On Wednesday Oct 23, 2002, I plan to change the "alias" www.nevis.columbia.edu to point to ada.nevis.columbia.edu instead of nevis1.nevis.columbia.edu. The new web server is already up and running; here are some sample links:

http://ada.nevis.columbia.edu/
http://ada.nevis.columbia.edu/particle/
http://ada.nevis.columbia.edu/heavyion/
http://ada.nevis.columbia.edu/~zajc/
http://ada.nevis.columbia.edu/~shaevitz/talks/

Note that, while navigating the above pages, if you hit any link with https://www.nevis.columbia.edu/, you'll go back to nevis1 (at least, until the alias is changed).

I shall turn off the web server on nevis1 a few days after the switch, to give time for the new alias to propagate on the world's DNS servers.

Why is this being done?

There are two main reasons for this switch:

1. It's part of a general move of Nevis system services off of nevis1 and onto the Linux cluster.

2. The web server on nevis1 was installed by Xihong Yang and Dave Leon back in 1995. I've made some security fixes in the past (apply proper protections to cgi scripts, etc.) but basically the server has not been patched since then.

   Web standards have changed since 1995, and the server on nevis1 is not compatible with all of them. This is dramatically evident if you use Microsoft's Internet Explorer with all of the latest security patches. None of the pages served by nevis1 are correctly displayed.

   So there's a choice: Try to upgrade a 7-year-old web server on a old machine, or install a new server on a new machine. We've chosen the latter approach.

Do any web pages need to be converted?

Hopefully, none of your web pages need to be changed. However, any links of the following form will be incorrect once the web server changes:

In order to help you check your web pages quickly, I've written a small utility: WWW-convert. It's available on both the Linux cluster and on nevis1. This PERL script will do the following:

• search through the current directory and all sub-directories;
• duplicate any file that ends in .html or .htm, adding a .bak extension.
• scan the HTML files for any string containing one of the invalid forms above, and replace it with the correct form (https://www.nevis.columbia.edu or ftp://ftp.nevis.columbia.edu, as appropriate.

To use this utility, go to your web directory and execute the command:

There are a couple of options: --verbose means to display each line as it's changed; --test means not to actually change any files. So you may want to see how this script will affect your files with the sequence:

Do any web pages have to be moved?

The new web server is part of the Linux cluster, and shares the same view of the home directories. So if your Linux cluster home directory is not on nevis1, then you must move your ~/WWW directory to the cluster.

I will send out a separate mail message to those users affected by this. If you received such a message, all you have to do is log in to the Linux cluster, and execute the following command:

The only problem you may encounter is that if you're actively changing the contents of your web site around the time of the web server conversion, you'll have to keep synchronizing your web pages between the two servers. I suggest you keep doing this for a day or so after the conversion, since it will take time for the DNS servers across the world to pick up the new alias.

Will there be any changes after moving to the new server?

The only issues I've found so far are:

• Web page counters still work. However, I have to manually copy the data files over from nevis1. If you need your web counter to be absolutely accurate, let me know and I'll try to copy your counter just as I switch the web server.

• The only CGI script that doesn't work yet is the one that displays the man pages via the web; e.g., man ls. I'm still working on this.

  Note added 28-Oct-2002: This problem has been fixed.

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