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• Getting started with SVG graphics objects in JSF 2.0 pages.

  - by AlanObject

  What I want to do is create web pages with interactive SVG content. I had this working as a Java desktop application using Batik to render my SVG and collect UI events like mouseclick. Now I want to use those SVG graphics files in my JSF (Primefaces) web application in the same way. Trying to get started, I found this didn't work: <h:graphicImage id="gloob" value="images/sprinkverks.svg" alt="Graphic Goes Here"/> I don't mind doing some reading to get up the learning curve. It was just a bit surprising that some google searches didn't turn up anything useful. What I did find suggested that I would have to do this with the f:verbatim tag as if I were hand-coding the HTML. I would then have to add some script to capture the SVG events and feed them back into the AJAX code. If I have to do all that I will, but I was hoping there would be an easier and automated way. So the questions are: How to get the image to render in the first place? How to get the DOM events from the SVG portion of the page back to the backing beans? Much thanks for any pointers.

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• DDD principlers and ASP.NET MVC project design

  - by kaivalya

  Two part questions I have a product aggregate that has; Prices PackagingOptions ProductDescriptions ProductImages etc I have modeled one product repository and did not create individual repositories for any of the child classes. All db operations are handled through product repository. Am I understanding the DDD concept correctly so far? Sometimes the question comes to my mind that having a repository for lets say packaging options could make my life easier by directly fetching a the packaging option from the DB by using its ID instead of asking the product repository to find it in its PackagingOptions collection and give it to me.. Second part is managing the edit create operations using ASP.MVC frame work I am currently trying to manage all add edit remove of these child collections of product through product controller(sound right?). One challenge I am now facing is; If I edit a specific packaging option of product through mydomain/product/editpackagingoption/10 I have access to the id of the packaging option But I don't have the ID of the product it self and this forces me to write a query to first find the product that has this specific packaging option then edit that product and the revelant packaging option. I can do this as all packaging option have their unique ID but this would fail if I have collections that don't have unique ID. That feels very wrong.. The next option I thought of is sending both the product and packaging option IDs on the url like; mydomain/product/editpackagingoption/3/10 But I am not sure if that is a good design either. So I am at a point that I am a bit confused. might be having fundamental misunderstandings around all of this... I would appreciate if you bear with the long question and help me put this together. thanks!

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• Cocoa Virtual Keystrokes Pain

  - by bhargav

  I'm writing an application to respond on a hotkey by copying highlighted text into NSPasteboard's generalPasteboard. After looking around here for a solution for sending virtual keystrokes, I found this: http://stackoverflow.com/questions/1505933/how-to-send-a-cmd-c-keystroke-to-the-active-application-in-objective-c-or-tell I tried the applescript suggested with NSAppleScript: NSLog(@"Hotkey Pressed"); NSPasteboard *pasteboard = [NSPasteboard generalPasteboard]; NSAppleScript *playScript; playScript = [[NSAppleScript alloc] initWithSource:@"tell application \"System Events\" to keystroke \"c\" using command down"]; if([playScript isCompiled] == NO){ [playScript compileAndReturnError:nil]; } id exerror = [playScript executeAndReturnError:nil]; if(exerror == nil){ NSLog(@"Script Failed"); } It works, but only on the first time I hit the hotkey. Each subsequent hit will not to grab the highlighted text. The generalPasteboard still contains the same contents as before the script is run again. Clearing the generalPasteboard before I run the code is no use, because then the code fails when attempting to read the pasteboard contents. So I tried the next suggested solution: CFRelease(CGEventCreate(NULL)); CGEventRef event1, event2, event3, event4; event1 = CGEventCreateKeyboardEvent (NULL, (CGKeyCode)50, true); event2 = CGEventCreateKeyboardEvent (NULL, (CGKeyCode)8, true); event3 = CGEventCreateKeyboardEvent (NULL, (CGKeyCode)8, false); event4 = CGEventCreateKeyboardEvent (NULL, (CGKeyCode)50, false); CGEventPost(kCGHIDEventTap, event1); CGEventPost(kCGHIDEventTap, event2); CGEventPost(kCGHIDEventTap, event3); CGEventPost(kCGHIDEventTap, event4); The above should send the keystrokes Command + c, but all I get is a beep, and the pasteboard contents are unchanged. I'm at wits end - can anyone enlighten me as to what I'm missing or point me out to what I'm overlooking for something so simple?

