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• Password Cracking Windows Accounts

  - by Kevin

  At work we have laptops with encrypted harddrives. Most developers here (on occasion I have been guilty of it too) leave their laptops in hibernate mode when they take them home at night. Obviously, Windows (i.e. there is a program running in the background which does it for windows) must have a method to unencrypt the data on the drive, or it wouldn't be able to access it. That being said, I always thought that leaving a windows machine on in hibernate mode in a non-secure place (not at work on a lock) is a security threat, because someone could take the machine, leave it running, hack the windows accounts and use it to encrypt the data and steal the information. When I got to thinking about how I would go about breaking into the windows system without restarting it, I couldn't figure out if it was possible. I know it is possible to write a program to crack windows passwords once you have access to the appropriate file(s). But is it possible to execute a program from a locked Windows system that would do this? I don't know of a way to do it, but I am not a Windows expert. If so, is there a way to prevent it? I don't want to expose security vulnerabilities about how to do it, so I would ask that someone wouldn't post the necessary steps in details, but if someone could say something like "Yes, it's possible the USB drive allows arbitrary execution," that would be great! EDIT: The idea being with the encryption is that you can't reboot the system, because once you do, the disk encryption on the system requires a login before being able to start windows. With the machine being in hibernate, the system owner has already bypassed the encryption for the attacker, leaving windows as the only line of defense to protect the data.

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• Grouping consecutive identical items: IEnumerable<T> to IEnumerable<IEnumerable<T>>

  - by Romain Verdier

  I've got an interresting problem: Given an IEnumerable<string>, is it possible to yield a sequence of IEnumerable<string> that groups identical adjacent strings in one pass? Let me explain. Considering the following IEnumerable<string> (pseudo representation): {"a","b","b","b","c","c","d"} How to get an IEnumerable<IEnumerable<string>> that would yield something of the form: { // IEnumerable<IEnumerable<string>> {"a"}, // IEnumerable<string> {"a","b","b"}, // IEnumerable<string> {"c","c"}, // IEnumerable<string> {"d"} // IEnumerable<string> } The method prototype would be: public IEnumerable<IEnumerable<string>> Group(IEnumerable<string> items) { // todo } Important notes : Only one iteration over the original sequence No intermediary collections allocations (we can assume millions of strings in the original sequence, and millions consecutives identicals strings in each group) Keeping enumerators and defered execution behavior Is it possible, and how would you write it?

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• Debugging SQL Server Slowness: Same Database, Different Servers

  - by Craig Walker

  For a while now we've been having anecdotal slowness on our newly-minted (VMWare-based) SQL Server 2005 database servers. Recently the problem has come to a head and I've started looking for the root cause of the issue. Here's the weird part: on the stored procedure that I'm using as a performance test case, I get a 30x difference in the execution speed depending on which DB server I run it on. This is using the same database (mdf) and log (ldf) files, detached, copied, and reattached from the slow server to the fast one. This doesn't appear to be a (virtualized) hardware issue: he slow server has 4x the CPU capacity and 2x the memory as the fast one. As best as I can tell, the problem lies in the environment/configuration of the servers (either operating system or SQL Server installation). However, I've checked a bunch of variables (SQL Server config options, running services, disk fragmentation) and found nothing that has made a difference in testing. What things should I be looking at? What tools can I use to investigate why this is happening?

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• Highlighting a Table Correctly Despite rowspan and colspan attributes - WITHOUT jQuery

  - by ScottSEA

  Thanks to some !#$#@ in another department who wrote some crap code, I am unable to use the jQuery library - despite my fervent desire to do so. Their software has already been released into the world, and I have to be compatible. ============================================ I am trying to highlight a table. Desired behavior: Clicking on a cell in the body highlights the row. Clicking on a cell in the head highlights the column. If a column and row are both highlighted, the intersection is highlighted a different color (super-highlight). Clicking on a previously super-highlighted cell turns off the highlights. This behavior is simple enough to do with a basic table, but when rowspans and colspans start rearing their ugly heads, things start to get a little wonky... highlighting cell[5], for instance, no longer works reliably. My thought, in order to speed execution time of the highlighting itself (by changing a class name), is to pre-calculate the 'offsets' of all cells - with a 'colStart' and 'colEnd', 'rowStart' and 'rowEnd' when the page loads and store that in an array somehow. The question: How would YOU implement this functionality? I am fairly rusty at my JavaScript, awfully rudimentary in my programming skills and would benefit greatly from some guidance. Thanks, Scott.

