The elements of PBNI
To enable the features described in the previous section, PBNI
provides interfaces, structures, global functions, and helper classes.
These elements are described in more detail in the reference section of
this guide. See PBNI Interfaces,
Structures, and Methods This section provides an overview.
Interfaces
The IPB_VM interface is used to load PowerBuilder applications in
third-party applications and interoperate with the PowerBuilder virtual
machine (PBVM).
IPB_Session is an abstract interface that defines methods for
performing various actions such as accessing PowerScript data, creating
PowerBuilder objects, and calling PowerScript functions.
The IPB_Value and IPB_Arguments interfaces enable you to pass values
between the PowerBuilder VM and PowerBuilder extension modules.
The IPB_Value interface represents a PowerBuilder value, which could
be one of the PowerBuilder standard datatypes such as integer, long,
string, and so forth. It provides information about each variable,
including its type, null flag, access privileges, array or simple type,
and reference type.
The IPB_Arguments interface represents the arguments passed to a
PowerScript function and is used to access the data.
The IPB_ResultSetAccessor and IPB_RSItemData interfaces enable you
to access data in a DataWindow or DataStore.
All PowerBuilder native classes inherit from the
IPBX_NonVisualObject interface or the IPBX_VisualObject interface, which
in turn inherit from the IPBX_UserObject interface. You must implement the
Invoke method in the inherited class to enable PowerBuilder to invoke
methods in the native class.
Marshaler extensions contain a class that inherits from the
IPBX_Marshaler interface. You must implement the InvokeRemoteMethod method
in the inherited class to enable PowerBuilder to invoke methods on remote
objects represented by a proxy.
Structures
The PBCallInfo structure holds arguments and return type information
for function calls between PBNI and PowerBuilder. To access the
information in PBCallInfo, use the IPB_Arguments interface.
The PBArrayInfo structure stores information about arrays.
The PB_DateData, PB_TimeData, and PB_DateTimeData structures are
used to pass DataWindow and DataStore data.
Global functions
Every PowerBuilder extension object must export global functions
that enable the PowerBuilder VM to create instances of the object and use
its methods. The PBX_GetDescription function describes the classes and
functions in the extension. The PBX_CreateNonVisualObject function enables
the PBVM to create instances of the nonvisual classes in an extension, and
the PBX_CreateVisualObject function does the same for visual
classes.
Helper classes
Several helper classes, such as PBObjectCreator, PBArrayAccessor,
and PBEventTrigger, make it easier to program with PBNI.
Interaction between an extension and the
PBVM
The following diagram summarizes how an extension interacts with the
PBVM.
Figure: Interaction between an extension and the PowerBuilder
VM
