pitfalls to avoid - Page 239

Java Instance of: Supertypes und Subtypes seem to be equal? How to test exaclty for Type?

- by jens

Hello, i would be thankful for your advice. I need to test, if an instance is exactly of a given type. But it seems that instanceof returns true also if the subtype is tested for the supertype (case 3). I never knew this before and I am quite surprised. Am I doing something wrong here? How do I exactly test for a given typen? //.. class DataSourceEmailAttachment extends EmailAttachment //... EmailAttachment emailAttachment = new EmailAttachment(); DataSourceEmailAttachment emailAttachmentDS = new DataSourceEmailAttachment(); if (emailAttachment instanceof EmailAttachment){ System.out.println(" 1"); } if (emailAttachment instanceof DataSourceEmailAttachment){ System.out.println(" 2"); } if (emailAttachmentDS instanceof EmailAttachment){ System.out.println(" 3 "); } if (emailAttachmentDS instanceof DataSourceEmailAttachment){ System.out.println(" 4"); } RESULT: 1 3 4 I want to avoid case 3, I only want "exact matches" (case 1 and 4) how to thest for them?? thanks!!! Jens

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How to disable the drop down function of combo box on certain conditions?

- by Angeline Aarthi

Hi, I have a combo box in my application. I also have a variable called "Status". I want the combo box to be enabled only when the value of the Status variable is 5 or 6. Otherwise, I should not be able to change the value in the combo box. It should have the previous value only.. I had written a click event to disable the combo box. But even though the combo box is disabled, I get the drop down list of the combo box, and If I select some othe value in the drop down,it changes..Only after that it gets disabled.. How to avoid this? I want the drop down function itself to be disabled. This is the code I have written. Someone guide me. <mx:FormItem label="Review Status:" width="100%" horizontalAlign="right"> <mx:HBox> <mx:Label width="30"/> <mx:ComboBox id="reviewStatus" dataProvider="{Status}" width="150" click="onStatusChange(event)"/> </mx:HBox> Action Script part: private function onStatusChange(event:Event):void { var i:int; for(i=0;i<defectDetails.length;i++) { var defStatusId:String=defectDetails.getItemAt(i).DefectStatusId; if(defStatusId=="5"){ reviewStatus.enabled=true; } else if(defStatusId=="6"){ reviewStatus.enabled=true; } else{ reviewStatus.enabled=false; //reviewStatus.selectedItem.label="Review"; reviewStatus.toolTip="Status can be changed only if Defect Status is Verified or Deferred."; //Alert.show("Status can be changed only if defect status is verified or deferred"); } } } If I use Change event also, for the first time the value is changed. Only after that,the combo box is disabled. How to retain the same value and disable the combo box when the status is not 5 or 6?

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twitter bootstrap typeahead (method 'toLowerCase' of undefined)

- by mmoscosa

I am trying to use twitter bootstrap to get the manufacturers from my DB. Because twitter bootstrap typeahead does not support ajax calls I am using this fork: https://gist.github.com/1866577 In that page there is this comment that mentions how to do exactly what I want to do. The problem is when I run my code I keep on getting: Uncaught TypeError: Cannot call method 'toLowerCase' of undefined I googled around and came tried changing my jquery file to both using the minified and non minified as well as the one hosted on google code and I kept getting the same error. My code currently is as follows: $('#manufacturer').typeahead({ source: function(typeahead, query){ $.ajax({ url: window.location.origin+"/bows/get_manufacturers.json", type: "POST", data: "", dataType: "JSON", async: false, success: function(results){ var manufacturers = new Array; $.map(results.data.manufacturers, function(data, item){ var group; group = { manufacturer_id: data.Manufacturer.id, manufacturer: data.Manufacturer.manufacturer }; manufacturers.push(group); }); typeahead.process(manufacturers); } }); }, property: 'name', items:11, onselect: function (obj) { } }); on the url field I added the window.location.origin to avoid any problems as already discussed on another question Also before I was using $.each() and then decided to use $.map() as recomended Tomislav Markovski in a similar question Anyone has any idea why I keep getting this problem?! Thank you

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Getter and Setter vs. Builder strategy

- by Extrakun

I was reading a JavaWorld's article on Getter and Setter where the basic premise is that getters expose internal content of an object, hence tightening coupling, and go on to provide examples using builder objects. I was rather leery of abolishing getter/setter but on second reading of the article, see to quite like the idea. However, sometimes I just need one cruical element of an entity class, such as the user's id and writing one whole class just to extract that cruical element seems like overkill. It also implies that for different view, a different type of importer/exporter must be implemented (or the whole data of the class to be exported out, thus resulting in waste). Usually I tend towards filtering the result of a getter - for example, if I need to output the price of a product in different currency, I would code it as: return CurrencyOutput::convertTo($product->price(), 'USD'); This is with the understanding that the raw output of a getter is not necessary the final result to be pushed onto a screen or a database. Is getter/setter really as bad as it is protrayed to be? When should one adopt a builder strategy, or a 'get the result and filter it' approach? How do you avoid having a class needing to know about every other objects if you are not using getter/setter?

