Study on Service-Oriented Cloud Conferencing

Transcription

1 Study on Service-Oriented Cloud Conferencing Junchao Li School of Computer Science and Technology University of Science and Technology of China Hefei, China Ruifeng Guo Shenyang Institute of Computing Technology Chinese Academy of Sciences Shenyang, China Xiuwu Zhang School of Computer Science and Technology University of Science and Technology of China Hefei, China Abstract Cloud computing, a new thing which is only three years old, becomes the most fashionable technology and developing trend in IT industry now. People say X as a service in the cloud computing, which means that everything including software and hardware can be taken as a service for consumers in the cloud. Meanwhile, a high quality multimedia conferencing has been an urgent requirement these years. The products in the market are immature. They can t support very large number of participants and multiple HD video in a meeting. In this paper, we consider conference as a service, and propose a feasible framework of multimedia conferencing in cloud. As it follows the structure of SOA, we name it Service- Oriented Cloud Conferencing. We then present the software structure and flow procedures. We prove that the cloud conferencing overcomes the deficiencies of existing products with the support of excellent characteristics of cloud. Keywords-cloud coferencing; SOA; cloud computing; multimedia confencing I. INTRODUCTION Cloud computing [1] has become the most advanced technology and fashionable trend in IT industry recent years. The aim of cloud computing is to deliver on demand IT resources of cloud consumers on a pay per use basis. Some researches [2, 3] highly remark it as the fifth utility (after water, electricity, gas, and telephony). However, cloud computing is one of the most vague technique terminologies in history [4], because it is used in many different application scenarios, and is developed by various companies. So people often say that everyone has an opinion on what is cloud computing. A lot of computing experts and researchers tried to give cloud computing an exact definition [5], but so far, we have not heard two people say the same thing about it. In our opinion, cloud computing is a conclusive and developed technology of cluster computing, Grid computing, parallel computing, distributed computing and utility computing, which is composed of a huge collection of interconnected and virtualized computers. It provides computing resources as a service to public based on service-level agreements. We always hear the terminology such as X as a service (XaaS). It means everything as a service or anything as a service. As shown in Fig. 1, values of X we have seen include infrastructure, platform and software. They are Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS). They are main services delivered from resource providers to end users. In the picture, we can see that examples of SaaS are Google Apps and Salesforce.com, which provide various software applications as services for convenience. The PaaS solutions, such as Google AppEngine and Microsoft Azure, provide users with a development platform for creating their own applications under some principles that can automatically scale. And the IaaS (the most famous and very successful example is Amazon EC2) offers consumers with physical or virtual resources including CPU, memory, OS and storage, to meet the demands of the users. Multimedia conferencing has been studied by lots of researchers for many years. It has great advantage for people who don t want to spend the time and money flying all over the world for meetings which require face-to-face contact. Two standards [6, 7] of centralized conferencing were taken out by IETF working groups. They adopt a tightly coupled centralized architecture. The most prominent Figure 1. Cloud computing service layers. 21

2 characteristic of this structure is that all functional parts are close integrated in the only conference server, which makes powerful control, effective management and efficient security. However, when the number of participants increases, the burden of a single server would become too heavy to keep running. Some papers [8-11] proposed some remarkable ideas of distributed conferencing. They enlarge the conference scale on the base of the frameworks of IETF standards. However, the weak control functions, the use of non-standard protocols, poor compatibility and robustness are short points. In our viewpoint, multimedia conferencing can be also seen as a service called conference service. It is surely a software application, which follows the concept of SaaS. In this way, we would not worry about the size of conference, since the cloud s wonderful characteristics makes this problem easy to resolve. In cloud conferencing, the chair or organizer of a conference can pay the service provider according to conference scale, duration, function and so on. The concrete fee can be negotiated between providers and consumers based on service-level agreements. In this paper, we propose the feasibility of cloud conferencing, and design a practical framework which has excellent characteristics such as scalability, extension, and robustness. This cloud conferencing relies on the SOA, because of its