Understanding PowerBuilder extensions – PB Docs 2019

A PowerBuilder extension is just what its name suggests: an
extension to PowerBuilder functionality provided by you, by a third
party, or by Appeon. All PowerBuilder extensions communicate with the
PBVM through an interface called IPB_Session. This interface and other
PBNI objects and interfaces are described in The elements of PBNI.

PowerBuilder provides its own extensions, including a PBDOM XML
parser and classes that support SOAP clients for Web services (obsolete). In future
releases, Appeon might develop more new features as PBNI extensions
instead of embedding them in the PowerBuilder VM (PBVM), so that the
size of the PBVM can be minimized. Extensions are also available from
third party contributors; for the latest samples and utilities, see the
PBNI section of the PowerBuilder Code Samples website at
https://www.appeon.com/developers/library/code-samples-for-pb.

Nonvisual extensions

The most frequently used type of PowerBuilder extension is a
nonvisual extension. Nonvisual extensions provide a way to call C and
C++ functions from PowerBuilder with more flexibility than the previous
solution of declaring a function in a script. They also allow you to use
object-oriented techniques when working with external objects.

A nonvisual extension is a DLL, written in C++, that exposes one
or more native classes and/or global functions. Classes are used in a
PowerBuilder application as though they were class user objects created
in PowerBuilder — a native class is simply a PowerScript class that is
implemented in C++. Global functions in an extension are used like
global functions declared in the Function painter.

Nonvisual extensions allow you to use datatypes in C++ that map to
standard PowerBuilder datatypes. PBNI provides predefined datatypes that
map to PowerBuilder datatypes, so that you can use PowerBuilder
datatypes when you invoke the methods of the native class, and the
native class can use predefined types to call back into PowerBuilder.
For more information about predefined types, see PBNI Types and Return
Values

You can use native classes to call back into the PBVM from the C++
code and trigger PowerBuilder events and invoke functions. You can also
call external functions that require callback functions. For example, if
your PowerBuilder application uses an extension that is a SAX XML
parser, the SAX parser can send information back to the PowerBuilder
application about the items it has encountered in the XML document that
it is parsing. In response, the PowerBuilder application can send back
instructions on how to handle those items.

Possible uses for a nonvisual extension include:

PowerBuilder extensions run faster than standard PowerBuilder user
objects because they are compiled in native machine code instead of
PowerBuilder pseudocode (Pcode). PBNI complies with the C++
specification, so well-programmed code is portable at the source code
level.

Visual extensions

Visual extensions can be used as if they were PowerBuilder visual
user objects — you can place them in windows or on other visual
controls. Visual extensions allow you to create a subclass of the
Windows procedure (winproc) of a visual component so that you can use
the latest “look and feel” for your applications.

Marshaler extensions

Marshaler extensions act as bridges between PowerBuilder and other
components, such as Enterprise JavaBeans (EJB) components, Java classes,
Web services, and CORBA components. PowerBuilder provides a marshaler
extension for creating clients for EJB components running in any
J2EE-compliant application server. Other techniques for calling EJBs
from PowerBuilder do not provide a standard way to marshal PowerBuilder
requests to other components and unmarshal the result back to
PowerBuilder.