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• "Unable To Load Client Print Control" - SSRS Printing problems again

  - by mamorgan1

  Please forgive me as my head is spinning. I have tried so many solutions to this issue, that I'm almost not sure where I am at this point. At this point in time I have these issues in my Production, Test, and Dev environments. For simplicity sake, I will just try to get it working in Dev first. Here is my setup: Database/Reporting Server (Same server): Windows Server 2003 SP2 SQL Server 2005 SP3 Development Box: Windows 7 Visual Studio 2008 SP1 SQL Server 2008 SP1 (not being used in this case, but wanted to include it in case it is relative) Internet Explorer 8 Details: * I have a custom ASP.NET application that is using ReportViewer to access reports on my Database/Reporting Server. * I am able to connect directly to Report Manager and print with no trouble. * When I view source on the page with ReportViewer, it says I'm am using version 9.0.30729.4402 . * The classid of the rsclientprint.dll that keeps getting installed to my c:\windows\downloaded program files directory is {41861299-EAB2-4DCC-986C-802AE12AC499}. * I have tried taking the rsclientprint.cab file from my Database/Reporting Server and installing it directly to my Development Box and had no success. I made sure to unregister the previously installed dll first. I feel like I have read as many solutions as I can, and so I turn to you for some assistance. Please let me know if I can provide further details that would be helpful. Thanks

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• Is there a perfect algorithm for chess?

  - by Overflown

  Dear Stack Overflow community, I was recently in a discussion with a non-coder person on the possibilities of chess computers. I'm not well versed in theory, but think I know enough. I argued that there could not exist a deterministic Turing machine that always won or stalemated at chess. I think that, even if you search the entire space of all combinations of player1/2 moves, the single move that the computer decides upon at each step is based on a heuristic. Being based on a heuristic, it does not necessarily beat ALL of the moves that the opponent could do. My friend thought, to the contrary, that a computer would always win or tie if it never made a "mistake" move (however do you define that?). However, being a programmer who has taken CS, I know that even your good choices - given a wise opponent - can force you to make "mistake" moves in the end. Even if you know everything, your next move is greedy in matching a heuristic. Most chess computers try to match a possible end game to the game in progress, which is essentially a dynamic programming traceback. Again, the endgame in question is avoidable though. -- thanks, Allan Edit: Hmm... looks like I ruffled some feathers here. That's good. Thinking about it again, it seems like there is no theoretical problem with solving a finite game like chess. I would argue that chess is a bit more complicated than checkers in that a win is not necessarily by numerical exhaustion of pieces, but by a mate. My original assertion is probably wrong, but then again I think I've pointed out something that is not yet satisfactorily proven (formally). I guess my thought experiment was that whenever a branch in the tree is taken, then the algorithm (or memorized paths) must find a path to a mate (without getting mated) for any possible branch on the opponent moves. After the discussion, I will buy that given more memory than we can possibly dream of, all these paths could be found.

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• dotRAS Disconnected State not triggered

  - by JD

  Can someone give me a heads up... I'm trying to use the dotRAS .NET control, and this code to change the value of internetConnected (boolean) using an event handler... But it seems that the state RasConnectionState.Disconnected is not triggered by dotRAS hangup().. Any ideas? Am I doing it totally wrong... or have I managed to find a bug? public class USBModem { // private vars private RasDialer dialer = new RasDialer(); private bool internetConnected = false; /// <summary> /// Default constructor for USBModem /// </summary> public USBModem() { // Add Events for dialer dialer.StateChanged += new EventHandler<StateChangedEventArgs>(dialer_StateChanged); } void dialer_StateChanged(object sender, StateChangedEventArgs e) { // Handle state changes here switch (e.State) { case RasConnectionState.Connected: internetConnected = true; Console.WriteLine(e.State.ToString()); break; case RasConnectionState.Disconnected: internetConnected = false; Console.WriteLine(e.State.ToString()); break; default: Console.WriteLine("INFO -> Unhandled state: " + e.State.ToString()); break; } } public void ConnectInternet(string connectionName) { // Dial dialer.PhoneBookPath = RasPhoneBook.GetPhoneBookPath(RasPhoneBookType.AllUsers); dialer.EntryName = connectionName; dialer.DialAsync(); } public void DisconnectInternet() { foreach (RasConnection connection in dialer.GetActiveConnections()) { connection.HangUp(); } } }

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• LinearLayout not expanding inside a ScrollView