loosely coupled structure meets the demands of SaaS well. So we decide to name it Service-Oriented Cloud Conferencing. The rest of this paper is structured as follows. In Section II, we introduce the related work with cloud computing, multimedia conferencing and Service-Oriented Architecture. In Section III, we describe the structure and advantages of cloud conferencing and detail service modules. In Section IV, we enumerate the flow procedures of holding conferences. At last, Section V presents the conclusion and outline of future research. II. RELATED WORK We introduce the related works with cloud computing, multimedia conferencing and Service-Oriented Architecture in this section. A. Cloud Computing There are numbers of definitions and metaphors of cloud computing. We have given our point of view in Section I, Figure 2. Standard conferencing framework. and here are some major publicly recognized characteristics of cloud computing: large scale of IT resources; high scalability and flexibility; both virtualized and physical resource pools; dynamic resource scheduling; and general purpose. The authors of paper [4] show us that there are three major cloud computing styles by resource abstraction technologies: (1) Amazon s cloud computing is based on server virtualization technology, such as Elastic Compute Cloud (EC2) and Scalable Storage Service (S3); (2) Google s style is based on technique-specific sandbox, by the guideline of a series of research such as Google File System [12], MapReduce [13] and BigTable [14]; (3) Microsoft Azure uses Windows Azure Hypervisor (WAH) as the underlying cloud infrastructure and.net as the application container. We can see that cloud computing has different definitions, different comprehensions and different implementations, so the presentation of software applications in cloud are agile and versatility. B. Research of Conferencing SIPPING working group and XCON working group, which both belong to IETF, are doing research of multimedia conferencing frameworks separately. They both exploit tightly coupled model, but put forward different structures. A sophisticated centralized conferencing framework is shown in Fig. 2. The focus has direct peer relationships with the participants by maintaining a separate SIP dialog with each participant. objects and their states are retained in focus. The mixer takes charge of media treatment, including receiving, mixing, and dispensing media streams. Focus and mixer are basic parts of a conference server. The right part is the functional part. SIPPING group exploits a policy server to manage conferences. XCON group divides it to three modules, a conference control server, a floor control server and a notification server. The conference control server is responsible for conference manipulation. The floor control server is in charge of resource assignment. The notification server provides updates about the conference instance state to authorized participants. C. Service-Oriented Architecture A service-oriented architecture is a flexible set of design principles used during the phases of systems development and integration. A deployed SOA-based architecture will provide a loosely-integrated suite of services that can be used within multiple business domains. The OASIS (Organization for the Advancement of Structured Information Standards) defines SOA as the following: A paradigm for organizing and utilizing distributed capabilities that may be under the control of different ownership domains. It provides a uniform means to offer, discover, interact with and use capabilities to produce desired effects consistent with measurable preconditions and expectations. As shown in Fig. 3, there are three roles in SOA. The service provider provides services according to contract, and 22

3 Figure 3. SOA model. publishes them to service broker. The service consumer is also named service user, which finds services on the broker and calls them on the providers. The service broker stores the information of services from providers. This model shows the most important characteristic of SOA, that is, the loosely coupled architecture. III. DESIGN OF CLOUD CONFERENCING In this section, we describe the integrated structure of cloud conferencing, and list the advantages of the framework. Then we show the layers of this software. Finally, we detail the service modules of the conferencing. A. Why to Use Cloud Conferencing The centralized conferencing adopts a tightly coupled structure. The most advantage is that all functional parts are close integrated in the only conference server, which makes it powerful control, effective management and efficient security. However, when the number of participants increases, the burden of a single server would become too heavy to keep running. Besides, the limited bandwidth is another kind of bondage. If the total reception content of media packets from participants exceeds the processing capability of mixer or traffic capacity of network, a block of media packet treatment would happen. For example, we have used a conference server called ISX-1000 before. The whole conference member is no more than 256. It is obviously a small number, which is not enough for a large conference. What about traditional distributed conferencing? The Figure 4. Macrostructure