B. Zenel and D. Duchamp. "A general purpose proxy filtering mechanism applied to the mobile environment." Proceedings of the Third Annual ACM/IEEE International Conference on Mobile Computing and Networking, September 1997.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....such customizations as filtering, prefetching and intelligent cache management at the local proxy [13, 14] Research that is closest to ours combines the use of proxies with mobile code to support dynamic downloading of filters t o a remote proxy. Zenel uses both high level and low level proxies [25], and in [10] object migration is used to move an application running on a proxy to a new host in order to follow the movements of a mobile client. There are also customization systems that do not use proxies per se, but rather use more general mobile code mechanisms to support remote processing ....

....connections between client and proxy as well as DNS prefetching to reduce round trip delay, and prefetching of inline images to improve link utilization. Zenel showed a 50 reduction in delay using HTTP protocol and text content compression for files larger than 16K over a dial up connection [25]. He also found a significant improvement in TCP throughput over error prone connections using a version of Snoop TCP [2] Loon and Bharghavan used user profile based prefetching cooperating with a cache, in a system with both a local and remote proxy, and found that Web surfing waiting times can ....

B. Zenel and D. Duchamp, "A general purpose proxy filtering mechanism applied to the mobile environment," Proceedings of the Third Annual ACM/IEEE International Conference on Mobile Computing and Networking, pp. 248-259, Budapest, Hungary, September 1997.

....of its choice. Provide services at the end points. A great deal of previous work in mobility management has relied on a proxy based architecture, providing enhanced services to mobile hosts by routing communications through a (typically fixed) way point that is not collocated with the host [8, 23, 40, 64, 89, 146]. It is often easier to deploy new services through a proxy, as the proxy can provide enhanced services in a transparent fashion, inter operating with legacy systems. Unfortunately, in order to provide adequate performance, it is not only necessary to highly engineer the proxy [64] but locate the ....

....proxy locations must be appropriately pre configured to participate. Further, in the face of general mobility, proxies (or at least their internal states) must be able to move with the mobile host in order to remain along the path from the host to its correspondent peers. This is a complex problem [146]; we observe that it can be completely avoided if the support is 145 collocated with the mobile host itself. Hence, Migrate support is implemented at each mobile end point. Optimize for the static case. When one considers movement patterns with respect to communication session durations, ....

Bruce Zenel and Dan Duchamp. A general purpose proxy filtering mechanism applied to the mobile environment. In Proc. 3rd Annual ACM/IEEE International Conference on Mobile Computing and Networking, pages 248--259, Budapest, Hungary, September 1997.

....on mobile agents [28] has focused on supporting distributed artificial intelligence, active proxies share many of the same systems level concerns, such as code mobility, naming, security, and coordination. Many projects have used transcoding to adapt service content to better suit small devices [6, 15, 29, 34, 35, 36, 49, 50]. Additionally, a number of projects have attempted to develop universal interfaces for large classes of devices, including the recent WAP protocol stack [44] Instead of assuming that a single standard will be adopted by all devices, the Ninja architecture allows multiple standards to be bridged ....

Bruce Zenel and Dan Duchamp. A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment. In Proceedings of the Third Annual A CM/IEEE Conference on Mobile Computing and Networking (Mobicom '97), New York, NY USA: ACM, 1997.

....[17] does target for wide area operation but does not address service scalability and fault tolerance; nor does it provide access from simple devices that are incapable of running java based communication protocol. Our work is heavily influenced by projects (e.g. 18] 19] 20] 21] 22] [23], 24] that transcode to adapt service content to better suit impoverished small devices. However, these approaches are vertically integrated. They do not use composition as a way to easily extend system functionality. Furthermore, quite a number of works have tried to develop a single interface ....

Bruce Zenel and Dan Duchamp, "A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment," in Thrid Annual ACM/IEEE Conference on Mobile Computing and Networking (Mobicom'97), New York, NY, 1997, ACM.