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• Asp.Net MVC2 Clientside Validation problem with controls with prefixes

  - by alexander

  The problem is: when I put 2 controls of the same type on a page I need to specify different prefixes for binding. In this case the validation rules generated right after the form are incorrect. So how to get client validation work for the case?: the page contains: <% Html.RenderPartial(ViewLocations.Shared.PhoneEditPartial, new PhoneViewModel { Phone = person.PhonePhone, Prefix = "PhonePhone" }); Html.RenderPartial(ViewLocations.Shared.PhoneEditPartial, new PhoneViewModel { Phone = person.FaxPhone, Prefix = "FaxPhone" }); %> the control ViewUserControl<PhoneViewModel>: <%= Html.TextBox(Model.GetPrefixed("CountryCode"), Model.Phone.CountryCode) %> <%= Html.ValidationMessage("Phone.CountryCode", new { id = Model.GetPrefixed("CountryCode"), name = Model.GetPrefixed("CountryCode") })%> where Model.GetPrefixed("CountryCode") just returns "FaxPhone.CountryCode" or "PhonePhone.CountryCode" depending on prefix And here is the validation rules generated after the form. They are duplicated for the field name "Phone.CountryCode". While the desired result is 2 rules (required, number) for each of the FieldNames "FaxPhone.CountryCode", "PhonePhone.CountryCode" The question is somewhat duplicate of http://stackoverflow.com/questions/2675606/asp-net-mvc2-clientside-validation-and-duplicate-ids-problem but the advise to manually generate ids doesn't helps.

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• How do you cast a LinqToSql Table<TEntity> as a Table<IEntity> where TEntity : IEntity?

  - by DanM

  I'm trying to use DbLinq with a SQLite database, but I'm running into a problem when I try to cast an ITable as a Queryable<TEntity>. There is a known bug in DbLinq (Issue 211), which might be the source of my problem, but I wanted to make sure my code is sound and, if it is, find out if there might be something I can do to work around the bug. Here is the generic repository method that attempts to do the cast: public IQueryable<TEntity> GetAll() { return Table.Cast<TEntity>(); // Table is an ITable } This compiles, but if I pass in the interface IPerson for TEntity and the type of the entities in the table is Person (where Person : IPerson), I'm getting this error from DbLinq: S0133: Implement QueryMethod Queryable.Cast. Why am I trying to do this? I have a library project that doesn't know the type of the entity until runtime, but it does know the interface for the entity. So, I'm trying to cast to the interface type so that my library project can consume the data. Questions: Am I attempting an impossible cast or is this definitely a bug in DbLinq? How else could I go about solving my problem?

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• Is it possible to use Indy 10.5.8.0 with Delphi XE?

  - by jachguate

  The case I'm trying to update the INDY to the latest version for my Delphi XE (Update 1), so I downloaded the latest INDY10 file (Indy_4545.zip) from indy.fulgan.com/ZIP. The packages compiles successfully and I can now even see the new version 10.5.8.0 on the about box dialog, but after a IDE restart I got a message saying: No se encuentra el punto de entrada del procedimiento @Idhttp@TIdCustomHTTP@GetRequestHeaders$qqrv en la biblioteca de vínculos dinámicos IndyProtocols150.bpl. My free translation to English: Entry point not found for procedure @Idhttp@TIdCustomHTTP@GetRequestHeaders$qqrv not found on the dynamic link library IndyProtocols150.bpl. After a quick comparision of old and new IdHTTP.pas I found a lot of changes on the TIdCustomHttp class, including the rename of some methods GetResponseHeaders to GetResponse GetRequestHeaders to GetRequest SetRequestHeaders to SetRequest Along with changed public/published method firms in this and other and classes interfaces. After the update, I got a lot of packages failing to load, including dclcxPivotGridOLAPD15.bpl, which in turns depends on dclDataSnapServer150.bpl which encounters the missing method on the bpl. AFAIK I can't recompile the dclDataSnapServer150.bpl (and maybe other failing packages, I just stopped here). DataSnap and DevExpress support on the IDE is a must for my day to day so The questions Is there a safe pre-established path to update to the newest INDY for Delphi XE? If not, am I on the safe side by just parching the source code by creating the old public methods and call the new ones on the implementation part? am I missing something else or am I really stuck with INDY 10.5.7 until the next Delphi minor/major release?

