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• ASP.NET Connection time out after being idle for a while

  - by yazz

  My ASP.NET website while trying to connect to the database for first time after a period of inactivity throws an time out exception. I understand the connections in the connection pool get terminated after some idle time for some reason (Firewall or Oracle settings) and the pool or app doesn't have a clue about it. Is there any way to validate the connection beforehand so that the first try doesn't throw an exception? I don't have much control over the DB or Firewall settings. So I have to deal with this is my application.(would prefer if there is any web.config settings) I am using: ASP.NET 2.0. Oracle server 11g, Microsoft Enterprise Library DAAB to do all my DB operations. I did some search on this topic but didnt find any solid solution for this yet :(

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• Generic WithEvents

  - by serhio

  Error: 'WithEvents' variables can only be typed as classes, interfaces or type parameters with class constraints Background: Public Class Tadpole(Of T As IVisibleChanged, P As IVisibleChanged) Private WithEvents _Tad As T ' ERROR ' Private WithEvents _Pole As P ' ERROR ' Public Property Tad() As T ... Public Property Pole() As P ... End Class ''' IVisibleChanged ''' Public Interface IVisibleChanged Property Visible() As Boolean Event VisibleChanged As EventHandler End Interface Workaround: a. Use AddHandler to handle events defined in a structure. EDIT b. use Private WithEvents _Tad AsIVisibleChanged (M.A. Hanin) c. ?

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• Findbugs warning: Equals method should not assume anything about the type of its argument

  - by Uri

  When running FindBugs on my project, I got a few instances of the error described above. Namely, my overriding versions of equals cast the RHS object into the same type as the object in which the overriding version is defined. However, I'm not sure whether a better design is possible, since AFAIK Java does not allow variance in method parameters, so it is not possible to define any other type for the equals parameter. Am I doing something very wrong, or is FindBugs too eager? A different way to phrase this question is: what is the correct behavior if the object passed to equals is not the same type as an LHS: Is this a false, or should there be an exception? For example: public boolean equals(Object rhs) { MyType rhsMyType = (MyType)rhs; // Should throw exception if(this.field1().equals(rhsMyType.field1())... // Or whatever }

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• ShellExecute not working from IDE but works otherwise.

  - by Altar

  I want to create and then open a txt file using the ShellExecute command. I have used this code for years with Delphi 7 and it worked: function Executa(CONST ExeName, Parameters: string): Boolean; begin if Parameters= '' then Result:= ShellExecute(0, 'open', PChar(ExeName), NIL , nil, SW_SHOWNORMAL)> 32 else Result:= ShellExecute(0, 'open', PChar(ExeName), PChar(Parameters), nil, SW_SHOWNORMAL)> 32; end; Now, I switch to Windows 7 (don't like it; they stuck it on my throat with my new laptop) 64 bit and the code is not working anymore when it runs from IDE. Delhi shows the CPU window with the caption "CPU-Process unknown (2352)". I close the CU windows and everything works fine until I close the application, when Delphi shows the CPU window one more time. If I run the app from outside IDE, it works fine. Looks like the debugger has something to say to me, but I don't know what.

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• How sophisticated should be DAL?

  - by Andrew Florko

  Basically, DAL (Data Access Layer) should provide simple CRUD (Create/Read/Update/Delete) methods but I always have a temptation to create more sophisticated methods in order to minimize database access roundtrips from Business Logic Layer. What do you think about following extensions to CRUD (most of them are OK I suppose): Read: GetById, GetByName, GetPaged, GetByFilter... e.t.c. methods Create: GetOrCreate methods (model entity is returned from DB or created if not found and returned), Create(lots-of-relations) instead of Create and multiple AssignTo methods calls Update: Merge methods (entities list are updated, created and deleted in one call) Delete: Delete(bool children) - optional children delete, Cleanup methods Where do you usually implement Entity Cache capabilities? DAL or BLL? (My choice is BLL, but I have seen DAL implementations also) Where is the boundary when you decide: this operation is too specific so I should implement it in Business Logic Layer as DAL multiple calls? I often found insufficient BLL operations that were implemented in dozen database roundtrips because developer was afraid to create a bit more sophisticated DAL. Thank you in advance!

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• How to leverage Spring Integration in a real-world JMS distributed architecture?

  - by ngeek

  For the following scenario I am looking for your advices and tips on best practices: In a distributed (mainly Java-based) system with: many (different) client applications (web-app, command-line tools, REST API) a central JMS message broker (currently in favor of using ActiveMQ) multiple stand-alone processing nodes (running on multiple remote machines, computing expensive operations of different types as specified by the JMS message payload) How would one best apply the JMS support provided by the Spring Integration framework to decouple the clients from the worker nodes? When reading through the reference documentation and some very first experiments it looks like the configuration of an JMS inbound adapter inherently require to use a subscriber, which in a decoupled scenario does not exist. Small side note: communication should happen via JMS text messages (using a JSON data structure for future extensibility).

