I wanted to add a live picture rotation to my site and i could not find any other way to do it so i decided that i need a cgi script that will:
1. Delete the first picture in the rotation (e.g. pic1.jpg)
2. Rename the rest of the pictures (e.g. rename pic2.jpg to pic1.jpg, pic3.jpg to pic2.jpg, pic4.jpg to pic3.jpg, etc...)
3. Do this every 5 minutes so that the viewers of my site will all be viewing the same picture pretty much at the sime time.
Any help will be much appreciated,
Thanks.
To make this work "so that the viewers of my site will all be viewing the same picture pretty much at the same time", you need to use different urls for each image or make sure you are telling browsers and proxies not to cache the pictures...and not caching is a really bad idea; your viewers will not appreciate it, nor will your server.
Sounds like a pretty bad idea, frankly. File operations are relatively slow, and tends to step on itself in a highly-concurrent application like a webapp.
Look for another way. How about using the current time as a key to choose among pictures?
currentImageIndex = currentTimeRoundedToTheNearestFiveMinutes %
totalNumberOfImages
Edited with more detail on request:
Basically, take the current time, and round it to the nearest five minutes. Doing something like currentHour / 12, using integer math, will give you this; otherwise, truncate the result. Then use the modulo operator (% in Perl, and many languages - handy operator that newcomers tend to overlook) to produce a number from 0 to n-1, where n is the total number of images you're serving. Then you can refer to a mapping table to go from that index to a filename.
Since you say in a comment that you don't need caching, rather than change the filenames of each file, why not have your page point to a file which is a symlink and then change the pointer of the symlink every few minutes. Seems like it would do what you need without the overhead of major file operations.
Related
I created a simple RME for TTeeGrid, a descendant perhaps of TGrid in Firemonkey. As shown below, the data are displayed at design time but not at runtime except the headers.
I've been breaking my head over this for weeks already but not luck.
Let me know if you need more details but what you see in the image are all you get.
I just need help to have the data displayed at runtime as shown in the design time.
UPDATE 1
This issue is not the case with TPrototypeBindSource. The data shown in the design time are displayed at runtime. Something is wrong somewhere.
I've never used the TeeGrid before, but the following worked fine
first time for me in Delphi Tokyo:
Download the TeeGrid trial from Steema.Com & install.
Create new multi-device app and place a TeeGrid and a FDMemTable on the form.
Load FDMemTable1 with the file Parts.Fds from the Delphi samples Data directory. Note, I did not then create any FieldDefs as I mentioned in my comment earlier as what I'm describing works without them.
Set the DataSource property of TeeGrid1 to FDMemTable1. TeeGrid1 immediately
creates columns for each of the Parts fields and populates them with data - see
screenshot below. I don't ordinarily include screenshots but in this case thought
I would as what I got was so clearly at odds with what you've reported.
Your TeeGrid etc are obviously more complicated than mine. so the best I can
suggest is that you backtrack to step 2 and see if you can replicate my result
with your data (either at design time or run time). It might be worth loading
your FDMemTable with some data at design time, as my impression is that live bindings
is less grief-prone when the datasource has some data.
Incidentally, fwiw the results of my own attempts to set up live bindings even with a regular TGrid have been rather patchy, until I discovered that instead of messing with the LB components myself, simply starting with a fresh TGrid, right-clicking on it and leaving the Live Bindings Wizard
to do its stuff consistently works fine.
IS there a way to add/initate a comment ( e.g. $dom->createComment ... ) such that it comments out an entire block of xml tags. Basically I want to turn-off the content between the comment.
For example, it would look like this:
<TT>
<AA>keep</AA>
<!-- comment to blocking
<BB>hideme1</BB>
<CC>hideme2</CC>
-->
<DD>d's content is good</DD>
</TT>
Actually this question is a pre-cursor to my attempt to figure-out a method to be able to markup/label/identify the changes to an xml files in support of new client software functionality, but be able to have the ability to remove / back-out these xml changes in the rare event the client needs to fall back to the previous software version (and no I can't just simply point back to the original xml file because the client is allowed to make minor modifications to existing node text values). This is all going to be controlled via a perl script and LibXML's core modules (I can't use modules the client doesn't have).
So basically I've identified three possible types of xml changes as a result of new client sw functionality:
1.) ADD new element node(s) (typically to support new sw functionality)
2.) DELETE element node(s), or blocks of (would be rare, but never-the-less a possibility)
3.) CHANGE node text values (rare, but the new sw may require a new value)
For all three types, the client needs the ability to back out the changes. One thing I was thinking to use is ATTRIBUTES since the existing xml files don't use them. For example, for an ADD change type, I could include an atribute like 'ADD="sw version 4.1"' . This way if it needs to be removed, I could just simply have the perl script find those attribute strings and delete them (using LibXML methods). Same thing with CHANGE change type - I could use an attribute like CHG="newvalue_oldvalue", then again use straight perl (or LibXML) to switch back the value based on the contents of the attribute. The DELETE change type is giving me a problem though (as welll as the others lol!). I want to be able to "keep" the deleted lines in the xml file soley for the purposes if the sw falls back a version (at some late point the perl script could eventually cleanup/delete them).
