StreamWriter(yourPath)) { for (int i = 0; i < yourTable.Rows.Count; i++) { DataRow row = yourTable.Rows[i]; // check for any null cells if (columns.Any(column => row.IsNull(column))) continue; string[] textCells = row.ItemArray .Select(cell => cell.ToString()) // may need to pick a text qualifier here .ToArray(); // check for non-null but EMPTY cells if (textCells.Any(text => string.IsNullOrEmpty(text))) continue; writer.WriteLine(string.Join(",", textCells)); } } But I get the error like System.UnauthorizedAccessException was unhandled Message="Access to the path 'D:\\Harikrishna\\Monthly Reports' is denied." What can be the problem and solution ?

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• set current user in asp.net mvc

  - by Tomh

  Hey guys, I'm not sure if this is the best way to do it, but I want to keep a user object alive during all requests of the current user. From reading several resources I learned that you should create your own IPrinciple which holds this. But I don't want to trigger the database every authentication request. Any recommendations on how to handle this? Is caching the db request a good idea? protected void Application_AuthenticateRequest(Object sender, EventArgs e) { HttpCookie authCookie = Request.Cookies[FormsAuthentication.FormsCookieName]; if (authCookie != null) { FormsAuthenticationTicket authTicket = FormsAuthentication.Decrypt(authCookie.Value); User user; using (HgDataContext hg = new HgDataContext()) { if (Session["user"] != null) { user = (from u in hg.Users where u.EmailAddress == authTicket.Name select u).Single(); } else { user = Session["user"] as User; } } var principal = new HgPrincipal(user); Context.User = principal; } }

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• WaitForSingleObject( )

  - by Rakesh Agarwal

  I have got myself stuck into a really amazing issue here.The code is like as below. class A { public: A(){ m_event = CreateEvent(NULL, false, false, NULL); // create an event with initial value as non-signalled m_thread = _beginthread(StaticThreadEntry, 0, this); // create a thread } static void StaticThreadEntry(A * obj) { obj->ThreadEntry(); } void ThreadEntry(); }; void A::ThreadEntry() { WaitforSingleObject(m_event,INFINITE); } int main() { A a; SetEvent(m_event); // sets the event to signalled state which causes the running thread to terminate WaitForSingleObject(m_thread, INFINITE); // waits for the thread to terminate return 0; } Problem : When the above code is run,sometimes( 1 out of 5 ) it hangs and the control gets stuck in the call to WaitforSingleObject()( inside the main function ).The code always calls SetEvent() function to ensure that the thread would terminate before calling Wait() function. I do not see any reason why it should ever hang?

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• How do I remove (or apply) transparency on a gdk-pixbuf?

  - by Andrew Stacey

  I have a c++ program in which a gdk-pixbuf is created. I want to output it as an image, so I call gdk_pixbuf_save_to_stream(pixbuf,stream,type,NULL,&err,NULL). This works fine when "type" is png or tiff, but with jpeg or bmp it just produces a black square. The original pixbuf consists of black-on-transparent (and gdk_pixbuf_get_has_alpha returns true) so I'm guessing that the problem is with the alpha mask. GdkPixbuf has a function to add an alpha channel, but I can't see one that removes it again, or (which might be as good) to invert it. Is there a simple way to get the jpeg and bmp formats to work properly? (I should say that I'm very new to proper programming like this.)

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• jQuery event handler queue

  - by resopollution

  Overview of the problem In jQuery, the order in which you bind a handler is the order in which they will be executed if you are binding to the same element. For example: $('#div1').bind('click',function(){ // code runs first }); $('#div1').bind('click',function(){ // code runs second }); But what if I want the 2nd bound code to run first? . My current solution Currently, my solution is to modify the event queue: $.data(domElement, 'events')['click'].unshift({ type : 'click', guid : null, namespace : "", data : undefined, handler: function() { // code } }); . Question Is there anything potentially wrong with my solution? Can I safely use null as a value for the guid? Thanks in advance. .