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• Can "\Device\NamedPipe\\Win32Pipes" handles cause "Too many open files" error?

  - by Igor Oks

  Continuing from this question: When I am trying to do fopen on Windows, I get a "Too many open files" error. I tried to analyze, how many open files I have, and seems like not too much. But when I executed Process Explorer, I noticed that I have many open handles with similar names: "\Device\NamedPipe\Win32Pipes.00000590.000000e2", "\Device\NamedPipe\Win32Pipes.00000590.000000e3", etc. I see that the number of these handles is exactly equal to the number of the iterations that my program executed, before it returned "Too many open files" and stopped. I am looking for an answer, what are these handles, and could they actually cause the "Too many open files" error? In my program I am loading files from remote drive, and I am creating TCP/IP connections. Could one of these operations create these handles?

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• Are any of these quad-tree libraries any good?

  - by Noctis Skytower

  It appears that a certain project of mine will require the use of quad-trees, something that I have never worked with before. From what I have read they should allow substantial performance enhancements than a brute-force attempt at the problem would yield. Are any of these python modules any good? Quadtree 0.1.2 <= No: unable to execute in Python 3.1 QuadTree <= Yes: simple while working with rectangles quadtree.py <= No: no support for needed operations EDIT: Does anyone know of a better implementation that the one presented on the pygame wiki article?

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• GIS: When and why to use ArcObjects over GDAL programming to work with ArcGIS rasters and vectors?

  - by anotherobject

  Im just starting off with GDAL + python to support operations that cannot be done with ArcGIS python geoprocessing scripting. Mainly I am doing spatial modeling/analysis/editing of raster and vector data. I am a bit confused when ArcObject development is required versus when GDAL can be used? Is there functionality of ArcObjects that GDAL does not do? Is the opposite true too? I am assuming that ArcObjects are more useful in developing online tools versus Desktop analysis and modeling where the difference is more to do with preference? In my case i prefer GDAL because of python support, which I believe ArcObjects lack. thanks!

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• Designing DAL in .NET to be "data-source independent" and not just "database independent" ?

  - by Munish Goyal

  How to design such flexible DAL (specifically in .NET) ? What interfaces .NET provides and what should be done on my own ? Its a greenfield project starting with SQL Server as data source but in future, parts of it will move to different NoSQL type of datastores. Also, we may need to experiment with lot of different datastores (like some data may have to go with Cassandra, some with RDBMS, some to other DHT etc.) Therefore easily switchable access layer will be needed. All i know right now is the 'data' and 'operations needed on that data'.

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• cached schwartzian transform

  - by davidk01

  I'm going through "Intermediate Perl" and it's pretty cool. I just finished the section on "The Schwartzian Transform" and after it sunk in I started to wonder why the transform doesn't use a cache. In lists that have several repeated values the transform recomputes the value for each one so I thought why not use a hash to cache results. Here' some code: # a place to keep our results my %cache; # the transformation we are interested in sub foo { # expensive operations } # some data my @unsorted_list = ....; # sorting with the help of the cache my @sorted_list = sort { ($cache{$a} or $cache{$a} = &foo($a)) <=> ($cache{$b} or $cache{$b} = &foo($b)) } @unsorted_list; Am I missing something? Why isn't the cached version of the Schwartzian transform listed in books and in general just better circulated because on first glance I think the cached version should be more efficient?

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• Can an Excel VBA UDF called from the worksheet ever be passed an instance of any Excel VBA object mo

  - by jtolle

  I'm 99% sure that the answer is "no", but I'm wondering if someone who is 100% sure can say so. Consider a VBA UDF: Public Function f(x) End Function When you call this from the worksheet, 'x' will be a number, string, boolean, error, array, or object of type 'Range'. Can it ever be, say, an instance of 'Chart', 'ListObject', or any other Excel-VBA object model class? (The question arose from me moving to Excel 2007 and playing with Tables, and wondering if I could write UDFs that accept them as parameters instead of Ranges. The answer to that seems to be no, but then I realized I didn't know for sure in general.)

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• Basic Login Script using php and mysql inquiry

  - by Matt

  Attempting to write a check for a login script to see if the username is available. Would the best way to write this query be to check if isset(!_POST[]) for both values (nick and pass) then connect to database WHERE the mysql database for the usernick requested return the user id if the usernick exists evaluate if isset($id) to see if the user name is taken and use that to continue to creating an entry Does this logically sound like a method to check for login without using excessive code sorry for not posting the code, it is on another computer and this computer is locked down by my administrator at work... Also, is there another way to evaluate if a value exists in the database? For instance, instead of setting $id to the return value of the mysql database can i just ping the mysql database for the information and have it return a Boolean result so I am not putting out any user information. Thanks, Matt

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• tool for adding parentheses to equations?