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pattern matching in .Net consistent with IsolatedStorageFile.GetFileNames() pattern matching

- by Mick N

Is the pattern matching logic used by this API exposed for reuse somewhere in the .Net Framework? Something of the form FilePatternMatch( string searchPattern, stringfileNameToTest ) is what I'm looking for. I'm implementing a temporary workaround for WP7 not filtering the results for this overload and I'd like the solution to both provide a consistent experience and avoid reinventing this functionality if it is exposed. If the behaviour is not exposed for reuse, a regular expression solution (like glob pattern matching in .NET) will suffice and would save me spending the time to test the fine details of what the behaviour should be. Perhaps one of the answers posted in the thread linked above is correct. Since I haven't confirmed the exact behaviour as yet, I wasn't able to determine this at a glance. Feel free to point me to one of those answers if you know it is behaviouraly an exact match to the API referenced in the question title. I could assume the pattern matching is consistent with how DOS handled * and ? in 8.3 file names (I'm familiar with behavioural nuances of that implementation), but it's reasonable to assume Microsoft has evolved pattern matching behaviour for file names in the decade+ since so I thought I would check before proceeding on that assumption.

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Asynchronous crawling F#

- by jlezard

When crawling on webpages I need to be careful as to not make too many requests to the same domain, for example I want to put 1 s between requests. From what I understand it is the time between requests that is important. So to speed things up I want to use async workflows in F#, the idea being make your requests with 1 sec interval but avoid blocking things while waiting for request response. let getHtmlPrimitiveAsyncTimer (uri : System.Uri) (timer:int) = async{ let req = (WebRequest.Create(uri)) :?> HttpWebRequest req.UserAgent<-"Mozilla" try Thread.Sleep(timer) let! resp = (req.AsyncGetResponse()) Console.WriteLine(uri.AbsoluteUri+" got response") use stream = resp.GetResponseStream() use reader = new StreamReader(stream) let html = reader.ReadToEnd() return html with | _ as ex -> return "Bad Link" } Then I do something like: let uri1 = System.Uri "http://rue89.com" let timer = 1000 let jobs = [|for i in 1..10 -> getHtmlPrimitiveAsyncTimer uri1 timer|] jobs |> Array.mapi(fun i job -> Console.WriteLine("Starting job "+string i) Async.StartAsTask(job).Result) Is this alright ? I am very unsure about 2 things: -Does the Thread.Sleep thing work for delaying the request ? -Is using StartTask a problem ? I am a beginner (as you may have noticed) in F# (coding in general actually ), and everything envolving Threads scares me :) Thanks !!