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• Query Optimizing Request

  - by mithilatw

  I am very sorry if this question is structured in not a very helpful manner or the question itself is not a very good one! I need to update a MSSQL table call component every 10 minutes based on information from another table call materials_progress I have nearly 60000 records in component and more than 10000 records in materials_progress I wrote an update query to do the job, but it takes longer than 4 minutes to complete execution! Here is the query : UPDATE component SET stage_id = CASE WHEN t.required_quantity <= t.total_received THEN 27 WHEN t.total_ordered < t.total_received THEN 18 ELSE 18 END FROM ( SELECT mp.job_id, mp.line_no, mp.component, l.quantity AS line_quantity, CASE WHEN mp.component_name_id = 2 THEN l.quantity*2 ELSE l.quantity END AS required_quantity, SUM(ordered) AS total_ordered, SUM(received) AS total_received , c.component_id FROM line l LEFT JOIN component c ON c.line_id = l.line_id LEFT JOIN materials_progress mp ON l.job_id = mp.job_id AND l.line_no = mp.line_no AND c.component_name_id = mp.component_name_id WHERE mp.job_id IS NOT NULL AND (mp.cancelled IS NULL OR mp.cancelled = 0) AND (mp.manual_override IS NULL OR mp.manual_override = 0) AND c.stage_id = 18 GROUP BY mp.job_id, mp.line_no, mp.component, l.quantity, mp.component_name_id, component_id ) AS t WHERE component.component_id = t.component_id I am not going to explain the scenario as it too complex.. could somebody please please tell me what makes this query this much expensive and a way to get around it? Thank you very very much in advance!!!

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• How to implement reject in parallel approval workflow?

  - by Dmitry Martynov

  I develop a SharePoint workflow with a Replicator activity to replicate a custom activity for every approver. The custom activity implements an approval branch for a particular user. It has classic form with CreateTask, While, OnTaskChanged and CompleteTask activities. I setup UntilCondition on the replicator to cancel execution after one approver chooses to reject the approval and then workflow finishes. The problem happens with other uncompleted tasks which "hang" in their current state. User does not see this state when open the task. I put UpdateAllTasks after the replacator to set the task status to Cancelled. But since there is no event activities between CompleteTask (for the rejected task) and UpdateAllTasks, the UpdateAllTask activity set Cancelled for the rejected task also. The question, what can I do to flush the pending change made by CompleteTask before UpdateAllTasks? Or perhaps, there is another way to implement such workflow. I was thinking about the way to implement Cancel handler for the custom activity with UpdateTask. But I do not know how to implement it and tell to the cancel handler that it executes in the case of the rejection.

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• restart of web dev server every time load ASP.NET MVC application

  - by kjm

  Hi, I continously get this problem (stack trace below) when I start my ASP.NET MVC application and have to restart the web dev server and then it goes away. It appears to be happening on when I make modification in my jquery and then try to restart the application. protected void Application_Start() { InitialiseIocContainer(); RegisterViewEngine(ViewEngines.Engines); RegisterRoutes(RouteTable.Routes); SetupLogging(); } It appears to get caugth on the Application_start in global.asax. I've done lots of search in google but no luck. ITS DRIVING ME BONKERS!!!! can anyone help please Server Error in '/' Application. -------------------------------------------------------------------------------- Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401) Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.IO.FileLoadException: Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401) Source Error: Line 30: RegisterRoutes(RouteTable.Routes); Line 31: SetupLogging(); Line 32: } Line 33: Line 34: private void SetupLogging() Source File: C:\UserData\SourceControl\LLNP4\Trunk\Web\Global.asax.cs Line: 32 Stack Trace: [FileLoadException: Loading this assembly would produce a different grant set from other instances. (Exception from HRESULT: 0x80131401)] LLNP4.MvcApplication.Application_Start() in C:\UserData\SourceControl\LLNP4\Trunk\Web\Global.asax.cs:32

