Internet data compression

There are several examples on the Internet of websites that are actively working toward providing free and unrestricted access to scientific data for the scientific community and general public. One of the biggest examples that is also closely related to chemistry is PubChem (http //pubchem.ncbi.nhn.nih.gov/), an online database of chemical compounds, their structures, and chemical and other related data. PubChem not only provides its data online on its webpages, but it also makes the chemical content easily accessible using automated tools (in this case, compressed SDfiles containing tens of thousands of structures each are used). 

Video data transmissions can require a significant bandwidth that depends on the video parameters such as frame rate, resolution and quality (compression). If talking about a virtual community built around VPN/LAN (high-speed intranet in which bandwidth is not an issue) higher-quality transmission can be setup. Even in such cases, there are limits to what a PC can reasonably capture, for example, the application shouldn t exceed 80% of CPU capacity on Windows. Most applications are deployed over the Internet and the bandwidth requirements can profoundly affect the application s functioning and the user experience. The proposed framework considers those aspects, that way the smallest appropriate dimensions and lowest acceptable frame rate is selected in a dynamic manner (within the bandwidth management function). 

True video formats go beyond this and use more advanced compression methods which exploit the similarity between subsequent frames. The most important video formats are MPEG (motion picture expert group which comes in three forms, MPEG I, MPEG II, and MPEG III, each with various format subtypes) and AVI (audio video interlaced). Both can contain audio tracks besides the video data. On Macintosh systems, Quicktime is another popular format. One major problem with video data of all formats is that even short clips tend to be of massive size and are therefore slow to transport over current Internet connections. Furthermore,... 

Current problems with Java-based applications are the still sluggish performance (expected to become better once JIT compilers are widely available) and the size of applets performing non-trivial tasks. Compressed JAR (Java Archive) libraries, which are automatically expanded to the receiver s side, can help to reduce the amount of data shipped. Considering today s speed of Internet connections, the routine download of a few hundred kbytes of applet classes before the applet starts to react is not a good idea outside local networks or institutions close to some fast network backbone. 

---