Datasnap.Provider.TCustomProvider
Delphi
TCustomProvider = class(TComponent)
C++
class PASCALIMPLEMENTATION TCustomProvider : public System::Classes::TComponent
Properties
| Type | Visibility | Source | Unit | Parent |
|---|---|---|---|---|
| class | public | Datasnap.Provider.pas Datasnap.Provider.hpp |
Datasnap.Provider | Datasnap.Provider |
Description
TCustomProvider is the base class for data providers.
TCustomProvider defines the fundamental properties, methods, and events required of all provider objects, either through abstract (in C++ terminology, pure virutal) method declarations, or through virtual methods that do nothing but provide a backstop.
Do not create instances of TCustomProvider. To add a provider component to a form or data module, use a descendant of TCustomProvider such as TDataSetProvider or TXMLTransformProvider.
A provider derived from TCustomProvider is an intermediate link between TClientDataSet or TXMLBroker object and a source dataset or source XML document. The source dataset or XML document can reside in the same application as the client dataset or XML broker, or it can be part of a separate application server. The provider packages data from the source dataset or XML document and passes it in one or more transportable data packets to the client dataset or XML broker. The client dataset reconstructs the data in the data packet to create a local, in-memory copy for user access. When user access is complete, the client dataset repackages any changed data and sends the updates back to the provider. The provider applies the updates to the database or source dataset.
When the provider supplies data to a client dataset, the client dataset reconstructs the data in the data packet to create a local, in-memory copy for user access. When user access is complete, the client dataset repackages any changed data and sends the updates back to the provider. The provider applies the updates to the database, to the source dataset, or to the source XML document.
If the provider can encode data packets in XML, it can supply data to an XML broker, which adds the data packet to an HTML document that is downloaded by a Web client. When the XML broker receives updates from the Web client, it sends the updates to the provider, which applies them to the database, to the source dataset, or to the source XML document.
Client datasets and XML brokers communicate with a provider through the IAppServer interface. In multi-tiered applications, this is the interface of the remote data module that contains the provider. To enable the remote data module to pass calls to the provider, the provider's Exported property must be true, and its Owner property must specify the remote data module.