  - by Felix

  I have a LinearLayout inside a ScrollView that has android:layout_height="fill_parent", but it doesn't expand to the full height of the ScrollView. My layout looks something like: level layout layout_width layout_height 1 LinearLayout fill_parent fill_parent 2 LinearLayout fill_parent wrap_content 3 (some irrelevant stuff) 2 ScrollView fill_parent fill_parent <-- this expands full height 3 LinearLayout fill_parent fill_parent <-- this does not (has orientation=vertical) (following stuff probably are irrelevant, but just to be sure:) 4 TextView fill_parent fill_parent 4 LinearLayout fill_parent wrap_content I can see that the LinearLayout doesn't expand the full height of the ScrollView because in Eclipse in Android Layout Editor, if I select the ScrollView (in the Outline panel) it is highlighted with a red border that fills the screen to the bottom but when I select the LinearLayout its highlight doesn't expand to the bottom of the screen. How can I get it to do so? The effect I'm trying to achieve is to have some text and a button below it (inside the LinearLayout in level 4 there's just a button). The text can be big enough to need a scrollbar, in which case I want the user to have to scroll down in order to see the button. In case the text is not big enough for a scroll bar, I want the LinearLayout containing the button to stick to the bottom of the screen.

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• InvalidOperationException (Lambda parameter not in scope) when trying to Compile a Lambda Expression

  - by Moshe Levi

  Hello, I'm writing an Expression Parser to make my API more refactor friendly and less error prone. basicaly, I want the user to write code like that: repository.Get(entity => entity.Id == 10); instead of: repository.Get<Entity>("Id", 10); Extracting the member name from the left side of the binary expression was straight forward. The problems began when I tried to extract the value from the right side of the expression. The above snippet demonstrates the simplest possible case which involves a constant value but it can be much more complex involving closures and what not. After playing with that for some time I gave up on trying to cover all the possible cases myself and decided to use the framework to do all the heavy lifting for me by compiling and executing the right side of the expression. the relevant part of the code looks like that: public static KeyValuePair<string, object> Parse<T>(Expression<Func<T, bool>> expression) { var binaryExpression = (BinaryExpression)expression.Body; string memberName = ParseMemberName(binaryExpression.Left); object value = ParseValue(binaryExpression.Right); return new KeyValuePair<string, object>(memberName, value); } private static object ParseValue(Expression expression) { Expression conversionExpression = Expression.Convert(expression, typeof(object)); var lambdaExpression = Expression.Lambda<Func<object>>(conversionExpression); Func<object> accessor = lambdaExpression.Compile(); return accessor(); } Now, I get an InvalidOperationException (Lambda parameter not in scope) in the Compile line. when I googled for the solution I came up with similar questions that involved building an expression by hand and not supplying all the pieces, or trying to rely on parameters having the same name and not the same reference. I don't think that this is the case here because I'm reusing the given expression. I would appreciate if someone will give me some pointers on this. Thank you.

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• Writing tests for Rails plugins

  - by Adam

  I'm working on a plugin for Rails that would add limited in-memory caching to ActiveRecord's finders. The functionality itself is mature enough, but I can't for the life of me get unit tests to work with the plugin. I now have under vendor/plugins/my_plugin/test/my_plugin_test.rb a standard subclass of ActiveSupport::TestCase with a couple of basic tests. I try running 'rake test' from the plugin directory, and I have confirmed that this task loads the ruby file with the test case, but it doesn't actually run any of the tests. I followed the Rails plugin guide (http://guides.rubyonrails.org/plugins.html) where applicable, but it seems to be horribly outdated (it suggests things that Rails now do automatically, etc.) The only output I get is this: Kakadu:ingenious_record adam$ rake test (in /Users/adam/Sites/1_PRK/vendor/plugins/ingenious_record) /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby -Ilib:lib:test "/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/gems/1.8/gems/rake-0.8.3/lib/rake/rake_test_loader.rb" "test/ingenious_record_test.rb" The simplest test case looks like this: require 'test_helper' require 'active_record' class IngeniousRecordTest < ActiveSupport::TestCase test "example" do assert false end end This should definitely produce at least some output, and the only test in that file should produce a failed assertion. Any ideas what I could do to get Rails to run my tests?

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• Android Activity is displayed after user unlocks the screen

  - by Dave

  Hi, I was wondering if anyone understood how to make your application be displayed when you unlock the screen. I have an application where the user turns on a Bluetooth device, it connects to the phone, and the user should be presented with a UI. Having them hunt for the app or using the notification menu is not a workable option (too much work and not the obvious behavior). The problem is that: When the screen is unlocked: - you can popup the activity from the background service when Bluetooth connects to a device - User is happy because the UI is right there When the screen is locked: - The application gets started but is destroyed - User unlocks the phone and nothing is there but the homescreen One work around would be to disable the keyguard when the application gets woken up but the nuclear option is a pretty bad option. PS: I know the standard Android assumption is that you shouldn't do this. In the normal case this behavior is fine, but in this case I explicitly did something I want the phone to respond without adding more work for the user to do. As per Google's guidelines if you don't like this behavior there can be an option for you to turn this off or you can not use the application.

