Pass Data Between BLL And UI In 3-layer (single Tier) Application?
Dec 4, 2009
I am a fairly rookie programmer who is trying to learn the basics of n-layered architecture (DAL, BLL, UI). The application I am programming is a single tier, 3-layer application written in VB.NET (.Net 3.5). Layers as follows:
DAL
BLL
UI
COMMON - contains DTO's right now.
I am having trouble determining what to pass between my BLL and UI. My instinct tells me that I should only pass data to the UI, and not the full business object from the BLL. Consider two scenarios:
1) Pass the BO directly from BLL to UI. This exposes BO methods and allows the UI direct access to the BO, which seems bad.
2) Pass only the pertinent data from the BO to the UI. For instance, a customer has a Name and Address. This data is really what we want to show/edit in the UI, so we would only return that data to the UI instead of the full BO. The UI would then call to the BLL to update a specific BO.
I am inclined to use #2, but I don't know the best way to implement it. The way I have it programmed now, if I only return data from the BLL, all references to my BO's will be lost and the GC will claim them. Based on this, I have some questions:
1) Should I keep business objects alive between calls to the BLL? The alternative is to re-create them every time I pass data through the BLL, which seems wrong.
2) What is the best way to keep a BO alive in a single tier architecture (how to hold a reference if we dont pass it to the UI?)
3) How do n-tier applications do this? Do they keep the BO's alive in the BLL and wait for an update from the UI? Doesn't this require a lot of "book keeping" in the BLL to make sure BO's are released when they are no longer needed?
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Jul 26, 2009
I am trying to prototype an application with a data layer on my computer at home using Visual Basic 2008 express edition with SQL Server Compact 3.5. My production situation at work is SQL Server 2000 and I am using Visual Basic 2005 professional for development.I am trying to write the code to create a seperate data layer. Here is my code. First the data layer:
Imports
System.Data
Imports[code].....
My Problem is that the data does not show up in the text boxes.
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Jul 25, 2011
I've never used a List(Of) before and I'm not sure how to pass it to the Data Layer of my application. The ColResCategory is a property within the Business Layer (See below) and it needs to be passed to the Data Layer. ReplaceResCategory (See 2nd Code view) is another class file within my Business Layer and the ColResCategory references it.
Public Property ColResCategory() As List(Of ReplaceResCategory)
Get
If IsNothing(mColResCategory) Then
mColResCategory = New List(Of ReplaceResCategory)
End If
Return mColResCategory
[Code] .....
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Feb 19, 2011
I'm creating a Data Layer for a Web Application and in one of my functions, I need to pass in a Structure full of Customer info. This Data Layer is essentially a DLL. My problem is that I'm not sure how to do this.Below is my code and what I want to do.
[Code]...
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Feb 7, 2011
I am generally following this tutorial, the main differences being I'm using 2008 R2 Express and Windows Forms, he is using 2005 & ASP.NET Web Site:'m building a minimalist Windows Form project for learning purposes. So I'm using a 1-table database with 2 columns, ContactID & Name. I added a dataset file, 'ContactsDataSet.xsd' to my project and added a single minimalist table adapter with just a fill() & getdata() method.Then I added a DataGridView control and connected it to the ContactsDataSet to confirm it was working and that worked fine. I ran it and it filled up with data as expected. Everything up to this point was auto-generated code.
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May 28, 2010
How to develop a 3 tier soution saying this. If you want to make a simple 3 layer system (3tier is for a longtime complete misused by marketing from Microsoft, 3 tier needs something like a Unix computer) However, do this: start a Windows Form project, then do 2 times File -> Add New -> Project -> Class Library while you name one DataLayer and the other BusinessLayer. While the DataLayer project is selected, you do Add New Item and take the Component (give it the name DataBaseHandling). Then while that component is open. In top Data -> and than what you want to select, however create in fact the DataSet and Adapter in that.
Don't forget to set in your main project a reference using Poject -> Project too your two datalayers. It is easy and don't need all those images, those you will see pasing by doing this. Try to avoid to use your DataLayer in your BusinessLayer which is often done, because then those layers make in fact no sence. i am not an expert The bussiness and datalayer in the same solution really? And when he said: "While the DataLayer project is selected, you do Add New Item and take the Component (give it the name DataBaseHandling)." What kind of component should i choose? and what about the presentation layer? how to call one layer to the other,
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Oct 20, 2010
The "named pipe" seems rediculous to pass data between processes (exe's). Is it possible to run a single instance of a VB.NET Class Libary (dll) such that two programs can access the same memory resident dll, thereby passing data via functions and or subs?When I try to make the class library as single instance, the "Enable Application Framework" is greyed out, and thus the option to "Make Application Single Instance" is also greyed out.When I try to call the dll from two processes, I simply just create two instances, so storing data in a module doesn't work
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Oct 14, 2009
Im trying to build my first N-Tier web application. And it seems like im doing it wrong. Ive been kinda working out of this book, but to me it doesnt seem like the right way to do this. In the book the guy builds User and Data centric objects but everywhere I see ntier everyone is always talking about BLL and DAL ive seen nothign on UC and DC objects.Right now I have Interfaces and serializable structures, user and data centric objects. The data centric object does all the validation and connecting to the db, as well as returns any violated rules, but when I once i started pulling it all together it just doesnt seem right.Ive already wrote a ____ load of code and now am kinda stuck. I dont know if i am doing this right and dont want to continue writing any code if this is all messed up.Ive been reading as much as humanly possible and im still just a little confused. I mean I understand the concepts of seperating the logic into different layers and tiers and all that but as far as my implementation of that I just feel somethings a bit off.