of cloud conferencing. Cisco Systems, Inc. has the most mature conference product in the market called WebEx. It is a distributed conferencing, with a huge number of servers in the world wide. The company propagates that its product can hold meeting with a thousand participants. However, it is still not enough. Our solution is cloud conferencing. The macrostructure of cloud conferencing is shown in Fig. 4, which overcomes the defections of early conferencing models. Participants in cloud can attend a conference at anywhere by various online tools. He can use a normal SIP terminal, which can be a soft client or a SIP Phone. This is the traditional usage for normal software. He also can use a PC, a notebook or a mobile phone which can use a Web browser such as IE, Firefox and Chrome. This is the typical cloud application method. There are numerous computers in the cloud. The number of composed computers can be enlarged easily. So we can suppose that the conferencing resource in cloud is unlimited in theory. When participant number creases, the conference room enlarges its size by get resource from resource pool in cloud. When participants leave, the resource would be returned to the pool. This scenario shows the most wonderful extension characteristic of cloud conferencing. Some other advantages are as follows: Low cost and high performance. We can use very cheap computers in the cloud instead of dear servers. The high performance is relied on the collaboration of a huge number of low cost computers as the nodes in cloud. We need not worry about whether cloud can process the requests and media packets or not. The nodes balance the workloads automatically. Scalability. We can upgrade any part of hardware or add any kinds of new nodes into cloud. These changes would not impact the conference running. The conferencing can also use these new components without any change. Availability and reliability. As the nodes are widespread on the earth, we need not worry about the conference running. If some nodes or network fail, or some data centers lose electricity, other parts in cloud can keep running. If there are some mistake happened in the system, the clouds can transfer the conference rooms from error computers to right nodes. After the error nodes recovered, the service can be transferred back. We also call this characteristic continuity or robustness. B. s of Cloud Conferencing We illustrate the layers of the whole cloud conferencing system in Fig. 5. We can divide the whole system into four layers from bottom to top in the print. They are physics layer, virtualization layer, platform layer and application layer. The physics layer is the hardware layer which is composed of physical computing, storage and networking resources. The virtualization layer is composed of virtualized computing, storage and networking resources. The IaaS, which delivers computer infrastructure, includes both those layers. The IaaS is typically billed on a utility computing basis and amount of resources consumed will typically reflect the level of activity. It is an evolution of virtual private server offerings. 23

4 The platform layer can be divided into two sub layers. One is the computing frameworks, which manage the transaction dispatching and task scheduling. The other sub layer is application capability layer, which includes basic tools for applications. The PaaS, which is the service for this layer, delivers a computing platform and solution stack as a service, often consuming cloud infrastructure and sustaining cloud applications. It facilitates deployment of applications without the cost and complexity of buying and managing the underlying hardware and software layers. The application layer is the top layer of this framework. It is the layer for SaaS, which delivers the conferencing application as a service over the Internet, eliminating the need to install and run the application on the customer's own computers and simplifying maintenance and support C. Services of Cloud Conferencing We develop cloud conferencing on the application layer as shown in Fig. 5. So we use a platform called Hadoop [15] as our experiment base. The Hadoop project develops software for reliable, scalable, distributed computing, which is a famous open-source implement based on the Google s researches [12, 13, 14]. We dedicate the software structure in Fig. 6, using SOA to design cloud conferencing. As shown in the picture, there are seven layers of the conferencing, followed the SOA module. The first layer is the operational system layer, which includes basic development environment, such as ERP (Enterprise Resource Planning), M (Service Component Architecture) and BI (Business Intelligence). The second layer is the enterprise component layer, which includes many components such as EJB (Enterprise JavaBean) and SCA (Service Component Architecture). These two layers are already existing environment, which are parts of platform layer in Fig. 5. The third layer is the most important layer called service layer, including atomic and composite services. The atomic services in the print include conference management service, conference member set service, floor control service, audio service, video service and other application services. They are basic services in conferencing. Other