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• iPhone SQLite Password Field Encryption

  - by Louis Russell

  Good Afternoon Guys and Girls, Hopefully this will be a quick and easy question. I am building an App that requires the user to input their login details for an online service that it links to. Multiple login details can be added and saved as the user may have several accounts that they would like to switch between. These details will be stored in an SQLite database and will contain their passwords. Now the questions are: 1: Should these passwords be encrypted in the database? My instinct would say yes but then I do not know how secure the device and system is and if this is necessary. 2: If they should be encrypted what should I use? I think encrypting the whole database file sounds a bit over-kill so should I just encrypt the password before saving it to the database? If this is case what could I use to achieve this? I have found reference to a "crypt(3)" but am having trouble finding much about it or how to implement it. I eagerly await your replies!

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• SqlBulkCopy causes Deadlock on SQL Server 2000.

  - by megatoast

  I have a customized data import executable in .NET 3.5 which the SqlBulkCopy to basically do faster inserts on large amounts of data. The app basically takes an input file, massages the data and bulk uploads it into a SQL Server 2000. It was written by a consultant who was building it with a SQL 2008 database environment. Would that env difference be causing this? SQL 2000 does have the bcp utility which is what BulkCopy is based on. So, When we ran this, it triggered a Deadlock error. Error details: Transaction (Process ID 58) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. I've tried numerous ways to try to resolve it. like temporarily setting the connection string variable MultipleActiveResultSets=true, which wasn't ideal, but it still gives a Deadlock error. I also made sure it wasn't a connection time out problem. here's the function. Any advice? /// <summary> /// Bulks the insert. /// </summary> public void BulkInsert(string destinationTableName, DataTable dataTable) { SqlBulkCopy bulkCopy; if (this.Transaction != null) { bulkCopy = new SqlBulkCopy ( this.Connection, SqlBulkCopyOptions.TableLock, this.Transaction ); } else { bulkCopy = new SqlBulkCopy ( this.Connection.ConnectionString, SqlBulkCopyOptions.TableLock | SqlBulkCopyOptions.UseInternalTransaction ); } bulkCopy.ColumnMappings.Add("FeeScheduleID", "FeeScheduleID"); bulkCopy.ColumnMappings.Add("ProcedureID", "ProcedureID"); bulkCopy.ColumnMappings.Add("AltCode", "AltCode"); bulkCopy.ColumnMappings.Add("AltDescription", "AltDescription"); bulkCopy.ColumnMappings.Add("Fee", "Fee"); bulkCopy.ColumnMappings.Add("Discount", "Discount"); bulkCopy.ColumnMappings.Add("Comment", "Comment"); bulkCopy.ColumnMappings.Add("Description", "Description"); bulkCopy.BatchSize = dataTable.Rows.Count; bulkCopy.DestinationTableName = destinationTableName; bulkCopy.WriteToServer(dataTable); bulkCopy = null; }

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• Where can I find clear examples of MVC?

  - by Tom

  I've read a couple of things about MVCs but I still don't understand when they should be used and when they shouldn't be used. I am looking for clear examples that say things like "if you're developing this then you should use MVC, like this" and "if you're developing this, you shouldn't use MVC." Most of the examples I've seen rely on complex frameworks which have already implemented everything and you have to learn the framework and use it a lot to understand what's really happening. To many programmers, phrasings such as "UI business logic" sound like marketing terms — for example, the words "Instead the View binds directly to a Presentation Model" are used in this post. I am aware of the dangers that may lurk in the shadows as MVC is a concept and everyone feels like they know it best, yet nobody really knows exactly how to use it because there may be a lot of variables involved and everyone is allowed to have a different perspective on how to dissect a project into the Model, the View and the Controller. There is a lot of theory out there but very few clear examples. What I'm looking for are not "the best" ways of doing it so this should not be considered as subjective; I'm looking for different simple implementations that would allow me to decide on my own which are the best approaches. Succinctly: What are good on-line resources that present pro and con arguments to using MVC in various situations and provide clear examples to help the reader understand the concept?

