N-tiers development method (how to use VB. NET to write COM + components)

Since the age of VB6, the method of writing and registering COM + components was not very complex, but it entered. net World, the process of writing has become more complicated.

Follow these steps:

Assume that you want to write a data access component of the data table (tdmomenu) in the database ddmo. You need to generate a package named [kdmo1000] in the component service, which contains a component pdmomenu. the dll contains two COM + components:
Project. Class

 

1. Pdmomenu. cdmomenu1 (without transaction): used to read data
2. Pdmomenu. cdmomenu2 (with transaction): used to maintain data

Writing steps:

2. Project Creation:
1. Create the directory [pdmomenu] of your component project under the appropriate directory]
2. Create Project and select class library. Set the directory to the directory of your project and the name to pdmomenu]
3. In Solution Explorer, click class1.vb. In properties, the file name is cdmomenu1.vb (without transaction) and cdmomenu2.vb (with transaction)
4. Right-click reference> Add reference and add system. enterpriseservices]
4. Project content:
1. Right-click a project → Properties)
2. Click sign and select sign component]
1. Select the strong name key file (choose a strong name key file ):
2. Select New> enter pdmomenu]
3. Click [ApplicationProgram(Application )]
   Check whether assembly name and root namespace are pdmomenu]
4. Click "component information" and tick "make component com-visiable (make assembly com-visiable )".
6. Assemblyinfo. VB:
1. Add imports at the top:
   Imports system. enterpriseservices
2. Add the following command at the bottom:
   <Assembly: applicationname ("kdmo1000")> '* sets the project name of the component service.
   <Assembly: applicationaccesscontrol (false)>
   <Assembly: applicationactivation (activationoption. Server)>
8. Class content:
2. No transaction class (cdmomenu1.vb ):

 Imports System. enterpriseservices Imports System. runtime. interopservices Imports System. Data. sqlclient Imports System. Data Imports System. Io 'Guid, please generate a new component when the component is created for the first time, and do not need to be changed later  "838a5fe4-2dcc-43df-8658-0697e8fb7c0f" ), _ Eventtrackingenabled ( True )> _ Public   Class Cdmomenu1 Inherits Servicedcomponent Const Dbname As   String = "Ddmo"            Public   Function Test1 ( Byval In1 () As   String , Byval Out1 () As   String , Byref P As   String , Byref R As   String , Byval User As   String )As   String            '*************************************** **********************************           *** Written by: topcat: 2006/8/9           '** Purpose: 1.           '** Practice:           '** 1.           '** Note:           '** 1.           '** 2.           '** Maintenance record:           '** Maintainer: Name maintenance Date: Date           '** Maintenance project:           '** 1.           '** 2.           '** Practice: 1.          '** 2.           '** Note:           '** 1.           '*************************************** **********************************           Dim Connstr As   String = Getconnstr (dbname) using Conn As   New Sqlconnection (connstr) Try Test1 = "Success"                     Catch Ex As Exception test1 = "False"                   Throw   New Exception (ex. Message) End   Try           End Using End   Function          Public   Function Getconnstr ( Byval Dbname As   String ) As   String            '*************************************** **********************************           *** Written by: topcat: 2006/2/8          '** Purpose: 1. Read the connection string           '** Practice:           '** 1. input the database name dbname parameter.           '** 2. Read text files through stream           '** 3. Return the obtained information           '** 4. Close related objects           '** Note:           '** 1.           '** 2.           '** Maintenance record:           '** Maintainer: Name (employee code) Maintenance Date: Date           '** Maintenance project:           '** 1.           '** 2.           '** Practice: 1.          '** 2.           '** Note:           '** 1.           '*************************************** **********************************            Dim Strmrd As   New Streamreader ( "C: \ datalink \" + Dbname + ". Ini" ) Dim Line As   String = ""            Dim Connstr As   String = ""            Try                Do Line = strmrd. Readline () If Line <> ""   Then Connstr + = line End   If                Loop   Until Line Is   Nothing Getconnstr = connstr Catch Ex As Exception Throw  New Exception (ex. Message. tostring) Finally Strmrd. Close () strmrd. Dispose () strmrd = Nothing             End   Try        End   Function    End   Class 

4. Transaction class (cdmomenu2.vb ):

 Imports System. enterpriseservices Imports System. runtime. interopservices Imports System. Data. sqlclientImports System. Data Imports System. Io "28549732-9a0f-4731-9688-10cee644500e" ) _, Transaction (transactionoption. Required) _, synchronization (synchronizationoption. Required) _, justintimeactivation ( True ) _, Eventtrackingenabled ( True )> _ Public   Class Cdmomenu2 Inherits Servicedcomponent Const Dbname As   String = "Ddmo" _Public   Function Test2 ( Byval In1 () As   String , Byval Out1 () As   String , Byref P As   String , Byref R As   String , Byval User As   String )As   String            '*************************************** **********************************           *** Written by: topcat: 2006/8/9           '** Purpose: 1.           '** Practice:           '** 1.           '** Note:           '** 1.           '** 2.           '** Maintenance record:           '** Maintainer: Name (employee code) Maintenance Date: Date           '** Maintenance project:           '** 1.           '** 2.           '** Practice: 1.          '** 2.           '** Note:           '** 1.           '*************************************** **********************************            Dim Connstr As   String = Getconnstr (dbname) using Conn As   New Sqlconnection (connstr) Try Test2 = "Success"               Catch Ex As Exception Test2 = "False"                  Throw   New Exception (ex. Message) End   Try           End Using End   Function          Public   Function Getconnstr ( Byval Dbname As   String ) As   String            '*************************************** **********************************           *** Written by: topcat: 2006/2/8          '** Purpose: 1. Read the connection string           '** Practice:           '** 1. input the database name dbname parameter.           '** 2. Read text files through stream           '** 3. Return the obtained information           '** 4. Close related objects           '** Note:           '** 1.           '** 2.           '** Maintenance record:           '** Maintainer: Name (employee code) Maintenance Date: Date           '** Maintenance project:           '** 1.           '** 2.           '** Practice: 1.          '** 2.           '** Note:           '** 1.           '*************************************** **********************************            Dim Strmrd As   New Streamreader ( "C: \ datalink \" + Dbname + ". Ini" ) Dim Line As   String = ""            Dim Connstr As   String = ""            Try                Do Line = strmrd. Readline () If Line <> ""   Then Connstr + = line End   If                Loop   Until Line Is   Nothing Getconnstr = connstr Catch Ex As Exception Throw  New Exception (ex. Message. tostring) Finally Strmrd. Close () strmrd. Dispose () strmrd = Nothing             End   Try        End   Function     End   Class 

After writing the relevant program, build the project, and then generate the DLL according to the position set by the Project property.