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Dec 12, 2009
I have a solution and I want to divide it up into Business Tier, Data Tier, etc. I think I have to do this by creating a project that contains the data source, another with the forms, etc. Every time I try to add a new project, it literally opens a new project, seperate from the first.
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Oct 16, 2011
i am on a project of two tier application with VB.NET + SQL server R2. except desk top applications i never done networked applications + i don't know asp.net
i require advise in few areas
(1) is the encryption required
(2) what are the security measures i must take in terms of connection security
(3) how to use the server effectively with out putting much burden through good client end design
(4) any other guide lines / pit falls
(5) should i continue with vb.net or must & should switch over to asp
(6) what should be the minimum configuration of client system,
(7) Preferable is the thin client systems , is it possible to use thin clients
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Apr 12, 2010
I have attempted to make my first 3 tier application. In the process I have run into one problem I am yet to find an optimal solution for. Basically all my objects use an IFillable interface which forces the implementation of a sub as follows
Public Sub Fill(ByVal Datareader As Data.IDataReader) Implements IFillable.Fill
This sub then expects the Ids from the datareader will be identical to the properties of the object as such.
Me.m_StockID = Datareader.GetGuid(Datareader.GetOrdinal("StockID"))
In the end I end up with a datalayer that looks something like this.
Public Shared Function GetStockByID(ByVal ConnectionString As String, ByVal StockID As Guid) As Stock
Dim res As New Stock
Using sqlConn As New SqlConnection(ConnectionString)[code].....
Mostly this pattern seems to make sense. However my problem is, lets say I want to implement a property for Stock called StockBarcodeList.Under the above mentioned pattern any way I implement this property I will need to pass a connectionstring to it which obviously breaks my attempt at layer separation.how I might be able to solve this problem or am I going about this the completely wrong way? I am deliberately trying to avoid using the dataset in any form.
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Oct 21, 2009
Using VB.NET 2008 I want to know what is 3 Tier Architecture for windows application? How to make a code for Inserting, Deleting, Updating in a database using 3 tier architecture.
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Feb 3, 2009
I'm sure this is possible but I've got no clue of what I'm looking for to even start to learn this. Basically I want to create a form that can load data from one software application and feed it to another.
Is it possible to change settings in other forms by another piece of software like if there was a flag = True and I wanted to change it to flag = False or instead of loading Dim processorID As String = String.Empty I can input Dim processorID As String = 1234
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Feb 8, 2011
Building a large application using 3 tier architecture in vb.net. Question: I am a vb.net developer. I have developed small and medium size application with 2 tier architecture. Now I am going to develop a large application. I have decided to develop that application using 3 tier architecture. So I studied about 3 tier. Now I know how what is 3 tier and how to develop a simple application. And also I studied about .Net Remoting and Web services. In my project, 7 modules are available. Each module has 3 layers. How can I manage in a Single Solution?
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Nov 30, 2010
I am working in VB.NET defining my own classes. I have 5 classes, Policy, Coverage, CoverageCollection, Layer, and LayerCollection. Policy has a bunch of data items, one of which is of type CoverageCollection. Coverage has a bunch of data items, one of which is of type LayerCollection.
Policy
private id as Long
private name as String[code].....
Then I do like "dim p as Policy". So, iIn order to get to properties on a Layer, I reference it like p.cov(0).lyr(0).face. What I am trying to do is add a readonly property to Layer that is calculated using some Layer information but also using something from Coverage (or even Policy). I can take this in as a parameter to the property, but I think there should be a way to get at Coverage/Policy information since I am "under" it already. Is there a way to do this?
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Oct 17, 2011
I am developing an application for internal use in our company. The purpose of this application is for document imaging. What we are wanting to do is print a barcode label to attach to documents so that when they are scanned in a piece of software such as vfiler will be able to read the barcodes and know how to file them.The main focus is our ERP system which is web based (PHP). We are wanting to modify the code to allow the user to print the barcode label immediately once they enter an order or PO. I have access to the source code for the ERP web pages. I don't know of any way to make a web page print to a printer without displaying the printer select dialog. So, I decided that I wanted to try and create a VB application that would do the printing of the barcodes. This would allow me to bypass the the printer select dialog.
