DTIC ADA445812: A Resource Reservation Scheme for Synchronized Distributed Multimedia Sessions

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T R R
ECHNICAL ESEARCH EPORT
A Resource Reservation Scheme for
Synchronized Distributed Multimedia
Sessions
by W. Zhao, S.K. Tripathi
T.R. 97-14
ISR
INSTITUTE FOR SYSTEMS RESEARCH
Sponsored by
the National Science Foundation
Engineering Research Center Program,
the University of Maryland,
Harvard University,
and Industry
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1997 2. REPORT TYPE 00-00-1997 to 00-00-1997
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A esource Reservation Scheme for Synchronized Distributed Multimedia
5b. GRANT NUMBER
Sessions
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Computer Science Department,Institute for Systems Research,University REPORT NUMBER
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unclassified unclassified unclassified
Standard Form 298 (Rev. 8-98)
Prescribed by ANSI Std Z39-18
A Resource Reservation Scheme for
(cid:3)
Synchronized Distributed Multimedia Sessions
(Extended Abstract)
Wei Zhao and Satish K. Tripathi
Department of Computer Science
University of Maryland at College Park
College Park, Maryland 20742
Email: fzw,[email protected]
Abstract utilization while providingservice guaranteesex-
pressed in terms of throughput, delay, delay jit-
Guarantees of services in a networked environment
ter, etc, for a given set of resources.
areprovidedbytheproperallocationandutilizationof
Inthispaper,weproposeaschemetotranslate
network and system resources. In this paper, we pro-
the service guarantees at the system level into
posea resourcereservationschemefora classofmul-
timedia applications. We characterize this class of the guarantees at the application level for mul-
multimedia applications as synchronized distributed timedia applications. In particular, we propose
multimedia sessions, which we believe represent a a resource reservation scheme for a large class
large number of multimedia applications. In addition ofmultimedia applications. We characterize this
tothisparticularclassofapplications,thereservation
class of multimedia applications as synchronized
scheme can also be applied to other applications with
distributed multimedia sessions (SDMS’s). In
synchronized resource requirements. Mechanisms are
addition to this particular class of applications,
devised sothat thescheme can (cid:12)nd afeasiblereserva-
tion whenever one exists, in contrast to existing pro- the reservation scheme can also be applied to
tocols where request can fail unpredictably even when otherapplications withsynchronizedresourcere-
there is available resource. Based upon a layer of re- quirements.
source abstraction, the scheme suits wellwith today’s An SDMS consists of a number of multime-
heterogeneous network environment.
dia streams from distributed sources whose pre-
sentation time intervals are interrelated. An
SDMS executes successfully only when all the
1 Introduction
component streams are presented with the spec-
i(cid:12)ed qualities during their respective time in-
Traditional best-e(cid:11)ortservices provided by com-
tervals as determined by its synchronization re-
puter systems are inadequate for new genera-
quirements. The synchronization requirements
tion applications such as multimedia applica-
ofSDMS implies resource requirements in a syn-
tions. Guarantees on the quality of service are
chronized fashion. For example, if stream B
needed. A lot of research work has been done
is to be presented immediately after stream A,
at the system level to achieve better resource
then once streamA (cid:12)nishes presentation, the re-
(cid:3)
Prepared through collaborative participation in the
source required by stream B must be available
Advanced Telecommunication/Information Distribution
forB’spresentation. Notethat,the resourcesre-
Research Program (ATIRP) Consortium sponsored by
the U.S. Army Research Laboratory under Cooperative quired by multimedia applications include both
Agreement DAAL01-96-2-0002. network resources for the data transmission and
1
end-system resources for the data processing.
Video1 Image1 1. Client c sends Object Reservation Request for all
multimedia objects to their locations. That is, for
each object o, c sends object reservation request
(o;I(o);Q(o);c) to the location of the object E(o),
Begin Slide1 D2e lsaeyc Text2 End whereI(o)andQ(o)representtheinterval andqual-
ity requirements of object orespectively.
Text1
2. For each source (called Server) s that receives the
Audio1 object reservation request (o;i;q;c),
Video2
2.1. Based upon the object o’sproperties, s deter-
mines theresourcerequirement R(o;q;c;i)for
Figure 1: A Petri-Net Synchronization Repre- its presentation.
sentation 2.2. s sends the Resource Inquiry Request for the
resource requirement computed in 2.1 to the
Currentlyavailable resourcereservationproto- resource managers for each resource involved,
cols such as RSVP and STII are inadequate to including itself.
provide this kind of resource requirement: the
3. Foreachresourcemanagerthatreceivestheresource
resources reserved by these protocols are time-
inquiry request, it checks its own resource reserva-
invariant over a session’s life time and there is tiontableandsendsbacktoclientctheStartTimes
no way to do a synchronized resource reserva- Intervalswhen the requested resource is available.
tion where resource requirement changes during
4. Whenclient cgetsbackall theresponses ofresource
a session; and, the reservation requests are of inquiry requestsfromresource managers,itrunsthe
an immediate fashion, each request either suc- Interval Intersection Finding Algorithm to (cid:12)nd the
ceeds with the resourceallocated immediately or starttimewhenallresourcerequirementscanbesat-
is(cid:12)ed.
failsdue toinsu(cid:14)ciency ofcurrentlyavailable re-
source. Itis uptotheapplication todecide when
4.1. If no intersection is found, it returns FAIL to
orwhether toresubmit the reservation request if the application.
it fails. Furthermore,there is no wayof knowing 4.2. If a start time is found, it sends back to the
when the request will succeed or whether it will resource managers the Con(cid:12)rmation Message
succeed at all. withthestarttimetocon(cid:12)rmthereservation.