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• WPF Accessing Items inside Listbox which has a UserControl as ItemTemplate

  - by Turker

  I have Window that has a ListBox ListBox(MyListBox) has a DataTable for its DataContext ListBox's ItemSource is : {Binding} Listbox has a UserControl(MyUserControl) as DataTemplate UserControl has RadioButtons and TextBoxes (At first They're filled with values from DataTable and then user can change them) Window has one Submit Button What I want to do is, when user clicks the submit button For each ListBox Item, get the values form UserControl's TextBoxes and RadioButtons. I was using that method for this job : foreach(var element in MyListBox.Items) { var border = MyListBox.ItemContainerGenerator.ContainerFromItem(element)as FrameworkElement; MyUserControl currentControl = VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(myBorder,0) as Border,0)as ContentPresenter,0)as MyUserControl; //And use currentControl } I realised nothing when using 3-5 items in Listbox. But when I used much more items, I saw that "var border" gets "null" after some elements looped in foreach function. I found the reason here : http://stackoverflow.com/questions/1675926/listview-itemcontainergenerator-containerfromitemitem-return-null-after-20-item So what can I do now? I want to access all items and get their values sitting on user controls. Thanks

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• Unix Piping using Fork and Dup

  - by Jacob

  Lets say within my program I want to execute two child processes, one to to execute a "ls -al" command and then pipe that into "wc" command and display the output on the terminal. How can I do this using pipe file descriptors so far the code I have written: An example would be greatly helpful int main(int argc, char *argv[]) { int pipefd[2] pipe(pipefd2); if ((fork()) == 0) { dup2(pipefd2[1],STDOUT_FILENO); close(pipefd2[0]); close(pipefd2[1]); execl("ls", "ls","-al", NULL); exit(EXIT_FAILURE); } if ((fork()) == 0){ dup2(pipefd2[0],STDIN_FILENO); close(pipefd2[0]); close(pipefd2[1]); execl("/usr/bin/wc","wc",NULL); exit(EXIT_FAILURE); } close(pipefd[0]); close(pipefd[1]); close(pipefd2[0]); close(pipefd2[1]); }