Now for the question. Is there any way to have a web page (PHP) running on the server call a VB app to perform a task? So, if I had a button on the webpage and the user clicked it, that button would somehow send the pertinent information (Order number) to the VB app and the VB app would print the barcode. The VB app will always be running on the machine. The label printers will be Zebra USB label printers on each person's machine.
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Jun 11, 2011
I have a windows forms application with one exe and several dlls(Class libraries) in a single solution. The application uses common data that is used across all the dlls. I would like to load the data when the application is starting up and use the loaded data at various points in the dlls so that I do not have to load the common data again and again. How can I share the data loaded in main EXE across the DLLs?
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Nov 5, 2009
I have followed this walkthough at http:[url]...but I am having problems working out how to save changes to the Local Database Cache so that I can use the bidirectional sync. This walkthough does not provide the code to save local changes,I have added the line of code for the bidirectional sync and it works if you drag datasources direct onto the form from the XSD but this uses the component TableAdapterManager and the method UpdateALL which I cannot see how to implement in this Walkthough ?how I change the local Database Cache and update back to server in this walkthrough ?
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Aug 15, 2009
I was wondering if it was possible to pass data from one vb.net application to another vb.net application? If yes, how is this done?
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Jun 21, 2010
tier coding in retrieving data from database and display it in label.
I got the code for data access layer but im not sure if it's right:
Public Function getFeedbackQ(ByVal Question1 As String, ByVal Question2 As String, ByVal Question3 As String) As System.Data.DataSet
[code].....
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Aug 12, 2010
What i am looking is how to create a layer between the application and database? I need to create an xml files where the application will fetches the data and updates the data into local cache. Later from the xml files the data has to be transferred to database. Here the application need to work even when the application is in offline and database is not been connected.
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Sep 22, 2009
I am trying to clean up my code in a project I have been working on by creating two separate modules one that disables a service and one that enables a service through the registry all of this worked fine in one big form all together but I would like to also reuse the module in some other projects, I am getting this message however "Warning1Function 'ApplicationLayerGatewayDisable' doesn't return a value on all code paths. A null reference exception could occur at run time when the result is used". [Code]. what do i need to do to get rid of these warnings ? or do I just ignore them?
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May 22, 2009
I am putting some heavy though into re-writing the data access layer in my software(If you could even call it that). This was really my first project that uses, and things were done in an improper manner. In my project all of the data that is being pulled is being stored in an arraylist. some of the data is converted from the arraylist into an typed object, before being put backinto an arraylist.Also, there is no central set of queries in the application.This means that some queries are copy and pasted, which I want to eliminate as well.This application has some custom objects that are very standard to the application, and some queries that are very standard to those objects.
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Feb 20, 2009
I am implementing a Data Access Layer (DAL), which is basically a set of classes with (VB.NET) Shared functions to actually execute the database (CRUD) calls. I am trying to figure out the best place to place the calls to the DAL within the class hierarchy. Let me give an example.Suppose I have a class Customer, with only standard ID, Name, Address1, etc. properties and maybe an overridden ToString function or so. I also have a DAL class with Shared methods, such as:[code]Would this be "cleaner" OOP? Or is it acceptable practice to let the presentation call the Dal, passing the business objects like my previous example:[code]
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Jun 16, 2009
I have recently built an N-Tier app using VB.Net 2008. The application is based on Beth Massi's tutorial at [URL] I am trying to incorporate a datagrridview control on a Parent form - one parent (father and mother) to many children. For example,
[Code]...
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Mar 23, 2010
Im experiencing some problems while attempting to read a connection string from an App.config file in my Data Access Layer.I added the App.Config to the DAL Class Library, and added my connection string to the connectionStrings section but when I try to read it from my DAL its Returing Nothing.
[Code]...
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May 28, 2009
Need a SQL Server "SQLClient" (VB) Data Layer Class?
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Oct 1, 2009
One of the time consuming factors of writing the DAL is adding and assigning paramters of teh stored procedure if ther are more than 10 parameters and must link more than 3 tables this process will take a horrible amount of time..
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Mar 1, 2010
Im writing a data access layer for my application.There are several functions that need to return a list of items like Employee Name, and EmployeeID so it can be bound to a dropdownlist.What would be the proper datatype to return, a Dictionary?The lists only contain 2 columns, a name and id.
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Feb 27, 2009
We have data that's updated nightly in a database residing in the same instance as my app's database. So to save on database calls, I want to cache this static-for-the-day data into a List(Of MyObject). From a theory point of view, should this cached List(Of ) be cached in the presentation layer code, via a global variable? Should it be in a global variable in the .DLL?I'm thinking in the .DLL, because I created a service layer, which is exposed publicly to the GUI and makes calls to the data access layer inside the .DLL:
Public Shared Function Search(ByVal criteria As Core.Other.Customer) As List(Of Core.Other.Customer)
' TODO: Check the customer cache to see if it has been populated yet. If not, populate it.
If 1 = 1 Then
[code]....
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