Apple HTC patent lawsuit : Exhibits A - E

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EXHIBIT A

Case 1:10-cv-00166-UNA Document 1-1 Filed 03/02/10 Page 1 of 42
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1700602

__ MLUNITED STATES DEPARTMENT OF COMMERCE

United States Patentand

TrademarkOffice

May 16 2008

THIS IS TO CERTIFY THAT ANNEXED HERETO IS TRUE COPY FROM

THE RECORDS OF THIS OFFICE OF

U.S PATENT 5519867

ISSUE DATE May 21 1996

By Authority of the

Under Secretary of Commerce for Intellectual Property

and Director of the United States lemark Office

Offi

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OBJECT-ORIENTED MULTITASKING

SYSTEM

Inventors Christopher Moeller Los Altos

Eugenic Bolton Sunnyvale Daniel

Cheraikoff Palo Alto Russell

Nakano Sunnyvale all of Calif

Assignee Taligent Inc Cupertino Calif

Notice The tenn of this patent shall not extend

beyond the expiration date of Pat No

5379432

Appl No 94673

Filed Jul 19 1993

list Cl.6 GO6F 9/40

U.S Cl 395700

Field of Search 395/650 700

References Cited

4821220 4/1989 Duisberg 364/578

4885717 12/1989 Beck et al 364/900

4891630 1/1990 Friedman et al 340/706

4953080 8/1990 Dysart et al 364/200

5041992 8/1991 Cunningham et al 364/518

5050090 9/1991 Golub et al 364/478

5060.276 10/1991 Morris et al 382/8

5075848 12/1992 Lai et al 3951425

5093.914 3/1992 Coplien et al 395/700

5119475 6/1992 Smith et al 395/156

5125091 6/1992 Staas Jr et al 395/650

5133075 7/1992 Risch 395/800

5136705 8 /1 99 2 S tu hh s et al 395/575

5151987 9/1992 Abraham et al 395/575

5181162 1/1993 Smith et al 364/419

5379432 1/1995 Orton et al 395/700

5404529 4/1 995 Chernihoff et al 395/700

OTHER PUBLICATIONS

Proc of the Summer 1988 Usenix Conf 20 Jun 1988 San

Francisco US pp 113 Using the Toolkit or How to

Write Widget by McCormack et al

New Directions for Unix Proc Autumn 1988 EUUG Conf

Oct 1988 Cascais Portugal pp 2537 Berna

beuAuban et al CloudsA Distributed ObjectBased

Operating System Architecture and Kernel Implementa

tion

Primary ExaminerAlvin Oberley

Assistant ExaminerJohn Chavis

Attorney Agent or FirmKeith Stephens

ABSTRACT

Anapparatus

forenabling an object-oriented application to

access in an object-oriented manner procedural operating

system having native procedural interface is disclosed The

apparatusincludes computer and memory component in

the computer code library is stored in the memory

component The code library includes computer program

logic implementing an object-oriented class library The

object-oriented class library comprises related object-ori

ented classes for enabling the application to access in an

object-oriented manner services provided by the operating

system The object-oriented classes include methods for

accessingthe

operating system services using procedural

function calls compatible with the native procedural inter

face of the operating system The computer processes

object-oriented statements contained in the application and

defined by the class library by executing methods from the

class library corresponding to the object-oriented state

ments The object-oriented application includes support for

multi-tasking

53 Claims 17 Drawing Sheets

United States Patent

Moeller et al

1 11 11 1 11 11 11 1 III 1 11 11 1 11 11 11111 10111111 1 11 11 1 11 11 1 11 11 11 11 11 III 11111 liii

USOO5S 19867A

Patent Number 5519867

Date of Patent May 21 1996

U.S PATENT DOCUMENTS

CODE

LIBRARY

110

CLAss

UBRARY

402

ThREAD cLAssEsj_.A04

TA5KCLA55E5

VIRTUAL MEMORY

CLASSEs.40E

pc cLAssEsk410

sYNCHRONIZATION

k412CLAsSEs

SCHEDUUNS

f4I4CLASsES

FAULT CLASSESk4b6

MACHINE CLASSES



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130A

0-

13213DB

129

28-J WRAPPER1

F1

k.- 134

114

104

116

102

-112

03

OPERATING SYSTEM DEVICE DRIVERS

MICROiNSTRUCTION CODE

j106RAM 108

CODE__11ib0LIBRARY

/118

INPUT

DEVICE

120 124126

TI ___DATA

DISPLAY

IPRINTERSTORAGE

DATA STORAGE 122

MEDIUM

ICODELIBRARY

FIGURE



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U.S Patent May 21 1996 Sheet of 17 5519867

LOCATE IN PROGRAMOBJECT-OR ENTEDSTATEMENT ACCESSINGOPERATING SYSTEM

EXECUTE PROCEDURALFUNCTION CALL

206

208

__ 210

202

START 204

TRANSLATE OBJECTORI ENTED STATEM ENT

TO PROCEDURAL

FUNCTION CALLCOMPATIBLE WITH

PROCEDURAL INTERFACEOF OPERATING SYSTEM

DONE 212



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3\

304

METHOD CODE IN

TASK ADDRESSSPACE

312

ACCESS LIBRARY SERVERAND COPY METHOD CODEFROM CODE LIBRARY TO

TASK ADDRESS SPACE

316

318



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SYNCH RON IZATION

CLASSES

MACHINE CLASSES

..A06

..%/41

j418

-.420

CLASS

LIBRARY

402

THREAD CLASSES -404

CODE

LIBRARY

110

TASK CLASSES

VIRTUAL MEMORY

CLASSES

IPC CLASSES

12SCHEDULING

CLASSES

FAULT CLASSES

SECURITY CLASSES



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512

518

Figure



9/179

601

disposition

start address

length

Figure

TlaskHandle

622

TMemoryObject



10/179

702

712

Figure

710

714



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Figure

802

start address

length

disposition

TMemorySu rrogate



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Figure

Handle Handle



13/179

1002

1004

Figure10

1006 1008



14/179

1102

11

1104

118

1110

1116

1114

Figure 11



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U.S Patent May 21 1996 Sheet 12 of 17 5519867

Figure 12

1202

1205

1210

1212

1220

1218

1230

KraiipossiTh

68KfyJ

1226 1228



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1302

1304

1326

1310

1312

1324

1314

Figure 13

1316

1318



17/179

U.S Patent May 21 1996 Sheet 14 of 17 5519867

iz

CD



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1502

1506

1504

1508

T386ThreadState_...-i

532

1512

1514

1524

1516

1526

1528

1518

FIGURE 15



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1614

Figure 16

1602

1604

1608

1618

1612



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1702label

1704

--

label

label

Figure17

uses for interface

uses for implementation

inherits compatible type

1710



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5519867

OBJECT-ORIENTED MULTiTASKINGThe fact that objects are encapsulated produces another

SYSTEM important fringebenefit that is sometimes referred to as data

a bstr action Abstr action is theprocess by which complex

portion of the disclosure of this patent application

ideas and s tr uc tu re s a re made more understandable by the

contains material which is subject to copyright protectionremoval of detail and the generalization of their behavior

From software perspective abstraction is in many ways the

The copyright owner has no objection to the facsimileantithesis of hard-coding Consider software wmdowmg

reproduction by anyone of the patent disclosure as itexample if every detail

of every window that appears on

appears in the Patent and TrademarkOffice

patentfiles or

users screen in graphical user interface GUI-based

records but otherwise reserves all copyright nghts whatso-program had to

have all of its state and behavior hard-coded

everinto program then both the program and the windows i

Field Of The Invention contains would lose almost all of their flexibility By

Thepresent

invention relates generally to object-oriented abstracting the concept of window into window object

computing environments and more particularly to system object-oriented systems permit the programmer to think only

and method for providing an object-oriented interface for 15 about the specific aspects that make particular window

p ro ce du ra l o pe ra ting system uniqueBehavior shared by all windows such as the ability