  - by jedierikb

  Is there an online tool for adding parentheses to simple math equations? For example, a + b * c into a + (b * c) Those who paid more attention in math class might be able to tackle order of operations for huge equations in their head, but I could often use some help (and verification of my thinking). I often encounter other people's libraries having equations and functions I need for my code, and this would be kind of helpful for debugging and understanding. I was hoping Wolfram Alpha would do this, but the output is not easy to plug back into most programming languages e.g. a + (bc)

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• Explain ML type inference to a C++ programmer

  - by Tsubasa Gomamoto

  How does ML perform the type inference in the following function definition: let add a b = a + b Is it like C++ templates where no type-checking is performed until the point of template instantiation after which if the type supports the necessary operations, the function works or else a compilation error is thrown ? i.e. for example, the following function template template <typename NumType> NumType add(NumType a, NumType b) { return a + b; } will work for add<int>(23, 11); but won't work for add<ostream>(cout, fout); Is what I am guessing is correct or ML type inference works differently? PS: Sorry for my poor English; it's not my native language.

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• How can I make a read only version of a class?

  - by Eric

  I have a class with various public properties which I allow users to edit through a property grid. For persistence this class is also serialized/deserialized to/from an XML file through DataContractSerializer. Sometimes I want to user to be able to save (serialize) changes they've made to an instance of the class. Yet at other times I don't want to allow the user to save their changes, and should instead see all the properties in the property grid as read only. I don't want to allow users to make changes that they'll never be able to save later. Similar to how MS Word will allow users to open documents that are currently opened by someone else but only as read only. My class has a boolean property that determines if the class should be read-only, but is it possible to use this property to somehow dynamically add a read-only attributes to the class properties at run-time? If not what is an alternative solution? Should I wrap my class in a read-only wrapper class?

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• KeyCode_Enter to next edittext

  - by soclose

  Hi, In edittext, after typing 'Enter' key, system make a new line inside it. I'd like to focus on next edittext, no new line. how to code? my code in xml is below <EditText android:id="@+id/txtNPCode" android:layout_width="fill_parent" android:layout_height="wrap_content" android:textSize="18sp" android:layout_alignLeft="@+id/lblNPCode" android:layout_below="@+id/lblNPCode" android:layout_centerHorizontal="true" /> <EditText android:id="@+id/txtCNPCode" android:layout_width="fill_parent" android:layout_height="wrap_content" android:textSize="18sp" android:layout_alignLeft="@+id/lblCNPCode" android:layout_below="@+id/lblCNPCode" android:layout_centerHorizontal="true" /> I also caputer key code in setOnKeyListener tCNPCode.setOnKeyListener(new OnKeyListener() { public boolean onKey(View v, int keyCode, KeyEvent event) { // TODO Auto-generated method stub if(keyCode == 66) { Toast.makeText(S_PCode.this, "Enter Key", Toast.LENGTH_LONG).show(); //tNPCode.setFocusable(true); } return false; } });

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• Class Methods Inheritence

  - by Roman A. Taycher

  I was told that static methods in java didn't have Inheritance but when I try the following test package test1; public class Main { /** * @param args the command line arguments */ public static void main(String[] args) { TB.ttt(); TB.ttt2(); } } package test1; public class TA { static public Boolean ttt() { System.out.println("TestInheritenceA"); return true; } static public String test ="ClassA"; } package test1; public class TB extends TA{ static public void ttt2(){ System.out.println(test); } } it printed : TestInheritenceA ClassA so do java static methods (and fields have) inheritance (if you try to call a class method does it go down the inheritance chai looking for class methods). Was this ever not the case,are there any inheritance OO languages that are messed up like that for class methods?

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• Unable to call WMP's controls.play() function in VisualBasic

  - by A.J.

  I have the following code: http://pastebin.com/EgjbzqA2 which is basically just a stripped down version of http://www.dreamincode.net/forums/topic/57357-mymusic-player/. I want the program to play one file repeatedly, however, this function doesn't work for some reason. The program plays each file once and then stops. Private Sub Player3_PlayStateChange(ByVal NewState As Integer) Handles Player3.PlayStateChange Static Dim PlayAllowed As Boolean = True Select Case CType(NewState, WMPLib.WMPPlayState) Case WMPLib.WMPPlayState.wmppsReady If PlayAllowed Then Player3.controls.play() End If Case WMPLib.WMPPlayState.wmppsMediaEnded ' Start protection (without it next wouldn't play PlayAllowed = False ' Play track Player3.controls.play() ' End Protection PlayAllowed = True updatePlayer() End Select End Sub

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• How to organize code using an optional assembly reference?

