Friday, March 29, 2019

Types Of Mobility For Mobile Computing Computer Science Essay

Types Of Mobility For Mobile Computing Computer Science endeavorThe development in last 20 years in the field of force of tele confabulation and the integration of telecommunication with profit has promised pervasive computing infrastructure. These pervasive systems altogetherow drug drug substance ab users to b anformer(a)(prenominal) their education on the meshing irrespective of their location. In addition, the advancement in devices miniaturization increases the emergence of port adequate to(p) devices connect to the internet desire vigorous phone, laptops, palmtops net books, PDAs, and so forth In these scenarios we stomach claim un standardised types of mobility. User mobility, Terminal mobility, Mobile rise to power to re man-made lakes. User mobility requires providing users with a uniform view of their preferred forming environments user preferences and subscribed serveindependent of their current positions in the net lock.1 Terminal mobility go aways devic es to transp atomic number 18ntly touch on and connect to different points of attachment.1 Mobile access is an emerging moment that involves the dynamic adaptation of wandering(a)-awargon resources and work that spry users and terminals cease automatically incur regard slight of their current location.1Having get a lineed the above types of mobility, prompt computing need an advanced infrastructure which should dynamically trace and relocate busy users and make coordination between roving entities. The infrastructure should also provide proper gage system level establish on cryptographic mechanisms and tools. According to the given inquiry paper three mobile computing dos prolong been proposed user virtual environment (UVE),mobile virtual terminal (MVT), and virtual resource prudence (VRM).UVE provides users with a uniform view of their working environments independent of current locations and specialized terminals. MVT extends traditional terminal mobility by pr eserving the terminal execution state for recurrence at new locations, including combat-ready processes and subscribed advantages. VRM permits mobile users and terminals to adjudge access to resources and services by automatically requalifying the bindings and moving specific resources or services to permit load balancing and replication.1SOMA-BASED MIDDLEWARESOMA stands for Secure and go around Mobile performer. SOMA is a service infrastructure for developing and implementing MA-based internet coats. SOMA consist of 4 levels. As doomn in figure 1Figure 1 http// upper most layer is for mobility support which provides UVE (User Virtual Environment), MVT(Mobile Virtual Terminal), VRM(Virtual Resource Management). The next layer provides naming, security, migration, interoperability, persistence, communication and Quality of table service. The different two layers are a JVM (JAVA Virtual Machine) and a heterogeneous dist ributed system.SOMA is basically a JAVA based mobile agent which has been objected to provide the requirements of mobility, scalability, dynamicity, security and openness which are the classifiable issues in the internet scenarios. The two main(prenominal) goals to develop SOMA were interoperability and security. On one side, SOMA is based on detailed security present and provide a good range of mechanisms and tools to develop and enforce genuine security policies with tractableness. On the new(prenominal) side, SOMA is able to communicate and move with different components of applications which are intentional with different programming languages and platforms. Apart from interoperability and security features, SOMA is automatically and dynamically manageable and configurable and it provides the location abstraction to acquire scalability in a global scenario.The mobility of the mobile devices has introduced new security challenges comparable mobile can be hacked by the execution of malicious environment, whitethorn be cloned illegally to cause DoS (denial of service), or whitethorn be denial for roaming. These issues encounter been overcome in SOMA implementation as SOMA permits to protect some(prenominal) agents come from malicious hosts and hosts from malicious agents. During the design and implementation of SOMA, number of challenges were faced to provide interoperability like SOMA application as server of COBRA, SOMA as COBRA clients, interoperability between COBRA components and SOMA, etc On the different hand, SOMA is a bit slow because of its extra security mechanisms, it involves different tools and techniques to provide more security which makes it slow as compare to opposite mobile agents but off course it is more secure than other mobile agents. As the bring in suggest secure and open mobile agent, its openness has introduced some more challenges to it especially for e-commerce applications so there is a need to improve it as nonh ing is perfect.Q2All the MA(Mobile Agent) standards seem to be a promising platforms for implementing and developing applications in distributed, heterogeneous and open environments like the Internet. MAs try to overcome most of the limits of the conventional Client/Server flummox because of the basic features they have, such(prenominal) as autonomy and flexibility and can effortlessly integ pose with the internet to extend accessibility