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Check mail attachment

- by comii

Hi! I am using vb.net to display email from outlook express! Everything work fine but when some message has attachment, i can not display message that email has attachment! This is my code: Private Sub LoginButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LoginButton.Click Dim oItem Dim i As Integer Dim Message As MAPI.Message Dim items As String() = New String(6) {} ' Items are the sender name,subject and date and read/unread value Dim PrSenderEmail, PrBodyEmail Session = CreateObject("MAPI.Session") ' we use a session object of MAPI Component Session.Logon(ProfileName:=Me.UserId.Text, ProfilePassword:=Me.Password.Text) Session.MAPIOBJECT = Session.MAPIOBJECT ' Folder = CObj(Session.Inbox) ' choose the folder Application = CreateObject("Outlook.Application") Namespace1 = Application.GetNamespace("MAPI") Namespace1.Logon() ' for getting the sender name and avoid security validation of Outlook/Exchange server 2003 ' we are using the "Redemption" component sItem = CreateObject("Redemption.SafeMailItem") Cursor.Current = Cursors.WaitCursor ' show we're busy doing the sort ListInbox.BeginUpdate() ' Notify that update begins ListInbox.Items.Clear() i = 0 ' first email message is 0 For Each Message In Folder.Messages Try i = i + 1 ' increment to the next email message 'get e-mail from the Inbox, can be any other item oItem = Application.Session.GetDefaultFolder(6).Items(i) ' GetDefaultFolder(6) refers to Inbox sItem.Item = oItem 'sItem is an object of Redemption COM and is used to get the senders name items(0) = sItem.SenderName() Catch items(0) = "error" End Try Dim objApp As Outlook.Application = New Outlook.Application 'Get Mapi NameSpace Dim objNS As Outlook.NameSpace = objApp.GetNamespace("MAPI") Dim oMsg As Outlook.MailItem Dim pp As String Dim b As Integer Dim objAttachment As Outlook.Attachment pp = Message.StoreID items(1) = Message.Subject items(2) = Message.TimeReceived items(4) = Message.Subject items(5) = Message.Size Dim objInbox As Outlook.MAPIFolder = objNS.GetDefaultFolder(Outlook.OlDefaultFolders.olFolderInbox) Dim objItems As Outlook.Items = objInbox.Items items(5) = Message.Size.ToString / 1000 & "kb" If Message.Unread = True Then items(3) = "unread" Else items(3) = "read" End If ListInbox.Items.Add(New ListViewItem(items)) Next ListInbox.EndUpdate() ' Notify that update ends Cursor.Current = Cursors.Default End If End Sub How I can display message that email has attachment?

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Simple in-place discrete fourier transform ( DFT )

- by Adam

I'm writing a very simple in-place DFT. I am using the formula shown here: http://en.wikipedia.org/wiki/Discrete_Fourier_transform#Definition along with Euler's formula to avoid having to use a complex number class just for this. So far I have this: private void fft(double[] data) { double[] real = new double[256]; double[] imag = new double[256]; double pi_div_128 = -1 * Math.PI / 128; for (int k = 0; k < 256; k++) { for (int n = 0; n < 256; n++) { real[k] += data[k] * Math.Cos(pi_div_128 * k * n); imag[k] += data[k] * Math.Sin(pi_div_128 * k * n); } data[k] = Math.Sqrt(real[k] * real[k] + imag[k] * imag[k]); } } But the Math.Cos and Math.Sin terms eventually go both positive and negative, so as I'm adding those terms multiplied with data[k], they cancel out and I just get some obscenely small value. I see how it is happening, but I can't make sense of how my code is perhaps mis-representing the mathematics. Any help is appreciated. FYI, I do have to write my own, I realize I can get off-the shelf FFT's.

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how to atomically claim a row or resource using UPDATE in mysql

- by Igor

i have a table of resources (lets say cars) which i want to claim atomically. if there's a limit of one resource per one user, i can do the following trick: UPDATE cars SET user = 'bob' WHERE user IS NULL LIMIT 1 SELECT * FROM cars WHERE user IS bob that way, i claim the resource atomically and then i can see which row i just claimed. this doesn't work when 'bob' can claim multiple cars. i realize i can get a list of cars already claimed by bob, claim another one, and then SELECT again to see what's changed, but that feels hackish. What I'm wondering is, is there some way to see which rows i just updated with my last UPDATE? failing that, is there some other trick to atomically claiming a row? i really want to avoid using SERIALIZABLE isolation level. If I do something like this: 1 SELECT id FROM cars WHERE user IS NULL 2 <here, my PHP or whatever picks a car id> 3 UPDATE cars SET user = 'bob' WHERE id = <the one i picked> would REPEATABLE READ be sufficient here? in other words, could i be guaranteed that some other transactions won't claim the row my software has picked during step 2?

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SharePoint 2010 / ASP.Net Integration - Looking for advice

- by jpennal

I have been Googling a problem that I have with trying to integrate the web application that I am working on with SharePoint 2010. The web application is a wiki style tool that allows users to log in via forms authentication or WIA against Active Directory and create content for themselves and others. What we would like to do is to allow a user have a page with the content they have created in our web application mixed in with content that they have living on the SharePoint server. For example, they may want to see a list of documents that they have on the SharePoint server mixed in with some of their content. To accomplish this, we would like to take the credentials the user has logged into our web application with (for example MYDOMAIN\jsmith) and be able to query SharePoint for the documents of that same user (MYDOMAIN\jsmith) WITHOUT the user being prompted to re-enter their credentials to access the SharePoint server (we are trying to avoid the double-hop problem) We have come up with some options for how we want to do this, but we are unsure of what the best approach is. For example, we could - Have a global user, shared by all users to get information we need from SharePoint. The downside is that we cannot filter SharePoint content to a particular user - We could store the users credentials when they log in, but that would only work for users authenticating via forms auth and would be a security issue that some users/clients would not like - Writing a SharePoint extension using WCF to allow us to access the information we need, however we'd still have the issue of figuring out how to impersonate the user we want. Neither of these options are ideal and in our investigation we came across the Claims Authentication/STS option which seems like it is trying to solve the problem we are having. So my question is, based on what I have written, is Claims/STS the best approach for us? We have not been able to find much direction on how to use this method to call into SharePoint from a Web Application and pass along the existing credentials. Does anyone have any experience with any of these issues?

