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• gethostbyname fails for local hostname after resuming from hibernate (Vista+7?)

  - by John

  Just wondering if anyone else has spotted this: On some user's machines running our software, occasionally the call to Win32 winsock gethostbyname fails with error code 11004. For the argument to gethostbyname, I'm passing in the result from gethostname. Now the docs say 11004 is WSANO_DATA. None of the descriptions seem to be relevant (it occurs if you pass in an IP6 address, but as I say, I'm passing in a hostname). Even more interesting is that the MSDN suggests that this combination (gethostname followed by gethostbyname) should never fail, not even if there is no IP address (in that case it would just return empty list of IPs). Here is the quote from the gethostname MSDN entry: ...it is guaranteed that the name returned will be successfully parsed by gethostbyname and WSAAsyncGetHostByName. It only ever happens after resuming from hibernate, in that short period when the network is restarting, and only on Vista/7 (well I've only seen it on Vista and 7). One theory I had was that it related to IP6. Maybe for a short period the network reports an IP6 address but not the corresponging IP4 address (I'm pretty sure that all the client machines are dual IP stack, but I could be wrong). I tried to reproduce by turning off my network card (to force no IP addresses) and couldn't reproduce. Anyone seen this before? Any ideas? John

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• How do you filter a view of a DataTable in .Net 3.5 sp1 using WPF c# and xaml?

  - by Tony

  I found the MSDN example code for getting the default view of a collection and adding a filter to the view, but most of it is for .Net 4.0. I'm on a team that is not currently switching to 4.0, so I don't have that option. None of the examples I found used a DataTable as the source, so I had to adapt it a little. I'm using a DataTable because the data is comming from a DB ans it's easy to populate. After trying to implement the MSDN examples, I get a "NotSupportedException" when I try to set the Filter. This is the c# code I have: protected DataTable _data = new DataTable(); protected BindingListCollectionView _filteredDataView; ... private void On_Loaded(Object sender, RoutedEventArgs e) { _filteredDataView = (BindingListCollectionView)CollectionViewSource.GetDefaultView(_data); _filteredDataView.Filter = new Predicate(MatchesCurrentSelections); // throws NotSupportedException } ... public bool MatchesCurrentSelections(object o){...} It seems that either BindingListCollectionView does not support filtering in .Net 3.5, or it just doesn't work for a DataTable. I looked at setting it up in XAML instead of the C# code, but the XAML examples use collections in resources instead of a collection that is a memberof the class, so I have no idea how to set that up. Does any one know how to filter a view to a DataTable?

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• How to get notified about changes on SharePoint groups.

  - by Flo

  Hi, I'm actual looking for a way to get notified about any changes on a SharePoint group. First I though I would be able to this by attaching a event handler to some kind of group list. But unfortunately there are no such list representing SharePoint groups. My second attempt was to bind a event handler to the content type SharePointGroup but this didn't work either. So are there any other options to get notified about events on a SharePoint group? Bye, Flo EDIT: Thanks for the reply so far. I forgot to mention that I've already googled and read about the user information list. Sorry. First I found a forum entry where they post the relative URL to the user information list (_catalogs/users/simple.aspx). When I'm using this link to see the list,it only contains users and no groups. I don't know but perhaps this link does some filtering on the list. The other information I found about in several blog and forum posts was that a event handler attached to the user information list are not fired up on an events. I have to admit after reading that it doesn't work so many times and even on MSDN (http://msdn.microsoft.com/en-us/library/aa979520.aspx), I didn't try it on my own. The problem attaching the event handler to the content type wasn't the attaching thing, the handler simply didn't get fired when I for example changed a group name or deleted a user from the group. I don't have an idea why the handler doesn't get called I pretty sure I implemented the right methods and attached them to the right events. Any other suggestions how to get informed about changes on SharePoint groups?

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• Does anyone have documentation on SHGetSysColor?

  - by Paulo Santos

  I'm trying to find any reference for this function, but I haven't found anything. All I have is an obscure KB from Microsoft referencing that a programmer made boo-boo when coding a part of the Windows Mobile 6 where he should call SHGetSysColor but instead he called GetSysColor that gives a complete different color, for the same spec. From what I could gather the GetSysColor read a color value in the registry from HKEY_LOCAL_MACHINE\Software\Microsoft\Color\SHColor or HKEY_LOCAL_MACHINE\Software\Microsoft\Color\DefSHColor and returns the color according to the index. In that registry I have the following value for a standard Win Mobile 6.5 "DefSHColor"=hex:\ ff,00,00,00,00,00,00,00,dd,dd,dd,00,ff,ff,cc,00,ff,ff,ff,00,15,af,bc,00,15,\ af,bc,00,c9,e7,e9,00,14,9c,a7,00,ff,ff,ff,00,14,9c,a7,00,14,9c,a7,00,14,9c,\ a7,00,15,af,bc,00,14,9c,a7,00,ff,ff,ff,00,c9,e7,e9,00,37,c7,d3,00,37,c7,d3,\ 00,ff,ff,ff,00,00,b7,c9,00,14,9c,a7,00,ff,ff,ff,00,15,af,bc,00,84,84,c3,00,\ 15,af,bc,00,14,9c,a7,00,ff,ff,ff,00,ff,ff,ff,00,00,00,00,00,ff,ff,ff,00,00,\ 00,00,00,ff,ff,ff,00,2e,44,4f,00,00,14,3c,00,00,f0,ff,00,ff,ff,ff,00,c9,e7,\ e9,00,14,9c,a7,00,ff,ff,ff,00,14,9c,a7,00 And I realized that each four bytes represents a different color (RR,GG,BB,AA -- The AA I'm assuming here, as every color there has the AA byte as 00 which would mean that it's a solid color). What I can't get a fix on is what each index mean, as I have 41 different colors in there. Googling for SHGetSysColor in gives me only 7 matches, two of them are the KB from Microsoft (one in English, the other in French) one is from a Russian site (which I don't read), yet another two are from the freepascal.org and one from Koders.com that is describing the commctl.def file. I went to the commctl.h trying to see if I could find reference tom this function, and found absolutely nothing. No search on MSDN, either fro Google, Bing, or the default MSDN search gave me any result. So, does anyone know what indexes are we talking about here?

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• How to get smartcard reader name in Windows 7 using C# or C/C++?

  - by AndrejaKo

  Hi! I'm trying to make a C# program which will use a C .dll (unfortunately, the .dll doesn't have good documentation) to access a smart card. One of the functions of the .dll uses name of the reader as argument. My problem is that I don't know how to get the name. After looking for answers I found something similar to what I need in an example here: http://msdn.microsoft.com/en-us/library/aa379803%28VS.85%29.aspx I'm looking for a way to get szReader value as described in the aforementioned example using C#. Can anyone help me or at least point me in the right direction? EDIT: Looks like nobody knows the answer so I'll expand the question: How do I get smartcard reader name using C/C++ and Windows API? I've read through MSDN site for smartcard API, but I couldn't find the function which will list readers. My idea is now to make a C/C++ .dll which will get in-between the smartcard .dll and C# program. It will produce list of readers, let user chose one and call the smartcard .dll using chosen name as argument.

