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• using Autofac in a multi-layered architecture

  - by Kamyar

  I'm fairly new to the DI/IoC concept and would like to use Autofac in a 3-layered ASP.NET Webforms application. UI layer: An ASP.NET webforms website. BLL: Business logic layer which calls the repositories on DAL. DAL: .EDMX file (Entity Model) and ObjectContext with Repository classes which abstract the CRUD operations for each entity. Entities: The POCO Entities. Persistence Ignorant. Generated by Microsoft's ADO.Net POCO Entity Generator. I have asked a more general question here. Basically, I'd like to create an obejctcontext per HttpContext in my DAL. But i don't want to add a reference to DAL in UI or access to HttpContext in DAL directly. I guess this is where IoC tools come to play. The answer to my previous question is a very good example of using Windsor Castle. I'd like to use Autofac as my IoC tool and Don't know how to achieve this. (How to access DAL in application_start to register the component while I don't want to reference it in my UI, what are the proper references to be able to use DAL component in BLL with Autofac, Should I register BLL as a component with Autofac too) Sorry folks for not providing an explicit question and requesting a kind of working example, But I'm very unfamiliar to the whole IoC concept and I don't think I can achieve it to use in my current time-limited project.

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• Delphi: Fast(er) widestring concatenation

  - by Ian Boyd

  i have a function who's job is to convert an ADO Recordset into html: class function RecordsetToHtml(const rs: _Recordset): WideString; And the guts of the function involves a lot of wide string concatenation: while not rs.EOF do begin Result := Result+CRLF+ '<TR>'; for i := 0 to rs.Fields.Count-1 do Result := Result+'<TD>'+VarAsString(rs.Fields[i].Value)+'</TD>'; Result := Result+'</TR>'; rs.MoveNext; end; With a few thousand results, the function takes, what any user would feel, is too long to run. The Delphi Sampling Profiler shows that 99.3% of the time is spent in widestring concatenation (@WStrCatN and @WstrCat). Can anyone think of a way to improve widestring concatenation? i don't think Delphi 5 has any kind of string builder. And Format doesn't support Unicode. And to make sure nobody tries to weasel out: pretend you are implementing the interface: IRecordsetToHtml = interface(IUnknown) function RecordsetToHtml(const rs: _Recordset): WideString; end; Update One I thought of using an IXMLDOMDocument, to build up the HTML as xml. But then i realized that the final HTML would be xhtml and not html - a subtle, but important, difference. Update Two Microsoft knowledge base article: How To Improve String Concatenation Performance

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• Convert C# Silverlight App To AZURE CLOUD Platform?!?!

  - by Goober

  The Scenario I've been following Brad Abrams Silverlight tutorial on his blog.... I have tried following Brads "How to deploy your app to the Cloud" tutorial however i'm struggling with it, even though it is in the same context as the first tutorial.... The Question Is the application structure essentially the same as the original "non-cloud based version"!? If not, which parts are different? (I get that there is a Cloud Service project added to the solution) - but what else?! Connection String Issue In my "Non-Cloud based application", I make use of the ADO.Net Entity Framework to communicate with my database. The connection string in my web.config file looks like: <add name="InmZenEntities" connectionString="metadata=res://*/InmZenModel.csdl|res://*/InmZenModel.ssdl|res://*/InmZenModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=CHASEDIGITALWS3;Initial Catalog=InmarsatZenith;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient" /></connectionStrings> However However the connection string that I get from SQL AZURE looks like: Server=tcp:k12ioy1rsi.ctp.database.windows.net;Database=master;User ID=simongilbert;Password=myPassword;Trusted_Connection=False; So how do I go about merging the two when I move the "non-cloud based application" to THE CLOUD?! Any help regarding converting a silverlight application to a cloud service and deploying it would be greatly appreciated

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• silverlight security with WCF service, Forms Authentication and Custom Form Ticket

