Re: Missing ETag in 304 Header
I submitted a fix for this, and it has been accepted for release 5.5.24 and 6.0.14. Bugzilla report: http://issues.apache.org/bugzilla/show_bug.cgi?id=42497 -- Len On 5/16/07, Joe Mun [EMAIL PROTECTED] wrote: Hi guys... so according to the HTTP 1.1 spec ( http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html), 304 Not Modified responses must include the ETag in the header. However, Tomcat doesn't seem to be adding it... I am serving a static text file, and the header only returns: HTTP/1.x 304 Not Modified Server: Apache-Coyote/1.1 Date: Wed, etc... Is there a reason that the Etag is not being included? Is there a way to configure Tomcat to include this? My company is working with a caching solution provider, and they are complaining about the missing ETag. thanks. - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Missing ETag in 304 Header
On 5/16/07, Joe Mun [EMAIL PROTECTED] wrote: Hi guys... so according to the HTTP 1.1 spec ( http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html), 304 Not Modified responses must include the ETag in the header. Well, according to RFC 2616's section 10.3.5 on 304 Not Modified - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request , but the header is sent in a 304 response. That's why there's no ETag I am serving a static text file, and the header only returns: HTTP/1.x 304 Not Modified Server: Apache-Coyote/1.1 Date: Wed, etc... A 304 however returns If-None-Match which includes entity-tag , which is the same as ETag for the requested resource. RFC2616 14.26 If-None-Match If-None-Match = If-None-Match : ( * | 1#entity-tag ) Status=Not Modified - 304 If-None-Match= W/13035-1163859776458 Status=OK - 200 Etag=W/13035-1163859776458 Is there a reason that the Etag is not being included? Because it is not supposed to be included --- see above. Is there a way to configure Tomcat to include this? My company is working with a caching solution provider, and they are complaining about the missing ETag. The caching provider should be looking for Http Status code. If they status code is 200 , then they should look for Etag header, if the status code is 304 then they should look for If-None-Match header. thanks. -Rashmi - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Missing ETag in 304 Header
I think you've got that wrong. 1. Spec says: The response MUST include the following header fields: ... - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request 2. ETag header *was* sent in a 200 response to the same request. (See the header logs I posted earlier.) 3. Therefore, the 304 response must include the ETag. (I'm pretty sure that's right, it seems straightforward to me.) -- Len On 5/19/07, Rashmi Rubdi [EMAIL PROTECTED] wrote: On 5/16/07, Joe Mun [EMAIL PROTECTED] wrote: Hi guys... so according to the HTTP 1.1 spec ( http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html), 304 Not Modified responses must include the ETag in the header. Well, according to RFC 2616's section 10.3.5 on 304 Not Modified - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request , but the header is sent in a 304 response. That's why there's no ETag I am serving a static text file, and the header only returns: HTTP/1.x 304 Not Modified Server: Apache-Coyote/1.1 Date: Wed, etc... A 304 however returns If-None-Match which includes entity-tag , which is the same as ETag for the requested resource. RFC2616 14.26 If-None-Match If-None-Match = If-None-Match : ( * | 1#entity-tag ) Status=Not Modified - 304 If-None-Match= W/13035-1163859776458 Status=OK - 200 Etag=W/13035-1163859776458 Is there a reason that the Etag is not being included? Because it is not supposed to be included --- see above. Is there a way to configure Tomcat to include this? My company is working with a caching solution provider, and they are complaining about the missing ETag. The caching provider should be looking for Http Status code. If they status code is 200 , then they should look for Etag header, if the status code is 304 then they should look for If-None-Match header. thanks. -Rashmi - 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]
Re: Missing ETag in 304 Header
I might be wrong but I have a few doubts On 5/19/07, Len Popp [EMAIL PROTECTED] wrote: I think you've got that wrong. 1. Spec says: The response MUST include the following header fields: ... - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request By *same request* , I think you are saying that the request was sent from the same browser instance. So on first load of the static resource http://localhost:8080/tomcat.gif , the Http Status is 200 On second load (when browser is refreshed), but the static resource is now cached and so the Http Status is 304. But HTTP is stateless, how will the server know about the *same request* ? Please correct me if I'm wrong, but it is my understanding that when the browser is refreshed , a new request is sent hence, it is not the *same request* . 2. ETag header *was* sent in a 200 response to the same request. (See the header logs I posted earlier.) 3. Therefore, the 304 response must include the ETag. (I'm pretty sure that's right, it seems straightforward to me.) -- Len -Regards Rashmi - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Missing ETag in 304 Header