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• How to tell what account my webservice is running under in Visual Studio 2005

  - by John Galt

  I'm going a little nuts trying to understand the doc on impersonation and delegation and the question has come up what account my webservice is running under. I am logged as myDomainName\johna on my development workstation called JOHNXP. From Vstudio2005 I start my webservice via Debug and the wsdl page comes up in my browser. From Task Manager, I see the following while sitting at a breakpoint in my .asmx code: aspnet_wp.exe pid=1316 UserName=ASPNET devenv.exe pid=3304 UserName=johna The IIS Directory Security tab for the Virtual Directory that hosts my ws.asmx code has "Enable Anonymous access" UNCHECKED and has "Integrated Windows Authentication" CHECKED. So when the MSDN people state "you must configure the user account under which the server process runs", what would they be refering to in the case of my little webservice described above? I am quoting from: http://msdn.microsoft.com/en-us/library/aa302400.aspx Ultimately, I want this webservice of mine to impersonate whatever authenticated domain user browses through to an invoke of my webservice. My webservice in turn consumes another ASMX webservice on a different server (but same domain). I need this remote webservice to use the impersonated domain user credentials (not those of my webservice on JOHNXP). So its getting a little snarly for me to understand this and I see I am unclear about the account my web service uses. I think it is ASPNET in IIS 5.1 on WinXP but not sure.

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• ASP.NET ListView, custom DataSources, and editing items

  - by Andrew Shepherd

  The MSDN walkthroughs provide a number of examples where you can drag a DataSource from the toolbox, run through some simple configuration steps, then drag a ListView onto the screen, point it at the DataSource, and hey - you've got full table editing. Now I'm trying to write my own DataSource class (a class that implements System.Web.UI.IDataSource) and my own DataSourceView class. I now assign an instance of this custom DataSource class to the ListView.DataSource propery. The display of all the items is working well. However, updating, inserting and deleting just is not working. I'm overriding every function I can in my DataSourceView class, and they just aren't being called. This is such a huge topic, I'll focus this question on one simple example: When you press the "Edit" button (the button inside the ItemTemplate with a CommandName of "Edit", you expect the ItemTemplate to be replaced by an EditItemTemplate. This did not happen. The only way I could get it to happen was to handle the onitemediting event. protected void _listViewPublicHolidays_ItemEditing(object sender, ListViewEditEventArgs e) { _listViewPublicHolidays.EditIndex = e.NewEditIndex; _listViewPublicHolidays.DataBind(); } This is hardly a problem, but how come I had to do it at all? In the MSDN walkthroughs where I attach a ListView to a LinqDataSource, this code doesn't have to be written. Can someone who's been here before hazard a guess as to what would be different or missing in my custom datasource?

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• JQuery code in ASP .NET content pages

  - by user2645830

  I have made a very simple sample project where I want to toggle an asp .net calendar control through jquery. Could anyone please point out why it is not working. I have made no changes to master page from the sample project provided for ASP .NET web application. <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication5._Default" %> <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent"> <script type="text/javascript" src="scripts/jquery-1.4.1.min.js"> </script> <script language="javascript" type="text/javascript"> // <![CDATA[ function Button1_onclick() { alert( $('<%=Calendar1.ClientID%>')); $('<%=Calendar1.ClientID%>').toggle(); } // ]]> </script> </asp:Content> <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent"> <h2> Welcome to ASP.NET! </h2> <p> To learn more about ASP.NET visit <a href="http://www.asp.net" title="ASP.NET Website">www.asp.net</a>. </p> <input id="Button1" type="button" value="button" onclick="return Button1_onclick()" /> <asp:Calendar ID="Calendar1" runat="server"></asp:Calendar> <p> You can also find <a href="http://go.microsoft.com/fwlink/? LinkID=152368&amp;clcid=0x409" title="MSDN ASP.NET Docs">documentation on ASP.NET at MSDN</a>. </p> </asp:Content>

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• Does unboxing just return a pointer to the value within the boxed object on the heap?

  - by Charles

  I this MSDN Magazine article, the author states (emphasis mine): Note that boxing always creates a new object and copies the unboxed value's bits to the object. On the other hand, unboxing simply returns a pointer to the data within a boxed object: no memory copy occurs. However, it is commonly the case that your code will cause the data pointed to by the unboxed reference to be copied anyway. I'm confused by the sentence I've bolded and the sentence that follows it. From everything else I've read, including this MSDN page, I've never before heard that unboxing just returns a pointer to the value on the heap. I was under the impression that unboxing would result in you having a variable containing a copy of the value on the stack, just as you began with. After all, if my variable contains "a pointer to the value on the heap", then I haven't got a value type, I've got a pointer. Can someone explain what this means? Was the author on crack? (There is at least one other glaring error in the article). And if this is true, what are the cases where "your code will cause the data pointed to by the unboxed reference to be copied anyway"? I just noticed that the article is nearly 10 years old, so maybe this is something that changed very early on in the life of .Net.

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• Can't seem to get .Union to work (merging 2 array's together, exclude duplicates)

  - by D. Veloper

  I want to combine two array's, excluding duplicates. I am using a custom class: public class ArcContact : IEquatable<ArcContact> { public String Text; public Boolean Equals(ArcContact other) { if (Object.ReferenceEquals(other, null)) return false; if (Object.ReferenceEquals(this, other)) return true; return Text.Equals(other.Text); } public override Int32 GetHashCode() { return Text == null ? 0 : Text.GetHashCode(); } } I implemented and the needed IEquatable interface as mentioned in this msdn section. I only want to check the Text property of the ArcContact class and make sure an Array of ArcContact have an unique Text. Here I pasted the code that I use, as you can see I have method with two parameters, array's to combine and below that the code I got from the previous mentioned msdn section. internal static class ArcBizz { internal static ArcContact[] MergeDuplicateContacts(ArcContact[] contacts1, ArcContact[] contacts2) { return (ArcContact[])contacts1.Union(contacts2); } internal static IEnumerable<T> Union<T>(this IEnumerable<T> a, IEnumerable<T> b); } What am I doing wrong?

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• Does F# documentation have a way to search for functions by their types?

  - by Nathan Sanders

  Say I want to know if F# has a library function of type ('T -> bool) -> 'T list -> int ie, something that counts how many items of a list that a function returns true for. (or returns the index of the first item that returns true) I used to use the big list at the MSR site for F# before the documentation on MSDN was ready. I could just search the page for the above text because the types were listed. But now the MSDN documentation only lists types on the individual pages--the module page is a mush of descriptive text. Google kinda-sorta works, but it can't help with // compatible interfaces ('T -> bool) -> Seq<'T> -> int // argument-swaps Seq<'T> -> ('T -> bool) -> int // type-variable names ('a -> bool) -> Seq<'a> -> int // wrappers ('a -> bool) -> 'a list -> option<int> // uncurried versions ('T -> bool) * 'T list -> int // .NET generic syntax ('T -> bool) -> List<'T> -> int // methods List<'T> member : ('T -> bool) -> int Haskell has a standalone program for this called Hoogle. Does F# have an equivalent, like Fing or something?

