Application Techniques

Publishing Data Between Databases

How to publish a table from one database to another database on the same SilverStream server. This technique uses an invoked business object and a data source object.

About this technique



Data Access Techniques> Data source objects


You'll learn about:

You can run this technique code from:

  • Database: DataXpress3 (choose Publish from the application home page)

NOTE   First make sure that database is running on your localhost SilverStream server

Related reading

Objects used in this technique   Top of page

The publish data feature of the DataXpress sample application implements the following objects:


What it is

What it does


Client page for the publish data option

Gets the user-selected data and calls the invoked business object invPublishTableData


SilverStream-invoked business object

Contains two AgaDatas (AgaSource and AgaDest), each of which is bound to dsoEditTableData; the invoked object populates AgDest with the rows to be added to the database and calls dsoEditTableData to update the data source


SilverStream-invoked business object that deletes data from a selected table

Uses JDBC calls to get a connection to the database from the SilverStream connection pool, executes the SQL for deleting the data, and then closes the connection (the implementation of this object is not described in this technique)


SilverStream data source object

This object instantiates JDBCDataSource, which implements the AgiDataSource object for the DataXpress application


AgiDataSource object

Gets the table from the data source and copies it to the data destination

This object instantiates several utility objects in the JDBC package; for more information, see Developing a DSO for use by Multiple Clients

Data flow   Top of page

  1. The client pgCopy constructs a data view with table names from the source database selected by the user. The contents of the data view are stored in a member variable of type AgiRowCursor (m_datamanagerRC).

  2. When the user chooses the Submit button, pgCopy constructs a hashtable (htparams) to pass to the invoked object. The hash table contains the following items available from two locations:

    From here

    These items are available

    Choice-box selections

    The source database selected by the user

    The destination database selected by the user


    The source table(s) selected by the user

    The destination table(s) specified by the user

    The user's choice to purge or not to purge the destination table

  3. The page calls invPublishTableData using the invokeBusinessObject() method, passing htparams as a parameter. It calls the invoked object for each table selected in the data view.

  4. invEditTableData tests the boolean variable for purging the destination table. If true, it:

  5. After testing bpurge, invEditTableData calls invokeQuery() on AgSource, passing the source database and table values to the data source object. Then it calls invokeQuery() on AgDest, passing the destination database and table values to the data source object.

  6. The data source object instantiates JDBCDataSource, the object that implements AgiDataSource. This object responds to the AgiRowCursor method calls from the invoked object (see step 7).

  7. The invoked object calls the user-defined method copyDataset() passing AgSource and AgDest as AgiRowCursor objects. This method loops through the AgiRowCursors and copies the rows from the source row cursor to the destination row cursor.

  8. The invoked object calls updateRows() on AgDest, which triggers the data source object to prepare and commit the rows to the destination database.

Passing data to the invoked business object   Top of page

When the page is submitted, the code uses the AgiRowCursor.copy() method to copy the user data from the data view (stored in member variable m_dataManagerRC) to a new AgiRowCursor. Then it loops through the row cursor, gets the user's selections, and stores the results in a hashtable. Finally, the code calls the invoked object, passing the hashtable as a parameter.

  private void handle_btnSubmit_pageActionPerformed(ActionEvent evt) 
      throws Exception   
     // Reset the output box 
      StringBuffer sbResults = new StringBuffer(); 
      // Loop over all the items in the list and 
      // copy items selected 
      AgiRowCursor mylRC = m_dataManagerRC.copy(); 
      // Start download 
      // Do while ... 
        Boolean copyTable = (Boolean) mylRC.getProperty("Copy"); 
         if (copyTable.booleanValue()) 
          Hashtable htParms = new Hashtable(); 
             // Invoke the business object, passing the hashtable 
             Double d = (Double) invokeBusinessObject 
            // Get number of rows copied from invoked object 
            sbResults.append(" " + d.toString() + " Rows Copied"); 
          catch (Exception e)  
            sbResults.append(" Error-" + e.toString()); 
         } // Selected 
      } while (mylRC.gotoNext()); 
      // Display number of rows copied 

Invoking the data source object   Top of page

The invoked object tests the boolean variable for deleting the target table. If true, the code invokes another business object to delete the data. Next the code invokes the data source object on each of its AgaDatas, passing the database and table selected by the user.

Next the code calls copyDataset(), passing the two AgaDatas as AgiRowCursor objects (see Copying the data to the destination table). After the data is copied, the code calls updateRows(), which triggers the AgiDataSource object (JDBCDataSource) to commit the rows in AgaDest to the actual data source. Finally, the code in the invoked method gets the number of rows copied and returns it to the page.

  public void invoked(AgoInvokedEvent evt) 
      throws Exception 
      Hashtable htParms = new Hashtable(); 
      Hashtable h = (Hashtable) evt.getParameter();     
      Boolean bPurge = (Boolean) h.get("purge"); 
      if (bPurge.booleanValue())  
      // If specified by the user, delete the destination table  
  	     // first 
           Hashtable htPurge = new Hashtable(); 
           // Get an AgiDatabase object 
           AgiDatabase aDatabase = evt.getDatabase(); 
           // Call a business object to delete the data 
           // The invoked object will open a direct JDBC 
           // connection and delete the data 
       // Get the AgaDatas on this object... 
       AgaData agaSource = evt.getAgaData("agaSource"); 
         if (agaSource==null) System.out.println( 
           "agaSource is null");       
        AgaData agaDest = evt.getAgaData("agaDest"); 
        if (agaSource==null) System.out.println( 
           "agaSource is null"); 
        // Get the db and table passed in and invoke the dso on  
        // each AgaData... 
        htParms.put ("DBNAME", h.get("srcDBName")); 
        htParms.put ("TABLENAME", h.get("srcTableName")); 
        agaSource.invokeQuery (htParms);     
        htParms.put ("DBNAME", h.get("destDBName")); 
        htParms.put ("TABLENAME", h.get("destTableName")); 
        agaDest.invokeQuery (htParms); 
        // Call local method to manipulate the AgiRowCursors  
        // and get the number of rows copied. 
        long x = copyDataset((AgiRowCursor)  
        // Update the destination database.  
        // Return rows copied to the caller      
        evt.setResult(new Double(x)); 

Copying the data to the destination table   Top of page

The copyDataset() is a user-defined method called by the invoked object. It loops through each AgiRowCursor, calling navigation and update methods to copy the data from the AgaSource to AgaDest.

  public long copyDataset(AgiRowCursor agiSource,  
     AgiRowCursor agiDest) 
        long count = 0; 
          System.out.println ("copyp AgiRowCursor"); 
          int colCount = agiSource.getPropertyCount(); 
          boolean rc = agiSource.gotoFirst(); 
          while (rc) 
             for ( int x = 0; x < colCount; x++)  
              Object obj = agiSource.getProperty (x); 
            rc = agiSource.gotoNext();           
        } // Try 
        catch (Exception _e){ 
          System.out.println ("==>boCopyTest -- copyDataset " + _e); 
        return count; 

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