server-side or proxy-side adaptation (Malandrino el. a/., 2010) operate in isolation, .... The cu~rent server load checks by SLA assessor and estimates the value ...
Incorporating Human Psychological Factor in Assessing the Deliverability of Quality of Service (QoS) for Multimedia Content Adaptation Services Mohamed J."', Fudzee M. F. M.' and Ismail M.N.'
ABSTRACT Content adaptation is a potential solution for tailoring ~nulti~nedia web content according to the users' preferences and heterogeneous devices' constraints. Content adaptation can be done as third party service over the Internet. Users may pay for the service thus demand quality. The quality should include the human psychological factors. One of these factors is the ~naxi~nurn time a user can wait for the output to be displayed. Thus, response time is one of the qualities of service (QoS) to be considered in assessing the deliverability of content adaptation services. However, the advertised response time may not be deliverable accordingly during the actual service execution due to heavy load. Practically, the service provider should able to determine a cun.ent deliverable response time before the service level agreement (SLA) is settlcd with the users. In this paper, we propose a strategy for service providers to evaluate incoming requests and capable of offering the new response time. The proposed strategy takes into account the current server load and enables a ~nechanismfor the user to evaluate whether the new response time can be accepted or not. We analyzed the performance of the proposed strategy in terms of SLA settlement under various conditions. The results indicate that the proposed stl-ategy p e ~ f o r ~ \veil. ns Keywords: ~nulti~nediacontent adaptation, QoS, SLA, Service-oriented content adaptation.
I INTRODUCTION Content adaptation has in fact already gained considerable importance in today's ~nultimedia co~n~nunicationsand will certainly become an essential functionality of any service, application or systeln in the near future (Carreras el. 01, 2009). As the heterogeneity of mobile device such as smart phone and tabs growth, searching websites througli nob bile device is also demanding. The recent trend is that content adaptations are largely demancled and became protitable nob bile contents of its quality to the Internet as third party services (Arai & Tolle, 2010). Existing content adaptation systems employing these approaches such as client-side,
server-side or proxy-side adaptation (Malandrino el. a/., 2010) operate in isolation, often encounter
limited adaptation functionality, get overload if too Inany concurrent users and open to single point of failure, thus limiting the scope and scale of their services (Yang & Shao, 2007). Digital lnultilnedia services and devices are now mediated through increasin~lypropol-tion of human activities such as social interactions, ente~iainment, shopping, and gathering info~lnation (Kosinski, Stillwell & Graepel, 2013). To get more accuracy and rapid infonnation, users may pay for the service thus dellland quality. Generally, the response of those services is not very i ~ n ~ n e d i a t e l ~ but rather delayed to a certain extent depends on the type of request and the type of desired response. At the end, these response times is lasgely dominated to user-perceived quality (Egger et. 01, 20 12). The idea of establishing content adaptation as a service to allow potential solution for tailoring multimedia web content according to the users' prefel-ences and heterogeneous devices' conslraints has been endorsed. Typically, there are Inany service providers offering a variety of content adaptation that can be suit. Therefore, the solution for these services is to cooperate with each other through service co~nposition to co~npletely.serve the request that they cannot attain intlividually. This is termed as Service-oriented Content Adaptation (SOCA). SOCA presents a nod el to enable content adautation to be consumed as Web services (Fudzee & ~ b a w a i y , 201 I). However, current sb~utions from (Alha~natl,Dillon & Chang, 2010) do not take into account the human psychology in negotiating with services. Figure 1: SOCA Framework shows the architecture of service level agreement (SLA) by SOCA framework. This systeln is based from the service oriented architectuse (SOA). The purpose of the SOCA framework is to give out user expectation by offering added value of content and also to provitle tlexible and scalable service-based content delive~y mechanism. The framework consists of components that provide access to content servers, develop user request to source fonnat, manage and provide
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content description (Fudzee, Abawajy & Deris, 2010).
evaluate whether the new response time can be accepted or not. We analyzed the p e ~ f o ~ l n a n cofe --------------------------------the proposed strategy in terms of SLA settlement client l rn \ under various conditions. The results indicate that laver 1 ,-----~--_-__----_---------------L1 0O O O O 0 the proposed strategy pelforms well. This paper ---------------------------------, consist of six section which includes our related rnoker work in section 2, the proposed solution in section layer I 3, the perfo~lnanceevaluation in section 4, result and discussion in section 5 and the conclusion for this paper in section 6.
