Sharing data across sessions
Sharing DataWindow objects
You can
share the data from primary, delete, and filter buffers of read-only DataWindow
objects across Web Forms application sessions. The Web.config file
global property PBCachedAndSharedDWs is available for this purpose. You
must set its value to the string of comma-delimited names of the DataWindow
objects you want to share across application sessions.
For information on modifying global properties, see “Configuring ASP.NET for
a .NET project”.
The following restrictions apply to DataWindow controls that
have a DataWindow object included in the PBCachedAndSharedDWs property setting:
- Only a single invocation of Retrieve is
allowed, and the Retrieve call must not include
parameters. - No filtering or sorting is allowed.
- No deletions, insertions, data modifications, or
updates are allowed. - No invocation of ShareData or ShareDataOff is
allowed.
When this form of sharing is used, the retrieval events are
not fired. This is because the Retrieve method
shares the data in the cache and no actual retrieval occurs.
Sharing DDDW objects
It
is also possible to share the data of DropDownDataWindow objects
across Web Forms application sessions. The global property PBCachedAndSharedDDDWs
is used for this purpose. You can set its value to a string of comma-delimited
names of DataWindow objects. Each DataWindow object that you list
can then be shared as the child DataWindow of a DropDownDataWindow
column.
Response windows affect DDDW visibility In a Web Forms application, response windows are components
of main windows rather than separate browser instances. By default,
when a response window is opened, DDDW columns are temporarily hidden
behind a layer displaying the response window. The columns become
visible again when the response window is closed. You can prevent
the temporary visibility issue by changing the value of the PBDataWindowEnableDDDW
global property.
For more information about rendering DDDW columns, see “DataWindow objects and
controls”.
The following restrictions apply to DataWindowChild object
references included in the PBCachedAndSharedDDDWs property setting:
- No invocation of Retrieve is
allowed. - No filtering or sorting is allowed.
- No deletions, insertions, data modifications, or
updates are allowed. - No invocation of ShareData or ShareDataOff is
allowed.