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• ASMLib

  - by wcoekaer

  Oracle ASMlib on Linux has been a topic of discussion a number of times since it was released way back when in 2004. There is a lot of confusion around it and certainly a lot of misinformation out there for no good reason. Let me try to give a bit of history around Oracle ASMLib. Oracle ASMLib was introduced at the time Oracle released Oracle Database 10g R1. 10gR1 introduced a very cool important new features called Oracle ASM (Automatic Storage Management). A very simplistic description would be that this is a very sophisticated volume manager for Oracle data. Give your devices directly to the ASM instance and we manage the storage for you, clustered, highly available, redundant, performance, etc, etc... We recommend using Oracle ASM for all database deployments, single instance or clustered (RAC). The ASM instance manages the storage and every Oracle server process opens and operates on the storage devices like it would open and operate on regular datafiles or raw devices. So by default since 10gR1 up to today, we do not interact differently with ASM managed block devices than we did before with a datafile being mapped to a raw device. All of this is without ASMLib, so ignore that one for now. Standard Oracle on any platform that we support (Linux, Windows, Solaris, AIX, ...) does it the exact same way. You start an ASM instance, it handles storage management, all the database instances use and open that storage and read/write from/to it. There are no extra pieces of software needed, including on Linux. ASM is fully functional and selfcontained without any other components. In order for the admin to provide a raw device to ASM or to the database, it has to have persistent device naming. If you booted up a server where a raw disk was named /dev/sdf and you give it to ASM (or even just creating a tablespace without asm on that device with datafile '/dev/sdf') and next time you boot up and that device is now /dev/sdg, you end up with an error. Just like you can't just change datafile names, you can't change device filenames without telling the database, or ASM. persistent device naming on Linux, especially back in those days ways to say it bluntly, a nightmare. In fact there were a number of issues (dating back to 2004) : Linux async IO wasn't pretty persistent device naming including permissions (had to be owned by oracle and the dba group) was very, very difficult to manage system resource usage in terms of open file descriptors So given the above, we tried to find a way to make this easier on the admins, in many ways, similar to why we started working on OCFS a few years earlier - how can we make life easier for the admins on Linux. A feature of Oracle ASM is the ability for third parties to write an extension using what's called ASMLib. It is possible for any third party OS or storage vendor to write a library using a specific Oracle defined interface that gets used by the ASM instance and by the database instance when available. This interface offered 2 components : Define an IO interface - allow any IO to the devices to go through ASMLib Define device discovery - implement an external way of discovering, labeling devices to provide to ASM and the Oracle database instance This is similar to a library that a number of companies have implemented over many years called libODM (Oracle Disk Manager). ODM was specified many years before we introduced ASM and allowed third party vendors to implement their own IO routines so that the database would use this library if installed and make use of the library open/read/write/close,.. routines instead of the standard OS interfaces. PolyServe back in the day used this to optimize their storage solution, Veritas used (and I believe still uses) this for their filesystem. It basically allowed, in particular, filesystem vendors to write libraries that could optimize access to their storage or filesystem.. so ASMLib was not something new, it was basically based on the same model. You have libodm for just database access, you have libasm for asm/database access. Since this library interface existed, we decided to do a reference implementation on Linux. We wrote an ASMLib for Linux that could be used on any Linux platform and other vendors could see how this worked and potentially implement their own solution. As I mentioned earlier, ASMLib and ODMLib are libraries for third party extensions. ASMLib for Linux, since it was a reference implementation implemented both interfaces, the storage discovery part and the IO part. There are 2 components : Oracle ASMLib - the userspace library with config tools (a shared object and some scripts) oracleasm.ko - a kernel module that implements the asm device for /dev/oracleasm/* The userspace library is a binary-only module since it links with and contains Oracle header files but is generic, we only have one asm library for the various Linux platforms. This library is opened by Oracle ASM and by Oracle database processes and this library interacts with the OS through the asm device (/dev/asm). It can install on Oracle Linux, on SuSE SLES, on Red Hat RHEL,.. The library itself doesn't actually care much about the OS version, the kernel module and device cares. The support tools are simple scripts that allow the admin to label devices and scan for disks and devices. This way you can say create an ASM disk label foo on, currently /dev/sdf... So if /dev/sdf disappears and next time is /dev/sdg, we just scan for the label foo and we discover it as /dev/sdg and life goes on without any worry. Also, when the database needs access to the device, we don't have to worry about file permissions or anything it will be taken care of. So it's a convenience thing. The kernel module oracleasm.ko is a Linux kernel module/device driver. It implements a device /dev/oracleasm/* and any and all IO goes through ASMLib - /dev/oracleasm. This kernel module is obviously a very specific Oracle related device driver but it was released under the GPL v2 so anyone could easily build it for their Linux distribution kernels. Advantages for using ASMLib : A good async IO interface for the database, the entire IO interface is based on an optimal ASYNC model for performance A single file descriptor per Oracle process, not one per device or datafile per process reducing # of open filehandles overhead Device scanning and labeling built-in so you do not have to worry about messing with udev or devlabel, permissions or the likes which can be very complex and error prone. Just like with OCFS and OCFS2, each kernel version (major or minor) has to get a new version of the device drivers. We started out building the oracleasm kernel module rpms for many distributions, SLES (in fact in the early days still even for this thing called United Linux) and RHEL. The driver didn't make sense to get pushed into upstream Linux because it's unique and specific to the Oracle database. As it takes a huge effort in terms of build infrastructure and QA and release management to build kernel modules for every architecture, every linux distribution and every major and minor version we worked with the vendors to get them to add this tiny kernel module to their infrastructure. (60k source code file). The folks at SuSE understood this was good for them and their customers and us and added it to SLES. So every build coming from SuSE for SLES contains the oracleasm.ko module. We weren't as successful with other vendors so for quite some time we continued to build it for RHEL and of course as we introduced Oracle Linux end of 2006 also for Oracle Linux. With Oracle Linux it became easy for us because we just added the code to our build system and as we churned out Oracle Linux kernels whether it was for a public release or for customers that needed a one off fix where they also used asmlib, we didn't have to do any extra work it was just all nicely integrated. With the introduction of Oracle Linux's Unbreakable Enterprise Kernel and our interest in being able to exploit ASMLib more, we started working on a very exciting project called Data Integrity. Oracle (Martin Petersen in particular) worked for many years with the T10 standards committee and storage vendors and implemented Linux kernel support for DIF/DIX, data protection in the Linux kernel, note to those that wonder, yes it's all in mainline Linux and under the GPL. This basically gave us all the features in the Linux kernel to checksum a data block, send it to the storage adapter, which can then validate that block and checksum in firmware before it sends it over the wire to the storage array, which can then do another checksum and to the actual DISK which does a final validation before writing the block to the physical media. So what was missing was the ability for a userspace application (read: Oracle RDBMS) to write a block which then has a checksum and validation all the way down to the disk. application to disk. Because we have ASMLib we had an entry into the Linux kernel and Martin added support in ASMLib (kernel driver + userspace) for this functionality. Now, this is all based on relatively current Linux kernels, the oracleasm kernel module depends on the main kernel to have support for it so we can make use of it. Thanks to UEK and us having the ability to ship a more modern, current version of the Linux kernel we were able to introduce this feature into ASMLib for Linux from Oracle. This combined with the fact that we build the asm kernel module when we build every single UEK kernel allowed us to continue improving ASMLib and provide it to our customers. So today, we (Oracle) provide Oracle ASMLib for Oracle Linux and in particular on the Unbreakable Enterprise Kernel. We did the build/testing/delivery of ASMLib for RHEL until RHEL5 but since RHEL6 decided that it was too much effort for us to also maintain all the build and test environments for RHEL and we did not have the ability to use the latest kernel features to introduce the Data Integrity features and we didn't want to end up with multiple versions of asmlib as maintained by us. SuSE SLES still builds and comes with the oracleasm module and they do all the work and RHAT it certainly welcome to do the same. They don't have to rebuild the userspace library, it's really about the kernel module. And finally to re-iterate a few important things : Oracle ASM does not in any way require ASMLib to function completely. ASMlib is a small set of extensions, in particular to make device management easier but there are no extra features exposed through Oracle ASM with ASMLib enabled or disabled. Often customers confuse ASMLib with ASM. again, ASM exists on every Oracle supported OS and on every supported Linux OS, SLES, RHEL, OL withoutASMLib Oracle ASMLib userspace is available for OTN and the kernel module is shipped along with OL/UEK for every build and by SuSE for SLES for every of their builds ASMLib kernel module was built by us for RHEL4 and RHEL5 but we do not build it for RHEL6, nor for the OL6 RHCK kernel. Only for UEK ASMLib for Linux is/was a reference implementation for any third party vendor to be able to offer, if they want to, their own version for their own OS or storage ASMLib as provided by Oracle for Linux continues to be enhanced and evolve and for the kernel module we use UEK as the base OS kernel hope this helps.