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• How does the recursion here work?

  - by David

  code 1: public static int fibonacci (int n){ if (n == 0 || n == 1) { return 1; } else { return fibonacci (n-1) + fibonacci (n-2); } } how can you use fibonacci if you haven't gotten done explaining what it is yet? I've been able to understand using recursion in other cases like this: code two: class two { public static void two (int n) { if (n>0) { System.out.println (n) ; two (n-1) ; } else { return ; } } public static void main (String[] arg) { two (12) ; } } In the case of code 2 though n will eventualy reach a point at which it doesnt satisfy n0 and the method will stop calling itself recursivly. in the case of code 2 though i don't see how it would be able to get itself from 1 if n=1 was the starting point to 2 and 3 and 5 and so on. Also i don't see how the line `return fibonacci (n-1) + fibonacci (n-2) would work since fibbonacci n-2 has to contain in some sense fibonacci n-1 in order to wrok but it isn't there yet. I know my question is worded poorly but looking at this is making my mind explode. the book i'm looking at says it will work. how does it work? `

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• Join 3 tables in 1 LINQ-EF

  - by user100161

  I have to fill warehouse table cOrders with program using Ado.NET EF. I have SQL command but i don't know how to do this with LINQ. static void Main(string[] args) { var SPcontex = new PI_NorthwindSPEntities(); var contex = new NorthwindEntities(); dCustomers dimenzijaCustomers = new dCustomers(); dDatum dimenzijaDatum = new dDatum(); ... CREATE TABLE PoslovnaInteligencija.dbo.cOrders( cOrdersID int PRIMARY KEY IDENTITY(1,1), OrderID int NOT NULL, dCustomersID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dCustomers(dCustomersID), dEmployeesID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dEmployees(dEmployeesID), OrderDateID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dDatum(sifDatum), RequiredDateID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dDatum(sifDatum), ShippedDateID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dDatum(sifDatum), dShippersID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dShippers(dShippersID), dShipID int FOREIGN KEY REFERENCES PoslovnaInteligencija.dbo.dShip(dShipID), Freight money, WaitingDay int ) INSERT INTO PoslovnaInteligencija.dbo.cOrders (OrderID, dCustomersID, dEmployeesID, OrderDateID, RequiredDateID, dShippersID, dShipID, Freight, ShippedDateID, WaitingDay) SELECT OrderID, dc.dCustomersID, de.dEmployeesID, orderD.sifDatum, requiredD.sifDatum, dShippersID, ds.dShipID, Freight, ShippedDateID=CASE WHEN (ShippedDate IS NULL) THEN -1 ELSE shippedD.sifDatum END, WaitingDay=CASE WHEN (shippedD.sifDatum - orderD.sifDatum) IS NULL THEN -1 ELSE shippedD.sifDatum - orderD.sifDatum END FROM PoslovnaInteligencija.dbo.dShippers AS s, PoslovnaInteligencija.dbo.dCustomers AS dc, PoslovnaInteligencija.dbo.dEmployees AS de, PoslovnaInteligencija.dbo.dShip AS ds,PoslovnaInteligencija.dbo.dDatum AS orderD, PoslovnaInteligencija.dbo.dDatum AS requiredD, PoslovnaInteligencija.dbo.Orders AS o LEFT OUTER JOIN PoslovnaInteligencija.dbo.dDatum AS shippedD ON shippedD.datum=DATEADD(dd, 0, DATEDIFF(dd, 0, o.ShippedDate)) WHERE o.ShipVia=s.ShipperID AND dc.CustomerID=o.CustomerID AND de.EmployeeID=o.EmployeeID AND ds.ShipName=o.ShipName AND orderD.datum=DATEADD(dd, 0, DATEDIFF(dd, 0, o.OrderDate)) AND requiredD.datum=DATEADD(dd, 0, DATEDIFF(dd, 0, o.RequiredDate));

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• Fix common library functions, or abandon then?