And returns the starttime to the application.
2 Methodology 5. Whenresourcemanagersreceivethereservationcon-
(cid:12)rmationmessages,theymodifytheirresourcereser-
vation tables to mark the resources as reserved.
We propose a resource reservation scheme that
overcomes the above problems.
Essentially, the resource reservation scheme Figure 2: The Resource Reservation Scheme
for an SDMS collects the individual resource re-
quirementsgeneratedbymultimedia objectsand
inquires resources about the satis(cid:12)abilities of in-
dividual resource requirements. After collecting (cid:12)nding algorithm. Instead of the yes/no type of
temporal intervals in which individual resource responses on resource satis(cid:12)abilities that other
requirements can be satis(cid:12)ed, the scheme inte- resourcereservationprotocolsuse,weexpressre-
grates them to provide the resource guarantee source satis(cid:12)abilities in terms of available tem-
for the whole SDMS by determining the feasi- poral intervals. The use of temporal intervals
ble session start time via temporal intersection enables us to coordinate available resources for
2
thewholeSDMSonthetemporalaxisandmakes i; B(i;j), E(i;j) are the end points of the jth
it possible for in-advance reservations. interval of resource i; C(i) and T(i) keep track
Compared to RSVP and STII, our scheme re- ofthecurrentintervalandcandidateintersection
serves resources in a synchronized fashion as re- on resource i, respectively.
quired by an SDMS. It is also an in-advance re- Resources
source reservation scheme. When the required
resource is not available at the time of the re- T FinalT
quest, the scheme returns the time that the re-
source will be available and reserve theresources
accordingly. Unlike many multimedia presenta-
tion schedule generation techniques, ourscheme,
like RSVP, leaves the resource satis(cid:12)ability de-
cisions to the resource side, making the scheme
very (cid:13)exible.
t
Figure 4: An Example ofTime-Axis Walk in the
function Intersection
T B(0;0) Insection Finding Algorithm
fork 0 to N(cid:0)1 do
C(k) 0 Figure 4 shows a running instance of the algo-
T(k) (cid:0)1 rithm on a sample set of intervals. Basically, the
end for
algorithmis a time-axis walkby looping through
i 1
resources and inspecting the intervals in order.
while TRUE do
if T =T(i) return T Anintersectionisfoundoncethecandidateinter-
j C(i) section T remains the same after a loop through
while (j<0 or E(i;j)<T) do
the set of resources.
if j<I(i)(cid:0)1 then j j+1
For improved e(cid:14)ciency, we devised a early
else return FAIL
C(i) j start and greedy progress strategy for running
T max(B(i;j);T) the intersection (cid:12)nding algorithm. The idea is
T(i) T
that the algorithm does not have to wait till all
i (i+1)mod N
intervals are collected. Instead, it can start run-
end while
end ning as soon as the (cid:12)rst interval arrives and as
long as the inspected interval is available. Im-
mediately after an intersection is found, the al-
Figure 3: The Interval Intersection Finding Al- gorithm stops and sends messages to resource
gorithm managers to stop the generation of more inter-
vals. Thegreedystrategyreducesthereservation
latency by exploiting the execution structure of
The temporal interval intersection (cid:12)nding al- the algorithm.
gorithm used in the scheme is given in (cid:12)gure 3. Due to the delay between resource inquiry
The goal of the algorithm is to (cid:12)nd a time in- and commit messages, resource allocation may
stant that falls in at least one interval of ev- have changed between these two time instants.
ery resource. In (cid:12)gure 3, N is the number of A commit message may fail due to this kind
resources; T is the current candidate intersec- of resource con(cid:13)ict. To handle multiple con-
tion; I(i) is the number of intervals of resource current resource reservation requests with pos-
3
Client Side
der on active requests on some resource. The
Send Request
technique is proved to guarantee progress. A re-
laxed version of partially ordered technique fur-
Receive Intervals
ther enhanced the parallelism while maintaining
the guaranteed progress property. The partially
Find Intersection
ordered technique is shown in (cid:12)gure 5.
