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What's New in Remote Data Service 1.5
Remote Data Service — A New Name for the Advanced Data Connector
The Advanced Data Connector (ADC) has now been integrated with ActiveX Data Objects (ADO) to provide data remoting within the same programming model as ADO. This makes it easier to design, code, and deploy both Web-based and LAN-based applications. For example, the ADOR.Recordset now supports all of the methods and properties available on the ADODB.Recordset object.
To clarify the relationship of ADC to ADO, the Advanced Data Connector is now known as the Remote Data Service (RDS) of ADO.
The objects also have new names. The AdvancedDataControl is now the RDS.DataControl, the AdvancedDataFactory is now the RDSServer.DataFactory, and the AdvancedDataSpace is now the RDS.DataSpace. The prefix (RDS for DataControl and DataSpace; RDSServer for DataFactory) is required. Of course, for backward-compatibility, the old names are still recognized — you don’t need to rewrite any of your version 1.0 code.
Client Cursor Engine — A New Name for the Virtual Table Manager
The new and improved VTM is now known as the Client Cursor Engine, because it provide client-side cursor functionality. Other Client Cursor Engine improvements for Version 1.5 include asynchronous population and updatability with other databases.
Asynchronous Population
The Client Cursor Engine now lets you open and populate a disconnected Recordset asynchronously. The following DataControl method and properties make this possible.
Property/Method Description ExecuteOptions Indicates whether the DataControl object’s Refresh method is to execute asynchronously by running on a separate thread. FetchOptions Indicates whether the fetching of records into an DataControl object’s Recordset is to occur asynchronously. ReadyState Returns the state of the DataControl object's Recordset, such as whether the Recordset load has completed. Cancel Cancels the currently running asynchronous execution or fetch.
Updatability with Other Databases
Updatability is defined as being able to insert and delete records, and update the contents of one or more records of a result set.
With the Client Cursor Engine in Remote Data Service 1.5, you can update a number of databases, including Microsoft SQL Server, Microsoft Access, Oracle, and so forth. This is different from previous versions, which supported updatability only with Microsoft SQL Server databases.
Sorting and Filtering
The following DataControl properties and methods provide sorting and filtering functionality on the client-side cache. The sorting functionality orders records by values from one column. The filtering functionality displays a subset of the original Recordset based on a find criteria, while the full Recordset is maintained in the cache.
Method or Property Description SortColumn Specifies the name or alias of the column to sort the Recordset by. SortDirection Specifies the sort order; True = ascending and False = descending. FilterValue Specifies a value to filter records with, for example, 'Programmer'or125.FilterCriterion Specifies the evaluation operator of the FilterValue to the records. Can be any one of the following: <, <=, >, >=, =, <> FilterColumn Specifies the column name to evaluate the filter criteria on. Reset Executes the sort or filter based on the properties set. Rewrites the Recordset as read-only if it is not already read-only. Does not re-execute the query. Reset will fail if there are pending changes.
Operability within Internet Explorer 4.0
Remote Data Service now supports Microsoft Internet Explorer 4.0. Internet Explorer 4.0 includes all of the Remote Data Service client components, so that you don't need to use the CODEBASE parameter to download the Remote Data Service .cab file. This makes it easier to deploy Remote Data Service applications.
Data Binding Extensions to HTML
Two relationships are key to data binding with Internet Explorer 4.0: source and consumer. Data consumers specify binding by referencing the data source to which they are bound. To achieve this, your data consumers (controls such as text boxes or grids) specify the source of the data and the type of the data being bound. You specify the DATASRC parameter to identify the data source object (in this case, the DataControl object), and a DATAFLD parameter to identify a column of the data set.
This is slightly different coding notation from previous versions of Remote Data Service, which used the DataControl object’s Bindings property to bind controls to data.
See Also For more information about how to use the data binding extensions to HTML with Internet Explorer 4.0, see the Data Binding section of this SDK, under Dynamic HTML.
ConvertToString Method
The ConvertToString method of the DataFactory object converts a Recordset to a MIME string that represents the data.
CreateRecordset Method
The CreateRecordset method now applies to the DataControl object and the DataFactory object. This means that you can now create a Recordset object directly with the DataControl on the client side whereas with 1.0 you could only do this on the server side. This results in fewer network roundtrips, and provides more flexibility for your application.
SourceRecordset Property vs. Recordset Property
The DataControl object now supports Recordset and SourceRecordset properties. SourceRecordset is a write-only property and Recordset is a read-only property.
HTTP Protocol Settings
RDS now supports all three of the Microsoft Internet Information Server Permissions settings.
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