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Calling MethodBase's Invoke on a constructor (reflection)

- by Alix

Hi everyone. First of all, sorry if this has been asked before. I've done a pretty comprehensive search and found nothing quite like it, but I may have missed something. And now to the question: I'm trying to invoke a constructor through reflection, with no luck. Basically, I have an object that I want to clone, so I look up the copy constructor for its type and then want to invoke it. Here's what I have: public Object clone(Object toClone) { MethodBase copyConstructor = type.GetConstructor( new Type[] { toClone.GetType() }); return method.Invoke(toClone, new object[] { toClone }); //<-- doesn't work } I call the above method like so: List list = new List(new int[] { 0, 1, 2 }); List clone = (List) clone(list); Now, notice the invoke method I'm using is MethodBase's invoke. ConstructorInfo provides an invoke method that does work if invoked like this: return ((ConstructorInfo) method).Invoke(new object[] { toClone }); However, I want to use MethodBase's method, because in reality instead of looking up the copy constructor every time I will store it in a dictionary, and the dictionary contains both methods and constructors, so it's a Dictionary<MethodBase>, not Dictionary<ConstructorInfo>. I could of course cast to ConstructorInfo as I do above, but I'd rather avoid the casting and use the MethodBase method directly. I just can't figure out the right parameters. Any help? Thanks so much.

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php scandir --> search for files/directories

- by Peter

Hi! I searched before I ask, without lucky.. I looking for a simple script for myself, which I can search for files/folders. Found this code snippet in the php manual (I think I need this), but it is not work for me. "Was looking for a simple way to search for a file/directory using a mask. Here is such a function. By default, this function will keep in memory the scandir() result, to avoid scaning multiple time for the same directory." <?php function sdir( $path='.', $mask='*', $nocache=0 ){ static $dir = array(); // cache result in memory if ( !isset($dir[$path]) || $nocache) { $dir[$path] = scandir($path); } foreach ($dir[$path] as $i=>$entry) { if ($entry!='.' && $entry!='..' && fnmatch($mask, $entry) ) { $sdir[] = $entry; } } return ($sdir); } ?> Thank you for any help, Peter

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SecurityNegotiationException in WCF Service Hosted on IIS

