Interface WebRowSet

public interface WebRowSet
extends CachedRowSet

The standard interface that all implementations of a WebRowSet must implement.

1.0 Overview

The WebRowSetImpl provides the standard reference implementation, which may be extended if required.

The standard WebRowSet XML Schema definition is available at the following URI:

 http://java.sun.com/xml/ns/jdbc/webrowset.xsd
 

It describes the standard XML document format required when describing a RowSet object in XML and must be used be all standard implementations of the WebRowSet interface to ensure interoperability. In addition, the WebRowSet schema uses specific SQL/XML Schema annotations, thus ensuring greater cross platform inter-operability. This is an effort currently under way at the ISO organization. The SQL/XML definition is available at the following URI:

 http://standards.iso.org/iso/9075/2002/12/sqlxml
 

The schema definition describes the internal data of a RowSet object in three distinct areas:

• properties
These properties describe the standard synchronization provider properties in addition to the more general RowSet properties.
• metadata
This describes the metadata associated with the tabular structure governed by a WebRowSet object. The metadata described is closely aligned with the metadata accessible in the underlying java.sql.ResultSet interface.
• data
This describes the original data (the state of data since the last population or last synchronization of the WebRowSet object) and the current data. By keeping track of the delta between the original data and the current data, a WebRowSet maintains the ability to synchronize changes in its data back to the originating data source.

2.0 WebRowSet States

The following sections demonstrates how a WebRowSet implementation should use the XML Schema to describe update, insert, and delete operations and to describe the state of a WebRowSet object in XML.

2.1 State 1 - Outputting a WebRowSet Object to XML

In this example, a WebRowSet object is created and populated with a simple 2 column, 5 row table from a data source. Having the 5 rows in a WebRowSet object makes it possible to describe them in XML. The metadata describing the various standard JavaBeans properties as defined in the RowSet interface plus the standard properties defined in the CachedRowSet^TM interface provide key details that describe WebRowSet properties. Outputting the WebRowSet object to XML using the standard writeXml methods describes the internal properties as follows:

 <properties>
       <command>select co1, col2 from test_table</command>
      <concurrency>1</concurrency>
      <datasource/>
      <escape-processing>true</escape-processing>
      <fetch-direction>0</fetch-direction>
      <fetch-size>0</fetch-size>
      <isolation-level>1</isolation-level>
      <key-columns/>
      <map/>
      <max-field-size>0</max-field-size>
      <max-rows>0</max-rows>
      <query-timeout>0</query-timeout>
      <read-only>false</read-only>
      <rowset-type>TRANSACTION_READ_UNCOMMITED</rowset-type>
      <show-deleted>false</show-deleted>
      <table-name/>
      <url>jdbc:thin:oracle</url>
      <sync-provider>
              <sync-provider-name>.com.rowset.provider.RIOptimisticProvider</sync-provider-name>
              <sync-provider-vendor>Oracle Corporation</sync-provider-vendor>
              <sync-provider-version>1.0</sync-provider-name>
              <sync-provider-grade>LOW</sync-provider-grade>
              <data-source-lock>NONE</data-source-lock>
      </sync-provider>
 </properties>
 

The meta-data describing the make up of the WebRowSet is described in XML as detailed below. Note both columns are described between the column-definition tags.

 <metadata>
      <column-count>2</column-count>
      <column-definition>
              <column-index>1</column-index>
              <auto-increment>false</auto-increment>
              <case-sensitive>true</case-sensitive>
              <currency>false</currency>
              <nullable>1</nullable>
              <signed>false</signed>
              <searchable>true</searchable>
              <column-display-size>10</column-display-size>
              <column-label>COL1</column-label>
              <column-name>COL1</column-name>
              <schema-name/>
              <column-precision>10</column-precision>
              <column-scale>0</column-scale>
              <table-name/>
              <catalog-name/>
              <column-type>1</column-type>
              <column-type-name>CHAR</column-type-name>
      </column-definition>
      <column-definition>
              <column-index>2</column-index>
              <auto-increment>false</auto-increment>
              <case-sensitive>false</case-sensitive>
              <currency>false</currency>
              <nullable>1</nullable>
              <signed>true</signed>
              <searchable>true</searchable>
              <column-display-size>39</column-display-size>
              <column-label>COL2</column-label>
              <column-name>COL2</column-name>
              <schema-name/>
              <column-precision>38</column-precision>
              <column-scale>0</column-scale>
              <table-name/>
              <catalog-name/>
              <column-type>3</column-type>
              <column-type-name>NUMBER</column-type-name>
      </column-definition>
 </metadata>
 

Having detailed how the properties and metadata are described, the following details how the contents of a WebRowSet object is described in XML. Note, that this describes a WebRowSet object that has not undergone any modifications since its instantiation. A currentRow tag is mapped to each row of the table structure that the WebRowSet object provides. A columnValue tag may contain either the stringData or binaryData tag, according to the SQL type that the XML value is mapping back to. The binaryData tag contains data in the Base64 encoding and is typically used for BLOB and CLOB type data.