  - by user74825

  I have a silverlight application with login on the silverlight page. It uses Forms Authentication with WCF authentication service and customer Membership Provider. Something like : http://blogs.msdn.com/phaniraj/archive/2009/09/10/using-the-ado-net-data-services-silverlight-client-library-in-x-domain-and-out-of-browser-scenarios-ii-forms-authentication.aspx So, SL page login page calls the WCF service authentication service, it validates using DB - brings back username and password. Now, in each subsequent calls (in Global.asax in Authenticate_Request, I get HttpContext.User.IsAuthenticated and HttpContext.User.UserName). I have all this working properly. But, I just don't want the username, but more information surrounding the user, like UserId, UserAddress, UserAssociateCustomer etc. I tried couple of different approaches. 1) Use HttpContext.Cache as a dictionary to save the item and get it off based on httpcontext.user.name, problem is cache can be erased if there memory is being used heavily. 2) Tried CustomFormsAuth Ticket, when forms authentication writes a ticket, I intercept CreatingCookie method and write additional info in formauthentication ticket, so that I can read it in subsequent requests, I am having problems with this approach, I don't find the ticket in subsequent requests. I read about how we should use REsponse.Redirect, but where do I redirect user from WCF call. How do you guys implement the above scenario? Any best practices.? Any issues you see with going on HTTPS? All examples (or most of them) just explains simple forms authentication with "I am logged in message".. Any suggestions ?

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• how to update the table in sql database from a Paradox DB table using delphi

  - by Sreenath Krishnakumar

  I am doing a project in Delphi6 which enables the user to update the table in SQL server database ; if there is any changes in the table of Paradox DB. An update button has been created and whenever the user clicks it, all the changes made in the paradox db table have to be updated in the SQL server table. Only if there is any changes the table need to be updated else ; it should close automatically. For that I have created a table, "Schedule" ,both in Paradox DB and SQL server. But I am stuck with this Paradox DB thing. Which component can I drop in the form for connecting the table in Paradox DB ? For SQL server I used ado table component. For this Paradox also can I use that ? I am not a regular programmer so I am not well versed this Delphi6 also. So I am seeking a help for this. Can anybody give me an example coding also ?

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• Access ADP - For/Against?

  - by webworm

  I have been tasked with taking an Access 97 application and moving the back-end data to SQL Server while moving the front end to Access 2003 (using Access Data Projects). In the process of this migration the back-end data structures will be changed significantly to support new functionality. If I had my wish we would not be using Access as the front end. I think our application would be much better served by WinForms, WPF, or a web application. We have the time needed to properly plan a business logic layer and implement an excellent solution but powers above me want to stay with Access because that is what they are familiar with. What I could use help with is pros/cons of continuing down this path of Access development. What are some legitimate arguments for and against using Access 2003? Here is what I have come up with so far. Pro Access: Already own Access 2003 licenses Easy GUI development Reports look nice Against Access Having to use VBA (Visual Basic for Applications) ADO vs DAO. Didn't Microsoft change things from Access 2002 to Access 2003? Not tied to Access runtime Choice in front end (WPF, WinForms, even ASP.NET) Maintainability True separation of logic from UI not possible Does Microsoft still support Access ADP? Perhaps there are other issues I am not aware off both for and against Access for application development. I am trying to keep an open mind while at the same time trying to maintain my sanity. I have been using C# since .NET was released and the thought of going back to VBA for six months makes my head hurt. Especially when I feel I could offer so much more if allowed to develop with modern languages and tools?

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• How to put large text data (~20mb) into sql cs 3.5 database?