....requires prior specific permission and or a fee. CCS01, November 5 8, 2001, Philadelphia, Pennsylvania, USA. Copyright 2001 ACM 1 58113 385 5 01 00011 5.00. 2. BACKGROUND ON MOBILE AUTHENTICATION APPLICATIONS AND THE USE OF PROXY SERVERS Proxy servers have been widely studied and utilized [2, 3] in mobile computing architectures. The following paragraphs review two relevant examples that apply proxies to mobile authentication: Charon [3] and the Wireless Application Protocol (WAP) Wireless Transport Level Security (WTLS) 4] 2.1 Charon The Charon protocol adapts standard Kerberos ....

Zenel, B., A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment. Wireless Networks, 1999. 5: p. 391-409.

....are highlighted in the later section on content scheduling. We have tested the algorithm to perform satisfactorily under heavy workloads, a common characteristic of public information systems. Transforming information for delivery to a heterogeneous group of devices is a wellresearched problem [4, 5, 14, 15]. In order to support such diversity, InfoSpaces makes use of existing work on client adaptation. Device specific proxies are defined for classes of devices (e.g. Web TVs, Electronic billboards, Tickers, etc) that perform information transformations on behalf of the end 2 points. In order for ....

B.Zenel, D.Duchamp, A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment, MobiCom 1997.

....e.g. workgroup. HP s e Speak [18] does target for wide area operation but does not address service scalability and fault tolerance; nor does it provide access from simple devices that are incapable of running java based communication protocol. Our work is heavily in uenced by projects (e.g. [1, 20, 29, 30, 31, 41, 40]) that transcode to adapt service content to better suit impoverished small devices. However, these approaches are vertically integrated. They do not use composition as a way to easily extend system functionality. Furthermore, quite a number of works have tried to develop a single interface for ....

Bruce Zenel and Dan Duchamp. A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment. In Thrid Annual ACM/IEEE Conference on Mobile Computing and Networking (Mobicom'97), New York, NY, 1997. ACM. 38

.... 4.1.3. Proxy Adaptation The third strategy in locating the adaptation mechanism is a compromise between the two extremes discussed above. It places the mechanism within the end to end path, at an intermediate node identified as the most appropriate for performing the most effective adaptation [37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 80, 81]. The intermediate node, usually denoted as proxy or gateway (see Figure 3) receives instructions from the receiver prior to the stream s initiation, regarding the parameters of the adaptation process. It then intercepts the stream coming from the source and transforms it according to the user s ....

....policy and notifies them in the event of a change in the adaptation process. The client then simply adjusts the presentation of the medium to the new format. Many of the existing solutions follow this approach in designing a proxy adaptation scheme, mainly due to its versatility and effectiveness [37, 39, 40, 42, 46, 47]. The complexity induced in the Internet infrastructure is still high, but the processing power and the communication resources consumed are drastically reduced compared to the receiver unaware solution. The clients can be versatile and display any kind of media without requiring specialized ....

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Zenel B, Duchamp D. A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment. Proceedings of MOBICOM'97; Budapest, Hungary, September 1997.

....views maintenance, file data synchronization, web information systems and information dissemination models. Network Middleware Network proxies have been proposed and used successfully as a mechanism for adaptation of mobile applications that access information services through wireless networks [24]. In addition to hiding from existing distributed applications the new protocols and services that are required for operation on mobile networks, proxies can be used to translate data into formats that are better adapted to the requirements of mobile users that access the network using resource ....

B. Zenel, D. Duchamp, A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment, Proceedings of the ACM/IEEE MOBICOM'97 Conference, pp.248259, September 1997.

....Secondly, many sites are aware of this problem but also want indexing by search engines and therefore provide alternative pages which link into the site contents. 7. RELATED AND FUTURE WORK The m Links system is related to middleware services that support wireless devices [1] 2] 3] 5] 7] 8] 15][17] as well as the general approach of using transducers on World Wide Web content [4] One way we categorize these mobile web systems is by the target device size and capabilities. The Web Digestor was developed to run on a range of devices but was most effective on PDAs. It employs a number of ....