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• REST application, Transactions, Cache drop

  - by Julian Davchev

  Hi, I am building REST API in php with memcache layer on top for caching all resources. After some reading experience it turns out it's best when documents are as simple as posible...mainly due to dropping cache sequences. So if there is 'building','room' entities for the 'room' document I would only place the id of the 'building' and not the whole data of it. Then on api client side I would merge data as needed. Problem becomes when I need to update/insert (most cases more than one table). I update one resource but on second update system fails or whatever and there becomes database inconsistancies. I see several solutions: 1. Implement rest transactions which I find wrong and complex as idea is to be stateless and easy. 2. On update/insert actions I pass more complex data (not single entities) so I can force transactions on API level. But this will make it weird that your GET document structure is same as PUT document structure. And again somehow make drop sequences complex. Any pointers are more than welcome. Cheers,

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• Using the MVVM Light Toolkit to make Blendable applications

  - by Dave

  A while ago, I posted a question regarding switching between a Blend-authored GUI and a Visual Studio-authored one. I got it to work okay by adding my Blend project to my VS2008 project and then changing the Startup Application and recompiling. This would result in two applications that had completely different GUIs, yet used the exact same ViewModel and Model code. I was pretty happy with that. Now that I've learned about the Laurent Bugnion's MVVM Light Toolkit, I would really like to leverage his efforts to make this process of supporting multiple GUIs for the same backend code possible. The question is, does the toolkit facilate this, or am I stuck doing it my previous way? I've watched his video from MIX10 and have read some of the articles about it online. However, I've yet to see something that indicates that there is a clean way to allow a user to either dynamically switch GUIs on the fly by loading a different DLL. There are MVVM templates for VS2008 and Blend 3, but am I supposed to create both types of projects for my application and then reference specific files from my VS2008 solution? UPDATE I re-read some information on Laurent's site, and seemed to have forgotten that the whole point of the template was to allow the same solution to be opened in VS2008 and Blend. So anyhow, with this new perspective it looks like the templates are actually intended to use a single GUI, most likely designed entirely in Blend (with the convenience of debugging through VS2008), and then be able to use two different ViewModels -- one for design-time, and one for runtime. So it seems to me like the answer to my question is that I want to use a combination of my previous solution, along with the MVVM Light Toolkit. The former will allow me to make multiple, distinct GUIs around my core code, while the latter will make designing fancy GUIs in Blend easier with the usage of a design-time ViewModel. Can anyone comment on this?

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• Experience migrating legacy Cobol/PL1 to Java

  - by MadMurf

  ORIGINAL Q: I'm wondering if anyone has had experience of migrating a large Cobol/PL1 codebase to Java? How automated was the process and how maintainable was the output? How did the move from transactional to OO work out? Any lessons learned along the way or resources/white papers that may be of benefit would be appreciated. EDIT 7/7: Certainly the NACA approach is interesting, the ability to continue making your BAU changes to the COBOL code right up to the point of releasing the JAVA version has merit for any organization. The argument for procedural Java in the same layout as the COBOL to give the coders a sense of comfort while familiarizing with the Java language is a valid argument for a large organisation with a large code base. As @Didier points out the $3mil annual saving gives scope for generous padding on any BAU changes going forward to refactor the code on an ongoing basis. As he puts it if you care about your people you find a way to keep them happy while gradually challenging them. The problem as I see it with the suggestion from @duffymo to Best to try and really understand the problem at its roots and re-express it as an object-oriented system is that if you have any BAU changes ongoing then during the LONG project lifetime of coding your new OO system you end up coding & testing changes on the double. That is a major benefit of the NACA approach. I've had some experience of migrating Client-Server applications to a web implementation and this was one of the major issues we encountered, constantly shifting requirements due to BAU changes. It made PM & scheduling a real challenge. Thanks to @hhafez who's experience is nicely put as "similar but slightly different" and has had a reasonably satisfactory experience of an automatic code migration from Ada to Java. Thanks @Didier for contributing, I'm still studying your approach and if I have any Q's I'll drop you a line.