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• ASP.Net Session Storage provider in 3-layer architecture

  - by Tedd Hansen

  I'm implementing a custom session storage provider in ASP.Net. We have a strict 3-layer architecture and therefore the session storage needs to go through the business layer. Presentation-Business-Database. The business layer is accessed through WPF. The database is MSSQL. What I need is (in order of preference): A commercial/free/open source product that solves this. The source code of a SqlSessionStateStore (custom session store) (not the ODBC-sample on MSDN) that I can modify to use a middle layer. I've tried looking at .Net source through Reflector, but the code is not usable. Note: I understand how to do this. I am looking for working samples, preferably that has been proven to work fine under heavy load. The ODBC sample on MSDN doesn't use the (new?) stored procs that the build in SqlSessionStateStore uses - I'd like to use these if possible (decreases traffic). Edit1: To answer Simons question on more info: ASP.Net Session()-object can be stored in either InProc, ASP.Net State Service or SQL-server. In a secure 3-layer model the presentation layer (web server) does not have direct/physical access to the database layer (SQL-server). And even without the physical limitations, from an architectural standpoint you may not want this. InProc and ASP.Net State Service does not support load balancing and doesn't have fault tolerance. Therefore the only option is to access SQL through webservice middle layer (business layer).

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• C++ NetUserAdd() not working?

  - by Brett Powell

  I posted earlier about how to do this, and got some great replies, and have managed to get the code written based off the MSDN example. However, it does not seem to be working properly. Its printing out the ERROR_ACCESS_DENIED message, but im not sure why as I am running it as a full admin. I was initially trying to create a USER_PRIV_ADMIN, but the MSDN said it can only use USER_PRIV_USER, but sadly neither work. Im hoping someone can spot a mistake or has an idea. Thanks! void AddRDPUser() { USER_INFO_1 ui; DWORD dwLevel = 1; DWORD dwError = 0; NET_API_STATUS nStatus; ui.usri1_name = L"DummyUserAccount"; ui.usri1_password = L"a2cDz3rQpG8"; //ignored by NetUserAdd //ui.usri1_password_age = -1; ui.usri1_priv = USER_PRIV_USER; //USER_PRIV_ADMIN; ui.usri1_home_dir = NULL; ui.usri1_comment = NULL; ui.usri1_flags = UF_SCRIPT; ui.usri1_script_path = NULL; nStatus = NetUserAdd(NULL, dwLevel, (LPBYTE)&ui, &dwError); switch (nStatus) { case NERR_Success: { Msg("SUCCESS!\n"); break; } case NERR_InvalidComputer: { fprintf(stderr, "A system error has occurred: NERR_InvalidComputer\n"); break; } case NERR_NotPrimary: { fprintf(stderr, "A system error has occurred: NERR_NotPrimary\n"); break; } case NERR_GroupExists: { fprintf(stderr, "A system error has occurred: NERR_GroupExists\n"); break; } case NERR_UserExists: { fprintf(stderr, "A system error has occurred: NERR_UserExists\n"); break; } case NERR_PasswordTooShort: { fprintf(stderr, "A system error has occurred: NERR_PasswordTooShort\n"); break; } case ERROR_ACCESS_DENIED: { fprintf(stderr, "A system error has occurred: ERROR_ACCESS_DENIED\n"); break; } } }

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• Reflection and Operator Overloads in C#

  - by TenshiNoK

  Here's the deal. I've got a program that will load a given assembly, parse through all Types and their Members and compile a TreeView (very similar to old MSDN site) and then build HTML pages for each node in the TreeView. It basically takes a given assembly and allows the user to create their own MSDN-like library for it for documentation purposes. Here's the problem I've run into: whenever an operator overload is encounted in a defined class, reflection returns that as a "MethodInfo" with the name set to something like "op_Assign" or "op_Equality". I want to be able to capture these and list them properly, but I can't find anything in the MethodInfo object that is returned to accurately identify that I'm looking at an operator. I definitely don't want to just capture everything that starts with "op_", since that will most certainly (at some point) will pick up a method it's not supposed to. I know that other methods and properties that are "special cases" like this one have the "IsSpecialName" property set, but appearantly that's not the case with operators. I've been scouring the 'net and wracking my brain to two days trying to figure this one out, so any help will be greatly appreciated.

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• Commited memory goes to physical RAM or reserves space in the paging file?

  - by Sil

  When I do VirtualAlloc with MEM_COMMIT this "Allocates physical storage in memory or in the paging file on disk for the specified reserved memory pages" (quote from MSDN article http://msdn.microsoft.com/en-us/library/aa366887%28VS.85%29.aspx). All is fine up until now BUT: the description of Commited Bytes Counter says that "Committed memory is the physical memory which has space reserved on the disk paging file(s)." I also read "Windows via C/C++ 5th edition" and this book says that commiting memory means reserving space in the page file.... The last two cases don't make sense to me... If you commit memory, doesn't that mean that you commit to physical storage (RAM)? The page file being there for swaping out currently unused pages of memory in case memory gets low. The book says that when you commit memory you actually reserve space in the paging file. If this were true than that would mean that for a committed page there is space reserved in the paging file and a page frame in physical in memory... So twice as much space is needed ?! Isn't the page file's purpose to make the total physical memory larger than it actually is? If I have a 1G of RAM with a 1G page file = 2G of usable "physical memory"(the book also states this but right after that it says what I discribed at point 2). What am I missing? Thanks.

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• C++/Win32 : XP Visual Styles - no controls are showing up?

  - by mrl33t

  Okay, so i'm pretty new to C++ & the Windows API and i'm just writing a small application. I wanted my application to make use of visual styles in both XP, Vista and Windows 7 so I added this line to the top of my code: #pragma comment(linker,"\"/manifestdependency:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'\"") It seemed to work perfectly on my Windows 7 machine and also Vista machine. But when I tried the application on XP the application wouldn't load any controls (e.g. buttons, labels etc.) - not even messageboxes would display. This image shows a small test application which i've just put together to demonstrate what i'm trying to explain: http://img704.imageshack.us/img704/2250/myapp.png In this test application i'm not using any particularly fancy or complicated code. I've effectively just taken the most basic sample code from the MSDN Library (http://msdn.microsoft.com/en-us/library/ff381409.aspx) and added a section to the WM_CREATE message to create a button: MyBtn = CreateWindow(L"Button", L"My Button", BS_PUSHBUTTON | WS_CHILD | WS_VISIBLE, 25, 25, 100, 30, hWnd, NULL, hInst, 0); But I just can't figure out what's going on and why its not working. Any ideas guys? Thank you in advanced. (By the way the application works in XP if i remove the manifest section from the top - obviously without visual styles though. I should also probably mention that the app was built using Visual C++ 2010 Express on a Windows 7 machine - if that makes a difference?)

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• How to delete ProgIDs from other user accounts when uninstalling from Windows?

