OLE compound documents enable users working within a single application to manipulate data written in various formats and derived from multiple sources. For example, a user might insert into a word processing document a graph created in a second application and a sound object created in a third application. Activating the graph causes the second application to load its user interface, or at least that part containing tools necessary to edit the object. Activating the sound object causes the third application to play it. In both cases, a user is able to manipulate data from external sources from within the context of a single document.
OLE compound document technology rests on a foundation consisting of COM, structured storage, and .uniform data transfer. As summarized below, each of these core technologies plays a critical role in OLE compound documents:
OLE's compound document technology benefits both software developers and users alike. Instead of feeling obligated to cram every conceivable feature into a single application, software developers are now free, if they like, to develop smaller, more focused applications that rely on other applications to supply additional features. In cases where a software developer decides to provide an application with capabilities beyond its core features, the developer can implement these additional services as separate DLLs, which are loaded into memory only when their services are required. Users benefit from smaller, faster, more capable software that they can mix and match as needed, manipulating all required components from within a single master document.