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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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• adding stock data to amibroker using c#

  - by femi

  hello, I have had a hard time getting and answer to this and i would really , really appreciate some help on this. i have been on this for over 2 weeks without headway. i want to use c# to add a line of stock data to amibroker but i just cant find a CLEAR response on how to instantiate it in C#. In VB , I would do it something like; Dim AmiBroker = CreateObject("Broker.Application") sSymbol = ArrayRow(0).ToUpper Stock = AmiBroker.Stocks.Add(sSymbol) iDate = ArrayRow(1).ToLower quote = Stock.Quotations.Add(iDate) quote.Open = CSng(ArrayRow(2)) quote.High = CSng(ArrayRow(3)) quote.Low = CSng(ArrayRow(4)) quote.Close = CSng(ArrayRow(5)) quote.Volume = CLng(ArrayRow(6)) The problem is that CreateObject will not work in C# in this instance. I found the code below somewhere online but i cant seem to understand how to achieve the above. Type objClassType; objClassType = Type.GetTypeFromProgID("Broker.Application"); // Instantiate AmiBroker objApp = Activator.CreateInstance(objClassType); objStocks = objApp.GetType().InvokeMember("Stocks", BindingFlags.GetProperty,null, objApp, null); Can anyone help me here? Thanks

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• Using HttpClient with SSL and certificates

  - by ChrisCM

  While I've been familiar with HTTPS and the concept of SSL, I have recently begun some development and found I am a little confused. The requirement was that I write a small Java application that runs on a machine attached to a scanner. When a document is scanned this is picked up and the file (usually PDF) sent over the internet to our application server that will then process it. I've written the application using Apache Commons libraries and HTTPClient. The second requirement was to connect over SSL, requiring a certificate. Following guidance on the HTTPclient page I am using AuthSSLProtocolSocketFactory from the contributions page. The constructor can take a keystore, keystore password, truststore and truststore password. As an initial test our DBA enabled SSL on one of our development webservers and provided me with a .p12 file which when I imported into IE allows me to connect successfully. I am a bit confused between keystores and truststores and what steps I need to take using the keytool. I tried importing the p12 into a keystore file but get the error: keytool error: java.lang.Exception: Input not an X.509 certificate I followed a suggestion of importing the p12 into Internet Explorer and exporting as a .cer which I can then successfully import into a keystore. When I supply this as a keystore argument of the AuthSSLProtocolSocketFactory I get a meaningless errror, but if I try it as a truststore it seems like it reads it fine but ultimately I get Caused by: javax.net.ssl.SSLHandshakeException: Received fatal alert: bad_certificate I am unsure if I have missed some steps, I am misunderstanding SSL and mutual authentication altogether or this is mis-configuration on the server side. Can anyone provide suggestions or point me towards resources that might help me figure this out please?

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• window.onload seems to trigger before the DOM is loaded (JavaScript)

  - by Dr. Monkey

  I am having trouble with the window.onload and document.onload events. Everything I read tells me these will not trigger until the DOM is fully loaded with all its resources, it seems like this isn't happening for me: I tried the following simple page in Chrome 4.1.249.1036 (41514) and IE 8.0.7600.16385 with the same result: both displayed the message "It failed!", indicating that myParagraph is not loaded (and so the DOM seems incomplete). <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en"> <head> <script type="text/javascript"> window.onload = doThis(); // document.onload gives the same result function doThis() { if (document.getElementById("myParagraph")) { alert("It worked!"); } else { alert("It failed!"); } } </script> </head> <body> <p id="myParagraph">Nothing is here.</p> </body> </html> I am using more complex scripts than this, in an external .js file, but this illustrates the problem. I can get it working by having window.onload set a timer for half a second to run doThis(), but this seems like an inelegant solution, and doesn't answer the question of why window.onload doesn't seem to do what everyone says it does. Another solution would be to set a timer that will check if the DOM is loaded, and if not it will just call itself half a second later (so it will keep checking until the DOM is loaded), but this seems overly complex to me. Is there a more appropriate event to use?

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• How to build an android test app with a dependency on another app using ant?