  - by Mordachai

  I've been investigating "how should a modern windows c++ application register its file types" with Windows (see http://stackoverflow.com/questions/2828637/c-how-do-i-correctly-register-and-unregister-file-type-associations-for-our-ap). And having combed through the various MSDN articles on the subject, the summary appears to be as follows: The installer (elevated) should register the global ProgID HKLM\Software\Classes\my-app.my-doc[.version] (e.g. HKLM\Software\Classes\TextPad.text) The installer also configures default associations for its document types (e.g. .myext) and points this to the aforementioned global ProgID in HKLM. NOTE: a user interface should be provided here to allow the user to either accept all default associations, or to customize which associations should be set. The application, running standard (unelevated), should provide a UI for allowing the current user to set their personal associations as is available in the installer, except that these associations are stored in HKCU\Software\Classes (per user, not per machine). The UN-installer is then responsible for deleting all registered ProgIDs (but should leave the actual file associations alone, as Windows is smart enough to handle associations pointing to missing ProgIDs, and this is the specified desired behavior by MSDN). So that schema sounds reasonable to me, except when I consider #4: How does an uninstaller, running elevated for a given user account, delete any per-user ProgIDs created in step #3 for other users? As I understand things, even in elevated mode, an uninstaller cannot go into another user's registry hive and delete items? Or can it? Does it have to load each given user hive first? What are the rules here? Thanks for any insight you might have to offer! EDIT: See below for the solution (My question was founded in confusion)

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• Programmatically setup a PEAP connection in Windows Mobile

  - by tomlog

  I have been working on this for a few days and this is doing my head in: Our application is built using the .NET Compact Framework 2.0 and running on Windows Mobile 5 & 6 devices. We can set the WLAN connection of the device programmatically using the Wireless Zero Config functions (described here: msdn.microsoft.com/en-us/library/ms894771.aspx), most notably the WZCSetInterface function which we pinvoke from our application. This works fine for WEP and WPA-PSK connections. In a recent effort to add support for WPA2 networks we decided to modify the code. We have successfully added support for WPA2 which uses a certificate for the 802.1x authentication by setting the correct registry settings before calling WZCSetInterface. Now we want to do the same for WPA2 using PEAP (MS-CHAPv2) authentication. When manually creating such a connection in Windows Mobile the user will be prompted to enter the domain/user/password details. In our application we will have those details stored locally and want to do this all programmatically without any user intervention. So I thought going along the same route as the certificate authentication, setting the correct registry entries before calling WZCSetInterface. The registry settings we set are: \HKCU\Comm\EAP\Config\[ssid name] Enable8021x = 1 (DWORD) LastAuthSuccessful = 1 (DWORD) EapTypeId = 25 (DWORD) Identity = "domain\username" (string) Password = binary blob containing the password that is encrypted using the CryptProtectData function (described here: msdn.microsoft.com/en-us/library/ms938309.aspx) But when these settings are set and I call WZCSetInterface with the correct parameters, it still prompts me with the User Logon dialog asking for the domain/username/password. Has anyone got an idea what I need to do to prevent the password dialog from appearing and connect straight away with the settings stored in the registry?

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• GetLongPathName Undeclared

  - by iwizardpro

  When I try to compile my code with the function GetLongPathName(), the compiler tells me that the function is undeclared. I have already read the MSDN documentation located @ http://msdn.microsoft.com/en-us/library/aa364980%28VS.85%29.aspx. But, even though I included those header files, I am still getting the undeclared function error. Which header file(s) am I supposed to include when using the function? #include <Windows.h> #include <WinBase.h> #define DLLEXPORT extern "C" __declspec(dllexport) DLLEXPORT char* file_get_long(char* path_original) { long length = 0; TCHAR* buffer = NULL; if(!path_original) { return "-10"; } length = GetLongPathName(path_original, NULL, 0); if(length == 0) { return "-10"; } buffer = new TCHAR[length]; length = GetLongPathName(path_original, buffer, length); if(length == 0) { return "-10"; } return buffer; } And, if it makes a difference, I am currently compiling using Dev-C++ on a Windows Vista 64-bit.

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• Serializing a class containing a custom class

  - by Netfangled

  I want to serialize an object as xml that contains other custom classes. From what I understand (I've been reading MSDN and SO mostly), the XmlSerializer doesn't take this into account. This is the line that's confusing me: XML serialization serializes only the public fields and property values of an object into an XML stream. XML serialization does not include type information. For example, if you have a Book object that exists in the Library namespace, there is no guarantee that it will be deserialized into an object of the same type. Taken from MSDN, here For example, I want to serialize an object of type Order, but it contains a list of Products, and each one contains an object of type Category: class Order { List<Product> products; } class Product { Category type; } class Category { string name; string description; } And I want my Order object to be serialized like so: <Order> <Product> <Category Name=""> <Description></Description> </Category> </Product> <Product> <Category Name=""> <Description></Description> </Category> </Product> <Order> Does the XmlSerializer already do this? If not, is there another class that does or do I have to define the serialization process myself?

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• Semaphore - What is the use of initial count?

  - by Sandbox

  http://msdn.microsoft.com/en-us/library/system.threading.semaphoreslim.aspx To create a semaphore, I need to provide an initial count and maximum count. MSDN states that an initial count is - The initial number of requests for the semaphore that can be granted concurrently. While it states that maximum count is The maximum number of requests for the semaphore that can be granted concurrently. I can understand that the maximum count is the maximum number of threads that can access a resource concurrently. But, what is the use of initial count? If I create a semaphore with an initial count of 0 and a maximum count of 2, none of my threadpool threads are able to access the resource. If I set the initial count as 1 and maximum count as 2 then only thread pool thread can access the resource. It is only when I set both initial count and maximum count as 2, 2 threads are able to access the resource concurrently. So, I am really confused about the significance of initial count? SemaphoreSlim semaphoreSlim = new SemaphoreSlim(0, 2); //all threadpool threads wait SemaphoreSlim semaphoreSlim = new SemaphoreSlim(1, 2);//only one thread has access to the resource at a time SemaphoreSlim semaphoreSlim = new SemaphoreSlim(2, 2);//two threadpool threads can access the resource concurrently

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• FreeText COUNT query on multiple tables is super slow

  - by Eric P

  I have two tables: **Product** ID Name SKU **Brand** ID Name Product table has about 120K records Brand table has 30K records I need to find count of all the products with name and brand matching a specific keyword. I use freetext 'contains' like this: SELECT count(*) FROM Product inner join Brand on Product.BrandID = Brand.ID WHERE (contains(Product.Name, 'pants') or contains(Brand.Name, 'pants')) This query takes about 17 secs. I rebuilt the FreeText index before running this query. If I only check for Product.Name. They query is less then 1 sec. Same, if I only check the Brand.Name. The issue occurs if I use OR condition. If I switch query to use LIKE: SELECT count(*) FROM Product inner join Brand on Product.BrandID = Brand.ID WHERE Product.Name LIKE '%pants%' or Brand.Name LIKE '%pants%' It takes 1 secs. I read on MSDN that: http://msdn.microsoft.com/en-us/library/ms187787.aspx To search on multiple tables, use a joined table in your FROM clause to search on a result set that is the product of two or more tables. So I added an INNER JOINED table to FROM: SELECT count(*) FROM (select Product.Name ProductName, Product.SKU ProductSKU, Brand.Name as BrandName FROM Product inner join Brand on product.BrandID = Brand.ID) as TempTable WHERE contains(TempTable.ProductName, 'pants') or contains(TempTable.BrandName, 'pants') This results in error: Cannot use a CONTAINS or FREETEXT predicate on column 'ProductName' because it is not full-text indexed. So the question is - why OR condition could be causing such as slow query?