- by Ram

Hi, I have hosted a WCF service on IIS. The configuration file is as follows <?xml version="1.0"?>  <configuration> <configSections> <sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"> <sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"> <section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/> <sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"> <section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="Everywhere" /> <section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> <section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> <section name="roleService" type="System.Web.Configuration.ScriptingRoleServiceSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication" /> </sectionGroup> </sectionGroup> </sectionGroup> </configSections> <appSettings/> <connectionStrings/> <system.web>  <compilation debug="false"> <assemblies> <add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/> <add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </assemblies> </compilation>  <authentication mode="Windows" />  <pages> <controls> <add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </controls> </pages> <httpHandlers> <remove verb="*" path="*.asmx"/> <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false"/> </httpHandlers> <httpModules> <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </httpModules> </system.web> <system.codedom> <compilers> <compiler language="c#;cs;csharp" extension=".cs" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <providerOption name="CompilerVersion" value="v3.5"/> <providerOption name="WarnAsError" value="false"/> </compiler> </compilers> </system.codedom> <system.web.extensions> <scripting> <webServices>    </webServices>  </scripting> </system.web.extensions>  <system.webServer> <validation validateIntegratedModeConfiguration="false"/> <modules> <add name="ScriptModule" preCondition="integratedMode" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> </modules> <handlers> <remove name="WebServiceHandlerFactory-Integrated"/> <add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/> <add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /> </handlers> </system.webServer> <system.serviceModel> <services> <service name="IISTest2.Service1" behaviorConfiguration="IISTest2.Service1Behavior">  <endpoint address="" binding="wsHttpBinding" contract="IISTest2.IService1">  <identity> <dns value="localhost"/> </identity> </endpoint> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/> </service> </services> <behaviors> <serviceBehaviors> <behavior name="IISTest2.Service1Behavior">  <serviceMetadata httpGetEnabled="true"/>  <serviceDebug includeExceptionDetailInFaults="false"/> </behavior> </serviceBehaviors> </behaviors> </system.serviceModel> </configuration> The client configuration file is as follows <?xml version="1.0" encoding="utf-8" ?> <configuration> <system.serviceModel> <bindings> <wsHttpBinding> <binding name="WSHttpBinding_IService1" closeTimeout="00:01:00" openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00" bypassProxyOnLocal="false" transactionFlow="false" hostNameComparisonMode="StrongWildcard" maxBufferPoolSize="524288" maxReceivedMessageSize="65536" messageEncoding="Text" textEncoding="utf-8" useDefaultWebProxy="true" allowCookies="false"> <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="16384" maxBytesPerRead="4096" maxNameTableCharCount="16384" /> <reliableSession ordered="true" inactivityTimeout="00:10:00" enabled="false" /> <security mode="Message"> <transport clientCredentialType="Windows" proxyCredentialType="None" realm="" /> <message clientCredentialType="Windows" negotiateServiceCredential="true" algorithmSuite="Default" establishSecurityContext="true" /> </security> </binding> </wsHttpBinding> </bindings> <client> <endpoint address="http://yyy.zzz.xxx.net/IISTest2/Service1.svc" binding="wsHttpBinding" bindingConfiguration="WSHttpBinding_IService1" contract="ServTest.IService1" name="WSHttpBinding_IService1"> <identity> <dns value="localhost" /> </identity> </endpoint> </client> </system.serviceModel> </configuration> When I tried to access the service from client application, I got SecurityNegotiationException and details are Secure channel cannot be opened because security negotiation with the remote endpoint has failed. This may be due to absent or incorrectly specified EndpointIdentity in the EndpointAddress used to create the channel. Please verify the EndpointIdentity specified or implied by the EndpointAddress correctly identifies the remote endpoint. If I host the service on ASP .NET Dev server, it work well but if I host on IIS above mentioned error occurs. Thanks, Ram

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How to deal with multiple sub-type of one super-type in Django admin

- by Henri

What would be the best solution for adding/editing multiple sub-types. E.g a super-type class Contact with sub-type class Client and sub-type class Supplier. The way shown here works, but when you edit a Contact you get both inlines i.e. sub-type Client AND sub-type Supplier. So even if you only want to add a Client you also get the fields for Supplier of vice versa. If you add a third sub-type , you get three sub-type field groups, while you actually only want one sub-type group, in the mentioned example: Client. E.g.: class Contact(models.Model): contact_name = models.CharField(max_length=128) class Client(models.Model): contact = models.OneToOneField(Contact, primary_key=True) user_name = models.CharField(max_length=128) class Supplier(models.Model): contact.OneToOneField(Contact, primary_key=True) company_name = models.CharField(max_length=128) and in admin.py class ClientInline(admin.StackedInline): model = Client class SupplierInline(admin.StackedInline): model = Supplier class ContactAdmin(admin.ModelAdmin): inlines = (ClientInline, SupplierInline,) class ClientAdmin(admin.ModelAdmin): ... class SupplierAdmin(admin.ModelAdmin): ... Now when I want to add a Client, i.e. only a Client I edit Contact and I get the inlines for both Client and Supplier. And of course the same for Supplier. Is there a way to avoid this? When I want to add/edit a Client that I only see the Inline for Client and when I want to add/edit a Supplier that I only see the Inline for Supplier, when adding/editing a Contact? Or perhaps there is a different approach. Any help or suggestion will be greatly appreciated.

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Does JAXWS client make difference between an empty collection and a null collection value as returne

- by snowflake

Since JAX-WS rely on JAXB, and since I observed the code that unpack the XML bean in JAX-B Reference Implementation, I guess the difference is not made and that a JAXWS client always return an empty collection, even the webservice result was a null element: public T startPacking(BeanT bean, Accessor<BeanT, T> acc) throws AccessorException { T collection = acc.get(bean); if(collection==null) { collection = ClassFactory.create(implClass); if(!acc.isAdapted()) acc.set(bean,collection); } collection.clear(); return collection; } I agree that for best interoperability service contracts should be non ambiguous and avoid such differences, but it seems that the JAX-WS service I'm invoking (hosted on a Jboss server with Jbossws implementation) is returning as expected either null either empty collection (tested with SoapUI). I used for my test code generated by wsimport. Return element is defined as: @XmlElement(name = "return", nillable = true) protected List<String> _return; I even tested to change the Response class getReturn method from : public List<String> getReturn() { if (_return == null) { _return = new ArrayList<String>(); } return this._return; } to public List<String> getReturn() { return this._return; } but without success. Any helpful information/comment regarding this problem is welcome !

