Re: [WSG] What do browsers download?
As stated, it is very much browser dependant. I use Firefox for daily browsing and I like to load pages in background tabs. I was surprised when I first noticed that switching to a tab Firefox would then fetch CSS images ( unless cached ). If you are really keen on the ordering of http requests by your browser then the best method is to use a local proxy like proximitron. Of course under Firefox you can use the "Live HTTP headers" extension which is awesome. Regards Chris Blown http://hinterlands.com.au On Wed, 2004-06-30 at 22:44, Chris Stratford wrote: > Im not 100% sure... > but here is what I think a browser would download, in what order.. > > 1st it would download the HTML code... > then any Images in the document... > then the DTD... > then the Stylesheets... > then the Stylesheet images... > then 3rd party gear - flash, java, other applets and mods... > > just my guess... > :) > > John Horner wrote: > > >> You mention an ABC internal standard of less than 60kb filesize. How > >> does this work with dynamic pages? > > > > > > There are relatively few dynamic pages on the ABC website, so it > > doesn't often come up, but of course I'd expect things like search > > results to be arranged using some sort of paging, with each page a > > sensible size. > > > >"Have You Validated Your Code?" > > John Horner(+612 / 02) 9333 2110 > > Senior Developer, ABC Online http://www.abc.net.au/ > > > > > > * > > The discussion list for http://webstandardsgroup.org/ > > See http://webstandardsgroup.org/mail/guidelines.cfm > > for some hints on posting to the list & getting help > > * > > > > > > > > * > The discussion list for http://webstandardsgroup.org/ > See http://webstandardsgroup.org/mail/guidelines.cfm > for some hints on posting to the list & getting help > * > > > * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
Re: [WSG] What do browsers download?
John Horner wrote: So, the question is, what does the browser actually do? Three developers, discussing this, came up with different answers. Does it download only the images required for that page, download all images, or does it download the ones needed right away and the others in the background? I read a description somewhere, but I can't remember where. The first thing downloaded is something I haven't seen anyone point out, are headers. * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
Re: [WSG] What do browsers download?
here is what I think a browser would download, in what order.. [snip] The only real problem with that is the phrase "a browser". Different browsers will almost certainly do it differently. Your theory certainly makes sense and maybe someone will do the experiment in more detail. I'd love to do some more tests when I have the time. jh "Have You Validated Your Code?" John Horner(+612 / 02) 9333 2110 Senior Developer, ABC Online http://www.abc.net.au/ * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
Re: [WSG] What do browsers download?
this may sound like a stupid answer but wouldnt it be like an html page of somesort. t94xr http://www.t94xr.net.nz/ * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
Re: [WSG] What do browsers download?
Im not 100% sure... but here is what I think a browser would download, in what order.. 1st it would download the HTML code... then any Images in the document... then the DTD... then the Stylesheets... then the Stylesheet images... then 3rd party gear - flash, java, other applets and mods... just my guess... :) John Horner wrote: You mention an ABC internal standard of less than 60kb filesize. How does this work with dynamic pages? There are relatively few dynamic pages on the ABC website, so it doesn't often come up, but of course I'd expect things like search results to be arranged using some sort of paging, with each page a sensible size. "Have You Validated Your Code?" John Horner(+612 / 02) 9333 2110 Senior Developer, ABC Online http://www.abc.net.au/ * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help * * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
Re: [WSG] What do browsers download?
You mention an ABC internal standard of less than 60kb filesize. How does this work with dynamic pages? There are relatively few dynamic pages on the ABC website, so it doesn't often come up, but of course I'd expect things like search results to be arranged using some sort of paging, with each page a sensible size. "Have You Validated Your Code?" John Horner(+612 / 02) 9333 2110 Senior Developer, ABC Online http://www.abc.net.au/ * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
Re: [WSG] What do browsers download?
John Whenever I've been forced to test IE5 Mac I've found it to be unreasonably slow - the rendering engine is a dud compared to other browsers. I'm sure it was cutting edge 3-5 years ago but not now. Safari is much faster and better but it tends to have a pretty fierce cache (like Opera), as I found when a site update occurred and all Safari users got the new markup with an old stylesheet. Fun. You mention an ABC internal standard of less than 60kb filesize. How does this work with dynamic pages? .. for instance I routinely query a database of 2 to 12 million or so rows, the filesize of the page doesn't really come into it here. I try to keep the script execution time to less than 15 seconds, something I monitor routinely - of course the transfer speed of the pipe between server and user is entirely up to the end user and not my domain. (they may have a 9.6kbps modem - which happened to me about a month ago :shock: ) It's definitely a standards and accessibility related thread - one of the biggest barriers to gaining information online is slow loading time. Cheers James John Horner wrote: In contrast, I've noticed that images called by css files (as div backgrounds) *all* download in IE and Safari on Mac (not sure about IEWin) That's interesting. My research found that only IE on Mac has this problem, that is, it downloads and caches all the images referenced in a stylesheet, even if they're not required for the page currently being viewed. Safari 1.2.2, at least, didn't display this behaviour. This would certainly explain why IE on Mac is sometimes very slow loading pages for no obvious reason. Is this off-topic? I apologise to those who think it is, but surely the idea that "smaller is better" is a standard, even if it's so obvious a standard that it goes without saying. We have an internal standard we try to enforce where pages should be 60Kb or less, and in order to test pages against that standard, I needed a tool, that's the origin of the problem... jh "Have You Validated Your Code?" John Horner(+612 / 02) 9333 2110 Senior Developer, ABC Online http://www.abc.net.au/ * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help * * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
Re: [WSG] What do browsers download?