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• .NET WebRequest.PreAuthenticate not quite what it sounds like

  - by Rick Strahl

  I’ve run into the  problem a few times now: How to pre-authenticate .NET WebRequest calls doing an HTTP call to the server – essentially send authentication credentials on the very first request instead of waiting for a server challenge first? At first glance this sound like it should be easy: The .NET WebRequest object has a PreAuthenticate property which sounds like it should force authentication credentials to be sent on the first request. Looking at the MSDN example certainly looks like it does: http://msdn.microsoft.com/en-us/library/system.net.webrequest.preauthenticate.aspx Unfortunately the MSDN sample is wrong. As is the text of the Help topic which incorrectly leads you to believe that PreAuthenticate… wait for it - pre-authenticates. But it doesn’t allow you to set credentials that are sent on the first request. What this property actually does is quite different. It doesn’t send credentials on the first request but rather caches the credentials ONCE you have already authenticated once. Http Authentication is based on a challenge response mechanism typically where the client sends a request and the server responds with a 401 header requesting authentication. So the client sends a request like this: GET /wconnect/admin/wc.wc?_maintain~ShowStatus HTTP/1.1 Host: rasnote User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506) Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en,de;q=0.7,en-us;q=0.3 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive and the server responds with: HTTP/1.1 401 Unauthorized Cache-Control: private Content-Type: text/html; charset=utf-8 Server: Microsoft-IIS/7.5 WWW-Authenticate: basic realm=rasnote" X-AspNet-Version: 2.0.50727 WWW-Authenticate: Negotiate WWW-Authenticate: NTLM WWW-Authenticate: Basic realm="rasnote" X-Powered-By: ASP.NET Date: Tue, 27 Oct 2009 00:58:20 GMT Content-Length: 5163 plus the actual error message body. The client then is responsible for re-sending the current request with the authentication token information provided (in this case Basic Auth): GET /wconnect/admin/wc.wc?_maintain~ShowStatus HTTP/1.1 Host: rasnote User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506) Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en,de;q=0.7,en-us;q=0.3 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive Cookie: TimeTrakker=2HJ1998WH06696; WebLogCommentUser=Rick Strahl|http://www.west-wind.com/|[email protected]; WebStoreUser=b8bd0ed9 Authorization: Basic cgsf12aDpkc2ZhZG1zMA== Once the authorization info is sent the server responds with the actual page result. Now if you use WebRequest (or WebClient) the default behavior is to re-authenticate on every request that requires authorization. This means if you look in  Fiddler or some other HTTP client Proxy that captures requests you’ll see that each request re-authenticates: Here are two requests fired back to back: and you can see the 401 challenge, the 200 response for both requests. If you watch this same conversation between a browser and a server you’ll notice that the first 401 is also there but the subsequent 401 requests are not present. WebRequest.PreAuthenticate And this is precisely what the WebRequest.PreAuthenticate property does: It’s a caching mechanism that caches the connection credentials for a given domain in the active process and resends it on subsequent requests. It does not send credentials on the first request but it will cache credentials on subsequent requests after authentication has succeeded: string url = "http://rasnote/wconnect/admin/wc.wc?_maintain~ShowStatus"; HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential("rick", "secret", "rasnote"); req.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested; req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; WebResponse resp = req.GetResponse(); resp.Close(); req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential("rstrahl", "secret", "rasnote"); req.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested; req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; resp = req.GetResponse(); which results in the desired sequence: where only the first request doesn’t send credentials. This is quite useful as it saves quite a few round trips to the server – bascially it saves one auth request request for every authenticated request you make. In most scenarios I think you’d want to send these credentials this way but one downside to this is that there’s no way to log out the client. Since the client always sends the credentials once authenticated only an explicit operation ON THE SERVER can undo the credentials by forcing another login explicitly (ie. re-challenging with a forced 401 request). Forcing Basic Authentication Credentials on the first Request On a few occasions I’ve needed to send credentials on a first request – mainly to some oddball third party Web Services (why you’d want to use Basic Auth on a Web Service is beyond me – don’t ask but it’s not uncommon in my experience). This is true of certain services that are using Basic Authentication (especially some Apache based Web Services) and REQUIRE that the authentication is sent right from the first request. No challenge first. Ugly but there it is. Now the following works only with Basic Authentication because it’s pretty straight forward to create the Basic Authorization ‘token’ in code since it’s just an unencrypted encoding of the user name and password into base64. As you might guess this is totally unsecure and should only be used when using HTTPS/SSL connections (i’m not in this example so I can capture the Fiddler trace and my local machine doesn’t have a cert installed, but for production apps ALWAYS use SSL with basic auth). The idea is that you simply add the required Authorization header to the request on your own along with the authorization string that encodes the username and password: string url = "http://rasnote/wconnect/admin/wc.wc?_maintain~ShowStatus"; HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest; string user = "rick"; string pwd = "secret"; string domain = "www.west-wind.com"; string auth = "Basic " + Convert.ToBase64String(System.Text.Encoding.Default.GetBytes(user + ":" + pwd)); req.PreAuthenticate = true; req.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested;req.Headers.Add("Authorization", auth); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; WebResponse resp = req.GetResponse(); resp.Close(); This works and causes the request to immediately send auth information to the server. However, this only works with Basic Auth because you can actually create the authentication credentials easily on the client because it’s essentially clear text. The same doesn’t work for Windows or Digest authentication since you can’t easily create the authentication token on the client and send it to the server. Another issue with this approach is that PreAuthenticate has no effect when you manually force the authentication. As far as Web Request is concerned it never sent the authentication information so it’s not actually caching the value any longer. If you run 3 requests in a row like this: string url = "http://rasnote/wconnect/admin/wc.wc?_maintain~ShowStatus"; HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest; string user = "ricks"; string pwd = "secret"; string domain = "www.west-wind.com"; string auth = "Basic " + Convert.ToBase64String(System.Text.Encoding.Default.GetBytes(user + ":" + pwd)); req.PreAuthenticate = true; req.Headers.Add("Authorization", auth); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; WebResponse resp = req.GetResponse(); resp.Close(); req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential(user, pwd, domain); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; resp = req.GetResponse(); resp.Close(); req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential(user, pwd, domain); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; resp = req.GetResponse(); you’ll find the trace looking like this: where the first request (the one we explicitly add the header to) authenticates, the second challenges, and any subsequent ones then use the PreAuthenticate credential caching. In effect you’ll end up with one extra 401 request in this scenario, which is still better than 401 challenges on each request. Getting Access to WebRequest in Classic .NET Web Service Clients If you’re running a classic .NET Web Service client (non-WCF) one issue with the above is how do you get access to the WebRequest to actually add the custom headers to do the custom Authentication described above? One easy way is to implement a partial class that allows you add headers with something like this: public partial class TaxService { protected NameValueCollection Headers = new NameValueCollection(); public void AddHttpHeader(string key, string value) { this.Headers.Add(key,value); } public void ClearHttpHeaders() { this.Headers.Clear(); } protected override WebRequest GetWebRequest(Uri uri) { HttpWebRequest request = (HttpWebRequest) base.GetWebRequest(uri); request.Headers.Add(this.Headers); return request; } } where TaxService is the name of the .NET generated proxy class. In code you can then call AddHttpHeader() anywhere to add additional headers which are sent as part of the GetWebRequest override. Nice and simple once you know where to hook it. For WCF there’s a bit more work involved by creating a message extension as described here: http://weblogs.asp.net/avnerk/archive/2006/04/26/Adding-custom-headers-to-every-WCF-call-_2D00_-a-solution.aspx. FWIW, I think that HTTP header manipulation should be readily available on any HTTP based Web Service client DIRECTLY without having to subclass or implement a special interface hook. But alas a little extra work is required in .NET to make this happen Not a Common Problem, but when it happens… This has been one of those issues that is really rare, but it’s bitten me on several occasions when dealing with oddball Web services – a couple of times in my own work interacting with various Web Services and a few times on customer projects that required interaction with credentials-first services. Since the servers determine the protocol, we don’t have a choice but to follow the protocol. Lovely following standards that implementers decide to ignore, isn’t it? :-}© Rick Strahl, West Wind Technologies, 2005-2010Posted in .NET  CSharp  Web Services  

