Object linking and embedding

Reuse is not necessarily code sharing. In effect, there seems to be a trend towards sharing components at a higher level of granularity, as possibly independent applications. This approach has, for example, been taken by the Microsoft object linking and embedding facility (OLE), which offers support for embedding (a copy) of a component in a (container) component, for including a link to another component, and for storing compound objects. See slide 11-ole.

Object-enabling technology

OLE

Features

Alternatives


slide: Object-enabling technology -- OLE

The OLE technology is characterized by its developers as object-enabling technology, to contrast it with a more classical language-dependent object oriented approach relying on inheritance. The object linking technology allows the user to maintain a link from one application to another, so that for example a text processor may directly employ the results of a spreadsheet. Moreover, object linking is dynamic and allows to reflect any updates in the spreadsheet application directly in the outcome of the text processor. In contrast, object embedding works more as the traditional cut and paste techniques in that it results in including only a copy of the material. To be embedded or linked, applications must satisfy a standard programmatic interface. In effect, the interface must provide facilities to request an update of the display of the information contained in the application. In this respect, the OLE technology may be characterized as document-centered. The component object model underlying OLE allows for distribution along the DCE standard discussed in section DCE. The commercial competitors are currently the Apple OpenDoc framework and the IBM SOM/DSOM realization of the OMG CORBA standard. It is interesting to note that future releases of OLE are also promised to be compatible with the CORBA standard.