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• while(1) block my recv thread

  - by zp26

  Hello. I have a problem with this code. As you can see a launch with an internal thread recv so that the program is blocked pending a given but will continue its execution, leaving the task to lock the thread. My program would continue to receive the recv data socket new_sd and so I entered an infinite loop (the commented code). The problem is that by entering the while (1) my program block before recv, but not inserting it correctly receives a string, but after that stop. Someone could help me make my recv always waiting for information? Thanks in advance for your help. -(IBAction)Chat{ [NSThread detachNewThreadSelector:@selector(riceviDatiServer) toTarget:self withObject:nil]; } -(void)riceviDatiServer{ NSAutoreleasePool *pool = [[NSAutoreleasePool alloc]init]; labelRicevuti.text = [[NSString alloc] initWithFormat:@"In attesa di ricevere i dati"]; char datiRicevuti[500]; int ricevuti; //while(1){ ricevuti = recv(new_sd, &datiRicevuti, 500, 0); labelRicevuti.text = [[NSString alloc] initWithFormat:@"%s", datiRicevuti]; //} [pool release]; }

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• Will fixed-point arithmetic be worth my trouble?

  - by Thomas

  I'm working on a fluid dynamics Navier-Stokes solver that should run in real time. Hence, performance is important. Right now, I'm looking at a number of tight loops that each account for a significant fraction of the execution time: there is no single bottleneck. Most of these loops do some floating-point arithmetic, but there's a lot of branching in between. The floating-point operations are mostly limited to additions, subtractions, multiplications, divisions and comparisons. All this is done using 32-bit floats. My target platform is x86 with at least SSE1 instructions. (I've verified in the assembler output that the compiler indeed generates SSE instructions.) Most of the floating-point values that I'm working with have a reasonably small upper bound, and precision for near-zero values isn't very important. So the thought occurred to me: maybe switching to fixed-point arithmetic could speed things up? I know the only way to be really sure is to measure it, that might take days, so I'd like to know the odds of success beforehand. Fixed-point was all the rage back in the days of Doom, but I'm not sure where it stands anno 2010. Considering how much silicon is nowadays pumped into floating-point performance, is there a chance that fixed-point arithmetic will still give me a significant speed boost? Does anyone have any real-world experience that may apply to my situation?

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• How do you handle key down events on Android? I am having issues making it work.

  - by user279112

  For an Android program, I am having trouble handling key down and key up events, and the problem I am having with them can almost certainly be generalized to any sort of user input event. I am using Lunar Lander as one of my main learning devices as I make my first meaningful program, and I noticed that it was using onKeyDown as an overridden method to receive key down events, and it would call one of their more original methods doKeyDown. But when I tried to implement a very small version of my own onKeyDown overide and the actual handler that it calls, it didn't work. I would probably copy and paste my implementations of those two methods, but that doesn't seem to be the problem. You see, I ran the debugger and noticed that they were not getting called - at all. The same goes for my implementations of onKeyUp and the handler that it calls. Something is a little weird here, and when I tried to look at the Android documentation for it, that didn't help at all. I thought that if you had an overide for onKeyDown, then when a key was pressed during execution of the program, onKeyDown would be called as soon as reasonably possible. End of story. But apparently there's something more to it. Apparently you have to do something else somewhere - possibly in the XML when defining the layout or something - to make it work. But I do not know what, and I could not find what in their documentation. What's the secret to this? Thanks!

