As mentioned in the preface, this thesis is part of the Advanced Mobile
Integration of General Operating Systems (AMIGOS) project which aims to design
and implement extensions for standard operating systems. These extensions should
transparently integrate mobile computers with stationary computers, regardless of
operating systems and location of the mobile computers .
The vision of the AMIGOS project is:
"...to make the mobile office a reality without making a mobile computer more
complicated to use than a stationary computer on a desk."
The AMIGOS project consists of five phases:
- A transparent communication layer, which is an extension of TCP/IP
with support for disconnected operation, and which--based on
availability--transparently selects either an Ethernet, a telephone line, or
a cellular phone line.
- A NFS caching layer, where the mobile host maintains a large
(10Mb-100Mb) cache of files, to enable the user to access files while
disconnected or semi-connected.
- A re-executable transaction scheme with support for semi-connected
operations. This differs from traditional transactions; the mobile
host--while disconnected--may be unable to obtain locks for an extended
period of time.
- An object-oriented resource management system, in which all
resources of the distributed system will be made available as objects. These
objects may be used for semi-connected operation by extending the transaction
scheme to cover these objects.
- A complete object-oriented environment, where distributed
object-oriented languages like Emerald and Ellie will be extended with
support for transactions.
This thesis belongs mainly to the second phase, continuing the investigations of
transactions in mobile computing  as part of phase three and
utilizing the TACO layer  developed as part of the first phase. These
two works will be presented in the following subsections.