of applications. Most of the application areas, like e-commerce, network management, mobile computing and discipline retrieval can advantage from the use of the mobile agent technology. There has been a lot of work done in this field. Like many mobile applications have been actual like we studies SOMA, there are some other application as well like SeMoA, Aglets, fraglets, etc. There are some advantages which all the mobile agents try to provide Dynamic adaptation, flexibility, tolerance to network errors/faults, parallel processing, etc. Dynami c adaptation is the adaptation of the different host environments. margin to network faults actor ability of mobile agent to operate with step to the fore an active connection between server and client. Flexibility means to only source must be updated whilst changing an action of the agent. Comparing SOMA with other mobile agents, SOMA provides more security and openness as its name says.If we talk about SeMoA (Secure Mobile Agent) it has its own limitations, such as SeMoA is not genuinely strong against a large number of Denial of Service (DoS) attacks like memory exhaustion. On the other hand SOMA has been designed taking into account security as a main station because SOMA protects both agents come from malicious hosts and hosts from malicious agents. Another difficulty with SeMoA is that there are many classes in the core package that sync on the object of class itself. As local classes are shared and the visibility of local classes is global so any agent that access them and acquires a lock on such class objects blocks other thread to access them. On the other hand if we compare SOMA with fraglets which is very small computer program which has been designed to serve as a part of active network instead of a mobile agent. Fraglets have the ability to execute the codes on the path the travel by such as routers or hubs.Part 2Q1.Pervasive computing is a intake of personal computing where future living environments are alter with non-intrusive, flawlessly operating services getable for the user. To fully understand this dream these services are to adapt to the present station of the environments, together with the economic/social situation of the user. Systems that use selective information about the state of every its system, users or the environment to settle in their behavior are called context- certain systems. Realizing context-awareness has introduced problems on different level First, defining a context. Second, how and what can be adjust w hen the context changes and where the context adaptation and definition comes from? Third, identify different contexts from sensor. Fourth, how a context can be represented and processed. But before that we have to understand the definition of context. The most cited definition of context by Dey is context of use is any knowledge that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and applications themselves.1RepresentationUnique IdentifiersThe system should be able to recognize different type of contexts and environments in the real world. Uniqueness allow the reuse of that selective information without conflicting between identifiers. For example, If the user is driving a machine so accelerometer can be used to detect the belt along of the user.ValidationValidation should always be allowed for an information taken by the sensor before performing any action with it. For example, if the accelerometer indicates that the speed of user is fast (i.e. he/she is in the car) this does not mean that he/she is driving, this information should be validated before performing any action. For instance consider the condition that if I am driving I cannot answer the calls so reject the call and enthrall a message saying I will call you later. But if I am in the car but I am not driving than I can answer the calls so the information from the accelerometer has to be validated before rejecting the calls. question and neither informationAs almost all of the context information of the real world is taken from the sensors, the information can be incomplete and uncertain. If we include reasoning uncertainty of the conclusions should follow the reasoning.Simplicity, reuse, and expandabilityA system should allow only as expressive representation as necessary to maintain the domain knowledge. A simple representation endorse reuse and expandability. Simplicity, flexibility and expandability are among the requirements of context representation.GeneralityGenerality of context representation means the ability to support all types of context information. In my estimation, generality of a context representation is mostly described by its conceptual structure. Nevertheless, the limpidity of a representation language which is used to generate the context information also vary its ability to generate context information at different levels of complexity.Q2.IntroductionWAP ( radio application protocol) is a protocol to offer mobile data services. WAP is an open international standard that permits users to access global information instantly through any wireless device mobile phone, PDA, etc. WAP is normally supported by all operating systems. Browsers that uses WAP are called micro-browser. The rate of transfer of data is still very lower than the normal modem. On the other hand, I-mode is a complete mobile internet service that includes