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• Bypass all cacheing on jQuery.autocomplete(1.02)

  - by technicalbloke

  I am using jQuery.autocomplete(1.02) on my search box and I want exact string and substring matching. I don't care (yet!) about the database load, I'm happy for it to fire off a query every keystroke and bypass the caching entirely - I just don't want anything missed. To this end I have tried setting cacheLength=1, the minimum permitted, but the autocomplete function refuses to fire off a GET request for each key up. searchbox GET_request 'a' -> http://localhost/service_search_request?q=a 'ar' -> http://localhost/service_search_request?q=ar 'ars' -> http://localhost/service_search_request?q=ars Instead, it sends the first and the third and misses the second, giving me the wrong results for 'ar' :-/ I've cleared my cache and sessions but it looks like some sort of caching is still going on. AFAIK I have no proxying going on and I'm shift-refreshing each time. It looks likely then that this behavior is from jQuery.autocomplete itself. So my questions are... A) Does this seem likely? i.e. is it a feature, or maybe a bug? B) If so is there a clean way around it?... C) If not, what autocomplete would you use instead? Naturally D) No you're just using it incorrectly you douche! is always a possibility, and indeed the one I'd prefer having spent time going down this road - assuming it comes with a link to the docs I've failed to find / read! Cheers, Roger :)

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• Good ways to dynamically generate the start image of an iPhone/iPad app

  - by Dr Dork

  I'm self-learning iPhone development and I see that one of the aspects of an iPhone/iPad app is the start image that gets displayed when your app is run. I'd like my start image to display some basic info about the user when the app is launched, but that info has to first be collected by the user when the app is first run. That tells me that I either need to dynamically generate the start image after the user enters their information or I need to place a label of some sort on top of my static start image in order to accomplish this. The first time the app launched and before the user enters their info, the start image can be anything or nothing at all, I'm not concerned about this. So, my two questions are this... Can you place controls, like a label, on top of the start image when your app is launched? If not, what's a good approach to dynamically generating the start image after the app is launched for the first time and the user info is collected? Thanks so much in advance for your help! I'm going to begin researching this question right now.

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• RESTful WCF Data Service Authentication

  - by Adrian Grigore

  Hi, I'd like to implement a REST api to an existing ASP.NET MVC website. I've managed to set up WCF Data services so that I can browse my data, but now the question is how to handle authentication. Right now the data service is secured via the site's built in forms authentication, and that's ok when accessing the service from AJAX forms. However, It's not ideal for a RESTful api. What I would like as an alternative to forms authentication is for the users to simply embed the user name and password into the url to the web service or as request parameters. For example, if my web service is usually accessible as http://localhost:1234/api.svc I'd like to be able to access it using the url http://localhost:1234/api.svc/{login}/{password} So, my questions are as follows: Is this a sane approach? If yes, how can I implement this? It seems trivial redirecting GET requests so that the login and password are attached as GET parameters. I also know how to inspect the http context and use those parameters to filter the results. But I am not sure if / how the same approach could be applied to POST, PUT and DELETE requests. Thanks, Adrian

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• Firefox Extension Socket Transport

  - by Nathan

  Hey, I'm making a firefox extension and I'm currently trying to get it to send XML data over a local socket to another application that's listening on that socket. Does anyone know what I'm doing wrong in this? Its probably something simple and I'm just having a monday. Thanks. socketConn: function() { var httpLoc = window.top.getBrowser(). selectedBrowser.contentWindow.location.href; var outputData = '<?xml version="1.0"?>' + '<site_data>' + '<session_id></session_id>' + 'site_url>' + httpLoc + '</site_url>' + '<mime_type></mime_type>' + '<data_file>' + filePath + '</data_file>' + '<capture_mode></capture_mode>' + '</site_data>\n'; var transportService = Cc["@mozilla.org/network/socket-transport-service;1"] .getService(Ci.nsISocketTransportService); var transport = transportService.createTransport(["starttls"], 1,"localhost",currentPort, null); var outstream = transport.openOutputStream(0, 0, 0); outstream.write(outputData, outputData.length); var stream = transport.openInputStream(0, 0, 0); var instream = Cc["@mozilla.org/scriptableinputstream;1"] .createInstance(Ci.nsIScriptableInputStream); instream.init(stream); var dataListener = { data : "", onStartRequest: function(request, context){}, onStopRequest: function(request, context, status){ instream.close(); outstream.close(); }, onDataAvailable: function(request, context, inputStream, offset, count){ this.data += instream.read(count); }, };//end dataListener var pump = Cc["@mozilla.org/network/input-stream-pump;1"] .createInstance(Ci.nsIInputStreamPump); pump.init(stream, -1, -1, 0, 0, false); pump.asyncRead(dataListener, null); }//end socketConn Please ask questions about this if you don't understand what I'm trying to do with this.