  - by Ian Boyd

  Imagine i have a function with a bug in it: Boolean MakeLocation(String City, String State) { //Given "Springfield", "MO" //return "Springfield, MO" return City+", "+State; } So the call: MakeLocation("Springfield", "MO"); would return "Springfield, MO" Now there's a slight problem, what if the user called: MakeLocation("Springfield, MO", "OH"); The called it wrong, obviously. But the function would return "Springfield, MO, OH". The system was functioning like this for many years, until i noticed the function being used wrong, and i corrected it. And i also updated the original function to catch such an obvious mistake - in case it's happening elsewhere: Boolean MakeLocation(String City, String State) { //Given "Springfield", "MO" //return "Springfield, MO" if (City.Contains, ",") throw new EMakeLocationException("City name contains a comma. You probably didn't mean that"); return City+", "+State; } And testing showed the problem fixed. Except we missed an edge case, and the customer found it. So now the moral dillema. Do you ever add new sanity checks, safety checks, assertions to exising code? Or do you call the old function abandoned, and have a new one: Boolean MakeLocation(String City, String State) { //Given "Springfield", "MO" //return "Springfield, MO" return City+", "+State; } Boolean MakeLocation2(String City, String State) { //Given "Springfield", "MO" //return "Springfield, MO" if (City.Contains, ",") throw new EMakeLocationException("City name contains a comma. You probably didn't mean that"); return City+", "+State; } The same can apply for anything: Question FetchQuestion(Int id) { if (id == 0) throw new EFetchQuestionException("No question ID specified"); ... } Do you risk breaking existing code, at the expense of existing code being wrong?

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• Ruby on rails generates tests for you. Do those give a false sense of a safety net?

  - by Hamish Grubijan

  Disclaimer: I have not used RoR, and I have not generated tests. But, I will still dare to post this question. Quality Assurance is theoretically impossible to get 100% right in general (Undecidable problem ;), and it is hard in practice. So many developers do not understand that writing good automated tests is an art, and it is hard. When I hear that RoR generates the tests for you, I get very skeptical. It cannot be that easy. Testing is a general concept; it applies across languages. So does the concept of code contracts, it is similar for languages that support it. Code contracts do not generate themselves. The programmer must add the requirements and the promises manually, after doing some thinking about the algorithm / function. If a human gets it wrong, then the tools will propagate the error. Similarly with testing - it takes human judgement about what should happen. Tests do not write themselves, and we are far from the day when a business analyst can just have a conversation with a computer and tell it informally what the requirements are and have the computer do all the work. There is no magic ... how can RoR generate good tests for you? Please shed some light on this. Opinions are ok, for this is a community wiki. Thanks!

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• UiPickerView change font color according data

  - by Fulkron

  I'm using a pickerView with multiple components related to several fields in a Database (CoreData). Is it possible to change the fontcolor for a specific component according the presence of data in the DB ? For example the field in the DB is null the component font color should be RED otherwise black. Any help will be appreciated ! Dario ================== Thanks Kenny, I have to apply to a single UIPicker only. So I', returning the view parametere (without modificatiosn). The result is all the pickers show empty rows. Thanks for help ! Here you will find the code fragment: - (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view { if (pickerView == tipoPk){ UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 100,30)]; label.textColor = [UIColor redColor]; switch (component) { case PK_Tipo: label.text = [tipoArray objectAtIndex:row]]; break; case PK_Settore: label.text = [settoreArray objectAtIndex:row]]; break; default: break; } return label; } else { return view; // <==== return view for non related pickerviews , but no rows shown } }

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• C++/CLI managed thread cleanup

  - by Guillermo Prandi

  Hi. I'm writing a managed C++/CLI library wrapper for the MySQL embedded server. The mysql C library requires me to call mysql_thread_init() for every thread that will be using it, and mysql_thread_end() for each thread that exits after using it. Debugging any given VB.Net project I can see at least seven threads; I suppose my library will see only one thread if VB doesn't explicitly create worker threads itself (any confirmations on that?). However, I need clients to my library to be able to create worker threads if they need to, so my library must be thread-aware to some degree. The first option I could think of is to expose some "EnterThread()" and "LeaveThread()" methods in my class, so the client code will explicitly call them at the beginning and before exiting their DoWork() method. This should work if (1) .Net doesn't "magically" create threads the user isn't aware of and (2) the user is careful enough to have the methods called in a try/finally structure of some sort. However, I don't like it very much to have the user handle things manually like that, and I wonder if I could give her a hand on that matter. In a pure Win32 C/C++ DLL I do have the DllMain DLL_THREAD_ATTACH and DLL_THREAD_DETACH pseudo-events, and I could use them for calling mysql_thread_init() and mysql_thread_end() as needed, but there seem to be no such thing in C++/CLI managed code. At the expense of some performance (not much, I think) I can use TLS for detecting the "usage from a new thread" case, but I can imagine no mechanism for the thread exiting case. So, my questions are: (1) could .net create application threads without the user being aware of them? and (2) is there any mechanism I could use similar to DLL_THREAD_ATTACH / DLL_THREAD_DETACH from managed C++/CLI? Thanks in advance.

