subject: Testing network applications using network emulators [print this page] Testing network applications using network emulators
A networked application is any application that intrinsically uses a network as part of its operation, e.g. web based applications, networked database access, file transfer programs, mail transfer programs, messaging protocols, streaming voice, video, radio etc. It does not include applications like MS Word, unless of course a file needs to be opened on a remote file share.
These networked applications are now core to many of the things every computer user does every day simple things like accessing bank accounts online, accessing emails & calendars, booking travel tickets, social networking, (Facebook), and smart phone applications. They also can be found in processes such as controlling traffic lights and operating modern IP based public CCTV.
There is a whole world of difference between how an application runs in the LAN and how it runs in the WAN, Satellite, Mobile 3G/GPRS etc., which cannot be simply resolved by increasing the available bandwidth.
For example, a file copy that takes 8 seconds to download in a LAN could take 75 seconds in a typical WAN/Internet link covering a distance of 165 miles even when both LAN and WAN have a bandwidth of 100Mbps. Even where available bandwidth is not a problem, latency' issues can really impact on performance particularly if an application is chatty' and needs lots of "acknowledgements" during transmission.
Having a way to experience how applications under development will perform when placed in the real network prior to actual roll out will become even more crucial going forwards. Developers will need to know that they are creating software that can cope well with the challenges of being delivered over "unfriendly" networks to avoid wasting time in retrospective rewrites and fixes.
Understanding Network Conditions
Networked applications will, at some point, experience a myriad of conditions as they travel over networks such as WAN, Home Cable, (A)DSL networks, and satellite networks, Wireless networks including GPRS, 3G, and WiMAX or LTE. Conditions that an application will experience will depend on the type of network but intrinsic to all are characteristics that are "unfriendly" such as latency, error, loss, jitter, insufficient bandwidth etc.
The best approach to overcome these problems is to get the development right by experiencing how an application will perform in these non-LAN networks during the development and test processes, but without using the live network.
Network emulators will allow the developer to re-create any of these difficult and complex networks in prototyping & development environments, and in test environments. They eliminate the need for the use of miles of cable, aerial masks, satellite dishes, mobile phone handsets etc. or using your corporate network in order to conduct realistic testing.