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Comlnonly, SOCA enables an adapted content to be delive~y by a nun~ber of services; service co~nposition based on quality of service (QoS) is known to be a practical solution. Hence, response time is one of the qualities of service (QoS) to be considered in assessing the deliverability of content adaptation services. However, the advertised response time may not be deliverable accordingly during the actual service execution due to heavy load.
I1 RELATED WORK Previous studies have overcome the problerns of service provider fi-0111 SOCA fi-amework. SOCA c o ~ n e swith existing one to one negotiation strategy (Md Fudzee & Abawajy, 201 1) that is most works dealing with client-side quality evaluation p e ~ l b n n reco~n~nendations during service selection process. In this strategy, the waiting time has been focusing to reflect the response time. The broker reaches the requested service by searching the priority function. The cu~rentserver load checks by SLA assessor and estimates the value ofrequest it can be served within offered waiting time. This strategy offered single session task by SLA assessor to be consider by waiting time and at the same time the new waiting time for the request that might be rejected. Figure 2: One-To-One Negotiation depicted an example of i~nplementing E(W) QoS negotiation between brokers with a content adaptation provider.
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The quality of i n o b ~ l eservices in content adaptation should include the human psychological factors. One of these factors is the ~naximumtime a user can wait for tlic output to be displayed. Lobo et. 01, (201 1) stress that there will be more frustration while making longer enough of time to wait for pagcs to load, so as a result they usually quit tlic task or t ~ yto find infol-mation to another site. This is also relevant to content adaptation service response time. Practically, the service provider should able to detennine a current deliverable response time before the service level agreement (SLA) is settled with the users. This strategy has been found out fi-o~n(Md Fudzee & Abawajy, 201 1) by proposed QoS negotiation nodel ling of response time by considering one to one negotiation strategy (from broker as user on behalf to service provider). In this paper, we propose a strategy for service providers to evaluate incoming requests ant1 capable of offering the new response time. The proposed strategy takes into account the current server load and enables a ~nechanisrnfor the user to
Figure 2: One-To-One Negotiation
From the Figure 2: One-To-One Negotialion. once the agreements are entered into, i t becomes necessary to monitor their conditions, which will com~nonly relate to timeliness, reliability and request throughput, at run time (Raimondi, Skene & Emmerich, 2005). Tlie problem with this strategy is broker should have to stick around for a few seconds to receive the adapted content. As a result, there will be a heavy load of incoming request, false of information and disclai~ned infonnation. To overcome this problem, we propose a strategy for service providers to evaluate incoming requests and capable of offering- the new response time. The proposed strategy called One-to-Multiple negotiation. This strategy takes into account the current server load and enables a mechanism for the user to evaluate whether the new response time can be accepted or not.
111
PROPOSED SOLUTION This section, we will describe about the proposed of One-to-Multiple Negotiation strategy that has capability to detennine that SLA can be settled with overall waiting time for all task rather than a single task. This improvement strategy based from (AlJaljouli & Abawajy, 2012) will consider less of response time by applying overall task to a certain request. Figure 3: One-To-Multiple Negotiation Strategy illustrates the one-to-multiple negotiation strategy.
strategy can allow user to get any responds from several task and it w i l l decrease user's perception about waiting time. By applying this method, the enhance user experience of the content adapted and also provide flexible and scalable service-based content delivery mechanism. An algorith~n is applied to this strategy at SLA assessor for improvement settlement rate of waiting time factor considers by QoS. Table 2: Common Symbol list the colmnon sy~nbol used for this paper based on proposed model. Table 2: Common Symbol Sylnbol Description
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