On 5/19/07, Rashmi Rubdi [EMAIL PROTECTED] wrote: 1. Spec says: The response MUST include the following header fields: ... - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request Just to test this, I created a JSP and put a jsp:froward tag inside the JSP, that *forwards* the *same request* to the static resource. In this case I got back an ETag, because the request to the JSP returns a 200 status code, and on JSP forward the same 200 status code is maintained. But as mentioned in my previous post, I think the browser refresh generates a new request, so the server would not know whether the static resource was requested from the same request or a new request. So then, the fact that the ETag doesn't appear is correct behavior IMHO. -Rashmi. - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Missing ETag in 304 Header
It's hypothetical. It says *if* the header *would have* been sent in a 200 response to the same request. I can know what Tomcat would have done, because I've seen what it *does* do with requests that are identical. In my test case, Tomcat *would have* included an ETag header *if* it responded 200 (because that's what it always does when it responds 200), therefore it *must* include an ETag header when it responds with a 304. -- Len On 5/19/07, Rashmi Rubdi [EMAIL PROTECTED] wrote: I might be wrong but I have a few doubts On 5/19/07, Len Popp [EMAIL PROTECTED] wrote: I think you've got that wrong. 1. Spec says: The response MUST include the following header fields: ... - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request By *same request* , I think you are saying that the request was sent from the same browser instance. So on first load of the static resource http://localhost:8080/tomcat.gif , the Http Status is 200 On second load (when browser is refreshed), but the static resource is now cached and so the Http Status is 304. But HTTP is stateless, how will the server know about the *same request* ? Please correct me if I'm wrong, but it is my understanding that when the browser is refreshed , a new request is sent hence, it is not the *same request* . 2. ETag header *was* sent in a 200 response to the same request. (See the header logs I posted earlier.) 3. Therefore, the 304 response must include the ETag. (I'm pretty sure that's right, it seems straightforward to me.) -- Len -Regards Rashmi - 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]
Re: Missing ETag in 304 Header
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Rashmi, Rashmi Rubdi wrote: 1. Spec says: The response MUST include the following header fields: ... - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request By *same request* , I think you are saying that the request was sent from the same browser instance. I think it means for any two requests that are indistinguishable from each other. In this case, I totally agree with Len. Len, I recommend you cross-post this (if you haven't already) to the tomcat-dev mailing list to see what they have to say. - -chris -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.7 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGT2WW9CaO5/Lv0PARAg9FAJ0XdEvzyyfB7RH/oifKPuK+DwBH8wCffLE1 7A1h+GbA/tlh6xNuMuAOL2Y= =Igah -END PGP SIGNATURE- - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Missing ETag in 304 Header
On 5/19/07, Christopher Schultz [EMAIL PROTECTED] wrote: Rashmi, Rashmi Rubdi wrote: 1. Spec says: The response MUST include the following header fields: ... - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request By *same request* , I think you are saying that the request was sent from the same browser instance. I think it means for any two requests that are indistinguishable from each other. In this case, I totally agree with Len. Thank you both for clarifying, I understand what you're saying. I don't mean to go off-track but, since If-None-Match header is being returned for Http Status 304 , I thought it might be a good idea to look at it's definition too. http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.26 The above definition mentions ETag , and the condition when it should be returned in the response header, but it seems a little unclear to me, because the