Background Of the Invention tobe dragged and moved can be shared by all window

Object-oriented technology OOT which generally objectsincludes o bject- or ie nted a na lysis OOA object-oriented This leads to a no th er b asic component of OOT which isdesign COD and object-oriented programming OOP is 20 the cla ss class includes set of data attributes plus seearning its place as one of the most important new tech- of allowable operations that is methods on

t he d at a

nologies in software development COT has already begun attributes Each object is an instance of some class As

to prove its ability to create significant increasesin

pro-natural outgrowth of encapsulation and abstraction OO

granimer productivity and in program maintainability By supportsinheritance class called subclass may b

engendering an environment in which data and the proce- 25 derived from a no th er cla ss calledbase class parent

dures that operate on t he d at a a re combined into packages class etcwherein the subclass inherits the d ata attributes

called objects and by adopting r ule tha t demands that and methods ofthe base class The subclass may specialize

objects communicate with one another only through well- the base class by adding code which overridest he d at a

defined messaging paths OOT removes much of the com- and/or methods of the base class or which adds new data

plexity of traditional procedure-oriented programming 30 attributes and methods Thus inheritance represents

The following paragraphs present brief overview of mechanism by which a bs tr ac ti on s a re made increasingly

some of the more imp or ta nt a sp ects of OOT More detailed concrete as s ub cl as se s a re created for greater levels o

discussions of COT are available in many publicly available specialization Inheritance is primary con tr ib utor to the

documents including Object Oriented Design With Appli- increased programmer efliciency provided by COP Inherit

cations by Grady Beech Benjamin/Cummings Publishing 35 ancemakes it possible for developers to minimize the

Company 1991 and Object-Oriented Requirements Analy-amount of new code they have t o w ri te t o create applica

sis and Logical Design by Donald Firesmith John Wileytions By providing significant portion of the functionality

Sons Inc 1993 The basic component of OOT is the needed for particular task classes in the inheritance

object An object includes and is characterized by set of h ie ra rc hy gi ve the programmer head start to program

data also called attributes and set of operations called 40 designand creation One

potentialdrawback to an object

methods that can operate on the data Generally an objects orientedenvironment lies in the

proliferationof objects tha

data may change only through the operationof the objects must exhibit behavior which is similar and which one would

methods like to use as single message name to describe Consider

method in an object is invoked by passing message for example an o bject- or ie nted g ra ph icalenvironment if

to the object this processis called message passing The 45 Draw message is sent to Rectangle object the Rectangle

message specifies method name and an argumentlist object responds by drawing shape with four sides

When the object receives the message code associated with Triangle object on the o th er hand responds by drawing

the named method is executed with the formal parameters of shape with three sides Ideally the object thatsends th

the method bound to the corresponding values in the argu- Draw message remains unaware of either the typeof

object

ment list Metho ds a nd message passing in COT are analo- so to which the message is addressed or of how that objecttha

gous to procedures and procedure calls in procedure-on-r ec ei ve s t he message will draw itself in response

If th

ented software environments However while procedures ideal can be achieved then it will be relatively simple to ad

operate to modify and return passed parameters methods new kind of shapelater for example hexagon and leave

operateto modify the internal state of the associated objects the code sending the Draw message completely unchanged

by modifying the data contained therein The combination ss In conventional procedure-oriented languages such

of data and methods in objects is called encapsulation linguistic approachwould wreak havoc In COT environ-

Perhaps the greatest single benefitof encapsulation is the ments the concept of polymorphism enables this to be done

fact tha t the sta te of any object can onlybe

changed bywith

impunityAs one

consequencemethods can be written

well-defined methods associated with that object When the that generically tell other objects to do somethingwithou

behavior of an object is confined tosuch well-defined 60

requiringthe sending object to have any knowledge at

a



22/179

to communicate with other processes or to schedule the

execution of process

Most conventional operating systems are procedure-

oriented and include native procedural interfaces Conse

quentty the services provided by these operating systems

can only be accessed by using the procedures defined by

theftrespective procedural interfaces

If program needs to

access service provided by one of these procedural oper

at.ing systems t he n t he program must include statement to

make theappropriate operating system procedure call This to

is the case whether the software program is object-oriented

procedure-oriented rule based etc Thus conventional

operating systems provide procedure-oriented environments

in which to develop and execute software Some of the

advantages of OOT are lost when an object-oriented pro

gram is developed and executed in procedure-oriented

environment This is true since all accesses to the proce

duraloperating system must

beimplemented using proce

dure calls defined by the operating systems native proce

dural interface Consequently some of the modularity

maintainabilityand

reusability advantages associated with

object-oriented programs are lost since it is not possible to

utilize classes objectsand other OOT features to their

fullest extent possible

One solutio n to this problem is to develop object-ori

entedoperating systems having native object-oriented inter

faces While thisultimately may be the best solution it

currentlyis not practical solution

s in ce t he resources

required to modify all of the major procedural operating

systems would be enormous Also such modification of 30

theseprocedural operating systems would render useless

thousands of procedure-oriented software programs There

fore what is needed is mechanism for enabling an object-

oriented application to interact in an object-oriented manner

with procedural operating system having native proce- 35

dural interface

SUMMARY OF THE INVENTION

Thepresent

invention is directed to system and method40

of enabling an object- or iented application to access in an

object-oriented manner procedural operating system hav

ing native procedural interface The system includes

computer and memory component in the computer code

library is stored in the memory component The code library

includes computer program logic implementing an object-

oriented classlibrary

Theobject-oriented

classlibrary com

prises related object-orientedclasses for

enablingthe appli

cation to access in an object-oriented manner services

provided by the operating system The object-oriented

classes include methods for accessing the operating system

services using procedural function calls compatible w it h t he

native procedural inter fa ce o f the operating system The

system also includes means for processing object-oriented

statements contained in the application and defined by the

class library by executing methods from the class library

corresponding to the object-oriented statements

Preferably the class library includes

thread classes for enabling an application to access in 60

an object-oriented manner operating system services to

virtual memory classes for enabling an application

access in an object-oriented manner operating system se

vices to access and manipulate virtual memory in com

puter

interprocess communication IPC classes fo

enabling an application to access in an object-oriented

manner operating system services to communicate wi

other threads during run-time execution of the application

computer

synchronixation classes for enabling an application


vices to synchronize execution of threads

scheduling classes for enabling an application


vices to schedule execution of threads

fault classes for enabling an application to access in a

object-oriented manner operating system services to process

system and user-defined processor faults and

20 machine classes for enabling an application to access

in an object-oriented manner operating system services

define and modify host and processor sets

Further features and advantages of the present inventio

as well as the structure and operation of various embod25

ments of the present invention are described in detail below

with reference to the accompanying drawings and in th

claims In the drawings identical reference numbers indicate

ide ntical o r functionally similar elements

BRIEF DESCRIPTEON OF THE DRAWINGS

The present inventionwill

be described with reference

the accompanying drawings wherein

HG illustrates block diagram of computer platformin which wrapper of the present invention operates