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• Unable to convert from Julian INT date to regular TSQL Datetime

  - by Bluehiro

  Help me Stackoverflow, I'm close to going all "HULK SMASH" on my keyboard over this issue. I have researched carefully but I'm obviously not getting something right. I am working with a Julian dates referenced from a proprietary tool (Platinum SQL?), though I'm working in SQL 2005. I can convert their "special" version of Julian into datetime when I run a select statement. Unfortunately it will not insert into a datetime column, I get the following error when I try: The conversion of a char data type to a datetime data type resulted in an out-of-range datetime value. So I can't setup datetime criteria for running a report off of the Stored Procedure. Original Value: 733416 Equivalent Calendar Value: 01-09-2009 Below is my code... I'm so close but I can't quite see what's wrong, I need my convert statement to actually convert the Julian value (733416) into a compatible TSQL DATETIME value. SELECT org_id, CASE WHEN date_applied = 0 THEN '00-00-00' ELSE convert(char(50),dateadd(day,date_applied-729960,convert(datetime, '07-25-99')),101) END AS date_applied, CASE WHEN date_posted = 0 THEN '00-00-00' ELSE convert(char(50),dateadd(day,date_posted-729960,convert(datetime, '07-25-99')),101) END AS date_posted from general_vw

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• Perl unpack in list context

  - by drewk

  A common 'Perlism' is generating a list as something to loop over in this form: for($str=~/./g) { print "the next character from \"$str\"=$_\n"; } In this case the global match regex returns a list that is one character in turn from the string $str, and assigns that value to $_ Instead of a regex, split can be used in the same way or 'a'..'z', map, etc. I am investigating unpack to generate a field by field interpretation of a string. I have always found unpack to be less straightforward to the way my brain works, and I have never really dug that deeply into it. As a simple case, I want to generate a list that is one character in each element from a string using unpack (yes -- I know I can do it with split(//,$str) and /./g but I really want to see if unpack can be used this way...) Obviously, I can use a field list for unpack that is unpack("A1" x length($str), $str) but is there some other way that kinda looks like globbing? ie, can I call unpack(some_format,$str) either in list context or in a loop such that unpack will return the next group of character in the format group until $str is exausted? I have read The Perl 5.12 Pack pod and the Perl 5.12 pack tutorial and the Perkmonks tutorial Here is the sample code: #!/usr/bin/perl use warnings; use strict; my $str=join('',('a'..'z', 'A'..'Z')); #the alphabet... $str=~s/(.{1,3})/$1 /g; #...in groups of three print "str=$str\n\n"; for ($str=~/./g) { print "regex: = $_\n"; } for(split(//,$str)) { print "split: \$_=$_\n"; } for(unpack("A1" x length($str), $str)) { print "unpack: \$_=$_\n"; }

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• Bulk Copy from one server to another

  - by Joseph

  Hi All, I've one situation where I need to copy part of the data from one server to another. The table schema are exactly same. I need to move partial data from the source, which may or may not be available in the destination table. The solution I'm thinking is, use bcp to export data to a text(or .dat) file and then take that file to the destination as both are not accessible at the same time (Different network), then import the data to the destination. There are some conditions I need to satisfy. 1. I need to export only a list of data from the table, not whole. My client is going to give me IDs which needs to be moved from source to destination. I've around 3000 records in the master table, and same in the child tables too. What I expect is, only 300 records to be moved. 2. If the record exists in the destination, the client is going to instruct as whether to ignore or overwrite case to case. 90% of the time, we need to ignore the records without overwriting, but log the records in a log file. Please help me with the best approach. I thought of using BCP with query option to filter the data, but while importing, how do I bypass inserting the existing records? If I need to overwrite, how to do it? Thanks a lot in advance. ~Joseph

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• ClassCastException When Calling an EJB that Exists on Same Server