Found Fail
For the resource reservation scheme, we did
Send Commit Return FAIL
not assume any particular resource management
and scheduling policies. We use only the re-
Receive Response
source satis(cid:12)ability decisions made by the re-
All Success Otherwise
sources to provide resource guarantees, no mat-
Send Finish CoSmemndit eRde lReeassoe utroces
terwhattechniques resourcemanagersuse. Asa
Return Intersection result ofthis design principle, the resource reser-
vation scheme can be applied to a wide range of
Resource Side heterogeneous environments. The (cid:13)exibility also
allows the seamless integration of any new re-
sourcemanagementandscheduling techniquesas
Receive Message
Request Release theyaredeveloped, thusproviding goodprogres-
Commit Finish sive scalability in fastly evolving environments.
intoIn Asecrtti vine ORerdqeure sts First in Order ? Remove Request Release Resource
no
Send Intervals yes Wait till First 3 Conclusion
Commit Resource We have proposed a resource reservation scheme
Succeed Fail capable of scheduling and reserving the resource
NewSe Inndte Srvuaclc eifs sd iafnfedr ent NSeenwd IFnateilr vaanld requirements generated by a class of multime-
dia applications we characterize as synchronized
distributed multimedia sessions. The scheme is
notanattempttosolveindividual resourceman-
Figure 5: Partially-Ordered Optimistic Concur-
agementproblems in speci(cid:12)c systems,instead, it
rency Handling Technique
utilizes and integrates the functionalities of indi-
vidual resource management enitities to provide
sible resource con(cid:13)icts, a few concurrency han- a global resource guarantee. Our scheme is ad-
dling techniques for the reservation scheme are vantageous to existing reservation protocols in a
proposed. The optimistic technique checks for few ways. Based on the idea of advance reser-
con(cid:13)icts only when the commit messages are re- vation, the scheme can handle the synchronized
ceived. Start time is recalculated if the commit resource allocations as required by many multi-
message fails. However, the scheme can cause media applications. Second, the scheme is guar-
in(cid:12)nite delay. For example, there could be some anteed to (cid:12)nd a feasible schedule of resources
requests whose commit messages always fail be- wheneveroneexistsandalsoeliminatestheprob-
cause of resource con(cid:13)icts with other incoming lem of application-level reservation failure-retry
requests and never get completed. A partially which may adversely a(cid:11)ect the network utiliza-
ordered optimistic technique is proposed to or- tion. Furthermore, instead of simply failing the
derthesequence ofcommitingrequeststoensure entire reservation as in existing protocols in the
that the in(cid:12)nite delay situation will not happen. event of resource contention, we proposed con-
The partial order is a projection of a total or- current reservation techniques that guarantees
4
progress. 7. N. Hirzalla, B. Falchuk, A. Karmouch, A Temporal
Model for Interactive Multimedia Scenarios, IEEE
This work can be extended in several ways.
Multimedia, Fall 1995.
First, some multimedia applications have soft
or elastic temporal relationships, where the syn- 8. D. Ferrari A. Gupta, G. Ventre, Distributed Ad-
chronization among multimedia objects is not vance Reservation of Real-time Connections, Pro-
ceedings of5th International Workshop onNetwork
(cid:12)xed but rather can vary within certain con-
and Operating System Support for Digital Audio
straints. Whether and/or how the proposed
and Video, April 1995.
reservation scheme can be extended to incorpo-
ratethisscenariois worthfurtherstudy. Second,
the scheme uses advance reservation which in-
creasesthe resource managementcomplexity, es-
pecially at reservation stage. Future work needs
to be done to study and quantify the increased
complexity. Third, the reservation dynamics
of the reservation scheme can be studied, from
which potential problems can be found and ad-
y
dressed.
4 References
1. L.Zhang,S.Deering, D.Estrin,S.Shenker,D.Zap-
pala, RSVP:ANew ResourceReservationProtocol,
IEEE Network,September 1993.
2. C. Topocic, Experimental Internet Stream Protocol
Version2 (ST-II),IETF RFC1190, October 1990.
3. L. Delgrossi and L. Berger, Internet Stream Proto-
colVersion2(ST2)ProtocolSpeci(cid:12)cation-Version
ST2+,August 1995.
4. L.Delgrossi, R.Herrtwich,C.Vogt,L.Wolf,Reser-
vation Protocols for Internetworks: A Comparison
ofSTIIandRSVP,Proceedingsof4thInternational
Workshop on Network and Operating System Sup-
port for Digital Audio and Video, November 1993.
5. L. Wolf, L. Delgrossi, R. Steinmetz, S. Schaller, H.
Wittig, Issues of Reserving Resources in Advance,
Proceedings of 5th International Workshop on Net-
workandOperatingSystemSupportforDigitalAu-
dio and Video, April 1995.
6. L. Hardman, D. Bulterman, G. Rossum, The Ams-
terdam Hypermedia Model, Communications of the
ACM,Vol 37, No. 2, February 1994.
y
The views and conclusions contained in this docu-
ment are those of the authors and should not be in-
terpreted as representing the o(cid:14)cial policies, either ex-
pressed or implied, of the Army Research Laboratory or
the U.S.Government.
5