  - by Mike

  I have a module called MyApp, and another module called MyAppTests which has a dependency on MyApp. Both modules produce APKs, one named MyApp.apk and the other MyAppTests.apk. I normally build these in IntelliJ or Eclipse, but I'd like to create an ant buildfile for them for the purpose of continuous integration. I used "android update" to create a buildfile for MyApp, and thanks to commonsware's answer to my previous question I've been able to build it successfully using ant. I'd now like to build MyAppTests.apk using ant. I constructed the buildfile as before using "android update", but when I run it I get an error indicating that it's not finding any of the classes in MyApp. Taking a que from my previous question, I tried putting MyApp.apk into my MyAppTests/libs, but unfortunately that didn't miraculously solve the problem. What's the best way to build a test app APK using ant when it depends on classes in another APK? $ ant debug Buildfile: build.xml [setup] Project Target: Google APIs [setup] Vendor: Google Inc. [setup] Platform Version: 1.5 [setup] API level: 3 [setup] WARNING: No minSdkVersion value set. Application will install on all Android versions. dirs: [echo] Creating output directories if needed... resource-src: [echo] Generating R.java / Manifest.java from the resources... aidl: [echo] Compiling aidl files into Java classes... compile: [javac] Compiling 5 source files to /Users/mike/Projects/myapp/android/MyAppTests/bin/classes [javac] /Users/mike/Projects/myapp/android/MyAppTests/src/com/myapp/test/GsonTest.java:3: cannot find symbol [javac] symbol : class MyApplication [javac] location: package com.myapp [javac] import com.myapp.MyApplication; [javac] ^

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• Automation Error upon running VBA script in Excel

  - by brohjoe

  Hi guys, I'm getting an Automation error upon running VBA code in Excel 2007. I'm attempting to connect to a remote SQL Server DB and load data to from Excel to SQL Server. The error I get is, "Run-time error '-2147217843(80040e4d)': Automation error". I checked out the MSDN site and it suggested that this may be due to a bug associated with the sqloledb provider and one way to mitigate this is to use ODBC. Well I changed the connection string to reflect ODBC provider and associated parameters and I'm still getting the same error. Here is the code with ODBC as the provider: Dim cnt As ADODB.Connection Dim rst As ADODB.Recordset Dim stSQL As String Dim wbBook As Workbook Dim wsSheet As Worksheet Dim rnStart As Range Public Sub loadData() 'This was set up using Microsoft ActiveX Data Components version 6.0. 'Create ADODB connection object, open connection and construct the connection string object. Set cnt = New ADODB.Connection cnt.ConnectionString = _ "Driver={SQL Server}; Server=onlineSQLServer2010.foo.com; Database=fooDB Uid=logonalready;Pwd='helpmeOB1';" cnt.Open On Error GoTo ErrorHandler 'Open Excel and run query to export data to SQL Server. strSQL = "SELECT * INTO SalesOrders FROM OPENDATASOURCE('Microsoft.ACE.OLEDB.12.0', & _ "'Data Source=C:\Database.xlsx; Extended Properties=Excel 12.0')...[SalesOrders$]" cnt.Execute (strSQL) 'Error handling. ErrorExit: 'Reclaim memory from the connection objects Set rst = Nothing Set cnt = Nothing Exit Sub ErrorHandler: MsgBox Err.Description, vbCritical Resume ErrorExit 'clean up and reclaim memory resources. cnt.Close If CBool(cnt.State And adStateOpen) Then Set rst = Nothing Set cnt = Nothing End If End Sub

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• Learning about the low level

  - by Anoners

  I'm interested in learning more about the PC from a lower (machine) level. I graduated from a school which taught us concepts using the Java language which abstracted out that level almost completely. As a result I only learned a bit from the one required assembly language course. In order to cram in ASM and quite a few details about architecture, it was hard to get a very deep picture of what is going on there. At work I focus on unix socket programming in C, so i'm much closer to the hardware now, but I feel I should learn a bit more about what streams really are, how memory management and paging works, what goes on when you call "paint()" on a graphics buffer, etc. I missed out on a lot of this and i'm looking for a good resource to get me started. I've heard a lot about the "Pink Book" by Peter Norton (Programmer's Guide to the IBM PC, Programmer's Guide to inside the PC, etc). It seems like this is on the right track, however the original is quite out dated and the newer ones have had conflicting reviews, with many people saying to stay away from it. I'm not sure what the SO crowd thinks about this book or if they have some suggestions for similar books, online resources, etc that may be good primers for this sort of thing. Any suggestions would be appreciated.