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• Issues in Convergence of Sequential minimal optimization for SVM

  - by Amol Joshi

  I have been working on Support Vector Machine for about 2 months now. I have coded SVM myself and for the optimization problem of SVM, I have used Sequential Minimal Optimization(SMO) by Mr. John Platt. Right now I am in the phase where I am going to grid search to find optimal C value for my dataset. ( Please find details of my project application and dataset details here http://stackoverflow.com/questions/2284059/svm-classification-minimum-number-of-input-sets-for-each-class) I have successfully checked my custom implemented SVM`s accuracy for C values ranging from 2^0 to 2^6. But now I am having some issues regarding the convergence of the SMO for C 128. Like I have tried to find the alpha values for C=128 and it is taking long time before it actually converges and successfully gives alpha values. Time taken for the SMO to converge is about 5 hours for C=100. This huge I think ( because SMO is supposed to be fast. ) though I`m getting good accuracy? I am screwed right not because I can not test the accuracy for higher values of C. I am actually displaying number of alphas changed in every pass of SMO and getting 10, 13, 8... alphas changing continuously. The KKT conditions assures convergence so what is so weird happening here? Please note that my implementation is working fine for C<=100 with good accuracy though the execution time is long. Please give me inputs on this issue. Thank You and Cheers.

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• is struts2 Framework dead? if so, which direction to go from here?

  - by Omnipresent

  I've been working in struts2 framework for the past year and a half. As I look around SO it seems like struts2 questions get the least amount of hits. At first I thought it was because the SO community is not much into struts2, but this is the case in other forums as well. Only the struts2 mailing list is pretty active. I think struts2 is slowly becoming a dinosaur framework and I want to move on. I've dabbled a little with other stuff like RoR, Grails, Django, .NET MVC but I've never really committed and made a pact with myself to sit down and learn these. Maybe its the fact that I dont know the languages that these frameworks are built on. Spending a day or two with RoR makes me want to choke some of the JAR files and struts2 html tags and .NET MVC looks promising but not knowing c# ties me back. My question is, have you been on the same path? Did anyone used to do struts2 before and now changed to something new? What would you suggest I learn after Struts2? And lastly, as a developer how do you motivate yourself to learn a new framework, or a language? for me, just typing the code provided in the book is dead boring.

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• Update table columns bound to NSArrayController

  - by Loz

  Hi, I'm fairly new to the world of bindings in cocoa, and I'm having some troubles (perhaps/probably due to a misunderstanding). I have a singleton that contains an NSMutableArray called plugins, containing objects of class Plugin. It has a method called loadPlugins which adds objects to the plugins array. This may be called at any point. It's been added as an instance in Interface Builder. Also in IB is an NSObjectController, whose content outlet is connected to the singleton. There is also an NSArrayController, whose contentArray is bound to the NSObjectController (controller key is 'selection', model key path is 'plugins', object class name is 'Plugin'). And finally I have a table view with 2 columns, the values of which are bound to the NSArrayController's arrangedObjects, using keys of properties in the Plugin class. So far so standard (as far as I can tell from tutorials at least). My trouble is that when the loadPlugins method is called in the singleton, and objects are added to the plugins array, the table doesn't update to show the objects (unless loadPlugins is called before the nib is loaded). -reloadData called on the tableView doesn't do anything. Is there a way to tell the NSArrayController that the referenced array has been updated? I understand there is the -add: method for NSArrayController, which could be used in the loadPlugins, but this isn't desirable as I want to keep the singleton totally separate from the display aspect. This seems related to: http://stackoverflow.com/questions/1623396/refresh-cocoa-binding-nsarraycontroller-combobox The line: "editing the array behind the controller's back" seems to perhaps pinpoint the problem, but I would hope that it would be possible to have the singleton not know about the controller. Thanks in advance.

