Protocol Dataset | Replicate Table

This mode tries to solve a common scenario where a table is replicated for all connected clients, example, if you have a server with a stock quotes table, you want broadcast stock changes to all clients, but you don't want that a client can connect to your database. So, every time there is a change in any stock quotes, the record information will be broadcasted to all connected clients. Every client will read the record and update his own table.

 

You can check in Demos folder, SQLLite/MultipleDatabase demo.

Configure Dataset Server

Create a new Dataset Protocol Server and configure using the following properties

 

• ApplyUpdates: set to True, every time there is a change, this will be broadcasted to clients
• AutoSynchronize: set to True, every time a new client connects to server, server will send all records (metadata and data), so client will get latest information from server.
• UpdateMode: set to upWhereAll or upWhereChanged. The difference is the first sends all fields of a record and the second only fields changed in an update.

 

oServer := TsgcWebSocketServer.Create(nil);
oProtocolDataset := TsgcWSPServer_Dataset.Create(nil);
oProtocolDataset.Server := oServer;
oProtocolDataset.Dataset := <...your dataset..>;
oProtocolDataset.ApplyUpdates := true;
oProtocolDataset.AutoSynchronize := true;
oProtocolDataset.NotifyUpdates := true;
oProtocolDataset.UpdateMode := upWhereAll;
oServer.Port := 80;
oServer.Active := true;

 

Configure Dataset Client

Create a new Dataset Protocol Client and configure using the following properties

 

• ApplyUpdates: set to True, every time there is a change, this will be sent to server.
• AutoSubscribe: set to True, every time a new client connects to server, the client subscribes automatically to update, delete and new record.
• UpdateMode: set to upWhereAll or upWhereChanged. The difference is the first sends all fields of a record and the second only fields changed in an update.

 

oClient := TsgcWebSocketClient.Create(nil);
oProtocolDataset := TsgcWSPClient_Dataset.Create(nil);
oProtocolDataset.Client := oClient;
oProtocolDataset.Dataset := <...your dataset..>;
oProtocolDataset.ApplyUpdates := true;
oProtocolDataset.AutoSubscribe := true;
oProtocolDataset.NotifyUpdates := true;
oProtocolDataset.UpdateMode := upWhereAll;
oClient.Host := '127.0.0.1';
oClient.Port := 80;
oClient.Active := true;