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• C# TCP Async EndReceive() throws InvalidOperationException ONLY on Windows XP 32-bit

  - by James Farmer

  I have a simple C# Async Client using a .NET socket that waits for timed messages from a local Java server used for automating commands. The messages come in asynchronously and is written to a ring buffer. This implementation seems to work fine on Windows Vista/7/8 and OSX, but will randomly throw this exception while it's receiving a message from the local Java server: Unhandled Exception: System.InvalidOperationException: EndReceive can only be called once for each asynchronous operation.     at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult, SocketError& errorCode)     at System.Net.Sockets.Socket.EndReceive(IAsyncResult asyncResult)     at SocketTest.Controller.RecvAsyncCallback(IAsyncResult ar)     at System.Net.LazyAsyncResult.Complete(IntPtr userToken)     ... I've looked online for this error, but have found nothing really helpful. This is the code where it seems to break: /// <summary> /// Callback to receive socket data /// </summary> /// <param name="ar">AsyncResult to pass to End</param> private void RecvAsyncCallback(IAsyncResult ar) { // The exception will randomly happen on this call int bytes = _socket.EndReceive(_recvAsyncResult); // check for connection closed if (bytes == 0) { return; } _ringBuffer.Write(_buffer, 0, bytes); // Checks buffer CheckBuffer(); _recvAsyncResult = _sock.BeginReceive(_buffer, 0, _buffer.Length, SocketFlags.None, RecvAsyncCallback, null); } The error doesn't happen on any particular moment except in the middle of receiving a message. The message itself can be any length for this to happen, and the exception can happen right away, or sometimes even up to a minute of perfect communication. I'm pretty new with sockets and network communication, and I feel I might be missing something here. I've tested on at least 8 different computers, and the only similarity with the computers that throw this exception is that their OS is Windows XP 32-bit.

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• Facebook like and share create a fanpage

  - by nblumoe

  We are using the facebook like plugin with the share button. The URL points to a resource of our app. For example http://apps.facebook.com/appname/resources/id The first time this resource/url is shared or liked, everything works fine. The share for example holds the URL given above. But if the same resource/url is shared again, an error occurs. Facebook did create a fanpage for that resource like http://www.facebook.com/pages/appname So from now on, share/likes refer to that page instead of the resource/url of our app. The URL we use for the like plugin is correct and always points to the app resource URL. The fbappid in there is correct, too. Furthermore the page of the resource holds open graph meta tags like og:url, also pointing to the correct URL. The facebook linter/debugger returns URLs to the correct app resource URLs, when checking the liked/shared resource. Why is a fanpage created instead and the URL exchanged in shares/likes? How to fix it? We want the share to include the URL of the app resource and to increase the like count for that open graph object.

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• Can a single developer still make money with shareware?

  - by Wouter van Nifterick

  I'm wondering if the shareware concept is dead nowadays. Like most developers, I've built up quite a collection of self-made tools and code libraries that help me to be productive. Some examples to give you an idea of the type of thing I'm talking about: A self-learning program that renames and orders all my mp3 files and adds information to the id3 tags; A Delphi component that wraps the Google Maps API; A text-to-singing-voice converter for musical purposes; A program to control a music synthesizer; A Gps-log <- KML <- ESRI-shapefile converter; I've got one of these already freely downloadable on my website, and on average it gets downloaded about a 150 times per month. Let's say I'd start charging 15 euro's for it; would there actually be people who buy it? How many? What would it depend on? If I could get some money for some of these, I'd finish them up a bit and put them online, but without that, I probably won't bother. Maintaining a SourceForge project is not very rewarding by itself. Is there anyone who is making money with shareware? How much? Any tips?

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• BackgroundWorker From ASP.Net Application

  - by Kevin

  We have an ASP.Net application that provides administrators to work with and perform operations on large sets of records. For example, we have a "Polish Data" task that an administrator can perform to clean up data for a record (e.g. reformat phone numbers, social security numbers, etc.) When performed on a small number of records, the task completes relatively quickly. However, when a user performs the task on a larger set of records, the task may take several minutes or longer to complete. So, we want to implement these kinds of tasks using some kind of asynchronous pattern. For example, we want to be able to launch the task, and then use AJAX polling to provide a progress bar and status information. I have been looking into using the BackgroundWorker class, but I have read some things online that make me pause. I would love to get some additional advice on this. For example, I understand that the BackgroundWorker will actually use the thread pool from the current application. In my case, the application is an ASP.Net web site. I have read that this can be a problem because when the application recycles, the background workers will be terminated. Some of the jobs I mentioned above may take 3 minutes, but others may take a few hours. Also, we may have several hundred administrators all performing similar operations during the day. Will the ASP.Net application thread pool be able to handle all of these background jobs efficiently while still performing it's normal request processing? So, I am trying to determine if using the BackgroundWorker class and approach is right for our needs. Should I be looking at an alternative approach? Thanks and sorry for such a long post! Kevin

