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Subject: Re: Sometimes map images do not display? (m)
Posted by HMG in Mass on December 6, 2002 at 1:33 PM:

In Reply to: Re: Sometimes map images do not display? (m) posted by JT from MD on December 6, 2002 at 9:30 AM:

First allow me to say, that I have not seen the code that generates WG Hit by State Maps. And secondly, if I had seen the code, I probably would not understand it. *laugh* The best that I can do is guess *smile* and suggest work arounds. I don't know why it does not work sometimes? Oh, by the way, I don't know too much about HTML and browsers. I am more versed in 4GL programming for relational databases, NT Network Administration, and PC support and repair.

However, I think you are headed in the correct direction concerning the browser cache.

Previously, what I should have said is: the problem may reside in the browser (or browser – WG database interface) with the person generating the map (not everyone trying to view their profile). If a bad URL is generated (or image is not correctly saved at the URL location) and the user does not hit the browser refresh button, they will view a previous good copy left in their cache.

Perhaps hitting the browser refresh button is a two way street. Not only does it move the image from the URL storage location at WG to our browser (viewing a profile), but it also moves the newly generated map from our browser (Your Bills map generator) to the URL storage location at WG.

An inconsistency which points me to the browser (or the browser – database interface) is: Say you have generated a map. Then you go and change some values: i.e. cutoff values and/or colors. The Legend gets updated correctly down the bottom under the image. However, the map does not change at all. It should. You must hit the browser refresh button to push your newest changes to the URL storage location. Maybe, it's a bug? But hitting the browser refresh button works. *smile* And on the other side, when trying to view the newly updated map on the profile, again you need to hit the browser refresh button to move the image from the WG URL storage to your browser.

Oh, and I state the obvious (not for you – but perhaps for others who may read this in the future). Once the map is generated, if I change the values or regenerate the map many times, the URL never changes. Thus, after the first time the URL is pasted in their profile, it is not necessary to paste it again. If the user re-locates the image in their profile, the risk is that the URL might inadvertently get changed (this may explain why the image could have disappeared). Then the user would have to copy the URL and paste again into their profile. *smile*

Maybe the generated map on the 'Your Bills' Hits by State – Map is only loaded in browser cache. However, due the current code, a browser refresh is required to move the generated Map URL to the storage location at: http://www.wheresgeorge.net/hitmaps

Ohhhh…. As I type this, here's a thought…. Perhaps a URL is created, but is never stored at WG. Perhaps, the first time a user generates a map, they copy the URL and paste it in their profile, without hitting the browser refresh button. If we follow my logic, they need to hit the browser refresh button to save the URL to WG storage. They see a map image on the 'Your Bills' page. They insert the URL and see it on their profile (they are seeing the cached image). Now, they close their browser. Later they come back and view the profile… "Hey, where's my map?" Well, there is nothing in cache and the image was not stored on WG (because there was no original browser refresh). Because we did not have the map loaded in our Cache and the map was not stored at URL location at WG, we are pointed to URL with no image stored, thus no image is displayed to us.

Then some kind soul (you) suggests that the user regenerate the map and NOW hit the browser button, and viola… it is now saved. And because it is now created and SAVED, the user will NOT be able to duplicate it. Perhaps, it even happened to me… It's been too long ago for me to remember. So, it's up you to monitor the next newbie's attempt at making a map (or you could create another WG, send in a FOG payment, and test it for yourself *laugh*).

I don't know why a browser refresh, clearing the cache, or shutting down your browser and coming back in (essentially a browser clear cache) works, but it does.

Funny thing – usually one needs to hit the WG button to refresh WG data. In this case, one needs to hit the browser refresh button to update the map, huh?

I'm not saying it is coded correctly or not. Perhaps, the image should be correctly displayed and saved without having to hit the browser refresh button. I don't know if Bruce will even investigate. I just know that browser refresh work around seems to work for me without fail. *smile* So, I will remind newbies of this in the future.

As I researched this subject, I noticed something odd. I have images of map in three places on my profile.

Profile at WG: http://www.wheresgeorge.com/user_profile_popup.php3?ukey=WGs6sacxF9L/w
http://www.wheresgeorge.net/hitmaps/hit_map_8c5602c2b9e5b4bb4f478e1be65c2b17.png?md=605ac13117bae148bd010f610833baad

WG Bill Notes: http://hansmguy.com/wg/wg_notes.htm
http://www.wheresgeorge.net/hitmaps/hit_map_8c5602c2b9e5b4bb4f478e1be65c2b17.png?

HMG Hits by State Map: http://hansmguy.com/wg/wg_hans_map.htm
http://www.wheresgeorge.net/hitmaps/hit_map_8c5602c2b9e5b4bb4f478e1be65c2b17.png?md=605ac13117bae148bd010f610833baad


It appears that you don't need any text following the '.png'" Intersesting. Apparently the string 'md=605ac13117bae148bd010f610833baad' that follows the 'png? is a parameter to the '.png' function (whatever that is?). I have since changed my profile to include the entire string.

Thanks for the engaging in this dialogue. I think I think toooo much. *smile*

Hans,

: : It probably does happen. If it has happened to me, I do not remember. With the limited supplied information, I would guess that it is a browser burp or a problem with my pc (usually memory related – and I have 896 MB of RAM in this baby – older processor: Pentium III 700 Mhz).

: : When I experience weird things, I do the following:
: : 1) WG 'Your Bills' refresh (if applicable to that screen)
: : 2) Browser refresh
: : 3) Close out of all Browsers, then open and try again
: : 4) Close all applications, shut down computer, wait 30 seconds to clear RAM, re-boot and re-try.
: : 5) If none of the above work, then I cry to and explain the steps taken to Hank. *laugh*


: When it happens, *nobody* can see the map. I can't believe that it is happening to everybody's browser and everybody's computer at the same time. Sorry, I can't buy that answer :-) The only thing that makes it comes back is to go to the map page and re-generate it. And then you have to be sure that you download a new copy as opposed to looking at one from the cache which will still be screwed up. As Elizabeth mentioned, she saw the map in her Profile. When I went to look at it there was no map. Then when she went back to look at it again, it was gone. It then eventually re-appeared after she re-generated it. I've gone though the same process with 2 or 3 other users in the last 6 months. I **think** AnnaKY was another one before that. If I see the problem again, or if my map will just do it, I will ask the user to email you the URL instead of re-generating the map. The problem is that they are naturally impatient to get the map into their profile.


:
: : : When I paste the URL into my Address/Location box I get a message that "the image cannot be displayed because it contains errors", or some such words.

: : Which Address/Location box?
: : 1) The browser URL window at the top (in a new browser window)? I use MS IE v 6.0. You are not talking about the field 'picture source' in a profile, correct?


: I do mean the one at the top of the page. IE calls it "Address". NS 4.x calls it "Location". NS 7.0 doesn't give it a name, just the box.


:
: : As I had mentioned in the previous post:
: : "Select Address URL (makes sure you move down and select the entire URL, even the portion that is not initially displayed in the URL window)".

: : I remember not copying the complete 'picture source' in the past, which gave me an error. I had to go back… select, drag down, and copy the entire URL to be pasted.


: The message does not appear to typical of an incomplete or incorrect URL. In that case the messages I've seen imply that the page cannot be "found". This wording is different. This wording (in NS 4. and 7. anyway) implies that the image was found, just that that it could not be displayed because of errors.


: : I doubt if any of this helps, sorry. *smile* Keep us updated?

: : Thanks,
: : Hans,





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