7.6 The Object structure

object_mode

Specification:

datatype object_mode =
LOCAL_OBJECT | REMOTE_OBJECT

Description:

Every object has an associated mode which governs the way in which foreign data can be accessed. In general, foreign objects access foreign data that is present locally, in store objects they are associated with.

However, some foreign objects access raw foreign data that is not local to a store but somewhere remote. You may not need to copy the foreign data to a store to do what you want with such data. A local access method based around stores is not appropriate in that case.

Object may therefore be in one of two modes: local or remote. An object in local mode can only access and modify data present within its associated store. An object in remote mode is located remotely to enable it to access foreign data without having first copied it back to a store. In addition, a remote object cannot modify or affect foreign data.

The modes provided are:

LOCAL_OBJECT

Foreign data is sited locally within a store workspace. The data can be read and written by ML and foreign code.

Pointer values are not restricted, that is, they can be simple indices (that is, relative values) or machine addresses.

REMOTE_OBJECT

Foreign data is sited remotely somewhere in the user's address space. The data can only be read by ML. It cannot be written by ML.

Pointer values are restricted to machine addresses.

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