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• Intercepting method with Spring AOP using only annotations

  - by fish

  In my Spring context file I have something like this: <bean id="userCheck" class="a.b.c.UserExistsCheck"/> <aop:config> <aop:aspect ref="userCheck"> <aop:pointcut id="checkUser" expression="execution(* a.b.c.d.*.*(..)) &amp;&amp; args(a.b.c.d.RequestObject)"/> <aop:around pointcut-ref="checkUser" method="checkUser"/> </aop:aspect> </aop:config> a.b.c.UserExistsCheck looks like this: @Aspect public class UserExistsCheck { @Autowired private UserInformation userInformation; public Object checkUser(ProceedingJoinPoint pjp) throws Throwable { int userId = ... //get it from the RequestObject passed as a parameter if (userExists(userId)) { return pjp.proceed(); } else { return new ResponseObject("Invalid user); } } And the class that is being intercepted with this stuff looks like this: public class Klazz { public ResponseObject doSomething(RequestObject request) {...} } This works. UserExistCheck is executed as desired before the call is passed to Klazz. The problem is that this is the only way I got it working. To get this working by using annotations instead of the context file seems to be just too much for my small brain. So... how exactly should I annotate the methods in UserExistsCheck and Klazz? And do I still need something else too? Another class? Still something in the context file?

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• How to debug browser crash when running Silverlight app

  - by onedozenbagels

  I am on a team of three people who are developing a Silverlight application. On two of our developers' machines the app seems to randomly crash. It never crashes on the third developer's machine. The nature of the crash is that internet explorer just dies with an "Internet Explorer has stopped working" message. The problem details look like this: Problem Event Name: BEX Application Name: IEXPLORE.EXE Application Version: 8.0.6001.18882 Application Timestamp: 4b3ed243 Fault Module Name: StackHash_2cd8 Fault Module Version: 0.0.0.0 Fault Module Timestamp: 00000000 Exception Offset: 0024df00 Exception Code: c0000005 Exception Data: 00000008 OS Version: 6.0.6002.2.2.0.256.6 Locale ID: 1033 Additional Information 1: 2cd8 Additional Information 2: 0c337fa6c2057a9dbce1860c5e2d8315 Additional Information 3: e13b Additional Information 4: 5da012709e52526a1af19795dc4a33fd Then windows displays this message: "To help protect your computer, Data Execution Prevention has closed Internet Explorer." If I am attached to the app with the Visual Studio debugger the only information I get is this line in the output window: "The program '[2140] iexplore.exe: Silverlight' has exited with code -1073741819 (0xc0000005)." How should I go about debugging this problem? I'm not really sure where to start.

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• SSIS package not picking up configuration files correctly

  - by blntechie

  We have recently migrated some 30 DTS packages in SQL Server 2000 to SSIS packages in SQL Server 2008. We have created packages in such a way that all environment related variables and other required information are picked from configuration files for maintenance of packages across different environments like Dev, QA and Prod. After setting up all the packages with the config files, when we tested the packages from Business Intelligence Development Studio, it worked fine and picked up the values from the configuration file. And when changing the values in config files to Dev or other env it correctly picked up the values and executed. Similarly, tried for 2 different environments and the packages worked fine. So we deployed to Prod and it was working fine. Yesterday, I had to make a functional change for one package and so I made the change in the package (it is just changing a parameter in a SQL procedure execution task and not related to any variables) and tested in BIDS with 2 environments and it worked fine. As the change was not related to any environment change, we deployed only the updated package (not the associated config file) manually in Prod (i.e without the use of manifest). The config file which was used by the package previously and working fine in Prod remained unaltered. But when the package was executed, the package was pointing to QA and the package didn't read from the config file I believe. One reason may be, it is still using the last executed values which remains in the .dtsx file(can be checked by opening the file in a text editor) usually. But normally, when a package is executed, the values will be overwritten from config file. Guess it is not happening. What are the possible reasons for this? We have tested extensively switching between test environments and it does not show this behavior. We have encountered this in Prod environment twice now. Anyone else have experienced this and how have you resolved this?