HG is high-level f lo w c ha rt illustrating the operationof the

present invention

FIG is more detailed flowchart illustrating the opera

tion of thepresent invention

HG is block diagram of code library containing a

object-oriented class libraryof the

present invention

FIG is class diagram of thread and task classes of th

present invention

HG is class diagram of virtual memory classes of th

present invention

HGS 79 are class diagrams of interprocess communi

cation classes of thepresent invention

HG 10 is class diagram of synchronization classesthe present invention

HG 11 is class diagram of scheduling classes of th

present invention

FIGS 12is are class diagrams of fault classes of th

present invention

HG 16 is class diagram of host and processor s

machine classes of the present invention and

HG 17 illustrates well-known icons for representingclass relationships and cardinality in class diagrams

DETAILED DESCRIPTION OF THE

5519867



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present invention emulates an object-oriented software envi

ronment on computer platform having procedural oper

ating system More particularly the present invention is

directed to system and method of enabling an object-

oriented application to access in an object-oriented manner

p ro ce du ra l o pe ra ting system having native procedural

interface duringrun-time execution of the application in

computer The present invention is preferably partof the

run-time environment of the computer in which the appli

cation executes In this patent application the present inven

tion is sometimes called an object-oriented wrapper since it

operatesto wrap p ro ce du ra l o pe ra ting system

with an

object-oriented software layer such that an object-oriented

application can access the operating system in an object-

oriented manner

FIG illustrates block diagram of computer platform

102 in which wrapper 128 129 of the present invention

operates It should be noted that the present invention

alternatively encompasses the wrapper 128 129in combi

n at io n w it h t he computer platform102 The computer plat

form 102 includes hardware components 103 such as20

random access memory RAM 108 and central processingunit CPU 106 It should be noted that the CPU 106 may

represent single processor but preferably represents mul

tiple processors operatingin

parallelThe computer platform

102 also includes peripheral devices which are connected to

the hardware components 103 These peripheral devices

include an input device or devices such as keyboard

mouse light pen etc data storage device 120 such as

hard disk or floppy disk display 124 and printer126

The datastorage

device 120 may interact with removable 30

datastorage

medium 122 such as removable hard disk

magnetic tape cartridge or floppy disk depending onthe

type of data storage device used The computer platform 102

also includes p ro ce du ra l o pe ra ting system 114 having

nativeprocedural

interface not shown The procedural

interface includes procedural functionswhich are called to

access services provided by the operating system 102

The computer platform 102 further includes device driv

ers 116 and may include microinstructionc ode 112 also

called firmware As indicated in FIG in performing their 40

required f un ct io ns t he d ev ic e drivers116 may interact with

the operating system 114 Application programs 130 132

134 described further below preferably interact with the

device drivers 116 v ia t he operating system 114 but may

alternativelyinteract directly with the device drivers 116 It 45

should be noted that theoperating system 114 may represent

substantiallyfull-function

operating system such as the

Disk Operating System DOS and the UNIX operating

system However the operating system 114 may represent

other typesof

operating systems For purposes of the present

invention the only requirement is that the operating system

114 be p ro ce du ra l o pe ra ting system having native

procedural interface Preferably the operating system 114

representslimited functionality p ro ce du ra l o pe ra ting sys

tem such as the Mach micro-kernel developed by CMIJ

which is well-known to those skilled in the relevant art For

illustrative purposes onlythe

presentinvention shall be

d escr ib ed h er ein with reference tothe Mach micro-kernel In

preferred embodiment of the present invention the com

p uter p la tfor m102 is an International Business Machines

theapplication programs 130 132

134 are adapted t

execute in different operating environments For exampl

theapplication programs 130A and 130B may be adapted t

operate in an object-oriented environment The application

program 132 may be adapted to operate in Microsof

Windows environment an IBM PSI2 environment or Unix

environment As will be appreciated by those skilled in th

relevant artthe

application programs 130A 130B and 13

cannot interact directly with the operating system 114 unless

theoperating system 114 implements an environment i

which the application programs 130A 130B and 132 ar

adapted to operate For example if the application 132

adapted to operate in the iBM PSI2 environment then th

application 132 cannot directly interact with the operating

system 114 u nless the operating system 114 is the IBM PS/2

operating system or compatible If the application pro

grams 130A and 130B are adapted to operate in an object

oriented environment t he n t he applications 130A 130B

cannotdirectly

interact with theoperating system 114 since

the operating system 114 has procedural inter fa ce In th

example shown in FIG the application 134 is adapted t

operatein the computing environment created by the ope

ating system 114 and the re fo re the application 134 is show

as being connected directly to the operating system 114

The wrapper 128 is directed to mechanism for providing

the operating system 114 with an object-oriented interface

The wrapper 128 e na bl es t he o bject- or ie nted a pp lica tion s

130A 130B to directly access in an object-oriented manner

the procedural operating system 114 during run-time exec

t io n o f the applications 130A 130B on the computer pla

form 102 The wrapper 129 is conceptuallysimilar to th

wrapper 128 The wrapper 129 provides an IBM PS/

interface for the operating system 114 such that the app

cation 132 c an directly access in PS/2 manner the proc

dural operating system 114 assuming that the application

132 is adapted to operate in the IBM PS/2 environment Th

discussion of thepresent

invention shall be limited herein

the wrapper 128 which provides an object-oriented inte

face to p ro ce du ra l o pe ra ting system having native

proceduralinterface

The wrapper 128 is preferably implemented as cod

library 110 which is stored in the RAM 108 The code librar

110 may also be stored in the data storage device 120 and/o

the data storagemedium 122 The c ode library 110 imp

ments an object-oriented class library 402 see FIGaccordance with the present invention the object-oriented

class library 402 includes related object-oriented classes fo

enabling an o bject- or ie nted a pp lica tion such as the app

cations 130A and 130B to access in an object-oriented

manner services provided by the operating system 114 Th

object-oriented classes comprise methods which include

proceduralfunction calls compatible with the n ative proce

dural interface of theoperating system 114 Object-oriented

statements defined by the object-oriented class library 40

such as object-oriented statements which invoke one

more of the methods of the class library 402 are insertabl

into the application130 to e na bl e t he application 130

access in an object-oriented manner the operating syste

services during r un -tim e e xe cu tion of the application 130 o

60 the computer platform 102 The object-orientedclass

libra

5519867

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35

50

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during mn-time This is explained in greaterdetail below