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• Localization approach for XSLT + RESX in ASP.NET

  - by frankadelic

  I have an ASP.NET web app where the back end data (XML format) is transformed using XSLT, producing XHTML which is output into the page. Simplified code: XmlDocument xmlDoc = MyRepository.RetrieveXmlData(keyValue); XslCompiledTransform xsl = new XslCompiledTransform(); xsl.Load(pathToXsl, XsltSettings.TrustedXslt, null); StringWriter stringWriter = new StringWriter(); xsl.Transform(xmlDoc, null, stringWriter); myLiteral.Text = stringWriter.ToString(); Currently my XSL file contains the XHTML markup elements, as well as text labels, which are currently in English. for example: <p>Title:<br /> <xsl:value-of select="title"/> </p> <p>Description:<br /> <xsl:value-of select="desc"/> </p> I would like the text labels (Title and Description above) to be localized. I was thinking of using .NET resource files (.resx), but I don't know how the resx string resources would get pulled in to the XSLT when the transformation takes place. I would prefer not to have locale-specific copies of the XSLT file, since that means a lot of duplicate transformation logic. (NOTE: the XML data is already localized, so I don't need to change that)

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• get column names from a table where one of the column name is a key word.

  - by syedsaleemss

  Im using c# .net windows form application. I have created a database which has many tables. In one of the tables I have entered data. In this table I have 4 columns named key, name,age,value. Here the name "key" of the first column is a key word. Now I am trying to get these column names into a combo box. I am unable to get the name "key". It works for "key" when I use this code: private void comboseccolumn_SelectedIndexChanged(object sender, EventArgs e) { string dbname = combodatabase.SelectedItem.ToString(); string path = @"Data Source=" + textBox1.Text + ";Initial Catalog=" + dbname + ";Integrated Security=SSPI"; //string path=@"Data Source=SYED-PC\SQLEXPRESS;Initial Catalog=resources;Integrated Security=SSPI"; SqlConnection con = new SqlConnection(path); string tablename = comboBox2.SelectedItem.ToString(); //string query= "Select * from" +tablename+; //SqlDataAdapter adp = new SqlDataAdapter(" Select [Key] ,value from " + tablename, con); SqlDataAdapter adp = new SqlDataAdapter(" Select [" + combofirstcolumn.SelectedItem.ToString() + "]," + comboseccolumn.SelectedItem.ToString() + "\t from " + tablename, con); DataTable dt = new DataTable(); adp.Fill(dt); dataGridView1.DataSource = dt; } This is beacuse I am using "[" in the select query. But it wont work for non keys. Or if I remove the "[" it is not working for key . Please suggest me so that I can get both key as well as nonkey column names.

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• Multiplication algorithm for abritrary precision (bignum) integers.

  - by nn

  Hi, I'm writing a small bignum library for a homework project. I am to implement Karatsuba multiplication, but before that I would like to write a naive multiplication routine. I'm following a guide written by Paul Zimmerman titled "Modern Computer Arithmetic" which is freely available online. On page 4, there is a description of an algorithm titled BasecaseMultiply which performs gradeschool multiplication. I understand step 2, 3, where B^j is a digit shift of 1, j times. But I don't understand step 1 and 3, where we have A*b_j. How is this multiplication meant to be carried out if the bignum multiplication hasn't been defined yet? Would the operation "*" in this algorithm just be the repeated addition method? Here is the parts I have written thus far. I have unit tested them so they appear to be correct for the most part: The structure I use for my bignum is as follows: #define BIGNUM_DIGITS 2048 typedef uint32_t u_hw; // halfword typedef uint64_t u_w; // word typedef struct { unsigned int sign; // 0 or 1 unsigned int n_digits; u_hw digits[BIGNUM_DIGITS]; } bn; Currently available routines: bn *bn_add(bn *a, bn *b); // returns a+b as a newly allocated bn void bn_lshift(bn *b, int d); // shifts d digits to the left, retains sign int bn_cmp(bn *a, bn *b); // returns 1 if a>b, 0 if a=b, -1 if a<b

