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2.3 All About Parts

   OpenDoc provides an object-oriented user model, where documents are 
   objects that contain other objects, and where each object may have 
   distinct behaviors.  However, object isn't a term that typical users 
   understand in a document context, so we use part instead (for "part of the 
   document").  Parts enable all kinds of content to be combined into a 
   single document.  The user sees each part as a self-contained entity with 
   its own content, behavior, and set of properties.  Each part contains one 
   kind of data that's intrinsic to it, and may contain other parts as well. 

   A component is the fundamental building block of a compound document.  It 
   consists, as shown in Figure 9, of the component data and the part 
   handler, which is the code to change and display the data.  OpenDoc also 
   has the concept of component viewers, which are a subsets of the part 
   handler.  They can display and print the data of a part but not change the 
   content. 


 


                                             



 
   Figure 9. OpenDoc Parts 


   Compnents are independently functional units, similar to am executable 
   program with following differences: 

   °   Components are compiled as DLLs note EXE. 
   °   Components are loaded dynamically. 

   Components are task-specific and specific for a certain data type.  The 
   kind of data may be text, graphics, a spreadsheet, sound, video, image or 
   even a button with a function.  Each kind of data is handled by a specific 
   part handler.  Components are designed to work cooperatively with other 
   components and are replacing today's monolithic applications. 
   Applications have become a configured set of components. 


   The following describes the differences between a document, consisting of 
   parts versus the document, created by conventional applications: 

   °   An OpenDoc document is built and manipulated in the way that you 
       assemble your document out of parts of any graphics part handler of 
       your choice.  For example, you may select a text component to write a 
       letter.  If you wish to embed illustrations in that text, you simply 
       select and embed a graphics component in your text component. 

   °   While editing, copying, or pasting a part, you do not need to be aware 
       of which part handler is being executed.  You directly manipulate the 
       component within the context of the document. 

Subtopics:

   2.3.1 Parts and Documents
   2.3.2 Intrinsic and Embedded Part Contents
   2.3.3 OpenDoc Part Editors and Viewers
   2.3.4 Properties of Parts
   2.3.5 Working with Parts

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