Since the computer program logic of the code library 110 is

not linked to application programs the computer program

logic can be modified at any time without having to modify

recompile and/or relink the application programs as long as

the inter fa ce to the code library 110 does not change As

noted above the present invention shall be describedherein

with reference to the Mach micro-kernel although the use of

thepresent

invention to wrap other operating systems falls

within the scope of the present invention

The Mach micro-kernelprovides

users with number of

services with are grouped into the following categories

threads tasks virtual memory interprocess communication

IPC scheduling synchronization fault processing and

host/processor set processing The class library 402 of the

presentinvention includes

setof related classes for each of

the Mach servicecategories Referring

to FIG the class

library 402 includes

thread classes 404 for enabling an application to

access in an object-oriented manner operating system ser

vices to spawn control and obtain information relating to

threads

task classes 406 for enabling an application to access

in an object-oriented manner operating system services to

reference and control tasks wherein the tasks each repre

sents an execution environment for threads respectively

a ss oc ia ted w it h t he tasks

virtual memory classes 408 for enabling an application

to access in an object-oriented manner operating system

services to access and manipulate virtual memory in

computer

IPC classes 410 for enabling an application to access


communicate with o th er processes during run-time execu

tion of the application in computer

synchronizationclasses 412 for enabling an applica

tio n to access in an object-oriented manner operating system

services to synchronizeexecution of threads

schedulingclasses 414 for enabling an application to


vices to schedule execution of threads

fault classes 416 for enabling an application to access


process system and user-defined processor faults and

machine classes 418 for enabling an application to


vices to define and modify host and processor sets

The class library 402 may include additional classes for

other service categoriesthat are offered by Mach in the

future For example security s ervice s a re currently being

developed for Mach Accordingly the class library 402 may

also include securityclasses 420 for enabling an application

to access in an object-oriented manner operating system

securityservices As will be appreciated the exact number

andtype

of classes included in the class library 402 depends

on the implementation of the underlying operating system

OperationalOverview of Preferred Embodiment

substantive stepof the flow chart 202 an object-oriente

statement which accesses service provided by the o

ing system 114 is located in the application 130A during

execution of the application 130A on the computer pla

102 The object-oriented statement is defined by the ob

o rien te d c la ss library 402 For example the object-oriente

statement may reference method defined by one o

classes of the class library 402 The following steps des

the manner in which the statement is executed by

computer platform 102

Instep 208 the object-oriented statement is translated

procedural function call compatible with the native

cedural inter fa ce o f the operating system 1 14 a nd c

sponding to the object-oriented statement In perfor

15

step 208 the statement is translated to the computer pro

logic from the code library 110 which implements

method referenced in the statement As noted above

method includes at least one procedural function call w

is compatible with the native procedural interface o

20operating system 114 In step 210 the procedural func

call from step 208 is executed in the computer platform

to thereby cause the operating system 114 to provid

service on behalf of the application 130A Step 2

performed by executing the method discussed in step

25thereby causing the procedural

function call to be invo

The operation of preferred embodiment shall no

described in more detail with reference to FIG w

illustrates detailed operational flowchart 302 o

present invention Again the present invention is descr

in the context of executing the object-oriented applica

130A on the computer platform 102 More particularly

present invention is described in the context of executin

single object-oriented statement of the object-oriented

cation 130A on the computer platform 102 The applica

130A includes statements which access services provide

theoperating system 114 and it is assumed that

s ta te me nts a re d efin ed by the class library 402 in

words the programmer c re ated the application130A

reference to the class library 402 As will be discusse

greater detail below the executable entity in the

micro-kernel is called thread The processing organiza

entityin the Mach micro-kernel is called task

includes one or more threads which may execute in

lel and an address space which represents block of v

memory in which the tasks threads can execute A

time there may be multiple tasks active on the com

platform 102 When executing on the computer platf

102 the application 130A could represent an entire

having one or more threads or could represent

threads which are part of task in this case the task w

have other threads which may or may not be r elated

operationof the

application 130A The scope of the pr

inventionencompasses the case

when the application

is an entire task or just few threads of task

ss Referring now to FIG in step 308 it is determ

whether the computer program logic also called com

code from the code library 110 which implements

method referenced in the statement is present in the

address space associated with the application 130A

60 computer program logic is present in the task address

then t 316 is processed described below If the

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related to the wrapper 128 wherein eachof the code

libraries i nc lud e t he computer program logic for one ofthe

object-orientedclasses of the cla ss library 402 As those

skilled inthe relevant art will appreciate there may also be

other code libraries not shown completely unrelated to the

wrapper 128

Associated with the code libraries are library servers each

of which manages the resources of designatedcode library

processing entity which desires access tothe computer

program logicof code library makes request to

the code

library s library server The request may includefor

example description of thedesired computer program

logicand d estina tion a dd re ss to which the computer

program logicshould be sent The library server processes

the request by accessing the desired computer program logic 15

from the code library and sending thedesired computer

program logicto the a re a of memory designated by

the

destination address The structure and operation of library

serve rs a re well known to those skilled in the relevant art

Thus in step 310 it is determined whetherthe library server 20

associated with the code library 110 which c on ta in s t he

relevant computer program logicis known Step 310 is

performed for example by referencing libraryserver table

which identifies the known library servers and the code

libraries which they service If the library serveris known

then step314 is processed discussed below Otherwise

step312 is processed In step 312

the library server asso

cia te d with the code library 110 is identified The identityof

the library server may be apparent for examplefrom the

content of the object-oriented statement whichis being

30

processed

After the library servera ss oc ia te d w it h t he code library

110 is ide ntifie d o r if the library server was already known

then step 314 is processedIn

step 314 requestis sent to

the library server askingthe

libraryserver to copy the

computer program logic associatedwith the method refer

ence in the statement to the task address space Upon

completion of step 314 the library serverhas copied the

requested computer program logic tothe task address space

Preferably the code library 110is shared library That is 40

the code library 110 may be simultaneouslyaccessed by

multiple threads However preferablythe computer pro

gram logic of thecode library 110 is physically stored

in

only one physical memory area The library server virtually

copies computer program logic from the code library 110 to

task address spaces That isinstead of physically copying

computer program logic from one partof physical memory

to another the library server places in the task address space

pointer tothe physical memory area containing

the rel

evant computer program logicIn step 316 the computer 50

program logicassociated with the object-oriented statement

is executed on the computer platform102 As noted above

in the case where the object-oriented statement accessesthe

operating system 114 the computer program logicassoci

ated with the method contains at least one procedural 55

function call which is compatible with the native procedural

interface of the operating system 114 Thus by executingthe

methods computer program logic the proceduralfunction

call is invoked and executed thereby causingthe operating

system 114 to provide theservice on behalf of the applica- 60

10

particular compiler which compilesthe application program

130A For example the run-time conventions may specify

that when an instruction accessing an operating system

service is encountered corresponding code from the code

library 110 should be transferred to the task a dd re ss space

via the associated library server andexecuted Compiler

run-Lime conventions are generally well kno wn Aswill be

appreciated run-time conventions are specificto the par

ticular compilers used The run-time conventions for use

with the present invention and with particular compiler

would be apparent to one skilled in the art b as ed o nthe

disclosure of the presentinvention contained herein par

ticularly tothe disclosure associated with t he f lo w c ha rt 302

in FIG As described above the wrapper 128 of the

presentinvention is implemented as

code library 110

which includes computer program logic implementingthe

object-orientedclass library 402 Alternatively the wrapper

128 maybe

implementedas hardware mechanism which

essentially operatesin accordance with the flow chart 302 of

FIG to translate object-oriented statements defined bythe

class library 402 in application programsto procedural

function calls compatible with the procedural interfaceof

the operating system 114 Or the wrapper 128 may be

implemented as backgroundsoftware

process operatingon

the computer platform102 which captures all accesses

to the

operating system 114 made by object-oriented statements

defined by the class library 402 andwhich translates the

accesses to proceduralfunction calls compatible with the

procedural inter fa ce o f the operating system114 Other

implementations of the wrapper128 will be apparent to

those skilled in the relevant artbased on the disclosure of the

present invention containedherein

Mach Services

This section provides an overview ofthe abstractions and

services provided by the Machmicro-kernel The services

are describedfor each of the major areas of the Mach

micro-kernel As noted above these include threads tasks

virtual memory IPC scheduling synchronizationservices

hardware faults and host/privilege services also called

machine services The Mach micro-kernel is further dis

cussed in many publicly available documents including

Loepere editor Mach Kernel Principles Open Software

Foundation and Carnegie Mellon University DrafiIndus

trial Specification September1992 and November 1992

Loepere editor Mach Kernel Interfaces Open Software

Foundation and Carnegie Mellon University DraftIndus

trial Spec jfication September1992 and November 1992

Loepere editor Mach ServerWriters Guide Open

Software Foundation and Carnegie Mellon UniversityDraft

Industrial Specification September1992 and November

1992 Loepere editor Mach ServerWriters Inter

faces Open Software Foundation and CarnegieMellon

University Draft Industrial Specification September1992

and November 1992 Silberschatz Peterson Galvin

Operating System Concepts Addison-Wesley July1992

and Tanenbaum Modern Operating Systems Prentice

Hall 1992

Threads

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10

15

20

25

30

35

40

11

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12

other data that make up its contextthread is always in one Tasks

of several scheduling states executing ready to execute orThe basic organizational entity in Mach for which