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• Setting up and using Bing Translate API Service for Machine Translation

  - by Rick Strahl

  Last week I spent quite a bit of time trying to set up the Bing Translate API service. I can honestly say this was one of the most screwed up developer experiences I've had in a long while - specifically related to the byzantine sign up process that Microsoft has in place. Not only is it nearly impossible to find decent documentation on the required signup process, some of the links in the docs are just plain wrong, and some of the account pages you need to access the actual account information once signed up are not linked anywhere from the administration UI. To make things even harder is the fact that the APIs changed a while back, with a completely new authentication scheme that's described and not directly linked documentation topic also made for a very frustrating search experience. It's a bummer that this is the case too, because the actual API itself is easy to use and works very well - fast and reasonably accurate (as accurate as you can expect machine translation to be). But the sign up process is a pain in the ass doubtlessly leaving many people giving up in frustration. In this post I'll try to hit all the points needed to set up to use the Bing Translate API in one place since such a document seems to be missing from Microsoft. Hopefully the API folks at Microsoft will get their shit together and actually provide this sort of info on their site… Signing Up The first step required is to create a Windows Azure MarketPlace account. Go to: https://datamarket.azure.com/ Sign in with your Windows Live Id If you don't have an account you will be taken to a registration page which you have to fill out. Follow the links and complete the registration. Once you're signed in you can start adding services. Click on the Data Link on the main page Select Microsoft Translator from the list This adds the Microsoft Bing Translator to your services. Pricing The page shows the pricing matrix and the free service which provides 2 megabytes for translations a month for free. Prices go up steeply from there. Pricing is determined by actual bytes of the result translations used. Max translations are 1000 characters so at minimum this means you get around 2000 translations a month for free. However most translations are probable much less so you can expect larger number of translations to go through. For testing or low volume translations this should be just fine. Once signed up there are no further instructions and you're left in limbo on the MS site. Register your Application Once you've created the Data association with Translator the next step is registering your application. To do this you need to access your developer account. Go to https://datamarket.azure.com/developer/applications/register Provide a ClientId, which is effectively the unique string identifier for your application (not your customer id!) Provide your name The client secret was auto-created and this becomes your 'password' For the redirect url provide any https url: https://microsoft.com works Give this application a description of your choice so you can identify it in the list of apps Now, once you've registered your application, keep track of the ClientId and ClientSecret - those are the two keys you need to authenticate before you can call the Translate API. Oddly the applications page is hidden from the Azure Portal UI. I couldn't find a direct link from anywhere on the site back to this page where I can examine my developer application keys. To find them you can go to: https://datamarket.azure.com/developer/applications You can come back here to look at your registered applications and pick up the ClientID and ClientSecret. Fun eh? But we're now ready to actually call the API and do some translating. Using the Bing Translate API The good news is that after this signup hell, using the API is pretty straightforward. To use the translation API you'll need to actually use two services: You need to call an authentication API service first, before you can call the actual translator API. These two APIs live on different domains, and the authentication API returns JSON data while the translator service returns XML. So much for consistency. Authentication The first step is authentication. The service uses oAuth authentication with a  bearer token that has to be passed to the translator API. The authentication call retrieves the oAuth token that you can then use with the translate API call. The bearer token has a short 10 minute life time, so while you can cache it for successive calls, the token can't be cached for long periods. This means for Web backend requests you typically will have to authenticate each time unless you build a more elaborate caching scheme that takes the timeout into account (perhaps using the ASP.NET Cache object). For low volume operations you can probably get away with simply calling the auth API for every translation you do. To call the Authentication API use code like this:/// /// Retrieves an oAuth authentication token to be used on the translate /// API request. The result string needs to be passed as a bearer token /// to the translate API. /// /// You can find client ID and Secret (or register a new one) at: /// https://datamarket.azure.com/developer/applications/ /// /// The client ID of your application /// The client secret or password /// public string GetBingAuthToken(string clientId = null, string clientSecret = null) { string authBaseUrl = https://datamarket.accesscontrol.windows.net/v2/OAuth2-13; if (string.IsNullOrEmpty(clientId) || string.IsNullOrEmpty(clientSecret)) { ErrorMessage = Resources.Resources.Client_Id_and_Client_Secret_must_be_provided; return null; } var postData = string.Format("grant_type=client_credentials&client_id={0}" + "&client_secret={1}" + "&scope=http://api.microsofttranslator.com", HttpUtility.UrlEncode(clientId), HttpUtility.UrlEncode(clientSecret)); // POST Auth data to the oauth API string res, token; try { var web = new WebClient(); web.Encoding = Encoding.UTF8; res = web.UploadString(authBaseUrl, postData); } catch (Exception ex) { ErrorMessage = ex.GetBaseException().Message; return null; } var ser = new JavaScriptSerializer(); var auth = ser.Deserialize<BingAuth>(res); if (auth == null) return null; token = auth.access_token; return token; } private class BingAuth { public string token_type { get; set; } public string access_token { get; set; } } This code basically takes the client id and secret and posts it at the oAuth endpoint which returns a JSON string. Here I use the JavaScript serializer to deserialize the JSON into a custom object I created just for deserialization. You can also use JSON.NET and dynamic deserialization if you are already using JSON.NET in your app in which case you don't need the extra type. In my library that houses this component I don't, so I just rely on the built in serializer. The auth method returns a long base64 encoded string which can be used as a bearer token in the translate API call. Translation Once you have the authentication token you can use it to pass to the translate API. The auth token is passed as an Authorization header and the value is prefixed with a 'Bearer ' prefix for the string. Here's what the simple Translate API call looks like:/// /// Uses the Bing API service to perform translation /// Bing can translate up to 1000 characters. /// /// Requires that you provide a CLientId and ClientSecret /// or set the configuration values for these two. /// /// More info on setup: /// http://www.west-wind.com/weblog/ /// /// Text to translate /// Two letter culture name /// Two letter culture name /// Pass an access token retrieved with GetBingAuthToken. /// If not passed the default keys from .config file are used if any /// public string TranslateBing(string text, string fromCulture, string toCulture, string accessToken = null) { string serviceUrl = "http://api.microsofttranslator.com/V2/Http.svc/Translate"; if (accessToken == null) { accessToken = GetBingAuthToken(); if (accessToken == null) return null; } string res; try { var web = new WebClient(); web.Headers.Add("Authorization", "Bearer " + accessToken); string ct = "text/plain"; string postData = string.Format("?text={0}&from={1}&to={2}&contentType={3}", HttpUtility.UrlEncode(text), fromCulture, toCulture, HttpUtility.UrlEncode(ct)); web.Encoding = Encoding.UTF8; res = web.DownloadString(serviceUrl + postData); } catch (Exception e) { ErrorMessage = e.GetBaseException().Message; return null; } // result is a single XML Element fragment var doc = new XmlDocument(); doc.LoadXml(res); return doc.DocumentElement.InnerText; } The first of this code deals with ensuring the auth token exists. You can either pass the token into the method manually or let the method automatically retrieve the auth code on its own. In my case I'm using this inside of a Web application and in that situation I simply need to re-authenticate every time as there's no convenient way to manage the lifetime of the auth cookie. The auth token is added as an Authorization HTTP header prefixed with 'Bearer ' and attached to the request. The text to translate, the from and to language codes and a result format are passed on the query string of this HTTP GET request against the Translate API. The translate API returns an XML string which contains a single element with the translated string. Using the Wrapper Methods It should be pretty obvious how to use these two methods but here are a couple of test methods that demonstrate the two usage scenarios:[TestMethod] public void TranslateBingWithAuthTest() { var translate = new TranslationServices(); string clientId = DbResourceConfiguration.Current.BingClientId; string clientSecret = DbResourceConfiguration.Current.BingClientSecret; string auth = translate.GetBingAuthToken(clientId, clientSecret); Assert.IsNotNull(auth); string text = translate.TranslateBing("Hello World we're back home!", "en", "de",auth); Assert.IsNotNull(text, translate.ErrorMessage); Console.WriteLine(text); } [TestMethod] public void TranslateBingIntegratedTest() { var translate = new TranslationServices(); string text = translate.TranslateBing("Hello World we're back home!","en","de"); Assert.IsNotNull(text, translate.ErrorMessage); Console.WriteLine(text); } Other API Methods The Translate API has a number of methods available and this one is the simplest one but probably also the most common one that translates a single string. You can find additional methods for this API here: http://msdn.microsoft.com/en-us/library/ff512419.aspx Soap and AJAX APIs are also available and documented on MSDN: http://msdn.microsoft.com/en-us/library/dd576287.aspx These links will be your starting points for calling other methods in this API. Dual Interface I've talked about my database driven localization provider here in the past, and it's for this tool that I added the Bing localization support. Basically I have a localization administration form that allows me to translate individual strings right out of the UI, using both Google and Bing APIs: As you can see in this example, the results from Google and Bing can vary quite a bit - in this case Google is stumped while Bing actually generated a valid translation. At other times it's the other way around - it's pretty useful to see multiple translations at the same time. Here I can choose from one of the values and driectly embed them into the translated text field. Lost in Translation There you have it. As I mentioned using the API once you have all the bureaucratic crap out of the way calling the APIs is fairly straight forward and reasonably fast, even if you have to call the Auth API for every call. Hopefully this post will help out a few of you trying to navigate the Microsoft bureaucracy, at least until next time Microsoft upends everything and introduces new ways to sign up again. Until then - happy translating… Related Posts Translation method Source on Github Translating with Google Translate without Google API Keys Creating a data-driven ASP.NET Resource Provider© Rick Strahl, West Wind Technologies, 2005-2013Posted in Localization  ASP.NET  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Metro, Authentication, and the ASP.NET Web API