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• NAudio: How can I get an event that tells me that the MP3 file reached the end?

  - by Rookian

  I tried to use this: private void CreateDevice() { _playbackDevice = new WaveOut(); _playbackDevice.PlaybackStopped += PlaybackDevicePlaybackStopped; } void PlaybackDevicePlaybackStopped(object sender, EventArgs e) { if (OnPlaybackStopped != null) { OnPlaybackStopped(this, e); } } But it never invoked. Then I tried to use the PlaybackState by polling the property with a timer: public PlaybackState PlaybackState { get { if (_playbackDevice == null) return default(PlaybackState); return _playbackDevice.PlaybackState; } } But when the song ends it does not change to "stopped". But when I call Stopped it changes correctly. Can someone help me?

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• How to make linq master detail query for 0..n relationship?

  - by JK

  Given a classic DB structure of Orders has zero or more OrderLines and OrderLine has exactly one Product, how do I write a linq query to express this? The output would be OrderNumber - OrderLine - Product Name Order-1 null null // (this order has no lines) Order-2 1 Red widget I tried this query but is not getting the orders with no lines var model = (from po in Orders from line in po.OrderLines select new { OrderNumber = po.Id, OrderLine = line.LineNumber, ProductName = line.Product.ProductDescription, } ) I think that the 2nd from is limiting the query to only those that have OrderLines, but I dont know another way to express it. LINQ is very non-obvious if you ask me!

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• Birt Global Integer

  - by matschie

  Hi there I have a Birt Report which read some stuff from a database. After that i want to increment a global Integer for every Detailrow that is loaded. So far i have initialized a global Integer with the following lines: importPackage(Packages.java.lang); reportContext.setPersistentGlobalVariable("minTotalPlus", new Integer(0)); After that i added the following line into a field in my detail row: reportContext.setGlobalVariable("minTotalPlus", new Integer reportContext.getGlobalVariable("minTotalPlus")) + 1); When i preview the report i get an "java.lang.NumberFormatException: null" which means that the global variable is null. Why is that so? How could I fix that?

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• How to detect open database connection with Hibernate / JPA?

  - by John K

  I am learning JPA w/Hibernate using a Java SE 6 project. I'd simply like to be able to detect if the connection between Hibernate and my database (MS SQL Server) is open. For example, I'd like to be able to detect this, log it, and try reconnecting again in 60 seconds. This is what I thought would work but isOpen() doesn't appear to be what I want (always is true): EntityManagerFactory emf = Persistence.createEntityManagerFactory("rcc", props); if (emf != null && emf.isOpen()) { EntityManager em = emf.createEntityManager(); if (em == null || !emf.isOpen()) // error connecting to database else ... This seems to me to be a simple problem, but I cannot find an answer!