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• Pros and cons of making database IDs consistent and "readable"

  - by gmale

  Question Is it a good rule of thumb for database IDs to be "meaningless?" Conversely, are there significant benefits from having IDs structured in a way where they can be recognized at a glance? What are the pros and cons? Background I just had a debate with my coworkers about the consistency of the IDs in our database. We have a data-driven application that leverages spring so that we rarely ever have to change code. That means, if there's a problem, a data change is usually the solution. My argument was that by making IDs consistent and readable, we save ourselves significant time and headaches, long term. Once the IDs are set, they don't have to change often and if done right, future changes won't be difficult. My coworkers position was that IDs should never matter. Encoding information into the ID violates DB design policies and keeping them orderly requires extra work that, "we don't have time for." I can't find anything online to support either position. So I'm turning to all the gurus here at SA! Example Imagine this simplified list of database records representing food in a grocery store, the first set represents data that has meaning encoded in the IDs, while the second does not: ID's with meaning: Type 1 Fruit 2 Veggie Product 101 Apple 102 Banana 103 Orange 201 Lettuce 202 Onion 203 Carrot Location 41 Aisle four top shelf 42 Aisle four bottom shelf 51 Aisle five top shelf 52 Aisle five bottom shelf ProductLocation 10141 Apple on aisle four top shelf 10241 Banana on aisle four top shelf //just by reading the ids, it's easy to recongnize that these are both Fruit on Aisle 4 ID's without meaning: Type 1 Fruit 2 Veggie Product 1 Apple 2 Banana 3 Orange 4 Lettuce 5 Onion 6 Carrot Location 1 Aisle four top shelf 2 Aisle four bottom shelf 3 Aisle five top shelf 4 Aisle five bottom shelf ProductLocation 1 Apple on aisle four top shelf 2 Banana on aisle four top shelf //given the IDs, it's harder to see that these are both fruit on aisle 4 Summary What are the pros and cons of keeping IDs readable and consistent? Which approach do you generally prefer and why? Is there an accepted industry best-practice?

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• Comet Jetty/Tomcat, having some browser issues with Firefox and Chrome

  - by ages04

  I am exploring the use of Comet for a project I am working on. I tried creating a test application first using Tomcat6 and CometProcessor API and then with Jetty7 Continuations. The application is kind of working on both but I am having some issues with the actual display of messages. I used the technique of creating an XMLHttpRequest Connection and keeping it open all the time so the server can continuously push data to all the clients connected whenever it is available. My client side code is something similar to this: function fn(){ var xhr = new XMLHttpRequest(); xhr.onreadystatechange = function(){ if (xhr.readyState==3){ document.getElementById('dv').innerHTML =(xhr.responseText); } if (xhr.readyState==4){ alert ('done'); } } xhr.open("GET", "First", true); xhr.send(null); } I found this thing of using readyState 3 somewhere online. I am facing 2 problems currently: In Firefox this code works perfectly. But if I open a new tab or even a new browser window, it does not make a new connection to the server and nothing shows up on the new tab or window, only the first tab/window gets the display. I used wireshark to check this and its shows only 1 connection even after the 2nd tab is opened. I am unable to understand why this would happen. I have read about the 2 connection limit, but here there is only one connection. Secondly in Chrome, the above code does not work, and the callback is not invoked for readystate of 3, only when the connection is closed by the server i get the output. I would also like to ask which is the best way/framework for doing Comet with Java. I am currently using jQuery on the client side. Any suggestions would be greatly appreciated!! Thanks

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• Getting values from DataGridView back to XDocument (using LINQ-to-XML)