  - by Stephen.Walther

  Imagine that you want to create a Metro style app written with JavaScript and you want to communicate with a remote web service. For example, you are creating a movie app which retrieves a list of movies from a movies service. In this situation, how do you authenticate your Metro app and the Metro user so not just anyone can call the movies service? How can you identify the user making the request so you can return user specific data from the service? The Windows Live SDK supports a feature named Single Sign-On. When a user logs into a Windows 8 machine using their Live ID, you can authenticate the user’s identity automatically. Even better, when the Metro app performs a call to a remote web service, you can pass an authentication token to the remote service and prevent unauthorized access to the service. The documentation for Single Sign-On is located here: http://msdn.microsoft.com/en-us/library/live/hh826544.aspx In this blog entry, I describe the steps that you need to follow to use Single Sign-On with a (very) simple movie app. We build a Metro app which communicates with a web service created using the ASP.NET Web API. Creating the Visual Studio Solution Let’s start by creating a Visual Studio solution which contains two projects: a Windows Metro style Blank App project and an ASP.NET MVC 4 Web Application project. Name the Metro app MovieApp and the ASP.NET MVC application MovieApp.Services. When you create the ASP.NET MVC application, select the Web API template: After you create the two projects, your Visual Studio Solution Explorer window should look like this: Configuring the Live SDK You need to get your hands on the Live SDK and register your Metro app. You can download the latest version of the SDK (version 5.2) from the following address: http://www.microsoft.com/en-us/download/details.aspx?id=29938 After you download the Live SDK, you need to visit the following website to register your Metro app: https://manage.dev.live.com/build Don’t let the title of the website — Windows Push Notifications & Live Connect – confuse you, this is the right place. Follow the instructions at the website to register your Metro app. Don’t forget to follow the instructions in Step 3 for updating the information in your Metro app’s manifest. After you register, your client secret is displayed. Record this client secret because you will need it later (we use it with the web service): You need to configure one more thing. You must enter your Redirect Domain by visiting the following website: https://manage.dev.live.com/Applications/Index Click on your application name, click Edit Settings, click the API Settings tab, and enter a value for the Redirect Domain field. You can enter any domain that you please just as long as the domain has not already been taken: For the Redirect Domain, I entered http://superexpertmovieapp.com. Create the Metro MovieApp Next, we need to create the MovieApp. The MovieApp will: 1. Use Single Sign-On to log the current user into Live 2. Call the MoviesService web service 3. Display the results in a ListView control Because we use the Live SDK in the MovieApp, we need to add a reference to it. Right-click your References folder in the Solution Explorer window and add the reference: Here’s the HTML page for the Metro App: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>MovieApp</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.1.0.RC/css/ui-dark.css" rel="stylesheet" /> <script src="//Microsoft.WinJS.1.0.RC/js/base.js"></script> <script src="//Microsoft.WinJS.1.0.RC/js/ui.js"></script> <!-- Live SDK --> <script type="text/javascript" src="/LiveSDKHTML/js/wl.js"></script> <!-- WebServices references --> <link href="/css/default.css" rel="stylesheet" /> <script src="/js/default.js"></script> </head> <body> <div id="tmplMovie" data-win-control="WinJS.Binding.Template"> <div class="movieItem"> <span data-win-bind="innerText:title"></span> <br /><span data-win-bind="innerText:director"></span> </div> </div> <div id="lvMovies" data-win-control="WinJS.UI.ListView" data-win-options="{ itemTemplate: select('#tmplMovie') }"> </div> </body> </html> The HTML page above contains a Template and ListView control. These controls are used to display the movies when the movies are returned from the movies service. Notice that the page includes a reference to the Live script that we registered earlier: <!-- Live SDK --> <script type="text/javascript" src="/LiveSDKHTML/js/wl.js"></script> The JavaScript code looks like this: (function () { "use strict"; var REDIRECT_DOMAIN = "http://superexpertmovieapp.com"; var WEBSERVICE_URL = "http://localhost:49743/api/movies"; function init() { WinJS.UI.processAll().done(function () { // Get element and control references var lvMovies = document.getElementById("lvMovies").winControl; // Login to Windows Live var scopes = ["wl.signin"]; WL.init({ scope: scopes, redirect_uri: REDIRECT_DOMAIN }); WL.login().then( function(response) { // Get the authentication token var authenticationToken = response.session.authentication_token; // Call the web service var options = { url: WEBSERVICE_URL, headers: { authenticationToken: authenticationToken } }; WinJS.xhr(options).done( function (xhr) { var movies = JSON.parse(xhr.response); var listMovies = new WinJS.Binding.List(movies); lvMovies.itemDataSource = listMovies.dataSource; }, function (xhr) { console.log(xhr.statusText); } ); }, function(response) { throw WinJS.ErrorFromName("Failed to login!"); } ); }); } document.addEventListener("DOMContentLoaded", init); })(); There are two constants which you need to set to get the code above to work: REDIRECT_DOMAIN and WEBSERVICE_URL. The REDIRECT_DOMAIN is