I know this is a lot, I'm new to LibXML (but not to perl). I was just wonder if any of you have any thoughts as to how to go about it or seen anything resembling this kind of request ... I'd be grateful for any kind of advice! Thank you...
I am using Brett's Mr. PHP thumb caching script along with phpThumb to create my thumbs. It works extremely well, except for one thing... I cannot get it to set and process the UnSharpMask filter. The relevant part of the script looks like this:
// generate the thumbnail
require('../phpthumb/phpthumb.class.php');
$phpThumb = new phpThumb();
$phpThumb->setSourceFilename($image);
$phpThumb->setParameter('w',$width);
$phpThumb->setParameter('h',$height);
$phpThumb->setParameter('q','95'); // set the quality to 95%
$phpThumb->setParameter('fltr[]','usm|80|0.5|3'); // <--- THIS SHOULD SET THE USM FILTER
$phpThumb->setParameter('f',substr($thumb,-3,3)); // set the output file format
if (!$phpThumb->GenerateThumbnail()) {
error('cannot generate thumbnail');
}
I'm guessing there's a problem with my syntax, since the fltr[] parameter requires brackets. I have tried escaping the brackets like so: 'fltr[]' but that didn't work either.
I've used several other possible parameters with good success (zoom cropping, max height, max width, etc...) Everything seems to work except the filters (including usm - UnSharpMask).
I don't get any errors. It spits out thumbs all day long. They're just not sharpened.
For reference, here's the official phpThumb readme file that discusses all the possible settings and filters.
Thanks for looking.
Well after much trial, error, and aggravation, I finally discovered the solution buried in one of the demo files that come with phpThumb.
It's a matter of removing the brackets all together. Basically changing this line:
$phpThumb->setParameter('fltr[]','usm|80|0.5|3');
to this:
$phpThumb->setParameter('fltr','usm|80|0.5|3');
After that, it's only a matter of tweaking the settings to get the desired amount of sharpness.
I'm trying to work out the best/most performant/easiest to maintain version for handling many different URLs in restlet.
eg, if I want to have an Item resource, is there a better way to do it than this?
router.attach("/items", ItemResource.class);
router.attach("/item/{itemid}", ItemResource.class);
router.attach("/items/list", ItemResource.ItemListResource.class);
router.attach("/items/weapons", ItemResource.WeaponListResource.class);
router.attach("/items/armours", ItemResource.ArmourListResource.class);
...
(I tried with having /items/{itemid}, but then /items/weapons etc could not be accessed.)
ItemResource then has #Get for fetching a single item, but also has #Put for saving an item when just /items is used. Something feels a bit wrong here... Is there a better way to have fetching/inserting/updating/listing for items in this case?
Also, this router.attach list is very long, 100 or so items. Since this has to be run through on every request it would probably be fairly slow. I know I can attach multiple routers together in a chain - but I can't find documentation on how to do this nicely. What's the best way to chain routers and keep them maintainable?
Just put the
router.attach("/item/{itemid}", ItemResource.class);
on the lowest part of the routing, since it will catch all path parameters, so before it matches everything, rout the typed path first. This should fix it based on my experience.
I have a Perl script I wrote for my own personal use that fetches image files from a website periodically. It then saves these images to a folder. These image files are quite often the same from fetch to fetch, and I'd like to not save duplicates if I can get around it.
My question: What would be the best way to compare/check if they are the same?
My only real thought so far is to open a file handle to existing one, md5 it, md5 the $response->content from the fetch and then compare them. Would that work?
Is there a better way?
EDIT:
Wow, already tons of great suggestions. Does it help if I tell you that this script runs daily via cron? I.e. it is guaranteed to always run at the exact same time everyday? Also: I'm looking at the last-modified headers on some of these, and they don't look 100% accurate, i.e. there are some that have a last-modified of over a week ago when I know the image is more recent than that. I'm assuming that's because the image file itself hasn't been modified on the server since then... which doesn't help me much...
Don't open and hash the stored image each time - stash the hash alongside the image when you store it. Compare sizes as well.
Don't issue a GET request straight away, do a HEAD first and compare the size, last modification date and any Etags to what you got last time.
There are a number of HTTP headers you can use for this -- if you save the time that you last retrieved the file, you can do a conditional get with
If-Modified-Since: <date>
Or, if the server returns an Etag header with the response, you can store that with the image, (or a collection of all of the etags you have seen for that image), and do:
If-None-Match: <all of your etags here>
If the server supports conditional gets, then you will get a "304 Not Modified" response, with no body.
Yep that sounsd right.
Depending on how you're getting the file and how frequently you might also be able to check for HTTP 304 Not Modified and save yourself the download.
md5 would work, but you'd still have to pull the file. Are there any useful metadata in the HTTP headers, content-length, cache-control directives, ETags, etc. ?
There's also a nice fdupes tool for the purpose. Don't know what system you're using and what systems the tool can be built for.