sentence starts with Instead... , it doesn't fully explain the context. If any of the entity tags match the entity tag of the entity that would have been returned in the response to a similar GET request (without the If-None-Match header) on that resource, or if * is given and any current entity exists for that resource, then the server MUST NOT perform the requested method, unless required to do so because the resource's modification date fails to match that supplied in an If-Modified-Since header field in the request. Instead, if the request method was GET or HEAD, the server SHOULD respond with a 304 (Not Modified) response, including the cache- related header fields (particularly ETag) of one of the entities that matched. For all other request methods, the server MUST respond with a status of 412 (Precondition Failed). And the definition of ETag : http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.19 mentions entity-tag , which is also the value of a few other caching tags: If-Match If-None-Match Vary The value of the above tags returns the same checksum for the static resource as the ETag does. I think ETag's value will only change if the static file's modified date changes according to it's definition here: http://en.wikipedia.org/wiki/HTTP_ETag So why have 2 headers with the same checksum for the same static resource when one would suffice? Unless the checksum is going to be different... which I doubt because it is calculate based on the i-node number , last modified time and size (in Apache though, not sure how Tomcat calculates it.). Len, I recommend you cross-post this (if you haven't already) to the tomcat-dev mailing list to see what they have to say. - -chris -Regards Rashmi - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Missing ETag in 304 Header
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Rashmi, Rashmi Rubdi wrote: Thank you both for clarifying, I understand what you're saying. [snip] And the definition of ETag : http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.19 mentions entity-tag , which is also the value of a few other caching tags: If-Match If-None-Match Vary Just because each of these headers has an entity-tag as its value does not mean that the server can just pick one and shove an Etag-appropriate value into the header. The entity-tag is just a data type. It's like saying the 'Date' header returns a date and the 'Last-Modified-Date' header also returns a date, therefore you can use the headers interchangeably. The value of the above tags returns the same checksum for the static resource as the ETag does. Really? That doesn't sound right. The Vary header does not contain any checksum of any kind. (At least not in the HTTP 1.1 spec). I think ETag's value will only change if the static file's modified date changes according to it's definition here: http://en.wikipedia.org/wiki/HTTP_ETag So why have 2 headers with the same checksum for the same static resource when one would suffice? Unless the checksum is going to be different... which I doubt because it is calculate based on the i-node number , last modified time and size (in Apache though, not sure how Tomcat calculates it.). I'm not really sure what you're talking about, here. It seems clear that the Etag ought to be sent with a 304 response if that same request would have returned an Etag with a 200 response instead. The fact that the Etag shouldn't change isn't the issue... it's the fact that it should be sent in the response regardless of 2xx or 3xx response. - -chris -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.7 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFGT3GC9CaO5/Lv0PARAtlNAJ0VofZyKlWiwoAVDE4f6dse1QxXLACfVRap RdLFVUr9U7HNh1NTeP7iyyM= =jwsf -END PGP SIGNATURE- - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Missing ETag in 304 Header
On 5/19/07, Christopher Schultz [EMAIL PROTECTED] wrote: Rashmi, Rashmi Rubdi wrote: Thank you both for clarifying, I understand what you're saying. [snip] And the definition of ETag : http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.19 mentions entity-tag , which is also the value of a few other caching tags: If-Match If-None-Match Vary Just because each of these headers has an entity-tag as its value does not mean that the server can just pick one and shove an Etag-appropriate value into the header. The entity-tag is just a data type. It's like saying the 'Date' header returns a date and the 'Last-Modified-Date' header also returns a date, therefore you can use the headers interchangeably. Got it. I just wasn't sure if they could be used interchangeably or not, may be not. The value of the above tags returns the same checksum for the static resource as the ETag does. Really? That doesn't sound right. The