blocked for some reason Threads are intended to be light

weight execution entities This is to encouragethe program-

resources are managed is known as task Tasks have many

mer to make use of multiple threads in applications thusobjects and attributes a ssocia te d with them

taskfunda

introducing more concurrency into the system thanhas been

mentally comprises three things task contains multiple

threads which are the executable entities in the systemfound in traditional operating systems Although threads are

t as k a ls o has an address space which represents virtual

not without some cost they really are fairly minimal and thememory in which its threads can execute And task has

typical application or serverin Mach environment can take

port name space which represents the valid IPC ports

advantage of this capability through which threads can communicate with other threads

Threads do have some elements associated with them in the system Each of these fundamental objects in task is

however The containing task and address space as well as discussed in greater detail in the following sections Note

the execution state have already been discussed Eachthat task is not of itself an executable entity in Mach

thread has scheduling policy which determines when and However tasks cancontain threads which are the execution

how o ften the threa d will be g iven p ro ce ssor on which toentities task has number of other entities associated with

run The scheduling services are discussed in moredetail in

it b esid es the fundamental ones noted above Several of

later sectionClosely

tied to the scheduling policy ofthese entities have to do with scheduling decisions the kernel

thread is the optional processor set designationwhich can needs to make for

the threads contained by the task The

be used in systems with multiple processors to more closelyscheduling parameters processor set designation and host

control the assignment of threads to processorsfor poten-

information all contribute to the scheduling of the tasks

threads task also has number of distinguished interprotially greater application performance As indicated before

cess commumcation ports that serve certain pre-definedan address space task can con ta in zero or more threads

functions Ports and other aspects of interprocess commuwhich execute concurrently The kernel makes no assump-

nication are discussed at length in latersection For now

lions about the relationship of the threads in an address spaceit is sufficient to know that port resou rces a re accumulated

or indeed in the entire system Ratherit schedules and

over time in task Most of these are managed explicitly by

executes the threads accordingto the scheduling parameters the programmer The distinguished ports mentioned

above

associated with t he m a nd the available processor resourcesgenerally have to do with establishing connections to several

in the system In particular there is no arrangement e.g important functions in the system Mach supplies three

hierarchical of threads in an address spaceand no assump- special ports with each task The first is the task self port

tions about how the y a re to interact with each otherIn order

which can be used to ask the kernel to perform certain

to control the o rd er of execution and the coordination of operations on the task The second special port is the

threads to some useful end Mach provides several synchro- bootstrap port which can b e u se d for anything itsOS

nization mechanisms The simplest and coarsest mecha- environment-specific but generally serves tolocate other

nism is thread-level suspend and resume operations Each services The third special port that each task hasis the host

thread has suspend count which is incremented and name port which a ll ow s t he t as k to obtaincertain informa

decremented by these operations thread whose suspendtion about the ma ch in e o n which it is running Additionally

count ispositive

remains blocked until the count goes to Mach supplies several registered ports with each taskthat

zero allow the threads contained in the task to communicatewith

Finer synchronization can b e obtained through the use ofcertain higher-level servers in the system e.g the Network

syn ch ro niza tion o bjects semaphores or monitors and con-Name Server the Service Server and the Environment

ditions which allow variety of different synchronizationServer

styles to be used Threads can also interact via inter-process Two o the r u se fu l s et s of ports existfor each task that

communication

IPCEach of these services is described in 45 allow fault processing and

programstate sampling to be

more detail in lat er sections Basic operations ex is t t o performed The fault ports of task provide common place

support creation termination and gettingand setting for processor faults encountered by

threads in the task to be

attributes for threads Several other control operations exist processed Fault processing is described more fullyi n l ate r

on threads that can be performed by any thread that has section The PC sample port allows profilingtoo ls to

repeat-

send right to the intended threads control port Threads can so edly monitor t he ex ec ut io n s ta te of thethreads in the task

be terminated explicitly They can also be interrupted from Many operations are possiblefor tasks Tasks can be created

the various possiblewalt situations and caused to resume and terminated Creation of new task involves specifying

execution with an indication that they were interrupted some existing task as prototype for the initial contents of

Threads can also be wired which means that they are the address space of the new task task can also be

marked as privileged with respect to kernel resources i.e 55 terminated which causes all of the containedthreads to be

they can consume physical memory when free memory is terminated as well Thethreads contained in task can b e

scarce This is used for threads in the default page-out path enumerated and informationabout the threa ds can be

Finally threads also have several important lit ports more extracted Coarse-grain execution of task more precisely

preciselythe send or receive rights to these ports which are the threads in the task can b e controlled through suspend

used for certain functions In particular each thread has 60 and resume operations Each taskhas suspend count that

thread self t which can beused to perform certain is incremented and decremented by the suspend