the domain that you entered when registering your app with Live. The WEBSERVICE_URL is the path to your web service. You can get the correct value for WEBSERVICE_URL by opening the Project Properties for the MovieApp.Services project, clicking the Web tab, and getting the correct URL. The port number is randomly generated. In my code, I used the URL  “http://localhost:49743/api/movies”. Assuming that the user is logged into Windows 8 with a Live account, when the user runs the MovieApp, the user is logged into Live automatically. The user is logged in with the following code: // Login to Windows Live var scopes = ["wl.signin"]; WL.init({ scope: scopes, redirect_uri: REDIRECT_DOMAIN }); WL.login().then(function(response) { // Do something }); The scopes setting determines what the user has permission to do. For example, access the user’s SkyDrive or access the user’s calendar or contacts. The available scopes are listed here: http://msdn.microsoft.com/en-us/library/live/hh243646.aspx In our case, we only need the wl.signin scope which enables Single Sign-On. After the user signs in, you can retrieve the user’s Live authentication token. The authentication token is passed to the movies service to authenticate the user. Creating the Movies Service The Movies Service is implemented as an API controller in an ASP.NET MVC 4 Web API project. Here’s what the MoviesController looks like: using System.Collections.Generic; using System.Linq; using System.Net; using System.Net.Http; using System.Web.Http; using JWTSample; using MovieApp.Services.Models; namespace MovieApp.Services.Controllers { public class MoviesController : ApiController { const string CLIENT_SECRET = "NtxjF2wu7JeY1unvVN-lb0hoeWOMUFoR"; // GET api/values public HttpResponseMessage Get() { // Authenticate // Get authenticationToken var authenticationToken = Request.Headers.GetValues("authenticationToken").FirstOrDefault(); if (authenticationToken == null) { return new HttpResponseMessage(HttpStatusCode.Unauthorized); } // Validate token var d = new Dictionary<int, string>(); d.Add(0, CLIENT_SECRET); try { var myJWT = new JsonWebToken(authenticationToken, d); } catch { return new HttpResponseMessage(HttpStatusCode.Unauthorized); } // Return results return Request.CreateResponse( HttpStatusCode.OK, new List<Movie> { new Movie {Title="Star Wars", Director="Lucas"}, new Movie {Title="King Kong", Director="Jackson"}, new Movie {Title="Memento", Director="Nolan"} } ); } } } Because the Metro app performs an HTTP GET request, the MovieController Get() action is invoked. This action returns a set of three movies when, and only when, the authentication token is validated. The Movie class looks like this: using Newtonsoft.Json; namespace MovieApp.Services.Models { public class Movie { [JsonProperty(PropertyName="title")] public string Title { get; set; } [JsonProperty(PropertyName="director")] public string Director { get; set; } } } Notice that the Movie class uses the JsonProperty attribute to change Title to title and Director to director to make JavaScript developers happy. The Get() method validates the authentication token before returning the movies to the Metro app. To get authentication to work, you need to provide the client secret which you created at the Live management site. If you forgot to write down the secret, you can get it again here: https://manage.dev.live.com/Applications/Index The client secret is assigned to a constant at the top of the MoviesController class. The MoviesController class uses a helper class named JsonWebToken to validate the authentication token. This class was created by the Windows Live team. You can get the source code for the JsonWebToken class from the following GitHub repository: https://github.com/liveservices/LiveSDK/blob/master/Samples/Asp.net/AuthenticationTokenSample/JsonWebToken.cs You need to add an additional reference to your MVC project to use the JsonWebToken class: System.Runtime.Serialization. You can use the JsonWebToken class to get a unique and validated user ID like this: var user = myJWT.Claims.UserId; If you need to store user specific information then you can use the UserId property to uniquely identify the user making the web service call. Running the MovieApp When you first run the Metro MovieApp, you get a screen which asks whether the app should have permission to use Single Sign-On. This screen never appears again after you give permission once. Actually, when I first ran the app, I get the following error: According to the error, the app is blocked because “We detected some suspicious activity with your Online Id account. To help protect you, we’ve temporarily blocked your account.” This appears to be a bug in the current preview release of the Live SDK and there is more information about this bug here: http://social.msdn.microsoft.com/Forums/en-US/messengerconnect/thread/866c495f-2127-429d-ab07-842ef84f16ae/ If you click continue, and continue running the app, the error message does not appear again.  Summary The goal of this blog entry was to describe how you can validate Metro apps and Metro users when performing a call to a remote web service. First, I explained how you can create a Metro app which takes advantage of Single Sign-On to authenticate the current user against Live automatically. You learned how to register your Metro app with Live and how to include an authentication token in an Ajax call. Next, I explained how you can validate the authentication token – retrieved from the request header – in a web service. I discussed how you can use the JsonWebToken class to validate the authentication token and retrieve the unique user ID.

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