Opening URLs

Introduction to Uniform Resource Locators (URLs)

"Uniform Resource Locators" (URLs) are a standard notation on the Internet for identifying the locations of files and other kinds of information. People often use this notation in postings to refer to a resource which is available elsewhere on the net.

Here's some examples of URLs:

news:j-doe-240687341230001@news.flunku.edu	A news article identified by its "message id".
news:comp.sys.mac.comm	A newsgroup.
news:*	All newsgroups.
news://news.flunku.edu/comp.sys.mac.comm	A newsgroups on a specific news server
nntp://news.flunku.edu/alt.archery/5238	Another way news articles are sometimes identified.
mailto:j-doe@flunku.edu	A person's email address.
ftp://ftp.flunku.edu/pub/wild-tetris/readme.txt	A file available via anonymous FTP.
http://www.flunku.edu/	A World Wide Web (WWW) site or page.
gopher://gopher.flunku.edu	A Gopher site or Gopher article.
wais://wais.flunku.edu:5520/usr/local/xxx/our-database	A WAIS site and search database.
telnet://big-unix-box.flunku.edu	A timesharing host which expects you to use "DEC VT100" terminal emulation.
tn3270://big-ibm-box.flunku.edu	A timesharing host which expects you to use "IBM 3270" terminal emulation.
finger://j-doe@flunku.edu	A reference to "finger" information about a person.
whois://j-doe@flunku.edu	A reference to "whois" information about a person.
ph://ns.flunku.edu/john%20doe	A reference to "ph" information about a person. ("Ph" is also known as the "UIUC CSO Nameserver". It is a directory information system.)

Note that these examples have the same format. They all start with "xxx:", where "xxx" is the kind of resource (news, nntp, mailto, ftp, etc.). Immediately following the colon is a string which uniquely identifies the resource.

If you want to access the resource referenced by a URL, hold down the Command key while clicking anywhere in the URL, or click anywhere in the URL and use the Open URL command in the Special menu.

For news articles (news and nntp URLs), MT-NewsWatcher opens the referenced article in a new article window. For news URLs which refer to a group, MT-NewsWatcher opens a subject window for the referenced group. For the "news:*" URL, MT-NewsWatcher displays the full group list. If the URL specifies a news server, MT-NewsWatcher attempts to connect to that news server, and fetch the article or group from there. This creates a temporary news server in the News Servers dialog, which will be saved with your servers if you visit the dialog in that session.

For email addresses, MT-NewsWatcher opens a mail message window addressed to the referenced person, unless you have the Use external "mailto:" helper option turned on, in which case it will tell your email client (as specified in Internet Config) to handle the URL. When MT-NewsWatcher is handling mailto: URLs, it can cope with mailto URLs like:

	<mailto:joe@example.com?cc=bob@example.com&body=hello>
		

For anonymous FTP files, MT-NewsWatcher runs a "helper program" to fetch the referenced file and copy it to your hard drive.

For the other kinds of URLs, MT-NewsWatcher runs other helper programs to connect to the host and display the referenced information. For example, for an http URL, MT-NewsWatcher runs your favorite web browser to connect to the host and display the web page.

When you open a URL, MT-NewsWatcher flashes it quickly three times and leaves it selected to give you feedback. If MT-NewsWatcher cannot recognize a URL when you command-click, it beeps.

When you open a URL, MT-NewsWatcher tries to figure out where the URL begins and ends for you. This usually works, but sometimes MT-NewsWatcher doesn't do it properly. In these cases, select the full URL manually first, then command-click it or use the Open URL command.

In addition to the notation used in the examples above, MT-NewsWatcher also accepts other formats of URLs. You can precede the URL with the string "URL:", and you can enclose the URL in angle brackets <...>. For example, all of the following are legal:

1. http://www.flunku.edu
2. <http://www.flunku.edu>
3. URL:http://www.flunku.edu
4. <URL:http://www.flunku.edu>

You can use the short form (1) when you place URLs on lines by themselves. For example,

  You can get the docs at:

    ftp://ftp.fluku.edu/pub/docs/
 
  The documents tell you everything you need to know.

You should also use one of the two forms with the angle brackets (2) or (4) if you include a URL embedded inside other text. For example,

You can get the docs at <ftp://ftp.fluku.edu/pub/docs/>. The documents tell you everything you need to know.

You should also use one of the two forms with the angle brackets (2) or (4) for URLs which contain spaces and for long URLs which are on multiple lines. For example,

<URL:ftp://ftp.flunku.edu/pub/docs/My User Doc> <URL:ftp://ftp.flunku.edu/directory1/directory2/directory3/
directory4/directory5/big-long-file-name.sea.hqx>

If you would like to try these features, open MT-NewsWatcher's about box. In the text, command-click the URL reference to the MT-NewsWatcher FTP site, and command-click the author's email address. Send me a note and say "hi"!