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• GAE Task Queue oddness

  - by b3nw

  I have been testing the taskqueue with mixed success. Currently I am using the default queue, in default settings ect ect.... I have a test url setup which inserts about 8 tasks into the queue. With short order, all 8 are completed properly. So far so good. The problem comes up when I re-load that url twice under say a minute. Now watching the task queue, all the tasks are added properly, but only the first batch execute it seems. But the "Run in Last Minute" # shows the right number of tasks being run.... The request logs tell a different story. They show only the first set of 8 running, but all task creation urls working successfully. The oddness of this is that if I wait say a minute between the task creation url requests, it will work fine. Oddly enough changing the bucket_size or execution speed does not seem to help. Only the first batch are executed. I have also reduced the number of requests all the way down to 2, and still found only the first 2 execute. Any others added display the same issues as above. Any suggestions? Thanks

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• Time to start returning IQueryable<T> instead of IList<T> to my Web UI / Web API Layer?

  - by JohnnyO

  I've got a multi-layer application that starts with the repository pattern for all data access and it returns IQueryable to the Services layer. The Services layer, which includes all of the business logic, returns IList to the Controllers (note: I'm using ASP.NET MVC for the UI layer). The benefit of returning IQueryable in the data access layer is that it allows my repositories to be extremely simple and the database queries to be deferred. However, I'm triggering the database queries in my services layer so that my unit tests is more reliable and I don't give flexibility to the Controllers to reshape my queries. However, I've recently encountered several situations where deferring the execution of queries down to the Controllers would have been significantly more performant because the Controllers had to do some projections on the data that was UI specific. Additionally, with the emergence of things like oData, I was starting to wonder if end points (e.g. web UI or web apis) should be working directly with IQueryable. What are your thoughts? Is it time to start returning IQueryable from the services layer to the UI layer? Or stick with IList? This thread here: http://stackoverflow.com/questions/718624/to-return-iqueryablet-or-not-return-iqueryablet seems to vouch for returning IList to the UI layers, but I was wondering if things are changing because of new emerging technologies and techniques.

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• Some general C questions.

  - by b-gen-jack-o-neill

  Hello. I am trying to fully understand the process pro writing code in some language to execution by OS. In my case, the language would be C and the OS would be Windows. So far, I read many different articles, but I am not sure, whether I understand the process right, and I would like to ask you if you know some good articles on some subjects I couldn´t find. So, what I think I know about C (and basically other languages): C compiler itself handles only data types, basic math operations, pointers operations, and work with functions. By work with functions I mean how to pass argument to it, and how to get output from function. During compilation, function call is replaced by passing arguments to stack, and than if function is not inline, its call is replaced by some symbol for linker. Linker than find the function definition, and replace the symbol to jump adress to that function (and of course than jump back to program). If the above is generally true and I get it right, where to final .exe file actually linker saves the functions? After the main() function? And what creates the .exe header? Compiler or Linker? Now, additional capabilities of C, today known as C standart library is set of functions and the declarations of them, that other programmers wrote to extend and simplify use of C language. But these functions like printf() were (or could be?) written in different language, or assembler. And there comes my next question, can be, for example printf() function be written in pure C without use of assembler? I know this is quite big question, but I just mostly want to know, wheather I am right or not. And trust me, I read a lots of articles on the web, and I would not ask you, If I could find these infromation together on one place, in one article. Insted I must piece by piece gather informations, so I am not sure if I am right. Thanks.