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• Trouble pre-populating drop down and textarea from MySQL Database

  - by Tony

  I am able to successfully pre-populate my questions using the following code: First Name: <input type="text" name="first_name" size="30" maxlength="20" value="' . $row[2] . '" /><br /> However, when I try to do the same for a drop down box and a textarea box, nothing is pre-populated from the database, even though there is actual content in the database. This is the code I'm using for the drop down and textarea, respectively: <?php echo ' <form action ="edit_contact.php" method="post"> <div class="contactfirstcolumn"> Prefix: <select name = "prefix" value="' . $row[0] . '" /> <option value="blank">--</option> <option value="Dr">Dr.</option> <option value="Mr">Mr.</option> <option value="Mrs">Mrs.</option> <option value="Ms">Ms.</option> </select><br />'; ?> AND Contact Description:<textarea id = "contactdesc" name="contactdesc" rows="3" cols="50" value="' . $row[20] . '" /></textarea><br /><br /> It's important to note that I am not receiving any errors. The form loads fine, however without the data for the drop down and textarea fields. Thanks! Tony

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• problem in displaying a slug with dash

  - by Mac Taylor

  hey guys i made a slug with dash for my stories urls such as : http://stackoverflow.com/questions/482636/fetching-records-with-slug-instead-of-id this is my code to create slug : function Slugit($title) { $title = strip_tags($title); // Preserve escaped octets. $title = preg_replace('|%([a-fA-F0-9][a-fA-F0-9])|', '---$1---', $title); // Remove percent signs that are not part of an octet. $title = str_replace('%', '', $title); // Restore octets. $title = preg_replace('|---([a-fA-F0-9][a-fA-F0-9])---|', '%$1', $title); $title = remove_accents($title); if (seems_utf8($title)) { if (function_exists('mb_strtolower')) { $title = mb_strtolower($title, 'UTF-8'); } $title = utf8_uri_encode($title, 500); } $title = strtolower($title); $title = preg_replace('/&.+?;/', '', $title); // kill entities $title = str_replace('.', '-', $title); $title = preg_replace('/[^%a-z0-9 _-]/', '', $title); $title = preg_replace('/\s+/', '-', $title); $title = preg_replace('|-+|', '-', $title); $title = trim($title, '-'); return $title; } as you can see dashes , up to here , everything is fine but when i click on the link , it can not open and find it my database as it's saved in normal and with no dashes so i wrote something to remove dashes $string = str_replace('-', '&nbsp;', $string); but when there is ? or . in url , then it can not dispaly ! any help to retrieve back the original url ?!

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• PHP function generate UL LI

  - by apis17

  hi.. i'm referring this address for function olLiTree http://stackoverflow.com/questions/753853/php-function-that-creates-a-nested-ul-li i have this array $tree = array("A"=array("B"=array("C"="C","D"="D"),"E"=array("F"="F","G"="G"))); but not able to use this function function olLiTree($tree) { echo '<ul>'; foreach($tree as $item) { if (is_array($item)) { olLiTree($item); } else { echo '<li>', $item, '</li>'; } } echo '</ul>'; } to generate <ul> <li>A</li> <li>B <ul> <li>C</li> <li>D</li> </ul> </li> <li>E <ul> <li>F </li> </ul> </li> <ul> <li>G</li> </ul> </ul> can anybody help me to fix this? thanks..

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• Multicolumn ListView in WPF - errors

  - by Will

  Hi, I am trying to define a multicolumn listview in xaml (visual studio 2008) and then add items to it in c#. I have seen many posts on this subject, and tried the various methods, but I am getting errors. my xaml code is below, VS does not flag any errors on it. <ListView Height="234.522" Name="chartListView" Width="266.337"> <ListView.View> <GridView> <GridViewColumn Header="Name" Width="70"/> <GridViewColumn Header="ID" /> </GridView> </ListView.View> </ListView> to try and add data to the columns, I created a button and put the code in the button click : private void button3_Click(object sender, RoutedEventArgs e) { chartListView.Items.Add("item1").SubItems.Add("item2"); } the error that is showing is on Subitems is: 'int' does not contain a definition for 'SubItems' and no extension method 'SubItems' accepting a first argument of type 'int' could be found (are you missing a using directive or an assembly reference?) D:\devel\VS\pchart\pchart\pchart\Window1.xaml.cs Also, I tried looking at some other posts on listview controls such as http://stackoverflow.com/questions/1260812/listview-inserting-items i tried the code there : ListViewItem item = new ListViewItem(); item.Text=anInspector.getInspectorName().ToString(); and got almost the same error on item.Text as i did with SubItems. is there something earlier in my code, or project definition that i am missing? Thanks for any help

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• How Do You Get the bufspec While Using Vimdiff Through Git