applications can be chat, white board, desktop share and so on. New services can Application Platform DataBase WebServer IDE Management Tools Server Cloud Conferencing Computing Frameworks Storage Network Physics Server Storage Network Figure 6. s of cloud conferencing. Presentation Business Process Services Management Enterprise Components Operational Systems Web Site Member Set Audio EJB VR Floor Control Video Audio Client Video SCA VR OR Other App ERP M BI Other App Figure 5. SOA layers of cloud conferencing. be added at any time. The composite services are composed of atomic services. They are conference room service, audio room service, video room service and other application room services. We use conference management service to manage conference members, and form a conference room. We use floor control service to decide the rights of media members. The fourth layer is the business process layer, which decides the process composition of services. We abbreviate conference room as, audio room as, video room as VR, and other application room as OR. The processes in the figure are audio conferencing, audio-visual conferencing, and multimedia conferencing with data collaboration. The fifth layer is the presentation layer which is presented to customers. The sixth and sevens layers would be considered all over the process. They include integration architecture, security and QoS services. IV. FLOW PROCEDURES In this section, we describe the flow procedures of the cloud conferencing. The running mechanism of conference is mostly composed of conference room s creation, running and end, and participants joining and leaving. Participants have different authorities depending on their roles in the meeting. A special role called moderator has the highest priority. In the conference, he can add or kick participants by conference management service. He can also manage the right of speech, video show, white board, PPT and so on by the floor control service. A. Begin In the creation phase, a customer, who wants to hold a new conference, can choose to start meeting immediately or sometime later. He firstly needs to send request for a registered conference object. Customers can get the information of blueprints the system provides. A conference blueprint is a conference model used to describe a typical conference setting supported by the system. The blueprints are actually templates of service process in the business process layer in Fig. 6. We can choose one kind of them to 24

5 ask the cloud conferencing system to build a registered conference, adding this meeting s start time and duration, and a list of people whom you want to invite via or dial-out directly at the beginning of the meeting. An active conference is actually another state of a registered conference. When the first participant enters a registered conference room, a new active conference object establishes. It means a new conference begins. The cloud conferencing initializes the active conference based on a registered conference. The active conference ends when there isn t any participant in the conference room or the conference time exceeds its duration time, which is defined when we build this conference or modified during the conference. B. Participants Add When a user wants to enter into an existing conference, he has two methods to choose. If a customer uses an online computer to enter the conference, the only thing he need is a Web browser. He can find the conference room by searching its room number. He may need a password to get the access of a private conference. If it is a public conference, no password is set. If a customer uses a SIP phone, he can get into the conference room too, since this system is compatible with IETF standards. Another way of adding participants to a conference is started from conference server called dial-out method. There are two scenarios of using this method. One is that at the start time of a conference, the system checks the list of people who should be invited, then dials-out to those in the list but haven t be present at this meeting. The other situation is that the moderator of a conference wants to add someone into this running conference, and he asks the system to add a participant by dial-out method. C. End There are three ways to terminate a session: a participant ends the connection by himself, the moderator kicks a participant out, and the conference ends at the reservation time. The difference of the three ways is who sends the end request. When a conference ends, the system automatically saves the meeting record into a file for future use. V. CONCLUSION AND FUTURE WORK In this paper, we have presented a design for a cloud conferencing. This system overcomes the deficiencies of existing conferencing products. Compared to traditional frameworks, it has a lot of advantages such as easy extension, high scalability, low cost, high performance, availability and reliability. This software follows the most fashionable and useful techniques, which include SOA and cloud computing. There are also some defects in this framework. The authors of [16] take out a list of obstacles to growth of cloud computing, such as data transfer bottlenecks, data lock-in and software licensing. 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