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IBM eNetwork(TM) 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.
This paper describes the design of Emulator Express (EE), an IBM program products that optimizes the operation of TN3270 and TN5250 emulation to enable mobile workers using laptops, notebooks, or other mobile devices to effectively access legacy host applications over wide-area wireless networks as well as low-bandwidth wireline modem connections. EE is part of IBM's SecureWay* and eNetwork* wireless product offerings, including the SecureWay Wireless Gateway and SecureWay Wireless Mobile Client software.1 EE is middleware that can be used with any wireless or wireline technology that implements the Transmission Control Protocol/ Internet Protocol (TCP/ItP). As confirmation of its success, some customers using EE technology 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 local area network (LAN).
Emulation. The IBM 3270 and 5250 display terminals are fixed-function, buffered, block-mode terminals with a certain amount of formatting capability built into the display. A large amount of the world's data is accessible through such terminals, and they are common in many types of businesses. The original terminals used binary synchronous communication (BSc) and later Systems Network Architecture (SNA) protocols to communicate with a host. Many emulators of these terminals are now available for personal computers, and it is common for emulators to use TCP/IP and a specific Telnet regime ('fN3270 or TN5250) to communicate to a...