a large range of internet standards such as e-mail, sports results, weather forecast, tidings headlines, etc. This information is provided to the user by particular services from mobile carriers who charge them for these services. As the rate of transfer of the data is lower than the norm modem, i-mode is not good enough for high resolution images and videos, it is basically competent for simple graphics and emails.ProtocolsWAP uses Wireless Markup Language (WML) for communication. while on the other hand i-Mode uses a different type of hypertext mark-up language which is called compact hypertext markup language (c-HTML).Capabilities of DevicesWAP devices have to have a specific WAP browser while i-Mode financial backing devices have to be able to display data from c-HTML. WAP capable devices show only textual information while i-Mode supporting devices shows multimedia images. WAP gives soaring among layered menus while i-Mode gives navigation via hyperl inks.ArchitectureWAP makes use of a rum language called WML (Wireless Markup Language) for interaction between a specific protocol rendition device called a Gateway of WAP (GW) and information on the Internet. The GW communicates between HTML and WML, permits supply of WAP content to a WAP supporting device. iMode obeys a dissimilar flak to allow users to access IP-based services via their portable device. i-MODE is uses packet data transmitting technology, a machine using this technology is continuously online. The transfer of the data makes use of the CDMA (Code Division Multiple Access).GraphicsOne of the most main difference that appears, are clearly the dissimilar graphic capabilities. While it is proficient that i-MODE only allows simple graphics, that is much more than WAP.ChargesAnother main inequality is the capability of being always-on in i-MODE. As consumer are not charged for how long they serve online, it doesnt seem more suitable, but also less expensive than h ave to pay for the time they spent online. As it is not needed that dial-up before using the a conformation of services based on IP, E-mail has become an SMS (Short Message Service).Part 3Q1.In CCA the InfoStations system is an infrastructural system concept offering many time, many-where access to wireless data services sustaining the portable communication process. This concept alters a variety of classes of portable devices to communicate with each other and with a large number of servers. Intelligent agents operating in the portable device users domain (Personal Assistants-PAs) and the InfoStations overhaul to facilitate a contextualized and personalized environment for the system users. System social functionality is offered as a set of flexible mobile services. To assist the personalization of these services, the User Agent Profile (UAProf) and Composite Capabilities/Preference Profile (CC/PP) terms are derived to enable thePersonal Assistants express capability and prefer ence information (CPI) about both the access device and the user as well. This makes sure that the offered services are adapted to suit the device capabilities, wireless network constraints and the user as well.Behavior of infoStationBecause of the fact that nature of the connection is defused, it is important for intelligent agents to work throughout the architecture. Being a PA (Personal Assistant), the agent may function automatically in order to convince any user service needs they encounter, while in or out of interaction with other agents which are working on InfoStation Centre or the InfoStation. The service sessions may be divided between different InfoStations, the personal assistant can make a service call while within the context of an InfoStation, and because go out of the coverage area. During this time when the user goes out from InfoStation coverage, the personal assistant functions automatically adopt the functionality of the service till the user has completed the task. The InfoStations houses the Discovery, Presentation and Rendering Self-Service module, which is used to establish connections to mobile devices which enter within range. Also housed is a cache of recently accessed user and service profiles, as well as a repository of available services.4Q2Behavior of infoStation CentreThe InfoStation Centre stands at the centre of the system, which deals with the formation and update of contents/objects throughout the system. From InfoStation Centre which acts as a central point, service updates can be spread across the whole system. All the infoStations are committed with the InfoStation centre which acts as a server of these infoStations. InfoStation centre is aware of all the devices connected to the infoStations but it communicates with infoStations only, it does not communicate directly to the devices connected to the infoStations. For instance a mobile device wants to communicate with the other mobile device connected with different Inf oStation then the device will send a request to its InfoStation then the InfoStation send this request to InfoStation Centre and then InfoStation centre sends the request to the InfoStation to which the receiver device is connected with.Q3Bob Alice .0 Alice Bob ( hi ).0 - Alice hello hello Q4BobAlice.0 AliceBob (hello).0 Q6BobAlice.0 AliceBob (hello).0 IS1in IS4.out.0 IS40 IS4in IS2.out.0

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