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• Error executing child request for handler in plugin

  - by user1348351

  I'm using nop commerce open source. I wanted to show the recently add products in home page. so what I did is I activated plugin Nop JCarousel in the admin panel. But if I select "Recently view product" as a Data source type it is working fine.But if I select "recently add product" Data source type there is error coming up. it says Server Error in '/' Application. Method not found: 'Nop.Core.IPagedList`1<Nop.Core.Domain.Catalog.Product> Nop.Services.Catalog.IProductService.SearchProducts(Int32, Int32, System.Nullable`1<Boolean>, System.Nullable`1<System.Decimal>, System.Nullable`1<System.Decimal>, Int32, System.String, Boolean, Int32, System.Collections.Generic.IList`1<Int32>, Nop.Core.Domain.Catalog.ProductSortingEnum, Int32, Int32, Boolean, System.Collections.Generic.IList`1<Int32> ByRef, Boolean)'. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.MissingMethodException: Method not found: 'Nop.Core.IPagedList`1<Nop.Core.Domain.Catalog.Product> Nop.Services.Catalog.IProductService.SearchProducts(Int32, Int32, System.Nullable`1<Boolean>, System.Nullable`1<System.Decimal>, System.Nullable`1<System.Decimal>, Int32, System.String, Boolean, Int32, System.Collections.Generic.IList`1<Int32>, Nop.Core.Domain.Catalog.ProductSortingEnum, Int32, Int32, Boolean, System.Collections.Generic.IList`1<Int32> ByRef, Boolean)'. Source Error: Line 3: @foreach (var widget in Model) Line 4: { Line 5: @Html.Action(widget.ActionName, widget.ControllerName, widget.RouteValues) Line 6: } Any idea on how to solve this?

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• How to reliably send a request cross domain and cross browser on page unload

  - by Agmin

  I have javascript code that's loaded by 3rd parties. The javascript keeps track of a number of metrics, and when a user exits the page I'd like to send the metrics back to my server. Due to XSS checks in some browsers, like IE, I cannot do a simple jquery.ajax() call. Instead, I'm appending an image src to the page with jquery. Here's the code, cased by browser: function record_metrics() { //Arbitrary code execution here to set test_url $esajquery('#MainDiv').append("<img src='" + test_url + "' />"); } if ($esajquery.browser.msie) { window.onbeforeunload = function() { record_metrics(); } } else { $esajquery(window).unload( function(){ record_metrics(); } ); } FF aborts the request to "test_url" if I use window.onbeforeunload, and IE8 doesn't work with jquery's unload(). IE8 also fails to work if the arbitrary test_url setting code is too long, although IE8 seems to work fine if the is immediately appended to the DOM. Is there a better way to solve this issue? Unfortunately this really needs to execute when a user leaves the page.

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• function's return address is different from its supposed value, buffer overflow,

  - by ultrajohn

  Good day everyone! I’m trying to understand how buffer overflow works. I’m doing this for my project in a computer security course I’m taking. Right now, I’m in the process of determining the address of the function’s return address which I’m supposed to change to perform a buffer overflow attack. I’ve written a simple program based from an example I’ve read in the internet. What this program does is it creates an integer pointer that will be made to point to the address of the function return address in the stack. To do this, (granted I understand how a function/program variables get organized in the stack), I add 8 to the buffer variable’ address and set it as the value of ret. I’m not doing anything here that would change the address contained in the location of func’s return address. here's the program: Output of the program when gets excecuted: As you can see, I’m printing the address of the variables buffer and ret. I’ve added an additional statement printing the value of the ret variable (supposed location of func return address, so this should print the address of the next instruction which will get executed after func returns from execution). Here is the dump which shows the supposed address of the instruction to be executed after func returns. (Underlined in green) As you can see, that value is way different from the value printed contained in the variable ret. My question is, why are they different? (of course in the assumption that what I’ve done are all right). Else, what have I done wrong? Is my understanding of the program’s runtime stack wrong? Please, help me understand this. My project is due nextweek and I’ve barely touched it yet. I’m sorry if I’m being demanding, I badly need your help.