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Avoiding shutdown hook

- by meryl

Through the following code I can play and cut and audio file. Is there any other way to avoid using a shutdown hook? The problem is that whenever I push the cut button , the file doesn't get saved until I close the application thanks ...................... void play_cut() { try { // First, we get the format of the input file final AudioFileFormat.Type fileType = AudioSystem.getAudioFileFormat(inputAudio).getType(); // Then, we get a clip for playing the audio. c = AudioSystem.getClip(); // We get a stream for playing the input file. AudioInputStream ais = AudioSystem.getAudioInputStream(inputAudio); // We use the clip to open (but not start) the input stream c.open(ais); // We get the format of the audio codec (not the file format we got above) final AudioFormat audioFormat = ais.getFormat(); // We add a shutdown hook, an anonymous inner class. Runtime.getRuntime().addShutdownHook(new Thread() { public void run() { // We're now in the hook, which means the program is shutting down. // You would need to use better exception handling in a production application. try { // Stop the audio clip. c.stop(); // Create a new input stream, with the duration set to the frame count we reached. Note that we use the previously determined audio format AudioInputStream startStream = new AudioInputStream(new FileInputStream(inputAudio), audioFormat, c.getLongFramePosition()); // Write it out to the output file, using the same file type. AudioSystem.write(startStream, fileType, outputAudio); } catch(IOException e) { e.printStackTrace(); } } }); // After setting up the hook, we start the clip. c.start(); } catch (UnsupportedAudioFileException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (LineUnavailableException e) { e.printStackTrace(); } }// end play_cut ......................

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How to log correct context with Threadpool threads using log4net?

- by myotherme

I am trying to find a way to log useful context from a bunch of threads. The problem is that a lot of code is dealt with on Events that are arriving via threadpool threads (as far as I can tell) so their names are not in relation to any context. The problem can be demonstrated with the following code: class Program { private static readonly log4net.ILog log = log4net.LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType); static void Main(string[] args) { new Thread(TestThis).Start("ThreadA"); new Thread(TestThis).Start("ThreadB"); Console.ReadLine(); } private static void TestThis(object name) { var nameStr = (string)name; Thread.CurrentThread.Name = nameStr; log4net.ThreadContext.Properties["ThreadContext"] = nameStr; log4net.LogicalThreadContext.Properties["LogicalThreadContext"] = nameStr; log.Debug("From Thread itself"); ThreadPool.QueueUserWorkItem(x => log.Debug("From threadpool Thread: " + nameStr)); } } The Conversion pattern is: %date [%thread] %-5level %logger [%property] - %message%newline The output is like so: 2010-05-21 15:08:02,357 [ThreadA] DEBUG LogicalContextTest.Program [{LogicalThreadContext=ThreadA, log4net:HostName=xxx, ThreadContext=ThreadA}] - From Thread itself 2010-05-21 15:08:02,357 [ThreadB] DEBUG LogicalContextTest.Program [{LogicalThreadContext=ThreadB, log4net:HostName=xxx, ThreadContext=ThreadB}] - From Thread itself 2010-05-21 15:08:02,404 [7] DEBUG LogicalContextTest.Program [{log4net:HostName=xxx}] - From threadpool Thread: ThreadA 2010-05-21 15:08:02,420 [16] DEBUG LogicalContextTest.Program [{log4net:HostName=xxx}] - From threadpool Thread: ThreadB As you can see the last two rows have no Names of useful information to distinguish the 2 threads, other than manually adding the name to the message (which I want to avoid). How can I get the Name/Context into the log for the threadpool threads without adding it to the message at every call?

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How can I 'transpose' my data using SQL and remove duplicates at the same time?