  - by Anindya Chatterjee

  I am using following query to insert some large text data : internal static string InsertStorageItem = "insert into Storage(FolderName, MessageId, MessageDate, StorageData) values ('{0}', '{1}', '{2}', @StorageData)"; and the code I am using to execute this query is as follows : string content = "very very large data"; string query = string.Format(InsertStorageItem, "Inbox", "AXOGTRR1445/DSDS587444WEE", "4/19/2010 11:11:03 AM"); var command = new SqlCeCommand(query, _sqlConnection); var paramData = command.Parameters.Add("@StorageData", System.Data.SqlDbType.NText); paramData.Value = content; paramData.SourceColumn = "StorageData"; command.ExecuteNonQuery(); But at the last line I am getting this following error : System.Data.SqlServerCe.SqlCeException was unhandled by user code Message=The data was truncated while converting from one data type to another. [ Name of function(if known) = ] Source=SQL Server Compact ADO.NET Data Provider HResult=-2147467259 NativeError=25920 StackTrace: at System.Data.SqlServerCe.SqlCeCommand.ProcessResults(Int32 hr) at System.Data.SqlServerCe.SqlCeCommand.ExecuteCommandText(IntPtr& pCursor, Boolean& isBaseTableCursor) at System.Data.SqlServerCe.SqlCeCommand.ExecuteCommand(CommandBehavior behavior, String method, ResultSetOptions options) at System.Data.SqlServerCe.SqlCeCommand.ExecuteNonQuery() at Chithi.Client.Exchange.ExchangeClient.SaveItem(Item item, Folder parentFolder) at Chithi.Client.Exchange.ExchangeClient.DownloadNewMails(Folder folder) at Chithi.Client.Exchange.ExchangeClient.SynchronizeParentChildFolder(WellKnownFolder wellknownFolder, Folder parentFolder) at Chithi.Client.Exchange.ExchangeClient.SynchronizeFolders() at Chithi.Client.Exchange.ExchangeClient.WorkerThreadDoWork(Object sender, DoWorkEventArgs e) at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e) at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument) InnerException: Now my question is how am I supposed to insert such large data to sqlce db? Regards, Anindya Chatterjee http://abstractclass.org

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• What is the basic pattern for using (N)Hibernate?

  - by Vilx-

  I'm creating a simple Windows Forms application with NHibernate and I'm a bit confused about how I'm supposed to use it. To quote the manual: ISession (NHibernate.ISession) A single-threaded, short-lived object representing a conversation between the application and the persistent store. Wraps an ADO.NET connection. Factory for ITransaction. Holds a mandatory (first-level) cache of persistent objects, used when navigating the object graph or looking up objects by identifier. Now, suppose I have the following scenario: I have a simple classifier which is a MSSQL table with two columns - ID (auto_increment) and Name (nvarchar). To edit this classifier I create a form which contains a single gridview and two buttons - OK and Cancel. The user can nearly directly edit the table in the gridview, and when he hits OK the changes he made are persisted to the DB (or if he hits cancel, nothing happens). Now, I have several questions about how to organize this: What should the lifetime of my ISession be? Should I create a single ISession for my whole application; an ISession for each of my forms (the application is single-threaded MDI); or an ISession for every DB operation/transaction? Does NHibernate offer some kind of built-in dirty tracking or must I do this myself? The manual mentions something like it here and there but does not go into details. How is this done? Is there not a huge overhead? Is it somehow tied with the cache(s) that NHibernate has? What are these caches for? Are they not specific to a single ISession? That is, if I use a seperate ISession for every transaction, won't it break the dirty tracking? How does the built-in dirty tracking detect deleted objects?

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• LinqKit stack overflow exception using predicate builder

  - by MLynn

  I am writing an application in C# using LINQ and LINQKit. I have a very large database table with company registration numbers in it. I want to do a LINQ query which will produce the equivalent SQL: select * from table1 where regno in('123','456') The 'in' clause may have thousands of terms. First I get the company registration numbers from a field such as Country. I then add all the company registration numbers to a predicate: var predicate = PredicateExtensions.False<table2>(); if (RegNos != null) { foreach (int searchTerm in RegNos) { int temp = searchTerm; predicate = predicate.Or(ec => ec.regno.Equals(temp)); } } On Windows Vista Professional a stack overflow exception occured after 4063 terms were added. On Windows Server 2003 a stack overflow exception occured after about 1000 terms were added. I had to solve this problem quickly for a demo. To solve the problem I used this notation: var predicate = PredicateExtensions.False<table2>(); if (RegNosDistinct != null) { predicate = predicate.Or(ec => RegNos.Contains(ec.regno)); } My questions are: Why does a stack overflow occur using the foreach loop? I take it Windows Server 2003 has a much smaller stack per process\thread than NT\2000\XP\Vista\Windows 7 workstation versions of Windows. Which is the fastest and most correct way to achieve this using LINQ and LINQKit? It was suggested I stop using LINQ and go back to dynamic SQL or ADO.NET but I think using LINQ and LINQKit is far better for maintainability.