  - by Elizabeth Buckwalter

  I've read Vimdiff and Viewing differences with Vimdiff plus doing various google searches using things like "vimdiff multiple", "vimdiff git", "vimdiff commands" etc. When using do or diffg I get the error "More than two buffers in diff mode, don't know which one to use". When using diffg v:fname_in I get "No matching buffer for v:fname_in". From the vimdiff documentation: :[range]diffg[et] [bufspec] Modify the current buffer to undo difference with another buffer. If [bufspec] is given, that buffer is used. If [bufspec] refers to the current buffer then nothing happens. Otherwise this only works if there is one other buffer in diff mode. and more: When 'diffexpr' is not empty, Vim evaluates to obtain a diff file in the format mentioned. These variables are set to the file names used: v:fname_in original file v:fname_new new version of the same file v:fname_out resulting diff file So, I need to get the name of bufspec, but the default variables (fname_in, fname_new, and fname_out) aren't set. I ran the command git mergetool on a linux box through a terminal. [Edit] A partial solution that bred more questions. I used the "filename" at the bottom of the buffer. It's only a half answer, because occasionally I get a file does not exist error. I believe it's consistently the remote version of the file that "does not exist". I suspect this has something to do with git and indexing. How do you get the bufspec value consistently while using vimdiff through git-mergetool?

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• Guice, JDBC and managing database connections

  - by pledge

  I'm looking to create a sample project while learning Guice which uses JDBC to read/write to a SQL database. However, after years of using Spring and letting it abstract away connection handling and transactions I'm struggling to work it our conceptually. I'd like to have a service which starts and stops a transaction and calls numerous repositories which reuse the same connection and participate in the same transaction. My questions are: Where do I create my Datasource? How do I give the repositories access to the connection? (ThreadLocal?) Best way to manage the transaction (Creating an Interceptor for an annotation?) The code below shows how I would do this in Spring. The JdbcOperations injected into each repository would have access to the connection associated with the active transaction. I haven't been able to find many tutorials which cover this, beyond ones which show creating interceptors for transactions. I am happy with continuing to use Spring as it is working very well in my projects, but I'd like to know how to do this in pure Guice and JBBC (No JPA/Hibernate/Warp/Reusing Spring) @Service public class MyService implements MyInterface { @Autowired private RepositoryA repositoryA; @Autowired private RepositoryB repositoryB; @Autowired private RepositoryC repositoryC; @Override @Transactional public void doSomeWork() { this.repositoryA.someInsert(); this.repositoryB.someUpdate(); this.repositoryC.someSelect(); } } @Repository public class MyRepositoryA implements RepositoryA { @Autowired private JdbcOperations jdbcOperations; @Override public void someInsert() { //use jdbcOperations to perform an insert } } @Repository public class MyRepositoryB implements RepositoryB { @Autowired private JdbcOperations jdbcOperations; @Override public void someUpdate() { //use jdbcOperations to perform an update } } @Repository public class MyRepositoryC implements RepositoryC { @Autowired private JdbcOperations jdbcOperations; @Override public String someSelect() { //use jdbcOperations to perform a select and use a RowMapper to produce results return "select result"; } }

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• Java Memory Model: reordering and concurrent locks

  - by Steffen Heil

  Hi The java meomry model mandates that synchronize blocks that synchronize on the same monitor enforce a before-after-realtion on the variables modified within those blocks. Example: // in thread A synchronized( lock ) { x = true; } // in thread B synchronized( lock ) { System.out.println( x ); } In this case it is garanteed that thread B will see x==true as long as thread A already passed that synchronized-block. Now I am in the process to rewrite lots of code to use the more flexible (and said to be faster) locks in java.util.concurrent, especially the ReentrantReadWriteLock. So the example looks like this: // in thread A synchronized( lock ) { lock.writeLock().lock(); x = true; lock.writeLock().unlock(); } // in thread B synchronized( lock ) { lock.readLock().lock(); System.out.println( x ); lock.readLock().unlock(); } However, I have not seen any hints within the memory model specification that such locks also imply the nessessary ordering. Looking into the implementation it seems to rely on the access to volatile variables inside AbstractQueuedSynchronizer (for the sun implementation at least). However this is not part of any specification and moreover access to non-volatile variables is not really condsidered covered by the memory barrier given by these variables, is it? So, here are my questions: Is it safe to assume the same ordering as with the "old" synchronized blocks? Is this documented somewhere? Is accessing any volatile variable a memory barrier for any other variable? Regards, Steffen