- by Remnant

I have the following data structure in my database: LastName FirstName CourseName John Day Pricing John Day Marketing John Day Finance Lisa Smith Marketing Lisa Smith Finance etc... The data shows employess within a business and which courses they have shown a preference to attend. The number of courses per employee will vary (i.e. as above, John has 3 courses and Lisa 2). I need to take this data from the database and pass it to a webpage view (asp.net mvc). I would like the data that comes out of my database to match the view as much as possible and want to transform the data using SQl so that it looks like the following: LastName FirstName Course1 Course2 Course3 John Day Pricing Marketing Finance Lisa Smith Marketing Finance Any thoughts on how this may be achieved? Note: one of the reasons I am trying this approach is that the original data structure does not easily lend itself to be iterated over using the typical mvc syntax: <% foreach (var item in Model.courseData) { %> Because of the duplication of names in the orignal data I would end up with lots of conditionals in my View which I would like to avoid. I have tried transforming the data using c# in my ViewModel but have found it tough going and feel that I could lighten the workload by leveraging SQL before I return the data. Thanks.

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Get directory path by fd

- by tylerl

I've run into the need to be able refer to a directory by path given its file descriptor in Linux. The path doesn't have to be canonical, it just has to be functional so that I can pass it to other functions. So, taking the same parameters as passed to a function like fstatat(), I need to be able to call a function like getxattr() which doesn't have a f-XYZ-at() variant. So far I've come up with these solutions; though none are particularly elegant. The simplest solution is to avoid the problem by calling openat() and then using a function like fgetxattr(). This works, but not in every situation. So another method is needed to fill the gaps. The next solution involves looking up the information in proc: if (!access("/proc/self/fd",X_OK)) { sprintf(path,"/proc/self/fd/%i/",fd); } This, of course, totally breaks on systems without proc, including some chroot environments. The last option, a more portable but potentially-race-condition-prone solution, looks like this: DIR* save = opendir("."); fchdir(fd); getcwd(path,PATH_MAX); fchdir(dirfd(save)); closedir(save); The obvious problem here is that in a multithreaded app, changing the working directory around could have side effects. However, the fact that it works is compelling: if I can get the path of a directory by calling fchdir() followed by getcwd(), why shouldn't I be able to just get the information directly: fgetcwd() or something. Clearly the kernel is tracking the necessary information. So how do I get to it?

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Android:Playing bigger size audio wav sound file produces crash

- by user187532

Hi Android experts, I am trying to play the bigger size audio wav file(which is 20 mb) using the following code(AudioTrack) on my Android 1.6 HTC device which basically has less memory. But i found device crash as soon as it executes reading, writing and play. But the same code works fine and plays the lesser size audio wav files(10kb, 20 kb files etc) very well. P.S: I should play PCM(.wav) buffer sound, the reason behind why i use AudioTrack here. Though my device has lesser memory, how would i read bigger audio files bytes by bytes and play the sound to avoid crashing due to memory constraints. private void AudioTrackPlayPCM() throws IOException { String filePath = "/sdcard/myWav.wav"; // 8 kb file byte[] byteData = null; File file = null; file = new File(filePath); byteData = new byte[(int) file.length()]; FileInputStream in = null; try { in = new FileInputStream( file ); in.read( byteData ); in.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } int intSize = android.media.AudioTrack.getMinBufferSize(8000, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_8BIT); AudioTrack at = new AudioTrack(AudioManager.STREAM_MUSIC, 8000, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_8BIT, intSize, AudioTrack.MODE_STREAM); at.play(); at.write(byteData, 0, byteData.length); at.stop(); at.release(); } Could someone guide me please to play the AudioTrack code for bigger size wav files?

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Grails - Recursive computing call "StackOverflowError" and don't update on show

- by Kedare

Hello, I have a little problem, I have made a Category domain on Grails, but I want to "cache" the string representation on the database by generating it when the representation field is empty or NULL (to avoid recursive queries at each toString), here is the code : package devkedare class Category { String title; String description; String representation; Date dateCreated; Date lastUpdate; Category parent; static constraints = { title(blank:false, nullable:false, size:2..100); description(blank:true, nullable:false); dateCreated(nullable:true); lastUpdate(nullable:true); autoTimestamp: true; } static hasMany = [childs:Category] @Override String toString() { if((!this.representation) || (this.representation == "")) { this.computeRepresentation(true) } return this.representation; } String computeRepresentation(boolean updateChilds) { if(updateChilds) { for(child in this.childs) { child.representation = child.computeRepresentation(true); } } if(this.parent) { this.representation = "${this.parent.computeRepresentation(false)}/${this.title}"; } else { this.representation = this.title } return this.representation; } void beforeUpdate() { this.computeRepresentation(true); } } There is 2 problems : It don't update the representation when the representation if NULL or empty and toString id called, it only update it on save, how to fix that ? On some category, updating it throw a StackOverflowError, here is an example of my actual category table as CSV : Uploaded the csv file here, pasting csv looks buggy: http://kedare.free.fr/Dist/01.csv Updating the representation works everywhere except on "IT" that throw a StackOverlowError (this is the only category that has many childs). Any idea of how can I fix those 2 problems ? Thank you !