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• Images from SQL Server JPG/PNG Image Column not being Type Converted to Bitmap in HttpHandlers (cons

  - by kanchirk

  Our Silverlight 3.0 Client consumes Images stored/retrieved on the File System thorough ASP.NET HttpHandlers successfully. We are trying to store and read back Images using a SQL Server 2008 Database. Please find the stripped down code pasted below with the Exception. "Bitmap is not Valid" //Store document to the database private void SaveImageToDatabaseKK(HttpContext context, string pImageFileName) { try { //ADO.NET Entity Framework ImageTable documentDB = new ImageTable(); int intLength = Convert.ToInt32(context.Request.InputStream.Length); //Move the file contents into the Byte array Byte[] arrContent = new Byte[intLength]; context.Request.InputStream.Read(arrContent, 0, intLength); //Insert record into the Document table documentDB.InsertDocument(pImageFileName, arrContent, intLength); } catch { } } =The method to Read Back the Row from the Table and Send it back is below.= private void RetrieveImageFromDatabaseTableKK(HttpContext context, string pImageName) { try { ImageTable documentDB = new ImageTable(); var docRow = documentDB.GetDocument(pImageName); //based on Imagename which is unique //DocData column in table is **Image** if (docRow!=null && docRow.DocData != null && docRow.DocData.Length > 0) { Byte[] bytImage = docRow.DocData; if (bytImage != null && bytImage.Length > 0) { Bitmap newBmp = ConvertToBitmap(context, bytImage ); if (newBmp != null) { newBmp.Save(context.Response.OutputStream, ImageFormat.Jpeg); newBmp.Dispose(); } } } } catch (Exception exRI) { } } // Convert byte array to Bitmap (byte[] to Bitmap) protected Bitmap ConvertToBitmap(byte[] bmp) { if (bmp != null) { try { TypeConverter tc = TypeDescriptor.GetConverter(typeof(Bitmap)); Bitmap b = (Bitmap)tc.ConvertFrom(bmp); **//This is where the Exception Occurs.** return b; } catch (Exception) { } } return null; }

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• Important question about linq to SQL performance on high loaded web applications

  - by Alex

  I started working with linq to SQL several weeks ago. I got really tired of working with SQL server directly through the SQL queries (sqldatareader, sqlcommand and all this good stuff).  After hearing about linq to SQL and mvc I quickly moved all my projects to these technologies. I expected linq to SQL work slower but it suprisongly turned out to be pretty fast, primarily because I always forgot to close my connections when using datareaders. Now I don't have to worry about it. But there's one problem that really bothers me. There's one page that's requested thousands of times a day. The system gets data in the beginning, works with it and updates it. Primarily the updates are ++ @ -- (increase and decrease values). I used to do it like this UPDATE table SET value=value+1 WHERE ID=@I'd It worked with no problems obviously. But with linq to SQL the data is taken in the beginning, moved to the class, changed and then saved. Stats.registeredusers++; Db.submitchanges(); Let's say there were 100 000 users. Linq will say "let it be 100 001" instead of "let it be increased by 1". But if there value of users has already been increased (that happens in my site all the time) then linq will be like oops, this value is already 100 001. Whatever I'll throw an exception" You can change this behavior so that it won't throw an exception but it still will not set the value to 100 002. Like I said, it happened with me all the time. The stas value was increased twice a second on average. I simply had to rewrite this chunk of code with classic ado net. So my question is how can you solve the problem with linq

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• When should I be cautious using data binding in .NET?

  - by Ben McCormack

  I just started working on a small team of .NET programmers about a month ago and recently got in a discussion with our team lead regarding why we don't use databinding at all in our code. Every time we work with a data grid, we iterate through a data table and populate the grid row by row; the code usually looks something like this: Dim dt as DataTable = FuncLib.GetData("spGetTheData ...") Dim i As Integer For i = 0 To dt.Rows.Length - 1 '(not sure why we do not use a for each here)' gridRow = grid.Rows.Add() gridRow(constantProductID).Value = dt("ProductID").Value gridRow(constantProductDesc).Value = dt("ProductDescription").Value Next '(I am probably missing something in the code, but that is basically it)' Our team lead was saying that he got burned using data binding when working with Sheridan Grid controls, VB6, and ADO recordsets back in the nineties. He's not sure what the exact problem was, but he remembers that binding didn't work as expected and caused him some major problems. Since then, they haven't trusted data binding and load the data for all their controls by hand. The reason the conversation even came up was because I found data binding to be very simple and really liked separating the data presentation (in this case, the data grid) from the in-memory data source (in this case, the data table). "Loading" the data row by row into the grid seemed to break this distinction. I also observed that with the advent of XAML in WPF and Silverlight, data-binding seems like a must-have in order to be able to cleanly wire up a designer's XAML code with your data. When should I be cautious of using data-binding in .NET?