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• Working around MySQL error "Deadlock found when trying to get lock; try restarting transaction"

  - by Anon Guy

  Hi all: I have a MySQL table with about 5,000,000 rows that are being constantly updated in small ways by parallel Perl processes connecting via DBI. The table has about 10 columns and several indexes. One fairly common operation gives rise to the following error sometimes: DBD::mysql::st execute failed: Deadlock found when trying to get lock; try restarting transaction at Db.pm line 276. The SQL statement that triggers the error is something like this: UPDATE file_table SET a_lock = 'process-1234' WHERE param1 = 'X' AND param2 = 'Y' AND param3 = 'Z' LIMIT 47 The error is triggered only sometimes. I'd estimate in 1% of calls or less. However, it never happened with a small table and has become more common as the database has grown. Note that I am using the a_lock field in file_table to ensure that the four near-identical processes I am running do not try and work on the same row. The limit is designed to break their work into small chunks. I haven't done much tuning on MySQL or DBD::mysql. MySQL is a standard Solaris deployment, and the database connection is set up as follows: my $dsn = "DBI:mysql:database=" . $DbConfig::database . ";host=${DbConfig::hostname};port=${DbConfig::port}"; my $dbh = DBI->connect($dsn, $DbConfig::username, $DbConfig::password, { RaiseError => 1, AutoCommit => 1 }) or die $DBI::errstr; I have seen online that several other people have reported similar errors and that this may be a genuine deadlock situation. I have two questions: What exactly about my situation is causing the error above? Is there a simple way to work around it or lessen its frequency? For example, how exactly do I go about "restarting transaction at Db.pm line 276"? Thanks in advance.

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• E-commerce platform for custom application integration

  - by Zach Smith

  We are building an online subscription-based website and I'm looking for recommendations on which e-commerce platform to use for the checkout process. Requirements include: Only four products. The sign-up process of the site is heavily customized, and after checkout the user should automatically get logged into the subscriber area. Subscriptions will last one year and can be renewed manually. Support for coupons/discount codes at a later point. Since the entire application is custom, we've weighed building a custom checkout but are strongly leaning towards using existing software to avoid having to build lots of admin reporting as well as a coupon engine down the road. The two questions we're pondering are: Is it better to a) build our application custom and use whatever e-commerce software we select just for the payment piece, or b) use the e-commerce software as the basis and build our application around it/as a module/etc? Which e-commerce platform should we use? I've looked into a variety of off the shelf e-commerce software, but it's not clear to me which would be easiest to integrate with. I've researched on the Web and looked at many of the threads on SO to compiled a list of potential candidates: www.magentocommerce.com/ (seems difficult to integrate with) www.prestashop.com/ www.nopcommerce.com/ www.opencart.com/ www.cubecart.com/ www.spreecommerce.com/ www.interspire.com/ www.tradingeye.com/ We're most concerned with the level of effort required with ramping up on the software and then doing the integration with our custom functionality. We're most proficient with PHP, ASP.NET and some ROR and are only considering those technologies. We prefer open source, but would be open to commercial if there's a significant upside. Any experiences with similar projects and advice is greatly appreciated.

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• How to inject a Session Bean into a Message Driven Bean?

