Chapter 9: Universal Network Objects

Overview

The internals of OpenOffice.org are based on Universal Network Objects (UNO). This chapter introduces the subroutines and functions supported by OpenOffice.org Basic that are related to UNO. This chapter covers methods that create and inspect objects that are vital to the internals of OpenOffice.org. Extra attention is given to the topic of UNO listeners.

Up to this point, I've mostly dealt with OOo capabilities that relate to handling text, and numbers , and manipulating things visible and familiar. The programming constructs I've presented also share a lot of commonality with other environments. Of course I dealt with the soffice library, because it is required to begin to use OOo Basic. I also dealt with DDE and Shell, which was my first opportunity to talk about what's "behind the scenes." In those cases, I was describing techniques for using functions provided by the operating system or external environment to supplement OOo Basic. Now I'll go further and deeper into OOo. In this chapter, I'll begin to discuss things related to the actual implementation of OOo-things that will allow you to exploit the real capabilities of OOo, using OOo Basic. You'll also begin to see more details about how OOo is implemented-which you need to build the really cool stuff that sets OOo apart as a really great programming environment.

The Universal Network Object (UNO) is a component model that offers interoperability between different programming languages, object models, machine architectures, and processes. In other words, it allows data to be passed between different computers; the computer scientists should note that this is similar to COM in functionality. OpenOffice.org is based on UNO. You use UNO to manipulate the internal workings of OOo using OOo's Application Programming Interface (API). Table 1 lists the OOo Basic functions used to deal with UNO.

Table 1: Functions related to Universal Network Objects in OOo Basic.

Function	Description
BasicLibraries	Access document Basic libraries
CreateUnoDialog()	Create an existing dialog
CreateUnoListener()	Create a listener
CreateUnoService()	Create a Universal Network Object Service
CreateUnoStruct()	Create a Universal Network Object
CreateUnoValue()	Create a Universal Network Object value
DialogLibraries	Document dialog libraries
EqualUNOObjects()	Are these the same?
FindObject()	Find object
FindObjectProperty()	Find object property
GetDefaultContext()	Get a copy of the default context
GetProcessServiceManager()	Get service manager
GlobalScope	Application-level libraries
HasUnoInterfaces()	Does it support these?
IsUnoStruct()	Is this variable a Universal Network Object?
ThisComponent	Special variable representing the current document

Understanding Universal Network Objects is important because most of the internals of OpenOffice.org are implemented using UNO. For example, the variable ThisComponent, which refers to the current document, is a Universal Network Object.