  - by aaronvargas

  I have 2 ejbs. Ejb-A that calls Ejb-B. They are not in the same Ear. For portability Ejb-B may or may not exist on the same server. (There is an external property file that has the provider URLs of Ejb-B. I have no control over this.) Example Code: in Ejb-A EjbBDelegate delegateB = EjbBDelegateHelper.getRemoteDelegate(); // lookup from list of URLs from props... BookOfMagic bom = delegateB.getSomethingInteresting(); Use Cases/Outcomes: When Ejb-B DOES NOT EXIST on the same server as Ejb-A, everything works correctly. (it round-robbins through the URLs) When Ejb-B DOES EXIST on the same server, and Ejb-A happens to call Ejb-B on the same server, everything works correctly. When Ejb-B DOES EXIST on the same server, and Ejb-A calls Ejb-B on a different server, I get: javax.ejb.EJBException: nested exception is: java.lang.ClassCastException: $Proxy126 java.lang.ClassCastException: $Proxy126 NOTE (not normal use case but may help): When Ejb-B DOES EXIST on the same server, and this server is NOT listed in the provider URLs for Ejb-B, and Ejb-A calls Ejb-B on a different server, I get the same Exception as above. I'm using Weblogic 10.0, Java 5, EJB3 Basically, if Ejb-B Exists on the server, it must be called ONLY on that server. Which leads me to believe that the class is getting loaded by a local classloader (on deployment?), then when called remotely, a different classloader is loading it. (causing the Exception) But it should work, as it should be Serialized into the destination classloader... What am I doing wrong?? Also, when reproducing this locally, Ejb-A would favor the Ejb-B on the same server, so it was difficult to reproduce. But this wasn't the case on other machines.

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• LINQ self referencing query

  - by Chris

  I have the following SQL query: select p1.[id], p1.[useraccountid], p1.[subject], p1.[message], p1.[views], p1.[parentid], case when p2.[created] is null then p1.[created] else p2.[created] end as LastUpdate from forumposts p1 left join ( select parentid, max(created) as [created] from forumposts group by parentid ) p2 on p2.parentid = p1.id where p1.[parentid] is null order by LastUpdate desc Using the following class: public class ForumPost : PersistedObject { public int Views { get; set; } public string Message { get; set; } public string Subject { get; set; } public ForumPost Parent { get; set; } public UserAccount UserAccount { get; set; } public IList<ForumPost> Replies { get; set; } } How would I replicate such a query in LINQ? I've tried several variations, but I seem unable to get the correct join syntax. Is this simply a case of a query that is too complicated for LINQ? Can it be done using nested queries some how? The purpose of the query is to find the most recently updated posts i.e. replying to a post would bump it to the top of the list. Replies are defined by the ParentID column, which is self-referencing.

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• ASP.Net RadioButton loses ViewState

  - by Carl

  I'm having trouble with a simple radio set of two radio buttons (I don't want to use a RadioButtonList [RBL] because RBL doesn't allow child controls, and in my case, if you select one option, I want to enable a textbox next to the button; yes you could hack this with jQuery to move the textbox, but that's dirty!). I would check one, submit the form (either explicitly or through AutoPostBack), and the CheckedChanged event would never fire. When the page was reloaded, both buttons would be unchecked, regardless of their initial state on non-postback load or the state before form submission. I took out the checkbox and stripped this down to the simplest example I could come up with. I tossed EnableViewState=true all over the place just in case it was being disabled somewhere I couldn't find. <form id="form1" runat="server" enableviewstate="true"> <div> <asp:RadioButton ID="foo" Text="foo" runat="server" AutoPostBack="true" OnCheckedChanged="rbChanged" Checked="true" GroupName="foobar" EnableViewState="true" /> <asp:RadioButton ID="bar" Text="bar" runat="server" AutoPostBack="true" GroupName="foobar" OnCheckedChanged="rbChanged" Checked="false" EnableViewState="true" /> <asp:Label runat="server" ID="resultLbl" /> </div> </form> protected void rbChanged(object sender, EventArgs e) { if (foo.Checked) resultLbl.Text = "foo is checked"; else if (bar.Checked) resultLbl.Text = "bar is checked"; else resultLbl.Text = "neither is checked"; }

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• Starter question of declarative style SQLAlchemy relation()