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ASP.NET MVC 2: How to write this Linq SQL as a Dynamic Query (using strings)?

- by Dr. Zim

Skip to the "specific question" as needed. Some background: The scenario: I have a set of products with a "drill down" filter (Query Object) populated with DDLs. Each progressive DDL selection will further limit the product list as well as what options are left for the DDLs. For example, selecting a hammer out of tools limits the Product Sizes to only show hammer sizes. Current setup: I created a query object, sent it to a repository, and fed each option to a SQL "table valued function" where null values represent "get all products". I consider this a good effort, but far from DDD acceptable. I want to avoid any "programming" in SQL, hopefully doing everything with a repository. Comments on this topic would be appreciated. Specific question: How would I rewrite this query as a Dynamic Query? A link to something like 101 Linq Examples would be fantastic, but with a Dynamic Query scope. I really want to pass to this method the field in quotes "" for which I want a list of options and how many products have that option. (from p in db.Products group p by p.ProductSize into g select new Category { PropertyType = g.Key, Count = g.Count() }).Distinct(); Each DDL option will have "The selection (21)" where the (21) is the quantity of products that have that attribute. Upon selecting an option, all other remaining DDLs will update with the remaining options and counts.

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"do it all" page structure and things to watch out for?

- by Andrew Heath

I'm still getting my feet wet in PHP (my 1st language) and I've reached the competency level where I can code one page that handles all sorts of different related requests. They generally have a structure like this: (psuedo code) <?php include 'include/functions.php'; IF authorized IF submit (add data) ELSE IF update (update data) ELSE IF list (show special data) ELSE IF tab switch (show new area) ELSE display vanilla (show default) ELSE "must be registered/logged-in" ?> <HTML> // snip <?php echo $output; ?> // snip </HTML> and it all works nicely, and quite quickly which is cool. But I'm still sorta feeling my way in the dark... and would like some input from the pros regarding this type of page design... is it a good long-term structure? (it seems easily expanded...) are there security risks particular to this design? are there corners I should avoid painting myself into? Just curious about what lies ahead, really...

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Capturing Set Behavior with Mutating Elements

- by Carl

Using the Guava library, I have the following situation: SetMultimap<ImmutableFoo, Set<Foo>> setMM = HashMultimap.create(); Set<Foo> mask = Sets.newHashSet(); // ... some iteration construct { setMM.put(ImmutableFoo1, Sets.difference(SomeSetFoo1,mask)); setMM.put(ImmutableFoo1, Sets.difference(SomeSetFoo2,mask)); mask.add(someFoo); } that is, the same iteration to create the setMM is also used to create the mask - this can of course result in changes to hashCode()s and create duplicates within the SetMultimap backing. Ideally, I'd like the duplicates to drop without me having to make it happen, and avoid repeating the iteration to separately construct the multimap and mask. Any easy libraries/Set implementations to make that happen? Alternatively, can you identify a better way to drop the duplicates than: for (ImmutableFoo f : setMM.keySet()) setMM.putAll(f,setMM.removeAll(f)); revisiting the elements is probably not a performance problem, since I could combine a separate filter operation that needs to visit all the elements anyway.

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what's an effective way to build a csproj file in C#?

- by jcollum

I'd like to avoid a command line for this. I've been using the MSBuild API ( Microsoft.Build.Framework and Microsoft.Build.BuildEngine) with code that looks like this: this.buildEngine = new Engine(); BuildPropertyGroup props = new BuildPropertyGroup(); props.SetProperty("Configuration", "Debug"); this.buildEngine.RegisterLogger(this.logger); Project proj = new Project(this.buildEngine); proj.LoadXml(this.projectFileAndPath, ProjectLoadSettings.None); this.buildEngine.BuildProject(proj, "Build"); However I've run into enough problems that I can't find answers for that I'm really wondering if I'm doing this right. First, I can't find the output (there's no bin directory in any of the places where I figured the dll's would end up). Second, I tried building a project that I had made in VS2008 and the line proj.LoadXml( fails for invalid xml encoding. But of course the xml file is valid, since VS2008 can build it (I checked). At this point I'm beginning to wonder if I've picked up some code that's way out of date or a methodology that's been superseded by something else. Opinions?

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