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• Code Behaviour via Unit Tests

  - by Dewald Galjaard

  Normal 0 false false false EN-ZA X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Some four months ago my car started acting up. Symptoms included a sputtering as my car’s computer switched between gears intermittently. Imagine building up speed, then when you reach 80km/h the car magically and mysteriously decide to switch back to third or even second gear. Clearly it was confused! I managed to track down a technician, an expert in his field to help me out. As he fitted his handheld computer to some hidden port under the dash, he started to explain “These cars are quite intelligent, you know. When they sense something is wrong they run in a restrictive program which probably account for how you managed to drive here in the first place...”  I was surprised and thought this was certainly going to be an interesting test drive. The car ran smoothly down the first couple of stretches as the technician ran through routine checks. Then he said “Ok, all looking good. We need to start testing aspects of the gearbox. Inside the gearbox there are a couple of sensors. One of them is a speed sensor which talks to the computer, which in turn will decide which gear to switch to. The restrictive program avoid these sensors altogether and allow the computer to obtain its input from other [non-affected] sources”. Then, as soon as he forced the speed sensor to come back online the symptoms and ill behaviour re-emerged... What an incredible analogy for getting into a discussion on unit testing software? Besides I should probably put my ill fortune to some good use, right? This example provide a lot of insight into how and why we should conduct unit tests when writing code. More importantly, it captures what is easily and unfortunately often the most overlooked goal of writing unit tests by those new to the art and those who oppose it alike - The goal of writing unit tests is to test the behaviour of our code under predefined conditions. Although it is very possible to test the intrinsic workings of each and every component in your code, writing several tests for each method in practise will soon prove to be an exhausting and ultimately fruitless exercise given the certain and ever changing nature of business requirements. Consequently it is true and quite possible whilst conducting proper unit tests, to call any single method several times as you examine and contemplate different scenarios. Let’s write some code to demonstrate what I mean. In my example I make use of the Moq framework and NUnit to create my tests. Truly you can use whatever you’re comfortable with. First we’ll create an ISpeedSensor interface. This is to represent the speed sensor located in the gearbox.  Then we’ll create a Gearbox class which we’ll pass to a constructor when we instantiate an object of type Computer. All three are described below.   ISpeedSensor.cs namespace AutomaticVehicle {     public interface ISpeedSensor     {         int ReportCurrentSpeed();     } }   Gearbox.cs namespace AutomaticVehicle {      public class Gearbox     {         private ISpeedSensor _speedSensor;           public Gearbox( ISpeedSensor gearboxSpeedSensor )         {             _speedSensor = gearboxSpeedSensor;         }         /// <summary>         /// This method obtain it's reading from the speed sensor.         /// </summary>         /// <returns></returns>         public int ReportCurrentSpeed()         {             return _speedSensor.ReportCurrentSpeed();         }     } } Computer.cs namespace AutomaticVehicle {     public class Computer     {         private Gearbox _gearbox;         public Computer( Gearbox gearbox )         {                     }          public int GetCurrentSpeed()         {             return _gearbox.ReportCurrentSpeed( );         }     } } Since this post is about Unit testing, that is exactly what we’ll create next. Create a second project in your solution. I called mine AutomaticVehicleTests and I immediately referenced the respective nunit, moq and AutomaticVehicle dll’s. We’re going to write a test to examine what happens inside the Computer class. ComputerTests.cs namespace AutomaticVehicleTests {     [TestFixture]     public class ComputerTests     {         [Test]         public void Computer_Gearbox_SpeedSensor_DoesThrow()         {             // Mock ISpeedSensor in gearbox             Mock< ISpeedSensor > speedSensor = new Mock< ISpeedSensor >( );             speedSensor.Setup( n => n.ReportCurrentSpeed() ).Throws<Exception>();             Gearbox gearbox = new Gearbox( speedSensor.Object );               // Create Computer instance to test it's behaviour  towards an exception in gearbox             Computer carComputer = new Computer( gearbox );             // For simplicity let’s assume for now the car only travels at 60 km/h.             Assert.AreEqual( 60, carComputer.GetCurrentSpeed( ) );          }     } }   What is happening in this test? We have created a mocked object using the ISpeedsensor interface which we've passed to our Gearbox object. Notice that I created the mocked object using an interface, not the implementation. I’ll talk more about this in future posts but in short I do this to accentuate the fact that I'm not not really concerned with how SpeedSensor work internally at this particular point in time. Next I’ve gone ahead and created a scenario where I’ve declared the speed sensor in Gearbox to be faulty by forcing it to throw an exception should we ask Gearbox to report on its current speed. Sneaky, sneaky. This test is a simulation of how things may behave in the real world. Inevitability things break, whether it’s caused by mechanical failure, some logical error on your part or a fellow developer which didn’t consult the documentation (or the lack thereof ) - whether you’re calling a speed sensor, making a call to a database, calling a web service or just trying to write a file to disk. It’s a scenario I’ve created and this test is about how the code within the Computer instance will behave towards any such error as I’ve depicted. Now, if you’ve followed closely in my final assert method you would have noticed I did something quite unexpected. I might be getting ahead of myself now but I’m testing to see if the value returned is equal to what I expect it to be under perfect conditions – I’m not testing to see if an error has been thrown! Why is that? Well, in short this is TDD. Test Driven Development is about first writing your test to define the result we want, then to go back and change the implementation within your class to obtain the desired output (I need to make sure I can drive back to the repair shop. Remember? ) So let’s go ahead and run our test as is. It’s fails miserably... Good! Let’s go back to our Computer class and make a small change to the GetCurrentSpeed method.   Computer.cs public int GetCurrentSpeed() {   try   {     return _gearbox.ReportCurrentSpeed( );   }   catch   {     RunRestrictiveProgram( );   } }     This is a simple solution, I know, but it does provide a way to allow for different behaviour. You’re more than welcome to provide an implementation for RunRestrictiveProgram should you feel the need to. It's not within the scope of this post or related to the point I'm trying to make. What is important is to notice how the focus has shifted in our approach from how things can break - to how things behave when broken.   Happy coding!

