INFO: Comparing RDS Technology to RDO and DAO (165804)

SUMMARY

NOTE: With version 1.5, the Remote Data Service (RDS) was renamed and merged with ActiveX Data Objects (ADO) to provide data remoting within the same programming model as ADO. Formerly, the Remote Data Service was known as the Advanced Data Connector (ADC). To clarify the relationship of ADC to ADO, ADC is now known as the Remote Data Service (RDS), a feature of ADO Web Data Access Feature of the ActiveX Data Objects (ADO).

Q. Is the Remote Data Service superior to RDO and DAO in getting at SQL
   data in a client-server application?

A. RDO and DAO are designed for a persistent sockets/pipes connection to
   your database server. The Remote Data Service (RDS) works disconnected    
   through HTTP over your intranet or the Internet through firewalls. RDS    
   also works over the Distributed Component Object Model (DCOM) but this    
   discussion focuses on HTTP.

   RDS passes a disconnected recordset to the client. This is a completely
   stateless model, which means the server could actually be shut down and
   restarted between RDS client requests. This is done through a Mime64    
   encoded Advanced Data Tablegram (ADTG) passed to the client, which then
   opens it and loads it into a client-side Virtual Table Manager (VTM). At    
   this time the client can walk the recordset, perform updates, and send     
   the changes back to the server for base table updates.

   RDO and DAO work in-process on the local computer or possibly over a LAN
   through DCOM if you wrap their functionality in a Visual Basic ActiveX 
   EXE. Currently DCOM does not support transport over HTTP so it is 
   impossible to pass a recordset through a firewall. Attempting to marshal 
   a recordset and its interfaces over DCOM to the client is also    
   unacceptably slow and will ultimately fail. Your alternative is to pass
   the recordset from the server to the client as a variant array
   (GetRows), which works well, but is very primitive compared to RDS
   technology.

   RDS also provides the support necessary to bind to data-aware OCXs in
   Microsoft Internet Explorer version 3.0 and later, support that is not 
   built into Internet Explorer 3.0. This data binding functionality is 
   very similar to the Visual Basic Data Control and Remote Data Control, 
   which require very little or no code.

REFERENCES

For a more detailed example of this code, please see the following article in the Microsoft Knowledge Base:

165297RDS: How To Use From Inside a Visual Basic Program

For additional information, please click the article numbers below to view the articles in the Microsoft Knowledge Base:

166277 HOWTO: Create a VB Component that Returns a Recordset in RDS

183294 Techniques for Returning a Recordset via RDS

183609 Rdsvb.exe Demonstrates How to Use RDS with Visual Basic

183628 HOWTO: Using the RDS DataFactory via Standard ADO Open Method

184606 HOWTO: Use RDS From an IIS 4.0 Virtual Server

The Remote Data Service Web site located at the following URL:

http://msdn.microsoft.com/dataaccessado/rds/default.htm