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• ASP.NET DropDownList posting ""

  - by Daniel

  I am using ASP.NET forms version 3.5 in VB I have a dropdownlist that is filled with data from a DB with a list of countries The code for the dropdown list is <label class="ob_label"> <asp:DropDownList ID="lstCountry" runat="server" CssClass="ob_forminput"> </asp:DropDownList> Country*</label> And the code that the list is Dim selectSQL As String = "exec dbo.*******************" ' Define the ADO.NET objects. Dim con As New SqlConnection(connectionString) Dim cmd As New SqlCommand(selectSQL, con) Dim reader As SqlDataReader ' Try to open database and read information. Try con.Open() reader = cmd.ExecuteReader() ' For each item, add the author name to the displayed ' list box text, and store the unique ID in the Value property. Do While reader.Read() Dim newItem As New ListItem() newItem.Text = reader("AllSites_Countries_Name") newItem.Value = reader("AllSites_Countries_Id") CType(LoginViewCart.FindControl("lstCountry"), DropDownList).Items.Add(newItem) Loop reader.Close() CType(LoginViewCart.FindControl("lstCountry"), DropDownList).SelectedValue = 182 Catch Err As Exception Response.Redirect("~/error-on-page/") MailSender.SendMailMessage("*********************", "", "", OrangeBoxSiteId.SiteName & " Error Catcher", "<p>Error in sub FillCountry</p><p>Error on page:" & HttpContext.Current.Request.Url.AbsoluteUri & "</p><p>Error details: " & Err.Message & "</p>") Response.Redirect("~/error-on-page/") Finally con.Close() End Try When the form is submitted an error occurs which says that the string "" cannot be converted to the datatype integer. For some reason the dropdownlist is posting "" rather than the value for the selected country.

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• Attachment_fu file saving problem

  - by Anand

  Attachment_fu plugin is kind of old, but I have to modify an old app and I can't use another plugin like paperclip etc. So here's the code without further ado Submissions table structure --------------------------- | content_type | varchar(255) | YES | | NULL | filename | varchar(255) | YES | | NULL app/models/submission.rb ------------------------ has_attachment :storage => :file_system, :path_prefix => 'public/submissions', :max_size => 2.megabytes, :content_type => ['application/pdf', 'application/msword', 'text/plain'] app/models/user.rb ------------------ has_one :submission, :dependent => :destroy app/views/user/some_action.html.erb ----------------------------------- <% form_for :user, :url => { :action => "some_action" }, :html => {:multipart => true} do |f| %> .... <%= file_field_tag "submission[uploaded_data]" %> <%end%> app/controllers/user_controller.rb ---------------------------------- @user = User.find_user(session[:user_id]) @submission = @user.submission if request.post? @submission.uploaded_data = params[:submission][:uploaded_data] end When the form is submitted, the database fields "content_type" and "filename" get updated and display the correct values, but the file does not appear in public/submissions/ directory. I have checked the permissions on the submissions directory. What am I missing? Many Thanks

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• Running an existing LINQ query against a dynamic object (DataTable like)

  - by TomTom

  Hello, I am working on a generic OData provider to go against a custom data provider that we have here. Thsi is fully dynamic in that I query the data provider for the table it knows. I have a basic storage structure in place so far based on the OData sample code. My problem is: OData supports queries and expects me to hand in an IQueryable implementation. On the lowe rside, I dont have any query support. Not a joke - the provider returns tables and the WHERE clause is not supported. Performance is not an issue here - the tables are small. It is ok to sort them in the OData provider. My main problem is this. I submit a SQL statement to get out the data of a table. The result is some sort of ADO.NET data reader here. I need to expose an IQueryable implementation for this data to potentially allow later filtering. Any ide ahow to best touch that? .NET 3.5 only (no 4.0 planned for some time). I was seriously thinking of creating dynamic DTO classes for every table (emitting bytecode) so I can use standard LINQ. Right now I am using a dictionary per entry (not too efficient) but I see no real way to filter / sort based on them.

