Boots – shoes – and leggings
Patent
1994-08-22
1997-11-25
Kriess, Kevin A.
Boots, shoes, and leggings
39520003, 395500, 395680, 39520004, 3642222, 3642844, G06F 1342
Patent
active
056921918
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to distributed data processing systems. More particularly, this invention relates to the control of resources distributed data processing systems.
BACKGROUND ART
In a distributed data processing system such as that schematically illustrated in FIG. 1 (the same reference numerals denote the corresponding integers in FIGS. 2 to 4), a computer user typically interacts with a local terminal 2 (also known as the server system), which is connected to a remote processing system 4 (also known as the client system). The remote processing system 4 may not necessarily be situated any great distance from the local terminal 2, e.g. a PC workstation and host processor in a local area network where the client processing system and the workstation server are in the same building or possibly even the same office.
At the disposal of the computer user are a number of resources such as graphical user interface 6, a graphics tablet 8, a database 10 and a laser printer 12. It is desirable that the user should be able to run more than one application program A1, A2, A3 at a time, so called multitasking. At least some of the resources, such as the graphical user interface 6, will be shared between the application programs, whilst others, such as the graphics tablet 8 and database 10, will only be used by one of the applications.
Each of the resources has associated with it an area of operating system address space in the computer memory to enable that resource to be controlled and operated. These areas are indicated in FIG. 1 by P for the printer, D for the database, W for the graphical user interface and T for the graphics tablet. Each of the application programs execute in separate operating system address space, so as to protect one application program's data from another's. However, in the case of a shared resource all the application programs need to be able to work in some way with the operating system address space for that resource. When a number of application programs are interfacing with a display device, the presentation system needs to manage shared resources (such as window geometry, fonts, metafiles, etc.) as well as inter-client communication resources (such as window messages, cut-and-paste operations, etc.).
One possible approach to this problem is that shown in FIG. 1. The resources are managed in application processing mode using shared memory. This provides all the application programs with access to all the resources with a relatively simple and efficient implementation, but allows one application program to adversely affect the system and other application programs if a problem occurs with that one application program.
Another possible approach is to manage the resources in a separate protected address space as illustrated in FIG. 2. This provides the required protection, but on many systems requires a relatively slow mode switch to enter this protected address space. It also introduces the need for the copying of data between the application and protected address space, as well as mode switching back and forth when call-backs are provided by the resource being addressed.
A further possible approach would be to provide for the resources to operate in the system address space as illustrated in FIG. 3. However, this sort of operation is only really suitable for low-level kernel system services which are unlikely to change frequently. Resources such as graphical user interfaces and printer support are usually independently developed from the system core and subject to an unacceptably high frequency of change.
None of these alternatives is able to provide a system which combines a high degree of intra-application isolation with good efficiency.
DISCLOSURE OF INVENTION
Viewed from one aspect the invention provides a data processing apparatus having a local processor coupled to a remote processor, for performing distributed multitasking processing with a plurality of application programs executable at said remote processor, and resources including at least one local r
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Anthias Taf
Halliwell Harry
Minshull John Francis
Banankhah Majid A.
Dillon Andrew J.
Emile Volel
International Business Machines - Corporation
Kriess Kevin A.
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