  - by apoorv020

  I am working on a project and want to optionally use an assembly if available. This assembly is only available on WS 2008 R2, and my ideal product whould be a common binary for both computers with and without the assembly. However, I'm primarily developing on a Windows 7 machine, where I cannot install the assembly. How can I organize my code so that I can (with minimum changes) build my code on a machine without the assembly and secondly, how do I ensure that I call the assembly functions only when it is present. (NOTE : The only use of the optional assembly is to instantiate a class in the library and repeatedly call a (single) function of the class, which returns a boolean. The assembly is fsrmlib, which exposes advanced file system management operations on WS08R2.) I'm currently thinking of writing a wrapper class, which will always return true if the assembly is not present. Is this the right way to go about doing this?

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• Relational algebra help?!

  - by Tom

  im new to relational algebra and finding it difficult. Ive answered a few questions, however they where relatively simple. Could do with help with these though. Database Patient (PatientCode, PatientSurname, PatientFirstname, PatientSex, PatientAge, PatientOccupation, PatientHeight, PatientWeight, PatientAddress) Doctor (DoctorCode, DoctorSurName, DoctorFirstName, DoctorPrivateAddress, MobileNo, Doctor Specilisim) Operation (Operation Code, PatientCode, DoctorCode, Date, Time, Result, OperationType) Is_Seen_By (PatientCode, DoctorCode, Date, Time). Q1. Find the surname and gender of the patients that have been operated on by doctor "DR333" and results have not been successful. Q2. Find the code of the operations that have been done on the 18th of November 2010 and have been successful, please also list the name of the doctors which were involved with the operation.

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• Javascript : assign variable in if condition statement, good practice or not?

  - by Michael Mao

  Hi all: I moved one years ago from classic OO languages such like Java to Javascript. The following code is definitely not recommended (or even not correct) in Java: if(dayNumber = getClickedDayNumber(dayInfo)) { alert("day number found"); } function getClickedDayNumber(dayInfo) { dayNumber = dayInfo.indexOf("fc-day"); if(dayNumber != -1) //substring found { //normally any calendar month consists of "40" days, so this will definitely pick up its day number. return parseInt(dayInfo.substring(dayNumber+6, dayNumber+8)); } else return false; } Basically I just found out that I can assign a variable to a value in an if condition statement, and immediately check the assigned value as if it is boolean. For a safer bet, I usually separate that into two lines of code, assign first then check the variable, but now that I found this, I am just wondering whether is it good practice or not in the eyes of experienced javascript developers? Many thanks in advance.

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• Developer oriented hardware benchmarks?

  - by Promit

  Perhaps I'm looking in the wrong places, but every hardware benchmark I've found, for nearly any component, is oriented towards gamers and/or workstations (video editing etc). Is there anyone doing benchmarks that are relevant to software developers? For example, take SSDs. I don't care how fast Crysis loads off an SSD -- that is completely worthless information. What I want to know is, which drive yields the quickest build times? What about Intellisense and refactoring operations? What RAID configuration has the biggest benefit? I could probably come up with more examples, but you get the point. Long story short, where are the benchmarks that tell me which hardware will be most effective in helping me be a productive software developer?

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• PDO update query with conditional?

  - by dmontain

  I have a PDO mysql that updates 3 fields. $update = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2, field3=:field3 WHERE key=:key"); But I want field3 to be updated only when $update3 = true; (meaning that the update of field3 is controlled by a conditional statement) Is this possible to accomplish with a single query? I could do it with 2 queries where I update field1 and field2 then check the boolean and update field3 if needed in a separate query. //run this query to update only fields 1 and 2 $update_part1 = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2 WHERE key=:key"); //if field3 should be update, run a separate query to update it separately if ($update3){ $update_part2 = $mypdo->prepare("UPDATE tablename SET field3=:field3 WHERE key=:key"); } But hopefully there is a way to accomplish this in 1 query?

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• Call an IOUSBDeviceInterface function on an obj-c object instead of a C structure

  - by b1onic

  Let's say I want to close an USB device. Here is a C structure representing the USB device: struct __USBDevice { uint16_t idProduct; io_service_t usbService; IOUSBDeviceInterface **deviceHandle; IOUSBInterfaceInterface **interfaceHandle; Boolean open; }; typedef struct __USBDevice *USBDeviceRef; Here is the code to close the device: // device is a USBDeviceRef structure // USBDeviceClose is a function member of IOUSBDeviceInterface C Pseudoclass (*device->deviceHandle)->USBDeviceClose(device->deviceHandle); Now imagine that the device properties are declared in an obj-c class @interface Device : NSObject { NSNumber idProduct io_service_t usbService; IOUSBDeviceInterface **deviceHandle; IOUSBInterfaceInterface **interfaceHandle; BOOL open; } @end How would I do to call USBDeviceClose() ?

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