and resume



27/179

Machsupports

sever al fea tu re s in its virtual memory

VM subsystem Both the external client interfaces as well

as the internal implementation offer featuresthat

arenot

found in many other operating systemsIn broadest terms

the Mach virtual memory system supports large sparsely

populated virtual address space for each of the tasks running

in the system Clients are provided with general services for

managing the composition of the a dd re ss space Some

aspects of the VM system are actually implemented by10

components that are outside of the micro-kernelwhich

allowsgreat flexibility

in tailoring certain policyfunctions to

different system environmentsThe internal architecture of

the Mach VM system has been divided into machine-

independent and machine-dependent modules for maximum 15

portability Porting to new processorIMMUarchitecture is

generally sma ll m atte r of implementing number of

functions that manipulate the b asichardware MMU struc

tures Mach has been ported to numberof different

processorarchitectures

attestingto the portability

of the20

overall kernel and the virtual memory system in particular

The address space of Machtask contains number of

virtual memory regions These regions are pieces ofvirtual

address space that have been allocated in various waysfor

use by the task They are the only locations where memory

can be legitimately accessed All references toaddresses

outside of the defined regions in the address spacewill result

in an improper memory reference f au lt vi rtu al memory

region has several interesting attributes It has page-

aligned starting address and size which must be multiple 30

of the system page size The pages in the region allhave the

same access protections these access protections can be

read-only read-write or execute The pages in regionalso

have the same inheritance characteristic which may beused

when new tusk is created from the cur re nt tusk The

inheritance characteristic for pages in region can be set to

indicate that new task should inherit read-write copy of

the region that it should inherit v irtual copyof the region

or that it should inherit no copy of the regionread-write

copy of region in new address space provides fully 40

shared mapping of the region betweenthe tasks while

virtual copy provides copy-on-write mappingthat essen

tially giveseach task its own copy of the region

but with

efficient copy-on-write sharing of the pages constitutingthe

region 45

Every virtual memory region is really mapping of an

abstract entity known as memory object memory object

is simply collection of datathat can be addressed in some

byte-wise fashion and about whichthe ker ne l m akes no

assumptions It is best thought of as some pure pieceof data 50

that can either be explicitly stored some place or c an b e

produced in some fashion as needed Manydifferent things

can serve as memory objects Somefamiliar examples

include files ROMs disk partitions or foats Memory

objectshave no Fe-defined operations or protocol

that they

are expected to follow The data contained in memory

object can only be accessed when it hasbeen t ied t o VM

region through mappingAfter

memory objecthas been

mapped to region t he d at a can be accessedvia normal

memory read and write loadand store operations 60

14

with the d ata from the corresponding byte addresses in the

associated memory object To accomplishthis the kernel

actually engages in well-defined and onerous protocol

with the pager whenever it needs to getdata for page faults

or when it needs to page-out data due to page replacements

This protocol which is known as the External Memory

Management Interface or EMMI a ls o h an dl es t he initial

ization sequences for memory objectswhen the y a re mapped

by client tusks and the termination sequences when any

associated memory regions are deallocated by client tasks

There c an b e any numberof

pagers running in the system

depending on which memory objects are in use bythe

various client tasks Pagers will typically be associatedwith

the various file systems that are mounted at given timefor

example Pagers could also exist to support certaindatabase

applicationswhich might have needs for operations beyond

what is supported by the file system Pagers could alsoexist

for certain servers that wish to supply data to their clients in

non-standard ways e.g generating the d ata computation-

ally rather than retrieving it from storage subsystem The

micro-kernel always expects to have certain distinguished

pager known as the default pager runningin the system The

default pager is responsiblefor managing the memory

objects associatedwith anonymous virtual memory such

stacks heaps etc Such memory is temporary and only of

use while client task is running As described above the

main entities in the Mach VM system are regions memory

objects and pagers Most clients howeverwill deal with

virtual memory through operations on rangesof memory

range c an b e portion of region orit could span multiple

con tigu ou s r eg io ns in the a dd re ss space Operations are

provided by Mach that allow users toallocate new ranges of

virtual memory in the address spaceand deallocate ranges as

desired Another important operation allows memory

object to be mapped into range of virtual memory as

described above Operations are also available to changethe

protections on ranges of memory change the inheritance

characteristics and wire or lock the pages of rangeinto

physical memory It is also possible to read rangesof

memory from another task or write into ranges inanother

task provided that the control port for the task isavailable

Additional services are available that allow t he u se r to

specify the expected reference pattern for range of

memory This c an b e u s ed bythe ker ne l as advice on ways

to adapt the page replacement policy todifferent situations

Yet another service is available to synchronize or flush the

contents of range of memory with the memory objects

backing it Finally ser vice s a re a va ilab le toobtain informa

tion aboutregions

and to enumerate the contents o f t usks

address space described in terms of the regions itcontains

InterprocessCommunication

Mach has four concepts that are central to its interprocess

communications facilities Ports Port Sets Port Rights and

Messages One of these concepts Port Rights is also used

by Mach as means to identify certain common resourcesin

the

system suchas threads tasks

memoryobjects etc.

Ports

13

Virtual Memory

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5519867

15 16

sagesthat can be enqueued on the port limit on the Port rights have several attributes

associated with t

maximum size of message that can be sent to port and the type of the right send send-once receive port s

count of how many rights to the port arein e xisten ce Por ts dead name and reference count for each of the a

exist solely in the kernel and can only be manipulated via types of rights When task acquires rightfor

po

port rightswhich it already has send or receive rights the correspo

ing reference count for the associated port name is i

mentedport

name becomes dead name when

Port Rightsassociated

portis destroyed That is all port names r

senting send or send-once rights for port whose rec

thread can add message to ports message queue if right is deallocated become dead names task can req

it has send right to tha t port Likewiseit can remove notification when one of its rights becomes dead The ke

message from ports message queuei f i t has receive right keeps system-wide count of the number of s en d

to that port Port rights are considered to be resourcesof send-once rights for each port Any task that h ol ds r ec

task not an individual thread There can be many send rights right such as server can request notification message

toport held by many different tasks however

there cansent when this number goes to zero indicating that the re

onlybe one receive right to port In fact port is created no more senders clients for the port This is called

by allocating receive right and portis d es tr oy ed o nl y more senders notification The request must include

when the r eceive right is deallocated either explicitly or right forport

to which the notification should be se

implicitlywhen the task dies In addition the attributes of

port are manipulated through the receive right Multiple 20

threads on the same or different tasks can send to port at

the same time and multiple threads on the same task canets

receive fromport

at the same time Port rights act as Por t sets provide the ability to receive from collectio

permission or capability to send messages to or receive ports simultaneously That is receive rights can be adde

messages from port and thus they implementlow-level 25 port set such that when receive is done on the por

form ofsecurity

for the system Theowner of

portis the

message will be receivedfrom one of the ports in t he

task that h olds the r eceive right The only way for another The name of the r eceive right whose port provided

task to getsend right for port is i f i t is explicitly given message is reported by the receive operation

the righteither by the owner or b y a nytask that holds

valid send right for the port This is primarily done by 30

including the right in message and sending the message to Messa es

another task Giving task send right grants it permission

to send as many messages to the port asit wants There is Mach IPC message comprises

header a nd a n in

another kind ofport right

called send-once right that only data portion and optionally someout-of-line me

a ll ow s t he h ol de r to send one message to the port at which regions and port rights If the messagecontains neither

time the send-once right become invalid and cant be used rights nor out-of-line memory then itis said to be s

again Note that ownership of port can be transferred by message otherwise it is complex message s

sending the ports receive right in message toanother task message c on ta ln s t he message header directly

followe

Tasks acquire port rights either by creatingthem or the in-line data portion The message

header contain

receiving them in message Receive rights can onlybe 40 destination port send right an optional

send right to w

createdexplicitly by doing port allocate as described

reply may be sent usuallysend-once right and

above send rights can be created either explicitlyfrom an length of the d ata portion of the message

The in-line d

existingsend or receive right or implicitly while being

of variable length subject to maximum specified

transmitted in message send-once right canbe created per-port basis and is copied without interpretation

explicitly or implicitlyfrom receive

rightonly When 45 plex message

consists of message header with the

rightis sent in message the sender can specify

that the rightformat as for simple message followed by count

is either copied moved or new right created bythe send number of out-of-line memory regions

and ports dispos

operation Receive rights can only be movedof course arrays describing

the kemels processing of these reg

Whenright

is moved the sen de r loo se s the right and theand ports and arrays containing

the out-of-line descrip

r eceive r g ains it When copied the sender retains the right 50and the port rights

but copy of the right is createdand given to the receiver The port right disposition array

c on ta in s t he de

When created the sender provides receive right and new processing of the right i.ewhether it should be co

send or send-once right is created and given to the receiver made or moved to the target task The out-of-line me

When task acquires port right bywhatever means Mach disposition array specifies for each memory range wh

assignsit name Note that ports themselves are not named 55 or not it should be de-allocated when

the message is qu

but theirport rights are Despite

this fact the creators of and whether the memory should be copied into the recei

Mach decided to r efer to the name of port right with the tasks address space or mappedinto the receiving ad

termport name instead of the

obviousport right name This space via virtual memory copy-on-right mechanism

name is sca la r value 32-bits on Intel machines that is out-of-line d escr ip to rs spe cify the size address and

guaranteed unique only withintask which means that 60 ment of the out-of-line memory region When task rece

several tasks cou ld each have t name with the same message the header in-line data and d escr ip to r a rr ay