In contrast, I've noticed that images called by css files (as div backgrounds) *all* download in IE and Safari on Mac (not sure about IEWin) That's interesting. My research found that only IE on Mac has this problem, that is, it downloads and caches all the images referenced in a stylesheet, even if they're not required for the page currently being viewed. Safari 1.2.2, at least, didn't display this behaviour. This would certainly explain why IE on Mac is sometimes very slow loading pages for no obvious reason. Is this off-topic? I apologise to those who think it is, but surely the idea that "smaller is better" is a standard, even if it's so obvious a standard that it goes without saying. We have an internal standard we try to enforce where pages should be 60Kb or less, and in order to test pages against that standard, I needed a tool, that's the origin of the problem... jh "Have You Validated Your Code?" John Horner(+612 / 02) 9333 2110 Senior Developer, ABC Online http://www.abc.net.au/ * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
Re: [WSG] What do browsers download?
On Wednesday, June 30, 2004, at 10:43 AM, Tim Lucas wrote: I know that for Gecko based browsers background images defined in stylesheets (inline or linked) are deferred from loading until they are asked to display themselves. This also helps because many style sheet rules containing images often don't apply to the elements of the current page. In contrast, I've noticed that images called by css files (as div backgrounds) *all* download in IE and Safari on Mac (not sure about IEWin) - which is why I stopped using a single css file for multiple pages with different images. The first-time download wait is horrendous. Zeldman was using images in div backgrounds for his page headers a while back, and his Home page was loading the header graphics for 3 or 4 other pages too... He stopped doing so with his next redesign... The advantage, of course, is that when you navigate to a page for which the image file has already downloaded, it renders instantly - but I equate that with waiting for a Flash download to give instant access to an entire interface. I'd rather see elements downloaded only as they're needed to actually display. I write separate css files for calls for image files and link to them from the html pages as needed. Clumsy, but faster for the visitor... Not sure if this getting OT - I think not, as bandwidth and site speed is one of the aims of Standards? Nick ___ Omnivision. Websight. http://www.omnivision.com.au/ * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
Re: [WSG] What do browsers download?
John Horner spoke the following wise words on 30/06/2004 10:01 AM EST: But these days of course it has to fetch the associated CSS files and add them -- but wait, there's more, as they say, it should also fetch any images called by the style sheet and add them to the total. Which is when the question arose, what is the actual size of a web page? Good question. Each browser has its own strategy -- there are no 'golden rules' when implementing a browser. What this means for us is that you you can really only calculate a webpage's maximum download size, assuming it downloads all referenced elements whether they apply to the the page or not. The HTTP standard says a UA should make a maximum of six simultaeneous requests to a single server, which you would have to take into account if trying to estimate the time. Also don't forget for a single page the elements needing to be loaded can exist on different servers. If you also consider caching between requests then it quickly becomes apparent there's little you can do for accurately estimating download size and times. The best solution, as in most cases, is to actually run some tests. Get your target user's UA set up and capture the http traffic for each UA. You'd also need to record the display of the UA if you wanted to understand the loading of the visual elements. I know that for Gecko based browsers background images defined in stylesheets (inline or linked) are deferred from loading until they are asked to display themselves. This also helps because many style sheet rules containing images often don't apply to the elements of the current page. -- tim lucas http://www.toolmantim.com * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
[WSG] What do browsers download?
I thought the list might be interested in some research I recently did. First of all, I was creating a web page size checker in Perl. This fetches the page, then any associated images, and adds the size of them. So far, so HTML 3.2. But these days of course it has to fetch the associated CSS files and add them -- but wait, there's more, as they say, it should also fetch any images called by the style sheet and add them to the total. Which is when the question arose, what is the actual size of a web page? If I have three pages, each with a different background image, but sharing a common style sheet, that means my script will count all three images as part of the total, because at the moment, I haven't been able to parse the CSS and count only the images *used* on the page, I just total up the size of all images. So, the question is, what does the browser actually do? Three developers, discussing this, came up with different answers. Does it download only the images required for that page, download all images, or does it download the ones needed right away and the others in the background? As I say, I've done some research on this, and I'll let you know what I found out in a second email a bit later, but I thought I'd raise the question for your interest/discussion first. "Have You Validated Your Code?" John Horner(+612 / 02) 9333 2110 Senior Developer, ABC Online http://www.abc.net.au/ * The discussion list for http://webstandardsgroup.org/ See http://webstandardsgroup.org/mail/guidelines.cfm for some hints on posting to the list & getting help *