Vary header does not contain any checksum of any kind. (At least not in the HTTP 1.1 spec). I got confused about the Vary header because over here: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.19 it says: The headers used with entity tags are described in sections 14.24, 14.26 and 14.44. where 14.44 points to the Vary header. So you're right the Vary header does not contain a checksum of any kind. But as mentioned previously If-Match and If-None-Match do contain the checksum that represents entity-tag. I think ETag's value will only change if the static file's modified date changes according to it's definition here: http://en.wikipedia.org/wiki/HTTP_ETag So why have 2 headers with the same checksum for the same static resource when one would suffice? Unless the checksum is going to be different... which I doubt because it is calculate based on the i-node number , last modified time and size (in Apache though, not sure how Tomcat calculates it.). I'm not really sure what you're talking about, here. It seems clear that the Etag ought to be sent with a 304 response if that same request would have returned an Etag with a 200 response instead. As you mentioned it may be a good idea to check with the Dev list or may be we could file a bug. The fact that the Etag shouldn't change isn't the issue... it's the fact that it should be sent in the response regardless of 2xx or 3xx response. Got it. - -chris -Regards Rashmi - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Missing ETag in 304 Header
On 5/19/07, Christopher Schultz [EMAIL PROTECTED] wrote: Len, I recommend you cross-post this (if you haven't already) to the tomcat-dev mailing list to see what they have to say. I will do this, today if I have time. -- Len - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: Missing ETag in 304 Header
Hi, the spec says that a 304 response MUST include header - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request Does Tomcat send an ETag header in a 200 response when it serves static content? If not (and I assume that it doesn't), I read the spec in a sense that it is o.k. for the 304 response not to include an ETag. For static content, last modified information usually is sufficient to decide whether a cache entry is still valid, so what additional should an ETag header deliver in that case? Regards, Matthias -Original Message- From: Rashmi Rubdi [mailto:[EMAIL PROTECTED] Sent: Friday, May 18, 2007 3:10 AM To: Tomcat Users List Subject: Re: Missing ETag in 304 Header On 5/16/07, Joe Mun [EMAIL PROTECTED] wrote: Hi guys... so according to the HTTP 1.1 spec ( http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html), 304 Not Modified responses must include the ETag in the header. However, Tomcat doesn't seem to be adding it... I am serving a static text file, and the header only returns: HTTP/1.x 304 Not Modified Server: Apache-Coyote/1.1 Date: Wed, etc... I examined the header returned by Tomcat 6.0.10 with Firefox's TamperData extension and also by uncommenting Tomcat's RequestDumperValve. You are right that the ETag header doesn't appear. However, I saw another cache related header if-none-match , which also shows a checksum in the same format as ETag , perhaps you may find that header useful. May 17, 2007 9:01:46 PM org.apache.catalina.valves.RequestDumperValve invoke INFO: header=if-none-match=W/6958-1163795820656 I don't really know what causes the ETag to appear, I would expect it to appear by default without any configuration similar to many other HTTP Caching Headers. I did notice the ETag for static files on one website that is hosted on Apache httpd + Tomcat. Is there a reason that the Etag is not being included? Is there a way to configure Tomcat to include this? My company is working with a caching solution provider, and they are complaining about the missing ETag. thanks. Regards Rashmi - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Missing ETag in 304 Header
Tomcat DOES return ETag headers with static resources, and DOES NOT return the ETag with 304 responses. That seems wrong according to the quoted part of the spec. Here are the headers from a couple of Firefox requests for the same file. Note the first response is a 200 with an ETag, the second is a 304 without an ETag. -- http://localhost:8080/tomcat.gif GET /tomcat.gif HTTP/1.1 Host: localhost:8080 User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.11) Gecko/20070312 Firefox/1.5.0.11 Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive Cookie: ShowOptions=1; loadDefault=Folder Pragma: no-cache Cache-Control: no-cache HTTP/1.x 200 OK Server: Apache-Coyote/1.1 Etag: W/1934-1173108368046 Last-Modified: Mon, 05 Mar 2007 15:26:08 GMT Content-Type: image/gif Content-Length: 1934 Date: Fri, 18 May 2007 15:16:46 GMT -- http://localhost:8080/tomcat.gif GET /tomcat.gif HTTP/1.1 Host: localhost:8080 User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.11) Gecko/20070312 Firefox/1.5.0.11 Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive Cookie: ShowOptions=1; loadDefault=Folder If-Modified-Since: Mon, 05 Mar 2007 15:26:08 GMT If-None-Match: W/1934-1173108368046 Cache-Control: max-age=0 HTTP/1.x 304 Not Modified Server: Apache-Coyote/1.1 Date: Fri, 18 May 2007 15:16:46 GMT -- -- Len On 5/18/07, Reich, Matthias [EMAIL PROTECTED] wrote: Hi, the spec says that a 304 response MUST include header - ETag and/or Content-Location, if the header would have been sent in a 200 response to the same request Does Tomcat send an ETag header in a 200 response when it serves static content? If not (and I assume that it doesn't), I read the spec in a sense that it is o.k. for the 304 response not to include an ETag. For static content, last modified information usually is sufficient to decide whether a cache entry is still valid, so what additional should an ETag header deliver in that case? Regards, Matthias -Original Message- From: Rashmi Rubdi [mailto:[EMAIL PROTECTED] Sent: Friday, May 18, 2007 3:10 AM To: Tomcat Users List Subject: Re: Missing ETag in 304 Header On 5/16/07, Joe Mun [EMAIL PROTECTED] wrote: Hi guys... so according to the HTTP 1.1 spec ( http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html), 304 Not Modified responses must include the ETag in the header. However, Tomcat doesn't seem to be adding it... I am serving a static text file, and the header only returns: HTTP/1.x 304 Not Modified Server: Apache-Coyote/1.1 Date: Wed, etc... I examined the header returned by Tomcat 6.0.10 with Firefox's TamperData extension and also by uncommenting Tomcat's RequestDumperValve. You are right that the ETag header doesn't appear. However, I saw another cache related header if-none-match , which also shows a checksum in the same format as ETag , perhaps you may find that header useful. May 17, 2007 9:01:46 PM org.apache.catalina.valves.RequestDumperValve invoke INFO: header=if-none-match=W/6958-1163795820656 I don't really know what causes the ETag to appear, I would expect it to appear by default without any configuration similar to many other HTTP Caching Headers. I did notice the ETag for static files on one website that is hosted on Apache httpd + Tomcat. Is there a reason that the Etag is not being included? Is there a way to configure Tomcat to include this? My company is working with a caching solution provider, and they are complaining about the missing ETag. thanks. Regards Rashmi - 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]
Re: Missing ETag in 304 Header
On 5/16/07, Joe Mun [EMAIL PROTECTED] wrote: Hi guys... so according to the HTTP 1.1 spec ( http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html), 304 Not Modified responses must include the ETag in the header. However, Tomcat doesn't seem to be adding it... I am serving a static text file, and the header only returns: HTTP/1.x 304 Not Modified Server: Apache-Coyote/1.1 Date: Wed, etc... I examined the header returned by Tomcat 6.0.10 with Firefox's TamperData extension and also by uncommenting Tomcat's RequestDumperValve. You are right that the ETag header doesn't appear. However, I saw another cache related header if-none-match , which also shows a checksum in the same format as ETag , perhaps you may find that header useful. May 17, 2007 9:01:46 PM org.apache.catalina.valves.RequestDumperValve invoke INFO: header=if-none-match=W/6958-1163795820656 I don't really know what causes the ETag to appear, I would expect it to appear by default without any configuration similar to many other HTTP Caching Headers. I did notice the ETag for static files on one website that is hosted on Apache httpd + Tomcat. Is there a reason that the Etag is not being included? Is there a way to configure Tomcat to include this? My company is working with a caching solution provider, and they are complaining about the missing ETag. thanks. Regards Rashmi - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Missing ETag in 304 Header
Hi guys... so according to the HTTP 1.1 spec ( http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html), 304 Not Modified responses must include the ETag in the header. However, Tomcat doesn't seem to be adding it... I am serving a static text file, and the header only returns: HTTP/1.x 304 Not Modified Server: Apache-Coyote/1.1 Date: Wed, etc... Is there a reason that the Etag is not being included? Is there a way to configure Tomcat to include this? My company is working with a caching solution provider, and they are complaining about the missing ETag. thanks.