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• Episerver Scheduled Job fails (scheduler service)

  - by Igor

  Our scheduled jobs started failing since yesterday with the following error message: CustomUpdate.Execute - System.NullReferenceException: Object reference not set to an instance of an object. at System.Web.Security.Roles.GetRolesForUser(String username) at EPiServer.Security.PrincipalInfo.CreatePrincipal(String username) The scheduled job uses anonymous execution and logs in programmatically using the following call: if (PrincipalInfo.CurrentPrincipal.Identity.Name == string.Empty) { PrincipalInfo.CurrentPrincipal = PrincipalInfo.CreatePrincipal(ApplicationSettings.ScheduledJobUsername); } I have put in some more logging around PrincipalInfo.CreatePrincipal call which is in Episerver.Security and noticed that PrincipalInfo.CreatePrincipal calls System.Web.Security.Roles.GetRolesForUser(username) and Roles.GetRolesForUser(username) returns an empty string array. There were no changes code wise or on the server (updates, etc). I checked that the user name used to run the task is in the database and has roles associated with it. I checked that applicationname is set up correctly and is associated with the user If i run the job manually using the same user it executes with no issues (i know there is a difference between running the job manually and using the scheduler) I also tried creating a new user, that didn’t work either. Has anyone come across the same or similar issue? Any thoughts how to resolve this issue?

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• singleton pattern in Windows Activation Service

  - by Joshua

  Hello I have a few WCF services that are currently being self hosted, in a very basic NT Service. I want to expand my application to add provisioning of WCF Services, and updates, as well as isolation (I want each WCF Service to be in its own AppDomain). These WCF Services contain logic that needs to be run on a regular basis, pinging the database, and getting information from external devices so that when a request comes in the data is readily available. I'm thinking about trying out Windows Activation Service, because i really like the provisioning, and isolation that comes with a managed services infrastructure. If I didn't use WAS I would essentially have to write the same code myself. From what I understand though WAS does not really support the model of having a service that is running before someone actually calls a method on the service. the article I read here MSDN Article Link states "That means in essence that out-of-the-box WAS hosting is not something that is really suited for sessionful or singleton services. It is more suitable for stateless per-call services." it does say that "Out of the box" so I'm wondering if anyone has used WAS to host a WCF service that really behaves more like an NT Service (starting and stopping independantly of having a method called upon it). Or any other ideas would be great. I was planning on writting this infrastructure myself, to host WCF services in a custom ServiceHost, and put their execution in a seporate AppDomain, as well as allow for provision of these services after initial installation, along with updates. However, I would MUCH MUCH MUCH rather not own that code if I don't have to. thanks Joshua

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• EF 4.0 : Save Changes Retry Logic

  - by BGR

  Hi, I would like to implement an application wide retry system for all entity SaveChanges method calls. Technologies: Entity framework 4.0 .Net 4.0 namespace Sample.Data.Store.Entities { public partial class StoreDB { public override int SaveChanges(System.Data.Objects.SaveOptions options) { for (Int32 attempt = 1; ; ) { try { return base.SaveChanges(options); } catch (SqlException sqlException) { // Increment Trys attempt++; // Find Maximum Trys Int32 maxRetryCount = 5; // Throw Error if we have reach the maximum number of retries if (attempt == maxRetryCount) throw; // Determine if we should retry or abort. if (!RetryLitmus(sqlException)) throw; else Thread.Sleep(ConnectionRetryWaitSeconds(attempt)); } } } static Int32 ConnectionRetryWaitSeconds(Int32 attempt) { Int32 connectionRetryWaitSeconds = 2000; // Backoff Throttling connectionRetryWaitSeconds = connectionRetryWaitSeconds * (Int32)Math.Pow(2, attempt); return (connectionRetryWaitSeconds); } /// <summary> /// Determine from the exception if the execution /// of the connection should Be attempted again /// </summary> /// <param name="exception">Generic Exception</param> /// <returns>True if a a retry is needed, false if not</returns> static Boolean RetryLitmus(SqlException sqlException) { switch (sqlException.Number) { // The service has encountered an error // processing your request. Please try again. // Error code %d. case 40197: // The service is currently busy. Retry // the request after 10 seconds. Code: %d. case 40501: //A transport-level error has occurred when // receiving results from the server. (provider: // TCP Provider, error: 0 - An established connection // was aborted by the software in your host machine.) case 10053: return (true); } return (false); } } } The problem: How can I run the StoreDB.SaveChanges to retry on a new DB context after an error occured? Something simular to Detach/Attach might come in handy. Thanks in advance! Bart