29/179

18

condition is true waiting thread is unblockedand th

re-acquires thelock before continuing execution thre

can also perform broadcast operation oncondition wh

unblocks all of the threads waiting for thatconditi

Optional time-outs can also be set on thec on di ti on w

operations tolimit the time thread will wait for

condition

Scheduling

Host and Processor Sets

17

Message TransmissionSemantics

5519867

Mach IPC is basically asynchronous in naturethread

sends message to port and oncethe message is queued

on the port the sending thread continues executionreceive

on portwill block if the re a re no messages queued on

the

port For efficiency there iscombined send/receive call that

wifi send message and immediatelyblock waiting for

message on specified reply port providingsynchronous

model timeout ca n b e set on all message operations 10

which will abort the operation if the messageis unable to be Since Mach is multiprocessor capable

itprovides for

sent or if no message isavailable to be received within the scheduling of threads

in multiprocessor environme

specified time period sendcall will block i f i t uses Mach defines processor sets

to group processorsand

send-right whose corresponding porthas reached its maxi- defines scheduling policies that can

be associated with th

mum number of messages If send uses send-onceright Mach provides two scheduling policies

timeshare and fi

the message is guaranteed tobe queued even if the port

ispriority

The timeshare policy is bas ed on the exponentia

full Message deliveryis reliable and messages are guar- average

of the threads usage of theCPU This policy

anteed to be received in the order they aresent Note that attempts to optimize

the time quantumbased on the num

there is special-case codein Mach which optimizes

for the of threads and processors The fixed priority policy does

synchronous model overthe asynchronous model the

fastest20

alter the prioritybut does round-robin scheduling on

IPC round-trip time isachieved by server doing receive threads

that are at the same priority thread can use

followed by repeated send/receivesin loop and the client

default scheduling policyof its processor set or explic

doing corresponding send/receivesin loop on its side use any

one of the scheduling policies enabledfor

processorset maximum priority can be setfor proces

Port Rights as Identifiers 25set and thread In Mach the lower the priority value

greater the urgency

Because the kernel guarantees boththat

port rightscannot

be counterfeited and that messages cannotbe misdirected or

Faults

falsified port rights provide veryreliable and secure

identifier Mach takes advantage of this by using port rightsThe Mach fault handling service s a re intended to pro

to representalmost everything

in the system including30

flexible mechanism for handling both standardand u

tasks threads memory objectsexternal

memorymanagers defined processor

faults The standard kernel facilities

permissions to do system-privileged operations processorthreads messages and ports are

used to provide the

allocationsand so on In addition since the

kernel can send handling mechanism This documentuses the word fa

and receive messages itself it representsitself as special where the Mach documentation uses

the word except

task the majority of the kernelservice s a re accessed via Such terminology has been changed

herein to disting

IPC messages insteadof system-call traps This

has allowed hardware faults from the exception mechanism of the

services to be migrated out of the kernel fairly easilywhere language Threads and

task have fault ports Theydiff

appropriatetheir inheritance rules and are expected to be used in sli

different ways Error handlingis expected to be done

Synchronization per-threadbasis and debugging is expected

to be handle

per-taskbasis Task fault ports are

inherited from pare

Currently Mach provides no direct supportfor synchro-

child tasks while thread fault ports are notinherited

nization capabilities However conventional operating sys- d efau lt to no handler Thread fault handlerstake preced

tems routinely provide synchronizationservices Such Syn-

over task fault handlers When thread causesfau

chronization services employ manywell-known

kerne l b lo cks the thread and sends fault message t

mechanisms such as semaphoresand monitors and condi-

threads fault h an di er v ia t he fault porthandler is

tions which are described below Semaphoresare syn-

that receives message fromthe fault port The mes

chronization mechanism which allows bothexclusive and

contains information about the fault the threadand the

shared access to resource Semaphores canbe acquired and

causing the fault The handler performsits function ac

released in either an exclusive orshared mode and they 50

ing tothe type of the fault

If appropriate the handler ca

can optionally specify thue-out periodson the acquire

and modify the e xe cu tion sta te of thethread that caused

operations Semaphores are optionallyrecoverable in the

fault Possible a ctio ns a reto cle ar the fault to terminate

sense that when thread thatis holding semaphore

thread or to pass the faultonto the task-level handler

terminates prematurely the countersassociated with the

are identified by types and data Machdefines

semaphore are adjustedand waiting threa ds a re

unblockedmachine-independent fault types that are supported

f

as appropriate Mach implementations e.g bad accessbad instruc

Monitors and con dition s a re syn ch ro niza tionmecha-

breakpoint etc. Otherfault types c an be implemen

nismwhich

implementsrelatively more disciplined and

dependent e.gf-line co-processor

violation etc.