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• .NET How would I build a DAL to meet my requirments?

  - by Jonno

  Assuming that I must deploy an asp.net app over the following 3 servers: 1) DB - not public 2) 'middle' - not public 3) Web server - public I am not allowed to connect from the web server to the DB directly. I must pass through 'middle' - this is purely to slow down an attacker if they breached the web server. All db access is via stored procedures. No table access. I simply want to provide the web server with a ado dataset (I know many will dislike this, but this is the requirement). Using asmx web services - it works, but XML serialisation is slow and it's an extra set of code to maintain and deploy. Using a ssh/vpn tunnel so that the one connects to the db 'via' the middle server, seems to remove any possible benefit of maintaining 'middle'. Using WCF binary/tcp removes the XML problem, but still there is extra code. Is there an approach that provides the ease of ssh/vpn, but the potential benefit of having the dal on the middle server? Many thanks.

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• Optimzing TSQL code

  - by adopilot

  My job is the maintain one application which heavy use SQL server (MSSQL2005). Until now middle server stores TSQL codes in XML and send dynamic TSQL queries without using stored procs. As I am able change those XML queries I want to migrate most of my queries to stored procs. Question is folowing: Most of my queries have same Where conditions against one table Sample: Select ..... from .... where .... and (a.vrsta_id = @vrsta_id or @vrsta_id = 0) and (a.podvrsta_id = @podvrsta_id or @podvrsta_id = 0) and (a.podgrupa_2 = @podgrupa2_id or @podgrupa2_id = 0) and ( (a.id in (select art_id from osobina_veze where podosobina_id in (select ado from dbo.fn_ado_param_int(@podosobina)) group by art_id having count(art_id)= @podosobina_count )) or ('0' = @podosobina) ) They also have same where conditions on other table. How I should organize my code ? What is proper way ? Should I make table valued function that I will use in all queries or use #Temp tables and simple inner join my query to that each time when proc executing? or use #temp filed by table valued function ? or leave all queries with this large where clause and hope that index is going to do their jobs. or use WITH(statement)

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• linq: SQL performance on high loaded web applications

  - by Alex

  I started working with linq to SQL several weeks ago. I got really tired of working with SQL server directly through the SQL queries (sqldatareader, sqlcommand and all this good stuff).  After hearing about linq to SQL and mvc I quickly moved all my projects to these technologies. I expected linq to SQL work slower but it suprisongly turned out to be pretty fast, primarily because I always forgot to close my connections when using datareaders. Now I don't have to worry about it. But there's one problem that really bothers me. There's one page that's requested thousands of times a day. The system gets data in the beginning, works with it and updates it. Primarily the updates are ++ @ -- (increase and decrease values). I used to do it like this UPDATE table SET value=value+1 WHERE ID=@I'd It worked with no problems obviously. But with linq to SQL the data is taken in the beginning, moved to the class, changed and then saved. Stats.registeredusers++; Db.submitchanges(); Let's say there were 100 000 users. Linq will say "let it be 100 001" instead of "let it be increased by 1". But if there value of users has already been increased (that happens in my site all the time) then linq will be like oops, this value is already 100 001. Whatever I'll throw an exception" You can change this behavior so that it won't throw an exception but it still will not set the value to 100 002. Like I said, it happened with me all the time. The stas value was increased twice a second on average. I simply had to rewrite this chunk of code with classic ado net. So my question is how can you solve the problem with linq

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• how can I save/keep-in-sync an in-memory graph of objects with the database?