Zenel, B., and Duchamp, D. A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment in Proceedings of MOBICOM (1997), ACM Press, 248-259

....work targets the improvement of network communication and bandwidth usage. Some of the solutions proposed are based on admission control and resource reservation [16] or on the use of proxies that perform data ltering or on demand dynamic distillation (data type speci c lossy compression) [7, 22]. Odyssey [19] sees adaptation as a collaborative partnership between the system and individual applications. Conductor [21] provides a general mechanism to select and dynamically deploy combinations of adaptive agents to multiple points in a network. Our approach to the problem of adapting to ....

B. Zenel and D. Duchamp. A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment. In Proceedings of MobiCom '97, Budapest, Hungary, Oct. 1997. 12

....part of the application on the stationary computer (the home computer in our model) will lter out the less important parts of the transmission from the remote computers to the laptop computer. This includes Email, Usenet news and web browsing. A proxy process doing ltering is a similar concept [30, 91]. In essence, application partitioning and ltering mechanisms are concerned with limiting the amount of data from remote computers to the laptop computer. Our approach is orthogonal to application partitioning because we are dealing only with operations on data ( les) already lying in the shared ....

B. Zenel and D. Duchamp. A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment. In Proceedings of the MOBICOM, 1997. 57

.... creative applications, including Kanji transcoding [48] Kanji to GIF transformation [60] application level stream transducing [8, 49] and personalized agent services for web browsing [6] It has been used to hide the e ects of error prone and low bandwidth wireless links [19, 34] Bruce Zenel [61] applies the proxy mechanism to the mobile environment: lters on an intermediary host drop, delay, or transform data moving between mobile and xed hosts. However, the lters are part of the application, complicating their reuse and making it awkward to support legacy applications. Proxies have ....

Zenel, B., and Duchamp, D. A General-purpose Proxy Filtering Mechanism Applied to the Mobile Environment. In Proceedings of MobiCom '97 (Budapest, Hungary, Oct. 1997). 15

....utilization, and support disconnected operation. While Mowgli provides a useful service, it is not designed for the extensible addition of new adaptations nor does it make any provisions for reliability in the case of proxy failure. Another proxy mechanism from researchers at Columbia University [29] provides a general purpose framework to support mobile clients. A proxy node is placed at the edge of the wired network. A mobile host can dynamically load, execute, and control adaptive filters on this proxy. Filtering is allowed at the application layer as well as lower protocol layers. While ....

Bruce Zenel and Dan Duchamp, "A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment," Proceedings of the Thrid Annual ACM/IEEE International Conference on Mobile Computing and Networking (MobiCom '97), Budapest, Hungary, September 1997.

....on the idea of renting resources, such as for example [3] where the main focus is on accounting CPU cycles and communications consumption made by the hosted processes. On the contrary, the main idea of our service is to rent storage. The second line exploits the use of proxies and software agents [7, 6, 4, 13, 5, 8, 9]. To our knowledge, our work is the first one to combine both aspects, by employing proxies and agents to provide users with storage external to their mobile computers. Finally, our work can benefit from other works, such as the CODA project [7] by implementing the ideas and techniques they ....

B. Zenel and D. Duchamp. A general purpose proxy filtering mechanism applied to the mobile environment. In Proceedings of the Third Annual ACM/IEEE International Conference on Mobile Computing and Networking, September 1997.

....a specific service such as Web browsing [8] or databases [15] In this case, using different services implies the deployment of different middle processes but adaptation may be more suitable to applications. Finally, the finest grained middle processes are those attached to a specific application [24] which allows to provide an adaptation policy tailored to each application but may imply the deployment of much more infrastructure. Fixed Station Mobile Device Fixed Station Middle Process Application Application (a) Middle process executed on the fixed network. Mobile Device Fixed Station ....

....Application Application Middle (b) Middle process executed on the mobile device. Figure 1. The middle process model. The second parameter in this model concerns the position for the execution of the middle process. A number of approaches propose the fixed network to execute the middle process [4, 24, 8]. This approach is depicted in figure 1(a) The exact position of the middle process at the fixed network depends on its role. Placing it at the fringe of the fixed network makes it easier to gather information about wireless link characteristics. Moreover, special network protocols can be used ....