You can open URLs in message windows as well as in article windows. For example, if you type a URL in one of your own postings, you can check it for typing errors before sending it by command-clicking the URL.

This MT-NewsWatcher feature is very useful, but it only works well if people use the URL notation when they refer to Internet resources. We hope that more people will get into the habit of using this simple format for references.

Opening Referenced Articles and Groups

When you open a news or nntp URL, MT-NewsWatcher gets the referenced article from the news server and displays it in a new article window.

In addition to full formal news and nntp URLs, MT-NewsWatcher recognizes one other format for news references: the message id of the article enclosed in angle brackets. For example, MT-NewsWatcher recognizes both of the following as news references:

news:j-doe-240687341230001@mac18.flunku.edu <j-doe-240687341230001@mac18.flunku.edu>

In other words, with article references, you can leave off the "news:" prefix if you enclose the message id in angle brackets.

This format is very common on Usenet. For example, many followup postings begin with an "attribution" line which looks like the following:

In article <message-id>, email-address (full-name) wrote:

If you want to open the article to which this article is a followup, command-click the message id. This is often useful.

MT-NewsWatcher also recognizes two other forms of the news URL which are sometimes used. For example:

news:comp.sys.mac.comm

Opens a subject window for the group comp.sys.mac.comm, as if the group had been opened from the full group list.

news:*

Shows the full group list window and makes it active (brings it to the front).

news://news.flunku.edu/comp.sys.mac.comm

Connect to the server specified in the first part of the URL, and fetch the given group.

Opening Email Addresses

When you open a mailto URL, MT-NewsWatcher opens a new mail message window with the To header field filled in with the email address from the URL. This makes it easy to send a mail message to the person.

In addition to full formal mailto URLs, MT-NewsWatcher recognizes simple email addresses without the "mailto:" prefix. For example, both of the following are recognized as email address references:

mailto:j-doe@flunku.edu j-doe@flunku.edu

Unfortunately, email addresses and message-IDs on Usenet are syntactically indistinguishable, although, strictly speaking, a message-ID is always enclosed in <angle brackets>. MT-NewsWatcher uses a heuristic to distinguish between message-IDs and email addresses (based on the number of digits in the part before the @), and in most cases will correctly distinguish one from the other.

Fetching Referenced Files

When you open an ftp URL, MT-NewsWatcher runs a helper program to fetch the referenced file and copy it to your hard drive.

People often use ftp URLs to refer to files which are available via anonymous FTP. For example, you might see the following text in a posting:

I have written the world's greatest version of Tetris for the Mac. It uses billions of colors and always lets you win. You can get it at: <ftp://ftp.flunku.edu/pub/hotstuff/wild-tetris.sit.hqx>

MT-NewsWatcher runs the FTP helper program in the background, so you don't have to wait for the file to be transferred from the FTP host to your Mac. You can continue to read the news in MT-NewsWatcher while the helper program fetches the file for you.

Sometimes people use URLs to refer to directories rather than to files. For example, you might see the following in a posting:

The documents are available at <ftp://ftp.flunku.edu/pub/docs/>.

Note that in this example the URL reference ends with a slash. This is what tells you that the URL refers to a directory rather than to a file.

This example also shows the bracketed URL form <ftp:...>. You should use this form if you embed URL references inside regular text as in the example.

For directory references, the FTP helper program connects to the FTP site, finds the directory, gets a list of files in the directory, and opens a window displaying the file list. You can then use the helper program to fetch the files you want from the directory. For directories, MT-NewsWatcher automatically brings the FTP helper program to the front instead of running it in the background.

Some Internet service providers offer FTP servers for their customers to use, but not HTTP servers (web servers). For this reason, some people publish their web pages using FTP URLs instead of HTTP URLs. When you open such a URL in MT-NewsWatcher, your FTP helper program runs instead of your HTTP helper program. This is inconvenient.

To solve this problem, there is a checkbox option in the Helper Applications preferences topic named Use HTTP helper instead of FTP helper for ".html" files. The default value is off. If you turn this option on, whenever you open an FTP URL for a file whose name ends in ".html" or ".htm", MT-NewsWatcher uses your HTTP helper instead of your FTP helper to open the URL. We have tested MacWeb, Netscape, and NCSA Mosaic, and they all do the right thing with these kinds of URLs (they fetch the files using FTP, then display them as web pages).

With this option, you can have MT-NewsWatcher use your web helper (HTTP helper) just for .html and .htm files, and still use your favorite FTP client (Anarchie or Fetch) for all other anonymous FTP files.