  - by Greg

  Question - What is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Background: That is say I have the classes Node and Relationship, and the application is building up a graph of related objects using these classes. There might be 1000 nodes with various relationships between them. The application needs to query the structure hence an in-memory approach is good for performance no doubt (e.g. traverse the graph from Node X to find the root parents) The graph does need to be persisted however into a database with tables NODES and RELATIONSHIPS. Therefore what is a good best practice approach for how can I save/keep-in-sync an jn-memory graph of objects with the database? Ideal requirements would include: build up changes in-memory and then 'save' afterwards (mandatory) when saving, apply updates to database in correct order to avoid hitting any database constraints (mandatory) keep persistence mechanism separate from model, for ease in changing persistence layer if needed, e.g. don't just wrap an ADO.net DataRow in the Node and Relationship classes (desirable) mechanism for doing optimistic locking (desirable) Or is the overhead of all this for a smallish application just not worth it and I should just hit the database each time for everything? (assuming the response times were acceptable) [would still like to avoid if not too much extra overhead to remain somewhat scalable re performance]

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• ADODB.Connection undefined

  - by Wes Groleau

  Reference http://stackoverflow.com/questions/1690622/excel-vba-to-sql-server-without-ssis After I got the above working, I copied all the global variables/constants from the routine, which included Const CS As String = "Driver={SQL Server};" _ & "Server=**;" _ & "Database=**;" _ & "UID=**;" _ & "PWD=**" Dim DB_Conn As ADODB.Connection Dim Command As ADODB.Command Dim DB_Status As Stringinto a similar module in another spreadsheet. I also copied Sub Connect_To_Lockbox() If DB_Status < "Open" Then Set DB_Conn = New Connection DB_Conn.ConnectionString = CS DB_Conn.Open ' problem! DB_Status = "Open" End If End SubI added the same reference (ADO 2.8) The first spreadsheet still works; the seccond at DB_Conn.Open pops up "Run-time error '-214767259 (80004005)': [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified" Removing the references on both, saving files, re-opening, re-adding the references doesn't help. The one still works and the other gets the error. ?!?

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• MSSQL in ASP.NET application getting unstable after a certain period

  - by Barslett

  Hello, I have an ASP.NET 2.0 application that I made to keep track of disruption reports about our public transport system. The architecture is pretty straight-forward; an MSSQL Express 2008 database, ADO.NET and a DataSet/DAL with a few methods to access the database. There is a set of .aspx pages for the UI in use by our dispatchers and on our public website, as well as a set of SOAP and REST webservices and an RSS feed. Everything worked just fine for more than a year, until two weeks ago. Now and then, it seems as the database enters an unstable mode, and the application starts responding something right, something wrong. The typical error is that apparently, an empty DataTable is returned to the public disruption overview or to the RSS generator. Thus, the user gets e.g. an empty GridView, but no exception is thrown AFAIK, and nothing is written to the Windows Application log. After a restart of the MSSQL Express service, the situation is back to normal. It has to be said that the situation first time appeared a few days after I made a new minor upgrade of the application. The RSS generator was slightly rewritten, and I added a WCF REST service. But the DAL and the database schema were untouched... Any hints of how we could keep the database stable? It is a bit annoying not to have a clue ;-)

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• Delphi Client-Server Application using Firebird 2.5 embedded connection error

  - by Japster

  0 down vote favorite 1 share [fb] share [tw] I have got a lengthy question to ask. First of all Im still very new when it comes to Delphi programming and my experience has beem mostly developing small single user database applications using ADO and an Access database. I need to take the transition now to a client server application and this is where the problem starts. I decided to use Firebird 2.5 embeded as my database, as it is open source, and it is can be used with the interbase components in Delphi and that multiple clients can access the database simultanously. So I followed the interbase tutorial in Delphi. I managed to connect the client to the server and see the data in the example (While both are running on my pc), but when i tried to move the client to another pc, keeping the server on mine and running it to see if I can connect to the server it gave me the following error. Exception EIdSocketError in module clientDemo.exe at 0029DCAC. Socket Error # 10061 Connection refused. I understand that this might be because the host is defined as localhost in the client. But here is my first question. In the TSQLConncetion you can set die hostname under Driver-Hostname. The thing I want to know is how do you do this at run time, as I cannot get the property when I try and make an edit box to allow the user to enter the value and then set it via code like for example: SQLConncetion1.Driver.Hostname := edtHost.text; This cannot be done this way and the only way I see you can set the hostname is with the object inspector, but that is not available at runtime and I need to set the hostname on the client when the program is running the first time, so how do you set the hostname/IP address at runtime? Im using Delphi XE2 There is still a lot of questions to come especially when it comes to deployment, but I will take this piece by piece and I appreciate the advice.