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B. Zenel and D. Duchamp. A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment. In Proc. of the 3rd Annual International Conference on Mobile Computing and Networking, Budapest, Hungary, Sept. 1997. 10

....on mobile agents [28] has focused on supporting distributed arti cial intelligence, active proxies share many of the same systems level concerns, such as code mobility, naming, security, and coordination. Many projects have used transcoding to adapt service content to better suit small devices [6, 15, 29, 34, 35, 36, 49, 50]. Additionally, a number of projects have attempted to develop universal interfaces for large classes of devices, including the recent WAP protocol stack [44] Instead of assuming that a single standard will be adopted by all devices, the Ninja architecture allows multiple standards to be bridged ....

Bruce Zenel and Dan Duchamp. A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment. In Proceedings of the Third Annual ACM/IEEE Conference on Mobile Computing and Networking (Mobicom '97), New York, NY USA: ACM, 1997.

.... creative applications, including Kanji transcoding [33] Kanji to GIF transformation [39] applicationlevel stream transducing [8, 34] and personalized agent services for web browsing [6] It has been used to hide the effects of error prone and low bandwidth wireless links [14, 23] Bruce Zenel [40] applies the proxy mechanism to the mobile environment: filters on an intermediary host drop, delay, or transform data moving between mobile and fixed hosts. However, the filters are part of the application, complicating their reuse and making it awkward to support legacy applications. Proxies ....

Zenel, B., and Duchamp, D. A General-purpose Proxy Filtering Mechanism Applied to the Mobile Environment. In Proceedings of MobiCom '97 (Budapest, Hungary, Oct. 1997).

....a place is created on the MU. Then, an agent called MU static agent is also created. This agent administers MU resources, decides which 2 Filters are programs used for processing every message coming or going to the MU. They can abolish, delay, reorganize into segments or transform the message [ZD97]. MU Mobile Unit Mobility Administrator for Manager Place and Agent Manager Resource GSN Generator Agent Supervisor Agent Generator Place Controller Place Manager Resource Controller User Mobile Place Manager Agent Manager Figure 2: MU and GSN main modules. filters must be applied to the ....

B. Zenel and D. Duchamp. A general purpose proxy filtering mechanism applied to the mobile environment. In Proceedings of the Third Annual ACM/IEEE International Conference on Mobile Computing and Networking, September 1997.

....increasing need for applications to adapt their services accordingly. At the same time, networks are increasingly heterogeneous and complex. Techniques for adaptation have typically focused on the last mile, assuming that a single host connects to a well connected network over a single poor link [5, 6]. Successes in these systems have shown that gracefully degraded services are desirable. But, connectivity is becoming more complex with increasing instances of home computer networks, inter building wireless links, and wireless workgroups. Success requires a more general solution for deploying ....

....compromise. TACC allows proxy services, composed of worker modules, to execute on a compute cluster. Columbia University researchers have constructed a generalpurpose proxy framework that allows dynamic loading of adaptor modules to a proxy node, giving even greater control to users [6]. Both of these systems focus on last mile issues, adapting data at a well connected proxy node before transmission across a low quality link. As a result, both systems are currently limited to a single proxy service per connection and make no provisions for distribution of adaptations or ....

Bruce Zenel and Dan Duchamp, "A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment," Proceedings of the Thrid Annual ACM/IEEE International Conference on Mobile Computing and Networking (MOBICOM '97), Oct. 1997, pp. 248-259.

....host, performing local retransmissions when a packet loss is detected. It is not very useful in the non transparent version of GSM data transmission, where RLP deals with information losses. In GSM, the main problem is not packet loss, but long, variable delays due to RLP retransmissions. In [19], an approach similar to our indirect architecture is presented. However, this work is focused on adaptation to heterogeneous network environments, giving a poor performance in a homogeneous environment. It is considered that mobile hosts may move unpredictably through areas whose networks have ....

