CS 576, Distributed Operating Systems

WebNFS Report

Claim: WebNFS - the filesystem for the World Wide Web

Origins: WebNFS is an enhanced version of SunSoft's NFS (Network File System) protocol. Taking NFS as a basis, SunSoft extended it to be applicable over the intranet and the Internet, allowing to read from and write to files over the Web instead of just viewing them through a browser.

There are currently about 10-12 million nodes connected to various NFS servers throughout the world. WebNFS allows access to the information on any one of these servers. Instead of having to use a Web browser to retrieve the files, switch tasks, and cut and paste the data into applications, WebNFS allows for a direct and transparent access to Web data from within the applications themselves, compatible with the way applications now access local disks.

WebNFS benefits:

Connection management: client can download multiple files over a single TCP connection.
Concurrency: Clients can issue multiple, concurrent requests to a NFS server, resulting in beter utilization of server and network resources.
Fault Tolerance: unlike many other Web applications today, when interrupted during a file download, WebNFS resumes from where it left off, not from the very beginning of the file.
Performance: NFS servers currently can handle over 21,000 operations per second, which is better than other common file access protocols, such as Novell Netware and Microsoft LANManager.
Higher Resource Utilization: instead of having a number of local copies of data, WebNFS allows applications to share this data across the Web. Also significantly facilitates distributed computing by allowing machines across the Internet to have full read and write priveleges for the same files.
Acceptance and Industry Support. NFS servers are already widely used throughout the world. There are 75 vendors who already support NFS, and such companies as IBM, Sequent, Sun, Auspex, Oracle, Spyglass, and JavaSoft have commited to integrate WebNFS into their browser and Internet server software.

WebNFS Disadvantages:

No reliable history of performance. At this point, NFS is virtually unknown on the Internet, and there is now history of how well it performs in the Internet's shaky environment.
SLOW!!! Although WebNfs claims to be up to 10 times faster than HTTP, it is still too slow to solely rely upon. A mere RTT latency imposed by the speed of light between Salt Lake City and Krasnoyarsk, Russia would be 100 milliseconds. WebNFS requires up to 5 turnarounds ( portmap, mount, portmap, lookup, read) to establish a READ connection, which would take half a second in the perfect case, and A LOT longer in the usual case.
Transparency - Good? Designers of WebNFS claim its complete transparency, which may take the decision of whether to go across the Web for a file away from the user. Although it makes things simpler, it may require to connect to a remote NFS server which can be extremely slow, or that server may be down altogether.
UDP vs. TCP. Historically, NFS has been using UDP protocol as a transport, since it is faster and suited better for LAN's. WebNFS, however, switches to TCP, common for the Internet. This adds to the complexity of protocol layers switching.
Security. WebNFS designers claim to support all firewalls. However, none of them offer a comlete security, neither for data traveling across the Internet, nor even for files residing on the server. Adopting WebNFS opens an additional door, making data more volnurable to both system design flaws and human errors.
Complete Internet dependency. By accepting WebNFS, the system becomes extremely dependent on the behavior of the Internet, which is not the most reliable thing in the world. The traffic is already very heavy, keeps growing exponentially, and unless radical measures are taken, is expected to crash in 5 years. Decision to adopt WebNFS may lead to a number of temporary and possibly terminal file system crashes.

Conclusion

WebNFS may turn out to be a very helpful solution for many Internet and intranet based applications, whenever data has to be shared across distant servers. It offers a relatively fast, convenient, and transparent way of data communication and may significantly facilitate the way many problems are approached and solved in the modern computer world. However, there is still a number of actual and potential problems associated with it, and it seems to be too early to talk about WebNFS as a final solution to the global integration problem.

Interesting links:

Introduction

Press Release

White paper.