  - by Pretzel

  Learning LINQ has been a lot of fun so far, but despite reading a couple books and a bunch of online resources on the topic, I still feel like a total n00b. Recently, I just learned that if my query returns an Anonymous type, the DataGridView I'm populating will be ReadOnly (because, apparently Anonymous types are ReadOnly.) Right now, I'm trying to figure out the easiest way to: Get a subset of data from an XML file into a DataGridView, Allow the user to edit said data, Stick the changed data back into the XML file. So far I have Steps 1 and 2 figured out: public class Container { public string Id { get; set; } public string Barcode { get; set; } public float Quantity { get; set; } } // For use with the Distinct() operator public class ContainerComparer : IEqualityComparer<Container> { public bool Equals(Container x, Container y) { return x.Id == y.Id; } public int GetHashCode(Container obj) { return obj.Id.GetHashCode(); } } var barcodes = (from src in xmldoc.Descendants("Container") where src.Descendants().Count() > 0 select new Container { Id = (string)src.Element("Id"), Barcode = (string)src.Element("Barcode"), Quantity = float.Parse((string)src.Element("Quantity").Attribute("value")) }).Distinct(new ContainerComparer()); dataGridView1.DataSource = barcodes.ToList(); This works great at getting the data I want from the XML into the DataGridView so that the user has a way to manipulate the values. Upon doing a Step-thru trace of my code, I'm finding that the changes to the values made in DataGridView are not bound to the XDocument object and as such, do not propagate back. How do we take care of Step 3? (getting the data back to the XML) Is it possible to Bind the XML directly to the DataGridView? Or do I have to write another LINQ statement to get the data from the DGV back to the XDocument? Suggstions?

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• How do I get the Silverlight Add-On for Visual Studio 2010 and some example code?

  - by xarzu

  How do I get the Silverlight Add-On for Visual Studio 2010? And where can I find lots of example code? When the interent and html was new, one could find examples of how to build a website on a few trusted web sites. The same web sites might not be the best choice for looking for examples for Silverlight, I guess. What are the best web sites where you can look at examples -- and most importantly -- look at the source code of some examples of Silverlight? Back when MFC existed as a option that programmers might use to develop windows applications, a coder could look at a huge list of sample code and step through that code to find something that somewhat did what he was looking for and use that example code to build his own app. Is there anything like that for Silverlight? I have found the http://gallery.expression.microsoft.com/ Expression Blend Gallery and I have found the http://www.silverlight.net/community/samples/silverlight-samples/ Silverlight dot net community samples. I guess that will keep me busy for a while. Are there other sites? There are video instructions on MSDN's Channel9: http://channel9.msdn.com/tags/curso-silverlight-4/ Are there any videos in English? The video instructions look very good. Where is the links to the English versions? I was suggested this site for learning silverlight: http://channel9.msdn.com/learn/courses/Silverlight4/ This online documentation mentions "The Silverlight 4 Tools for Visual Studio 2010" which "is an add-on for Visual Studio 2010 that provides tooling for Microsoft Silverlight 4 and WCF RIA Services. It can be installed on top of either Visual Studio 2010 or Visual Web Developer 2010 Express" where can I find this? Is it shipped with Visual Studio 2010?

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• Lua Alien Module - Trouble using WriteProcessMemory function, unsure on types (unit32)

  - by jefferysanders

  require "alien" --the address im trying to edit in the Mahjong game on Win7 local SCOREREF = 0x0744D554 --this should give me full access to the process local ACCESS = 0x001F0FFF --this is my process ID for my open window of Mahjong local PID = 1136 --function to open proc local op = alien.Kernel32.OpenProcess op:types{ ret = "pointer", abi = "stdcall"; "int", "int", "int"} --function to write to proc mem local wm = alien.Kernel32.WriteProcessMemory wm:types{ ret = "long", abi = "stdcall"; "pointer", "pointer", "pointer", "long", "pointer" } local pRef = op(ACCESS, true, PID) local buf = alien.buffer("99") -- ptr,uint32,byte arr (no idea what to make this),int, ptr print( wm( pRef, SCOREREF, buf, 4, nil)) --prints 1 if success, 0 if failed So that is my code. I am not even sure if I have the types set correctly. I am completely lost and need some guidance. I really wish there was more online help/documentation for alien, it confuses my poor brain. What utterly baffles me is that it WriteProcessMemory will sometimes complete successfully (though it does nothing at all, to my knowledge) and will also sometimes fail to complete successfully. As I've stated, my brain hurts. Any help appreciated.

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