B. Zenel, D. Duchamp. A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment, MOBICOM97, Budapest Hungary 1997.

.... creative applications, including Kanji transcoding [38] Kanji to GIF transformation [49] application level stream transducing [9, 39] and personalized agent services for web browsing [7] It has been used to hide the effects of error prone and low bandwidth wireless links [17, 27] Bruce Zenel [50] applies the proxy mechanism to the mobile environment: filters on an intermediary host drop, delay, or transform data moving between mobile and fixed hosts. However, the filters are part of the application, complicating their reuse and making it awkward to support legacy applications. Proxies ....

Zenel, B., and Duchamp, D. A General-purpose Proxy Filtering Mechanism Applied to the Mobile Environment. In Proceedings of MobiCom '97 (Budapest, Hungary, Oct. 1997).

....agent for the clients. The transformation agent can be placed anywhere on the network as long as it can intercept the client s packets. In our network, the base station is the logical choice for transformation agents. Use of proxies has been suggested in the literature for similar adaptations [15, 26, 37]. Transformer tunnels are not a replacement for proxies; rather they supplement proxies. Transformer tunnels differ from proxies in three ways. Layer of operation: Proxies usually operate at the application layer. Transformer tunnels, on the other hand, provide a low level application transparent ....

....If required, this module can propagate packets to some filter application. Other packets can be sent over the link without changes. Application filters can take appropriate actions and send the filtered packets back onto the network. Such a module would be similar to the low level proxies (LLP) [37] for application independent adaptation. 5 Evaluation This section describes the experiments we performed to evaluate the transformer tunnels. For all our experiments, we used a wireless LAN configuration. The wireless LAN consists of fixed hosts (or base stations) and mobile hosts. The fixed ....

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Bruce Zenel and Dan Duchamp. A general purpose proxy filtering mechanism applied to the mobile environment. In Proceedings of the 3rd MOBICOM Conference, pages 248--259, Budapest, Hungary, September 1997.

....quality of the network. CHAPTER 3. RELATED WORK 17 TranSend [7] provides a distillation proxy that reduces the data sent to a mobile application by compressing the data stream. MOWGLI [14, 16] provides a modified socket interface that uses a proxied architecture similar to I TCP. Finally, Zenel [30] describes a general purpose proxy architecture similar to the one proposed by this thesis. The TranSend proxy server (previously named Pythia) distills information sent from the proxy to the mobile host. Distillation involves data type specific lossy compression such that the semantic content ....

....require that each wireless network have a single wired attachment which also serves as the interception point. Another possibility is to tie the routing of packets bound to and from the wireless network to a single point on the intervening network. As proposed individually by Lioy [17] and Zenel [30], it may be possible to use the foreign agent (FA) of Mobile IP as the desired gateway. Since all traffic is forwarded to the FA before being decapsulated and sent on to the mobile, it could be combined with the proxy to provide both mobility and application protocol services. At the moment, the ....

[Article contains additional citation context not shown here]

B. Zenel and D. Duchamp. A general purpose proxy filtering mechanism applied to the mobile environment. In Proceedings of the Third Annual ACM/IEEE International Conference on Mobile Computing and Networking, pages 248--259, Budapest, Hungary, September 1997.

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B. Zenel and D. Duchamp. "A general purpose proxy filtering mechanism applied to the mobile environment." Proceedings of the Third Annual ACM/IEEE International Conference on Mobile Computing and Networking, September 1997.

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Zenel and D. Duchamp, "A general purpose proxy filtering mechanism applied to the mobile environment," Proceedings of the Third Annual ACM/IEEE International Conference on Mobile Computing and Networking, pp. 248-259, Budapest, Hungary, September 1

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B. Zenel, "A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment," Wireless Networks, vol. 5, pp. 391-409, 1999.

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Zenel and D. Duchamp, "A general purpose proxy filtering mechanism applied to the mobile environment," In Proceedings of the Third Annual ACM/IEEE International Conference on Mobile Computing and Networking, pp. 248-259, Budapest, Hungary, September 1997.

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B. Zenel and D. Duchamp, "A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment," Proceedings of MobiCom 97, Budapest, Hungary, October 1997. 37 Figure Captions

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B. Zenel, D. Duchamp, "A General Purpose Proxy Filtering Mechanism Applied to the Mobile Environment", MOBICOM 1997, pp. 248-259

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