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• Locking a table for getting MAX in LINQ

  - by Hossein Margani

  Hi Every one! I have a query in LINQ, I want to get MAX of Code of my table and increase it and insert new record with new Code. just like the IDENTITY feature of SQL Server, but here my Code column is char(5) where can be alphabets and numeric. My problem is when inserting a new row, two concurrent processes get max and insert an equal Code to the record. my command is: var maxCode = db.Customers.Select(c=>c.Code).Max(); var anotherCustomer = db.Customers.Where(...).SingleOrDefault(); anotherCustomer.Code = GenerateNextCode(maxCode); db.SubmitChanges(); I ran this command cross 1000 threads and each updating 200 customers, and used a Transaction with IsolationLevel.Serializable, after two or three execution an error occured: using (var db = new DBModelDataContext()) { DbTransaction tran = null; try { db.Connection.Open(); tran = db.Connection.BeginTransaction(IsolationLevel.Serializable); db.Transaction = tran; . . . . tran.Commit(); } catch { tran.Rollback(); } finally { db.Connection.Close(); } } error: Transaction (Process ID 60) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. other IsolationLevels generates this error: Row not found or changed. Please help me, thank you.

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• Change made in the Converter will notify the change in the bound property?

  - by Kishore Kumar

  I have two property FirstName and LastName and bound to a textblock using Multibinidng and converter to display the FullName as FirstName + Last Name. FirstName="Kishore" LastName="Kumar" In the Converter I changed the LastName as "Changed Text" values[1] = "Changed Text"; After executing the Converter my TextBlock will show "Kishore Changed Text" but Dependency property LastName is still have the last value "Kumar". Why I am not getting the "Changed Text" value in the LastName property after the execution?. Will the change made at converter will notify the bound property? <Window.Resources> <local:NameConverter x:Key="NameConverter"></local:NameConverter> </Window.Resources> <Grid> <TextBlock> <TextBlock.Text> <MultiBinding Converter="{StaticResource NameConverter}"> <Binding Path="FirstName"></Binding> <Binding Path="LastName"></Binding> </MultiBinding> </TextBlock.Text> </TextBlock> </Grid> Converter: public class NameConverter:IMultiValueConverter { #region IMultiValueConverter Members public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture) { values[1] = "Changed Text"; return values[0].ToString() + " " + values[1].ToString(); } public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture) { throw new NotImplementedException(); } #endregion }

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• SQL Server CLR stored procedures in data processing tasks - good or evil?

  - by Gart

  In short - is it a good design solution to implement most of the business logic in CLR stored procedures? I have read much about them recently but I can't figure out when they should be used, what are the best practices, are they good enough or not. For example, my business application needs to parse a large fixed-length text file, extract some numbers from each line in the file, according to these numbers apply some complex business rules (involving regex matching, pattern matching against data from many tables in the database and such), and as a result of this calculation update records in the database. There is also a GUI for the user to select the file, view the results, etc. This application seems to be a good candidate to implement the classic 3-tier architecture: the Data Layer, the Logic Layer, and the GUI layer. The Data Layer would access the database The Logic Layer would run as a WCF service and implement the business rules, interacting with the Data Layer The GUI Layer would be a means of communication between the Logic Layer and the User. Now, thinking of this design, I can see that most of the business rules may be implemented in a SQL CLR and stored in SQL Server. I might store all my raw data in the database, run the processing there, and get the results. I see some advantages and disadvantages of this solution: Pros: The business logic runs close to the data, meaning less network traffic. Process all data at once, possibly utilizing parallelizm and optimal execution plan. Cons: Scattering of the business logic: some part is here, some part is there. Questionable design solution, may encounter unknown problems. Difficult to implement a progress indicator for the processing task. I would like to hear all your opinions about SQL CLR. Does anybody use it in production? Are there any problems with such design? Is it a good thing?

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