Rdsvb.exe demonstrates how to use RDS with Visual Basic

• Building, debugging and testing a custom business object.
• Conflict resolution when submitting changes to the server.
• The "Three Techniques" for returning a recordset to a client using RDS, which include:
  
  
• Using the RDS.DataControl within Visual Basic.
• Using the RDS.DataSpace to generate a recordset from the default RDS business object, RDSServer.DataFactory.
• Using the RDS.DataSpace to generate a recordset from a custom business object.



• Generating a dynamic recordset using the CreateRecordset() method.

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About the RDSVB sample

• BusObj: An ActiveX DLL that has several methods both for validating the business object as well as for common activities used with RDS such as, conflict resolution and submitting a dynamically created Recordset.
• Local: Contains a minimalist interface for testing the business object outside of RDS.
• Remote: RDS Client implemented in Visual Basic that utilizes the Remote Data Service, and in particular, exercises the custom business object included with the sample.

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The BusObj project

   - Microsoft ActiveX Data Objects Library (Msado15.dll)
   - Microsoft Remote Data Services Server Library (Msadcf.dll)
				

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The Local Project

• A Connection String used to specify the datastore to be opened.
• A Query used to return data from the underlying datastore.
• A ProgID of the Business Object to be invoked.

• Create Custom Business Object and Open Recordset
  This button invokes the business object and calls the first three test methods. A recordset is cached locally upon successful completion of the underlying functionality.
• Automatically Add Record
  This button adds a record to the recordset returned previously by the business object. You use this button with multiple instances of either the local or remote client to test conflict resolution.
  This method looks at the last record in the Authors table, and adds a new one with a key 1 greater than the last existing record. If that record, say, has a key of 10, then a new record with a key of 11 is created. However, it is not posted to the datastore, so if multiple instances are running, each creates a new record with a key of 11. The first instance to submit its changes will (likely) post successfully. The next instance to attempt to submit its changes to the datastore fails, demonstrating the conflict resolution code of the custom business object.
• Submit Changes to Custom Business Object
  This method posts changes made to the recordset, such as records added with the previous button, to the business object. If any conflicts occurred, the business object returns details on which records failed.
• Create and Submit Dynamic Recordset
  This demonstrates how to use the CreateRecordset method to build a dynamic recordset, programmatically, and then pass it to the business object. This method actually cheats, because in theory your client application should be separate from RDS. However, in order to create a recordset programmatically, you have to do so with either the RDSServer.DataFactory or RDS.DataControl. To eliminate any dependence upon having IIS available, the sample uses the RDS.DataControl.

• Microsoft ActiveX Data Objects Recordset 1.5 Library (Msado15r.dll)
• Microsoft Remote Data Services 1.5 Library (Msadco.dll)

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The Remote Project

• The "Three Techniques" for retrieving data mentioned previously are demonstrated.
• Up to two columns from the recordset returned by each of the three techniques is visible, and navigation through the recordset is provided.
• The Remote Data Service is used to generate the business object. The Local project let us validate the third technique, by returning a recordset from a custom business object when that business object was invoked standalone. Now, the Remote sample demonstrates using RDS to invoke the business object to verify the same functionality.

• An incorrect URL was provided for the server running IIS/PWS, or else the server is not actually running.
• If you were testing with Local, it's possible an older version, or one without binary compatibility, of the business object is still loaded in memory. (In this case make sure you rebuild the DLL with binary compatibility, and that you do not have the Local Project open or executing, and therefore potentially the DLL still loaded in memory. The Remote Project references the following two typelibs:

    - Microsoft ActiveX Data Objects Recordset 1.5 Library (Msado15r.dll)
    - Microsoft Remote Data Services 1.5 Library (Msadco.dll)
  					

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Configuring and running the RDSVB sample

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Step 1: Compile and build the custom business object

1. Compile and build the DLL.
2. Using Regsvr32.exe, register the DLL in the location you want it to reside on the Web server.
3. Add the Registry key so that the business object is safe for launching:

   \HKEY_LOCAL_MACHINE
             \SYSTEM
                 \CurrentControlSet
                    \Services
                       \W3SVC
                           \Parameters
                               \ADCLaunch
                                  \VBCustBusObj.CBO]
   					

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Step 2: Verify the Local Client

1. Compile and build the Local Client.
2. Try each of the buttons in order. If you need to debug the business object, you will want to open the LocalTst.vbg Visual Basic Group file, instead of the Local Visual Basic Project file.

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Step 3: Verify the remote client

1. Open the Remote project. For your convenience, you might want to change the properties for the Server text box to indicate the URL of the server the Custom Business Object is registered on.
2. Compile and build the Remote project.
3. Open two instances of the compiled EXE. Try each of the techniques, and observe the results that occur when both EXEs try to post a new record with the same primary key. Now repeat this process, only distribute the Remote Client to another computer on the network.

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