safer style of synchronizationthan simple semaphores

monitor lock also called mutexis essentially binary 60



30/179

19

such information i nc lu de t he v er si onof the kernel or the

rightto gain access to the value

of the system clockAlmost

all other information is considered sensitive and higher

degree of privilege is required to getor manipulate the

information This added level of privilege is implied when

task holds send right to the host control port alsoknown

as the host privilege port This rightmust be given out very

carefully and selectively to tasksbecause having this right

enables task to do virtually e ve ryth in g p ossibleto the

kernel thus by-passing the security aspectsof the system

supported by theIPC services Various operations can be

performed withthis added privilege including altering

the

systems clock setting obtainingoverall performance and

resource usage statisticsfor the system and causing

the

machine to re-boot

Mach also exports the notions of processorsarid processor

sets which a llow tasks to more carefully specifywhen and

on what processorsits threads should execute Processors

andprocessor

sets can be enumerated and controlledwith

the h ost privilege port processor represents particular

processorin the system and processor

set represents

collection of processors Servicesexist t o create new pro

cessor sets and to add processors to setor remove them as

desired Services also exist to assign entire tasks or particu

lar threads to set Through these services programmer can

control on coarse grain when thethreads and tasks that

constitute an application actually getto execute This allows

programmer to specifywhen certain threads should be

executed in parallel in processor setThe default assign

ment for tasks and threads that do not explicitlyuse these

capabilitiesis to the system default processor set

which

generally contains any processorsin the system that arent

being used in o th er sets

Security

Mach may include other categoriesof services in addition

to those described above For example Mach mayinclude

services relating to security Inaccordance with the Mach

security services every task carries securit ytoken which

is scalar value that is uninterpreted by Mach There is

portcalle d the host security port

that is given to the bootstrap

task and passed on to the trusted securitysever tasks

security token can be set or changed by anytask that holds

sendright

to t he h os t security port while no special

permissions are needed to determinethe value of tasks

security token other than holdingthe tasks control port of

course At the time MachIPC message is received the

security token of the sender ofthe message is returned as one

of the output parameters to thereceive function Tasks that

hold the host security port can send messageand assign

different security token to that messageso that it appears to

have come from another task These services canbe used by

upper layersof the system to implement

various degrees of

security

Wrapper Class Library

This section provides an area-by-area descriptionof the

object-orientedinterface for the services provided by the

Mach micro-kernel This object-orientedint erface t o the

20

library 402 may includeadditional classes such as secu

classes 420 depending on the services provided by

underlying operating system114 Each area is describ

with class diagram and text detailingthe purpose

functionof each class Selected methods are presented

defined where appropriate the parameterlist of method

also provided Thus thissection provides complete op

tional definition and description of the wrapperclass lib

402 The implementation of the methodsof the wra

io class library 402 is discussed in latersection

The class diagrams are presented usingthe well-kno

Booch icons for representing class relationships andc

nalityThese Booch ico ns a re p re se nted in FIG 17

convenience purposes TheBooch i co ns a re discussed

15

Object Oriented Design With Applications byGrady Bo

referenced above The wrapper class library402 is pr

ably implemented usingthe well-known C-H- comp

programming language Howeverother programming

guages could alternativelyb e u se d Preferably the

20descriptions are grouped

into SPI System Programm

Interface API Application Programming Interface

nal and Noose methodsindicated by ifndef stateme

bracketingthe code in question or by comments

for N

methods SPI interfa ce s a re specific to the particular

25puter platform being used

For illustrative purposes

wrapper class library 402is

presented anddescribed h

with respect to computer platform operatingin accord

with the IBM MicroKernel which is based on Mach Ve

3.0 or compatible Personsskilled in the relevant art

30find it apparent to modify the

SPI classes to accommod

other computer platforms b as ed o nthe teachings conta

herein

API interfa ce s a re included in the wrapperclass li

402 regardless of the platform the systemis running on

Internal interfa ce s a re intended for use only bylow-

implementors The Noosemethods are provided sole

enable an application 130 operating with the wrapper1

communicate with an application 134 or servertha

writt en t o run on Mach 114 directly They provideacce

40the raw Mach facilities in such way that they

fail ou

of the intended object-oriented programmingmodel

lished by the wrapper 128Use of Noose methods is h

discouraged The SPI and API and perhapsthe Inte

classes and methods are sufficient to implement any

cation component or subsystem

Thread Classes

FIG is class diagram 501 of thethread classes 4 0

the task classes 406 The thread classes404 provi

object-oriented interface to the taskingand threading

tionality of Mach 114 number ofthe threa d cla sses

are handle classes so noted by their namewhich

that they representreference to the corresponding

entity The null constructors on thehandle classes cre

empty handle objectAn empty handle object

doe

initially correspond to any kernel entityitmust be

i zed vi a streaming an assignment or copy ope

Calling m et ho ds o n an emptyhandle will cause an exce

to be thrown Multiple copies ofhandle object c

made each of which point to the same kernel entity

so th

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21 22

v id es t he mechanism for spawning new threads in the SetThreadSchedule constflhreadSchedule ne

system Control operations include killing suspending/re- chedulesets the scheduling object in the thread to

suming and doing death wat ch on it Constructing newSchedule object This allows one tocontrol the w

TFhreadHandle and passing in TThreadProgram object thread is scheduled

causes new thread to be constructed on the current task GetS cheduleState TThreadHandle theBloc

The first code run in the new threa d a re the Prepare anddOnThread allows one to query t he c ur re nt s ta te o

Run methods of the TThreadProgram object Destroyingthread thefllockedOnThread on which this thread

TrhreadHandle does not destroy the thread it representsblocked

There may also be cancel operation onthe TThreadllandle

object Note that each TThreaclllandle object containssend CancelWaitAndPostException const causes bloc

right tothe control

portfor the thread This information is

10kernel call to be unblocked and TKernelException

not exported by the interface in general but because it doesthrown in the thread this

containport right

the only stream objectflhreadPro- WaitForDeathOf coast performs death watch on

gram can be streamed into is TlPCMessageStream threadblocks calling thread until the thread this te

Attempting to stream into other TStream objects will cause nates C re at eD ea th in ter es t c re at es notification int

an exception to be thrown.15

for the death of the thread this When the thread t

TmreadHandle provides number of methods for use by n ates the specified flnterest gets notification

debuggers and the runtime environmentand for supporting

flhreadProgram is an abstract base class that encainteractions with Mach tasks running outside of the envi-

laths all the information required to create new thread

ronment established by the wrapper 128 Thesemethods

includegetting

and setting the state o f t hr ea d spawning an20

i nc lu des t he code to be executed scheduling informa

empty thread in another task getting the threads faultand the threads stack To use it must be subclassed an

ports returning right to the threads control portand Begin

and Run methods overridden and then an insta

creating T1hreadHandle handle fromthread control port

tion of the object passed into the constructor for flhre

send rightHandle to spawn thread The Begin routine

is provide

As noted above the wrapper 128 establishes computingaid

startup synchronization Begin is executedin the

environment in which the applications 130 operate Forthread b ef or e t he TIhreadHandle constructor compl

brevity this computing environment established by theand the Run routine is executed after the flhreadHand

wrapper 128 shall be called CE With regard to the wrapperconstructor completes The methods CopyThreadSchedule

128 flhreadHandle spawnsCE runtime thread on the and GetStackSize return

the default thread schedule

current task thread can also be spawned on another task 30stack size lb provide values different from the default

instead of on the current task by using the CreateThreadmethods should be overridden to return the d esired th

methods in the flaskHandle class and in subclasses of schedule a nd /o r sta ck size flhreadProgrami nc lu de s

flaskHandle Creating thread on a no th er taskis not following methods

recommended as general programming model however TmreadProgram const flext taskDescripiion

To spawn CEthread on another CE task the TCETa5kHan- 35 Description provides text description

of task that c

dleCreateThread method is used by passing it Trhread- access vi a t he ThskHandleGetThskDescription me

Program describing the thread to be run To spawn non-CE Only in effect if the object is passed TlaskHandle

thread that is thread which does not operate in the structor If default constructor is used instead the inte

computing environment established by the wrapper 128 the will synthesize unique name for TraskHandle GetT

CreateThread method is used on the appropriate subclass of 40 Description to return

flaskHandle that is the subclass of T1askHandle that has GetStackSize returns the size of the stack to be s

heen created to operate with the othernon-CE computing

for the thread Override this method if you dont wan

environment For example to spawn anIBM OS2 thread on

default stack size

an 052 task you mightuse

TOS2TaskHandleCreateThread method It is not possible

GetStack Used to set up the threads stack Ove

this method if you want to provide your ownstack

to run CE thread on non-CE task nor is it possible to run

non-CE thread on CE taskRun represents the entry point for the code to be

the thread OVERRIDE THIS METHOD to providT1hreadllandle includes the following methods

code the thread is to execute

flhreadHandle const TrhreadProgram copyThread

Code creates new thread in the calling taskmakes an

internal COPY of the TmreadProgram which is deletedThsk Classes

upon termination of the thread See FIG for class diagram of the task cla sses

IThreadHandle TlhreadProgram adoptThreadCode

creates new thread in the calling taskADOPTs adopt-TTaskHandle is concrete base class that encapsulates

ThreadCode which is deleted upontermination of the thread

55 the attributes and operations of basic Mach task It c

The resources owned by t he t hr ea d a re also discardedused to refer to and control any task on the sy

copy of the TThreadProgram is NOTmade

f lask Handle c annot b e u se d directly to create

however because it doesnt have any knowledge abou

IThreadHandle EExecution yourself creates thead runtime environment It does provide sufficient protoc

handle for the calling thread 60 protected methods for subclasses with specific ru

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resuming the task and doingdeathwatch on the task The

informational methods include getting its host gettingand

settingits registered ports enomerating its ports

or virtual

memo regions getting its fault ports enumeratingits

threads etc TlhskHandle i nc lu de s t he following methods

T1askHandle EExecutionThread creat es t askhandle

for the specifiedthread

Suspend suspends the task i.eall threads contained by

the task Resume resumes the task i.eall threads

contained by the task10

Kill terminates the taskall threads contained bythe

task a re terminated

WaitForDeathOf performs death wa tc h o nthe task

The calling thread blocks until the task this terminates

C re at eD ea tb in te re st c rea te s notification interest forthe

death of the task The thread specifiedin the Tinterest object

gets notificationwhen the task this terminates

AilocateMemory size_t howManyBytes TMemorySur

rogate newRangeallocates range of anonymous

vir-

20

teal memory anywhere in the tasksaddress space The

desired size in bytesis specified in howManyBytes

The

startingaddress after page alignment and

ac

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