 <data>
      <currentRow>
              <columnValue>
                      firstrow
              </columnValue>
              <columnValue>
                      1
              </columnValue>
      </currentRow>
      <currentRow>
              <columnValue>
                      secondrow
              </columnValue>
              <columnValue>
                      2
              </columnValue>
      </currentRow>
      <currentRow>
              <columnValue>
                      thirdrow
              </columnValue>
              <columnValue>
                      3
              </columnValue>
      </currentRow>
      <currentRow>
              <columnValue>
                      fourthrow
              </columnValue>
              <columnValue>
                      4
              </columnValue>
      </currentRow>
 </data>
 

2.2 State 2 - Deleting a Row

Deleting a row in a WebRowSet object involves simply moving to the row to be deleted and then calling the method deleteRow, as in any other RowSet object. The following two lines of code, in which wrs is a WebRowSet object, delete the third row.

     wrs.absolute(3);
     wrs.deleteRow();
 

The XML description shows the third row is marked as a deleteRow, which eliminates the third row in the WebRowSet object.

 <data>
      <currentRow>
              <columnValue>
                      firstrow
              </columnValue>
              <columnValue>
                      1
              </columnValue>
      </currentRow>
      <currentRow>
              <columnValue>
                      secondrow
              </columnValue>
              <columnValue>
                      2
              </columnValue>
      </currentRow>
      <deleteRow>
              <columnValue>
                      thirdrow
              </columnValue>
              <columnValue>
                      3
              </columnValue>
      </deleteRow>
      <currentRow>
              <columnValue>
                      fourthrow
              </columnValue>
              <columnValue>
                      4
              </columnValue>
      </currentRow>
 </data>
 

2.3 State 3 - Inserting a Row

A WebRowSet object can insert a new row by moving to the insert row, calling the appropriate updater methods for each column in the row, and then calling the method insertRow.

 wrs.moveToInsertRow();
 wrs.updateString(1, "fifththrow");
 wrs.updateString(2, "5");
 wrs.insertRow();
 

The following code fragment changes the second column value in the row just inserted. Note that this code applies when new rows are inserted right after the current row, which is why the method next moves the cursor to the correct row. Calling the method acceptChanges writes the change to the data source.

 wrs.moveToCurrentRow();
 wrs.next();
 wrs.updateString(2, "V");
 wrs.acceptChanges();
 :
 

Describing this in XML demonstrates where the Java code inserts a new row and then performs an update on the newly inserted row on an individual field.

 <data>
      <currentRow>
              <columnValue>
                      firstrow
              </columnValue>
              <columnValue>
                      1
              </columnValue>
      </currentRow>
      <currentRow>
              <columnValue>
                      secondrow
              </columnValue>
              <columnValue>
                      2
              </columnValue>
      </currentRow>
      <currentRow>
              <columnValue>
                      newthirdrow
              </columnValue>
              <columnValue>
                      III
              </columnValue>
      </currentRow>
      <insertRow>
              <columnValue>
                      fifthrow
              </columnValue>
              <columnValue>
                      5
              </columnValue>
              <updateValue>
                      V
              </updateValue>
      </insertRow>
      <currentRow>
              <columnValue>
                      fourthrow
              </columnValue>
              <columnValue>
                      4
              </columnValue>
      </currentRow>
 </date>
 

2.4 State 4 - Modifying a Row

Modifying a row produces specific XML that records both the new value and the value that was replaced. The value that was replaced becomes the original value, and the new value becomes the current value. The following code moves the cursor to a specific row, performs some modifications, and updates the row when complete.

 wrs.absolute(5);
 wrs.updateString(1, "new4thRow");
 wrs.updateString(2, "IV");
 wrs.updateRow();
 

In XML, this is described by the modifyRow tag. Both the original and new values are contained within the tag for original row tracking purposes.

 <data>
      <currentRow>
              <columnValue>
                      firstrow
              </columnValue>
              <columnValue>
                      1
              </columnValue>
      </currentRow>
      <currentRow>
              <columnValue>
                      secondrow
              </columnValue>
              <columnValue>
                      2
              </columnValue>
      </currentRow>
      <currentRow>
              <columnValue>
                      newthirdrow
              </columnValue>
              <columnValue>
                      III
              </columnValue>
      </currentRow>
      <currentRow>
              <columnValue>
                      fifthrow
              </columnValue>
              <columnValue>
                      5
              </columnValue>
      </currentRow>
      <modifyRow>
              <columnValue>
                      fourthrow
              </columnValue>
              <updateValue>
                      new4thRow
              </updateValue>
              <columnValue>
                      4
              </columnValue>
              <updateValue>
                      IV
              </updateValue>
      </modifyRow>
 </data>