  - by jfding

  I am quite new to SQLAlchemy, or even database programming, maybe my question is too simple. Now I have two class/table: class User(Base): __tablename__ = 'users' id = Column(Integer, primary_key=True) name = Column(String(40)) ... class Computer(Base): __tablename__ = 'comps' id = Column(Integer, primary_key=True) buyer_id = Column(None, ForeignKey('users.id')) user_id = Column(None, ForeignKey('users.id')) buyer = relation(User, backref=backref('buys', order_by=id)) user = relation(User, backref=backref('usings', order_by=id)) Of course, it cannot run. This is the backtrace: File "/Library/Python/2.6/site-packages/SQLAlchemy-0.5.8-py2.6.egg/sqlalchemy/orm/state.py", line 71, in initialize_instance fn(self, instance, args, kwargs) File "/Library/Python/2.6/site-packages/SQLAlchemy-0.5.8-py2.6.egg/sqlalchemy/orm/mapper.py", line 1829, in _event_on_init instrumenting_mapper.compile() File "/Library/Python/2.6/site-packages/SQLAlchemy-0.5.8-py2.6.egg/sqlalchemy/orm/mapper.py", line 687, in compile mapper._post_configure_properties() File "/Library/Python/2.6/site-packages/SQLAlchemy-0.5.8-py2.6.egg/sqlalchemy/orm/mapper.py", line 716, in _post_configure_properties prop.init() File "/Library/Python/2.6/site-packages/SQLAlchemy-0.5.8-py2.6.egg/sqlalchemy/orm/interfaces.py", line 408, in init self.do_init() File "/Library/Python/2.6/site-packages/SQLAlchemy-0.5.8-py2.6.egg/sqlalchemy/orm/properties.py", line 716, in do_init self._determine_joins() File "/Library/Python/2.6/site-packages/SQLAlchemy-0.5.8-py2.6.egg/sqlalchemy/orm/properties.py", line 806, in _determine_joins "many-to-many relation, 'secondaryjoin' is needed as well." % (self)) sqlalchemy.exc.ArgumentError: Could not determine join condition between parent/child tables on relation Package.maintainer. Specify a 'primaryjoin' expression. If this is a many-to-many relation, 'secondaryjoin' is needed as well. There's two foreign keys in class Computer, so the relation() callings cannot determine which one should be used. I think I must use extra arguments to specify it, right? And howto? Thanks

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• Why are floating point values so prolific?

  - by Kibbee

  So, title says it all. Why are floating point values so prolific in computer programming. Due to problems like rounding errors, and not being able to even accurately represent numbers such as 0.1, I really can't see how they got as far as they did. I understand that the computation is faster with floating point numbers, however, I can think of only a few cases that they actually the right data type would be using. If you sat back and think about every time you used a floating point value, how many times did you say, well, some error would be ok, as long as the result was a few microseconds faster. It really makes me think because Jeff was talking about NP completeness, and how heuristics give an answer that is kind of right. And well, computers shouldn't do that. They should give you the answer that is correct. Yet we see floating point values used in many applications where they are completely not valid. What really bugs me, isn't that floating point exists, but that in many languages, there isn't even a viable alternative, non-floating point, decimal value. A lot of programmers when doing financial applications have to fall back to storing the number of cents in an integer field. Which brings with it all kinds of other problems. Why do floats continue to be so prolific, even though they can't represent the real answer, and we expect computers to be accurate? [EDIT] Just to clarify, I was talking about Base 2 floating points, and not base 10 floating points. .Net offers the Decimal data type, which is a base 10 floating point value which offers a much better representation of the numbers we deal with on a daily basis in most computer programs. I find it hard to believe that even modern languages like Java don't support base 10 floating point values, unless you want to move into the realm of things like BigDecimal, which isn't really the right answer either in a lot of situations.

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• Why does the the Java VM not recover after "Too many open files" errors?

  - by Michael

  In certain well-understood circumstances, our application will open too many sockets (database connections) and reach the maximum open files that the OS allows. We understand this; we are fixing the issue and also bumping up the limit. What we can't explain is why parts of our application don't recover even after the number of connections abates and we're well within the limit. In this case, it's an application running under Tomcat. When this happens, we first start seeing "Too many open files" errors: SEVERE: Socket accept failed java.net.SocketException: Too many open files at java.net.PlainSocketImpl.socketAccept(Native Method) at java.net.PlainSocketImpl.accept(PlainSocketImpl.java:390) at java.net.ServerSocket.implAccept(ServerSocket.java:453) at java.net.ServerSocket.accept(ServerSocket.java:421) at org.apache.tomcat.util.net.DefaultServerSocketFactory.acceptSocket(DefaultServerSocketFactory.java:61) at org.apache.tomcat.util.net.JIoEndpoint$Acceptor.run(JIoEndpoint.java:310) at java.lang.Thread.run(Thread.java:619) Eventually, we start seeing NoClassDefFoundErrors inside an application thread that's trying to open HTTP connections: java.lang.NoClassDefFoundError: org/apache/commons/httpclient/protocol/ControllerThreadSocketFactory at org.apache.commons.httpclient.protocol.DefaultProtocolSocketFactory.createSocket(DefaultProtocolSocketFactory.java:128) at org.apache.commons.httpclient.HttpConnection.open(HttpConnection.java:707) at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$HttpConnectionAdapter.open(MultiThreadedHttpConnectionManager.java:1349) [...] Caused by: java.lang.ClassNotFoundException: org.apache.commons.httpclient.protocol.ControllerThreadSocketFactory at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1387) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1233) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) ... 8 more When the errant connections go away, the server starts accepting connections again, and everything seems ok, but we're left with the latter error constantly being spewed to stderr. Although the application typically logs unloaded classes to stdout, I don't see any such logs just before, during or after the "Too many open files" errors. My initial theory was that the Hotspot JVM would unload seemingly unused classes when it encounters "Too many open files," but if so, it doesn't log the fact. I'd also expect it to recover if that were the case. Platform details: Java(TM) SE Runtime Environment (build 1.6.0_14-b08) Java HotSpot(TM) 64-Bit Server VM (build 14.0-b16, mixed mode) Apache Tomcat Version 6.0.18