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• Modelling deterministic and nondeterministic data separately

  - by Superstringcheese

  I'm working with the Microsoft ADO.NET Entity Framework for a game project. Following the advice of other posters on SO, I'm considering modelling deterministic and nondeterministic data separately. The idea for this came from a discussion on multiplayer games, but it seemed to make sense in a single-player scenario as well. Deterministic (things that aren't going to change during gameplay) Attributes (Strength, Agility, etc.) and their descriptions Skills and their descriptions and requirements Races, Factions, Equipment, etc. Base Attribute/Skill/Equipment loadouts for monsters Nondeterministic (things that will change a lot during gameplay) Beings' current AttributeModifers (Potion of Might = +10 Strength), current health and mana, etc. Player inventory, cash, experience, level Player quests states Player FactionRelationships ...and so on. My deterministic model would serve as a set of constants. My nondeterministic model would provide my on-the-fly operable data and would be serialized to a savegame file to maintain game state between play sessions. The data store will be an embedded SQL Compact database. So I might want to create relations between my Attributes table (deterministic model) and my BeingAttributeModifiers table (nondeterministic model), but how do I set that up across models? Det model/db Nondet model/db ____________ ________________________ |Attributes | |PlayerAttributeModifiers| |------------| |------------------------| |Id | |Id | |Name | |AttributeId | |Description | |SourceId | ------------ |Value | ------------------------ Should I use two separate models (edmx) that transact with a single database containing both deterministic-type and nondeterministic-type tables? Or should/can I use two separate databases in one model? Or two models each with their own database? With distinct models/dbs it seems like this will get really complicated and I'll end up fighting EF a lot, rolling my own transaction code, and generally losing out on a lot of the advantages of the framework. I know these are vague questions, I'm just looking for a sanity check before I forge ahead any further.

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• Entity Framework in layered architecture

  - by Kamyar

  I am using a layered architecture with the Entity Framework. Here's What I came up with till now (All the projects Except UI are class library): Entities: The POCO Entities. Completely persistence ignorant. No Reference to other projects. Generated by Microsoft's ADO.Net POCO Entity Generator. DAL: The EDMX (Entity Model) file with the context class. (t4 generated). References: Entities BLL: Business Logic Layer. Will implement repository pattern on this layer. References: Entities, DAL. This is where the objectcontext gets populated: var ctx=new DAL.MyDBEntities(); UI: The presentation layer: ASP.NET website. References: Entities, BLL + a connection string entry to entities in the config file (question #2). Now my three questions: Is my layer discintion approach correct? In my UI, I access BLL as follows: var customerRep = new BLL.CustomerRepository(); var Customer = customerRep.GetByID(myCustomerID); The problem is that I have to define the entities connection string in my UI's web.config/app.config otherwise I get a runtime exception. IS defining the entities connectionstring in UI spoils the layers' distinction? Or is it accesptible in a muli layered architecture. Should I take any additional steps to perform chage tracking, lazy loading, etc (by etc I mean the features that Entity Framework covers in a conventional, 1 project, non POCO code generation)? Thanks and apologies for the lengthy question.

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• Keeping updated with the latest technologies.

  - by Prashanth

  I am a software developer and I have been programming since the past six years. I simply love the mental challenge involved in trying to come up with solutions to hard problems, reading up programming literature, blogs by prominent developers and so on. I work on Microsoft platform and I have trouble keeping up with the pace at which various frameworks are rolled out. Remoting,WCF,ASP.NET,ASP.NET MVC, LINQ, WPF, WWF, OSLO, ADO.NET data services, DSL tools etc etc. Even understanding all these frameworks at an abstract level and see how they are all tied up with MS vision itself is a major hurdle. Now when you add other non microsoft technologies, programming languages etc to the equation, I wonder how do people manage? Given that there are only 24 hours in a day, how does one keep himself updated about so many technology changes that happen everyday? My question is , is it even worth doing that? The thing is, I am also interested in other fields such as literature, science. I try my best to at least gain a superficial understanding of what is happening in other fields of my interest and don't want to give up on that :)

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