  - by Hank

  Hi guys, I'm reasonably new to JEE, so this might be stupid.. bear with me pls :D I would like to inject a stateless session bean into a message-driven bean. Basically, the MDB gets a JMS message, then uses a session bean to perform the work. The session bean holds the business logic. Here's my Session Bean: @Stateless public class TestBean implements TestBeanRemote { public void doSomething() { // business logic goes here } } The matching interface: @Remote public interface TestBeanRemote { public void doSomething(); } Here's my MDB: @MessageDriven(mappedName = "jms/mvs.TestController", activationConfig = { @ActivationConfigProperty(propertyName = "acknowledgeMode", propertyValue = "Auto-acknowledge"), @ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Queue") }) public class TestController implements MessageListener { @EJB private TestBean testBean; public TestController() { } public void onMessage(Message message) { testBean.doSomething(); } } So far, not rocket science, right? Unfortunately, when deploying this to glassfish v3, and sending a message to the appropriate JMS Queue, I get errors that glassfish is unable to locate the TestBean EJB: java.lang.IllegalStateException: Exception attempting to inject Remote ejb-ref name=mvs.test.TestController/testBean,Remote 3.x interface =mvs.test.TestBean,ejb-link=null,lookup=null,mappedName=,jndi-name=mvs.test.TestBean,refType=Session into class mvs.test.TestController Caused by: com.sun.enterprise.container.common.spi.util.InjectionException: Exception attempting to inject Remote ejb-ref name=mvs.test.TestController/testBean,Remote 3.x interface =mvs.test.TestBean,ejb-link=null,lookup=null,mappedName=,jndi-name=mvs.test.TestBean,refType=Session into class mvs.test.TestController Caused by: javax.naming.NamingException: Lookup failed for 'java:comp/env/mvs.test.TestController/testBean' in SerialContext [Root exception is javax.naming.NamingException: Exception resolving Ejb for 'Remote ejb-ref name=mvs.test.TestController/testBean,Remote 3.x interface =mvs.test.TestBean,ejb-link=null,lookup=null,mappedName=,jndi-name=mvs.test.TestBean,refType=Session' . Actual (possibly internal) Remote JNDI name used for lookup is 'mvs.test.TestBean#mvs.test.TestBean' [Root exception is javax.naming.NamingException: Lookup failed for 'mvs.test.TestBean#mvs.test.TestBean' in SerialContext [Root exception is javax.naming.NameNotFoundException: mvs.test.TestBean#mvs.test.TestBean not found]]] So my questions are: - is this the correct way of injecting a session bean into another bean (particularly a message driven bean)? - why is the naming lookup failing? Thanks for all your help! Cheers, Hank

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• What scalability problems have you solved using a NoSQL data store?

  - by knorv

  NoSQL refers to non-relational data stores that break with the history of relational databases and ACID guarantees. Popular open source NoSQL data stores include: Cassandra (tabular, written in Java, used by Facebook, Twitter, Digg, Rackspace, Mahalo and Reddit) CouchDB (document, written in Erlang, used by Engine Yard and BBC) Dynomite (key-value, written in C++, used by Powerset) HBase (key-value, written in Java, used by Bing) Hypertable (tabular, written in C++, used by Baidu) Kai (key-value, written in Erlang) MemcacheDB (key-value, written in C, used by Reddit) MongoDB (document, written in C++, used by Sourceforge, Github, Electronic Arts and NY Times) Neo4j (graph, written in Java, used by Swedish Universities) Project Voldemort (key-value, written in Java, used by LinkedIn) Redis (key-value, written in C, used by Engine Yard, Github and Craigslist) Riak (key-value, written in Erlang, used by Comcast and Mochi Media) Ringo (key-value, written in Erlang, used by Nokia) Scalaris (key-value, written in Erlang, used by OnScale) ThruDB (document, written in C++, used by JunkDepot.com) Tokyo Cabinet/Tokyo Tyrant (key-value, written in C, used by Mixi.jp (Japanese social networking site)) I'd like to know about specific problems you - the SO reader - have solved using data stores and what NoSQL data store you used. Questions: What scalability problems have you used NoSQL data stores to solve? What NoSQL data store did you use? What database did you use before switching to a NoSQL data store? I'm looking for first-hand experiences, so please do not answer unless you have that.

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• General Question About WPF Control Behavior and using Invoke

  - by Phil Sandler

  I have been putting off activity on SO because my current reputation is "1337". :) This is a question of "why" and not "how". By default, it seems that WPF does not set focus to the first control in a window when it's opening. In addition, when a textbox gets focus, by default it does not have it's existing text selected. So basically when I open a window, I want focus on the first control of the window, and if that control is a textbox, I want it's existing text (if any) to be selected. I found some tips online to accomplish each of these behaviors, and combined them. The code below, which I placed in the constructor of my window, is what I came up with: Loaded += (sender, e) => { MoveFocus(new TraversalRequest(FocusNavigationDirection.Next)); var textBox = FocusManager.GetFocusedElement(this) as TextBox; if (textBox != null) { Action select = textBox.SelectAll; //for some reason this doesn't work without using invoke. Dispatcher.Invoke(DispatcherPriority.Loaded, select); } }; So, my question. Why does the above not work without using Dispatcher.Invoke? Is something built into the behavior of the window (or textbox) cause the selected text to be de-selected post-loading? Maybe related, maybe not--another example of where I had to use Dispatcher.Invoke to control the behavior of a form: http://stackoverflow.com/questions/2602979/wpf-focus-in-tab-control-content-when-new-tab-is-created

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