Hi André and every body, Thank you very mutch for the details:))
Tail ----- Mail Original ----- De: "André Warnier" <[EMAIL PROTECTED]> À: "Tomcat Users List" <users@tomcat.apache.org> Envoyé: Jeudi 20 Novembre 2008 22:44:34 GMT +01:00 Amsterdam / Berlin / Berne / Rome / Stockholm / Vienne Objet: Re: tomcat virtual host Caldarale, Charles R wrote: >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] >> Subject: Re: tomcat virtual host >> >> status, or does something else happen? Is the DNS name >> "mysvn" defined on the machine your browser is running on? >> >> Internet Explorer could not display this web page >> i test this in local machine, so i do not use a DNS. > mtail, The gurus here are flying high, and a bit intimidating sometimes. So allow me to try, since for once I can maybe be useful here. It is not enough to define a virtual host in Tomcat. Your browser must also know "where" that virtual host is (on which machine). Even if this all happens on one single machine, the browser does not know who "mysvn" is, unless you give him a way to find out. So let's start at the beginning. 1) When you type in your browser a URL like http://mysvn:8080/something.html the first thing the browser has to do, is to find an IP address that corresponds to the hostname "mysvn". That is because, on the Internet, machines find one another via IP addresses (like 123.23.34.102), and not by names (like "mysvn"). Names are only something for humans, easier to remember than numbers. 2) There are 2 places where the browser can find a translation of a host name into a host IP address, and it will try them in this order : (a) : in the local "hosts" file. Under Windows, it is usually c:/windows/system32/drivers/etc/hosts and under Unix, it is usually /etc/hosts (b) : using the DNS system. That means, the browser knows the IP address of a "DNS server", which is another computer which has access to a long list of translations between host "names" and host "IP addresses", and it will ask that server. So, the browser will first try (a). If the browser is looking for the IP address of "mysvn", and if there is a line in (a) like 1.2.3.4 mysvn then the browser is happy : it now knows that the server IP address of "mysvn" is 1.2.3.4, and it can stop looking. If the browser does not find a translation in (a), then it will ask (b) (the DNS system) for a translation. If the DNS system also does not know, then it will send back "I don't know", and your browser will say "Cannot display that page", because it cannot even find the IP address of the server to which it should be talking. 3) When the browser has obtained a translation for "mysvn" into an IP address, then (and only then) it can go one step further : It can now compose a HTTP request and send it to that IP address 1.2.3.4. This HTTP request will look like this : GET /something.html HTTP/1.1 The browser will also add a second line to that request, like Host: mysvn 4) If all the above happened correctly, then the Tomcat listening at the IP address 1.2.3.4 will receive the request from the browser. It is very important that you understand this : Tomcat only receives the request if the browser has sent it to the correct IP address of the host where the Tomcat server runs. That is true even if this all happens on one single machine. If your browser could not get an IP address for "mysvn", or if it got the wrong one, then Tomcat never even sees the request. 5) But let's suppose that everything above went fine, and that Tomcat receives the request. Tomcat now looks at the second line of the request, the one that says : Host: mysvn That is when the Tomcat virtual hosts come into play (but not before). Tomcat will now look if it has a Host named "mysvn". If it has one, it will use that Host configuration to answer the request. (If Tomcat has no such Host, then it will use its "default host" to answer the request anyway.) 6) Now there can still be an error : If the browser asked for the page "/something.html", and Tomcat does not find that page in the document area of that virtual Host, then Tomcat will return an error "not found" to the browser, and the browser will also say "Cannot display that page". But the point is, this is another kind of error, and it happens later. Your problem is probably due to the first reason : your browser cannot even find an IP address for the server "mysvn". It cannot find it, because it looks first in your local hosts file, and there is no line there with "mysvn". Then it asks the DNS system, and the DNS system also does not know the IP address of "mysvn". On the other hand, when your browser tries to find the address of "localhost", then it *does* find it in the local hosts file, and that is why your URL http://localhost:8080 works fine. -- note -- The IP address 127.0.0.1 is special : it always means "this machine". So if you do "ping 127.0.0.1" on any computer, that computer will always ping itself. Or if you ask your browser http://127.0.0.1 the browser will try to contact a HTTP server on this same machine. Similarly, on almost every computer, there is a line in the local hosts file, like this : 127.0.0.1 localhost That means that whenever a program on this machine is trying to get the address of the host "localhost", it will always find the response "127.0.0.1" (because it first looks in the hosts file). That's why, if you enter "ping localhost", you will see the same as if you enter "ping 127.0.0.1". It is also why, if you enter in your browser http://localhost:8080 the browser will try to contact the HTTP server on this same machine (because "localhost" is first translated to "127.0.0.1", and that IP address always means "this machine"). -- End of note -- To summarise : If you want your browser to find the correct (local) Tomcat virtual hosts "localhost" and "mysvn", and you want Tomcat to answer with the correct virtual host, and all of this happens on the same machine, then you have to do 2 things : A) you have to make sure that in your local hosts file, there are these 2 lines : 127.0.0.1 localhost 127.0.0.1 mysvn That is because you want your browser to send the HTTP request to the local machine (127.0.0.1) in both cases : - when you use the URL : http://localhost:8080 - and when you use the URL : http://mysvn:8080 B) you have to configure 2 virtual hosts in Tomcat : one <Host> for "localhost" and one <Host> for "mysvn" Both A and B are necessary. You have done B, but you probably did not think of A. --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