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• Command-Line Parsing API from TestAPI library - Type-Safe Commands how to

  - by MicMit

  Library at http://testapi.codeplex.com/ Excerpt of usage from http://blogs.msdn.com/ivo_manolov/archive/2008/12/17/9230331.aspx A third common approach is forming strongly-typed commands from the command-line parameters. This is common for cases when the command-line looks as follows: some-exe COMMAND parameters-to-the-command The parsing in this case is a little bit more involved: Create one class for every supported command, which derives from the Command abstract base class and implements an expected Execute method. Pass an expected command along with the command-line arguments to CommandLineParser.ParseCommand – the method will return a strongly-typed Command instance that can be Execute()-d. // EXAMPLE #3: // Sample for parsing the following command-line: // Test.exe run /runId=10 /verbose // In this particular case we have an actual command on the command-line (“run”), which we want to effectively de-serialize and execute. public class RunCommand : Command { bool? Verbose { get; set; } int? RunId { get; set; } public override void Execute() { // Implement your "run" execution logic here. } } Command c = new RunCommand(); CommandLineParser.ParseArguments(c, args); c.Execute(); ============================ I don't get if we instantiate specific class before parsing arguments , what's the point of command line argument "run" which is very first one. I thought the idea was to instantiate and execute command/class based on a command line parameter ( "run" parameter becomes instance RunCommand class, "walk" becomes WalkCommand class and so on ). Can it be done with the latest version ?

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• Executing a modified expression

  - by Sam

  I found this brief demo: http://msdn.microsoft.com/en-us/library/bb546136.aspx Which discusses modifying an expression. However the code starts with a Expression<Func<string, bool>> and ends up with a Expression so it's not complete. How do I take that expression and make it typed as Expression<Func<string,bool>> again? All the examples I have have found on executing an expression all involve dynamically created expressions which is not what this case has. Here the original expression is defined at compile time. And the code I want to write to do this won't know much about the expression, ideally as little as possible. I definately can't see how I would know what "Paramaters" to pass to Expression.LambdaExpression... In my particular case I want to search for any references to a particular propery of type A and swap them out with a reference to a property of type B then pass the expression to a call to IEnumerable.Where. ie. p=>p.Name == "Sam" where P is Foo1 becomes p=>p.FirstName == "Sam" where p is Foo2

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• Rails add a param to the end of a search query

  - by bob

  Hello, I am trying to implement a sort on the returned results of a search with rails. Filter by: 'recent' % | 'lowest_price' % | 'highest_price' % here are my links. I would like to add a filter to the end of my search query. So for example, I submit a search and I get back results and in my url I have http://localhost:3000/junks?search=handbag&condition=&category=&main_submit=Go! I would then like the user to be able to click one of the above links and have the page come back with a new query (i have this set up in the controller like such) con_id = params[:condition] if params[:category].nil? || params[:category].empty? cat_id = params[:category] results = Junk.search params[:search], :with => { :category_id => cat_id, :condition_id => con_id } case params[:filter] when "lowest_price" @junks = results.lowest_price.paginate :page => params[:page], :per_page => 12 when "highest_price" @junks = results.highest_price.paginate :page => params[:page], :per_page => 12 else @junks = results.paginate :page => params[:page], :per_page => 12 end else I would like the user to be able to click on of the above links and append a filter param to the end of the search query so that my controller can pick it up and call the correct database queries as seen in the case statement above. I'm guessing the url will look like this http://localhost:3000/junks?search=handbag&condition=&category=&main_submit=Go!&filter="lowest_price" How can I do this? Is there a better way?

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