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• Android: Memory leak due to AsyncTask

  - by Manu

  Hello, I'm stuck with a memory leak that I cannot fix. I identified where it occurs, using the MemoryAnalizer but I vainly struggle to get rid of it. Here is the code: public class MyActivity extends Activity implements SurfaceHolder.Callback { ... Camera.PictureCallback mPictureCallbackJpeg = new Camera.PictureCallback() { public void onPictureTaken(byte[] data, Camera c) { try { // log the action Log.e(getClass().getSimpleName(), "PICTURE CALLBACK JPEG: data.length = " + data); // Show the ProgressDialog on this thread pd = ProgressDialog.show(MyActivity.this, "", "Préparation", true, false); // Start a new thread that will manage the capture new ManageCaptureTask().execute(data, c); } catch(Exception e){ AlertDialog.Builder dialog = new AlertDialog.Builder(MyActivity.this); ... dialog.create().show(); } } class ManageCaptureTask extends AsyncTask<Object, Void, Boolean> { protected Boolean doInBackground(Object... args) { Boolean isSuccess = false; // initialize the bitmap before the capture ((myApp) getApplication()).setBitmapX(null); try{ // Check if it is a real device or an emulator TelephonyManager telmgr = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE); String deviceID = telmgr.getDeviceId(); boolean isEmulator = "000000000000000".equalsIgnoreCase(deviceID); // get the bitmap if (isEmulator) { ((myApp) getApplication()).setBitmapX(BitmapFactory.decodeFile(imageFileName)); } else { ((myApp) getApplication()).setBitmapX(BitmapFactory.decodeByteArray((byte[]) args[0], 0, ((byte[])args[0]).length)); } ((myApp) getApplication()).setImageForDB(ImageTools.resizeBmp(((myApp) getApplication()).getBmp())); // convert the bitmap into a grayscale image and display it in the preview ((myApp) getApplication()).setImage(makeGrayScale()); isSuccess = true; } catch (Exception connEx){ errorMessageFromBkgndThread = getString(R.string.errcapture); } return isSuccess; } protected void onPostExecute(Boolean result) { // Pass the result data back to the main activity if (MyActivity.this.pd != null) { MyActivity.this.pd.dismiss(); } if (result){ ((ImageView) findViewById(R.id.apercu)).setImageBitmap(((myApp) getApplication()).getBmp()); ((myApp) getApplication()).setBitmapX(null); } else{ // there was an error ErrAlert(); } } } }; private void ErrAlert(){ // notify the user about the error AlertDialog.Builder dialog = new AlertDialog.Builder(this); ... dialog.create().show(); } } MemoryAnalyzer indicated the memory leak at: ((myApp) getApplication()).setBitmapX(BitmapFactory.decodeByteArray((byte[]) args[0], 0, ((byte[])args[0]).length)); I am grateful for any suggestion, thank you in advance.

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