Ian Beaumont Shields

Emulator express: a system for optimizing emulator performance for wireless networks

IBM eNetworkTM Emulator Express is an IBM program product that optimizes the operation of Telnet 3270 and 5250 emulation over extremely low-bandwidth networks. These optimizations enable mobile workers using laptops, notebooks, or other mobile devices to access legacy host applications effectively over wide-area wireless networks as well as low-bandwidth wireline modem connections. This paper describes how the Emulator Express system intercepts the data stream and optimizes it transparently to both the client emulator and the Telnet server. The optimizations include a new data stream caching technology, a new optimized protocol that reduces the number of Telnet negotiation flows, and traditional compression. The data stream caching technology is particularly significant because it may be applied to other distributed application domains. The results of several performance experiments are reported that illustrate the improvements in data transport volume and response time when using Emulator Express.

Accelerating telnet performance in wireless networks

This paper describes the design of a system that significantly improves the performance of telnet data delivery for 3270 and 5250 emulation so that access to legacy applications via mobile units over low bandwidth wide area wireless networks is feasible. One of the key innovations of this technology is data stream caching. More generally, data stream caching can be used to reduce the transport volume for a broad class of data streams such as Lotus Notes or file transfer. The technology described herein is implemented in a system called Emulator Express (EE) [l], middleware that optimizes the operation of telnet 3270 and 5250 emulation. EE can be used with any wireless or wireline technology that implements the TCP/IP protocol. The success of the EE technology is reflected by some customers that report that the performance of running host applications when connected to their wireless networks often exceeds that of running the same applications when connected to a LAN.

On the existence of Hamiltonian paths in the cover graph of M(n)

The poset M(n) has as its elements the n-tuples of integers a = (a1, a2,...,an) satisfying 0 = a1 =... = aj < aj+1 <...< an ≤ n for some j, 0 ≤ j ≤ n. The order relation is defined by a ≤ b if ai ≤ bi for 1 ≤ i ≤ n. We show that the cover graph of M(n) has a Hamiltonian path if and only if(n+12) is odd and n ≠ 5.