Is it possible to go back in a page without reloading it?
I am developing a Web Forms website and every time a go back in history, the page reloads (and takes a long time).
Following is the curl of the page:
Honestly, no.
The life cycle of a Web Form is very specific and the page goes through it every time it is run (that is every time you request it through your browser).
On the other hand, you can always optimize your page to make it load faster. How you do it depends on many things one of which is what code runs on the server side upon loading and if any portions of that code can be either optimized for speed or moved in event handlers to be executed at a later point in time. For example, if you're fetching data from a database when your page loads consider applying paging to narrow the number of selected rows.
Please, feel free to ask a new question if you decide to take that course of action.
Related
I have a Django server. The server loads a webpage with almost all static content but a few numbers must load from the database.
I'm thinking about performance/price; I can host my Django server on a fast server and render the page using Django templates. or I can host the server on a slower machine and make a static page that loads the few numbers using ajax and host the page cheaply somewhere else like github.io.
The latter choice will have most of the page load real quick and real cheap.
I was wondering what are the trade-offs ?
Whichever server you decide to hire, you should always think of reducing the server load - no matter how fast your server is. By reducing server load I mean only make your server do what is really required at the moment.
Let's learn something from the big players like Facebook, for instance
You log into your account and you see that you've got 5 notifications and 3 new messages plus a couple of photos and highly interesting statuses of your friends. Cool! You now click on the notifications icon to find out if that hot girl (forgive me if you're a girl :D) has added you to her friends list or not. As you click a big white <div> pops up AND you see nothing but a loading gif! The notifications do appear, but after a couple of seconds. Try doing it with a slow internet connection, and you get to adore the beauty of the loading gif for a lot more time.
So, what do you make of it?
Facebook only made it's server count the number of notifications and new messages, and displayed those numbers to you. Thus reducing server load. It only displayed the notifications to you when you wanted to see them. And to load the notifications, all it took was a minimal AJAX call in which only around 10 KB of data was transferred!
Facebook does it all the time and everywhere. Consider this: Robert Downey Jr. posts a photo of himself on his Facebook page. A little while later, you see that it has got 10k+ comments. You decide to read them and click the comments button. An attractive loading gif pops up again for a little while and is soon replaced by comments. But hey, only 10 comments were loaded. What the ... Oh wait! That's how Facebook reduces its server load - read those 10 comments first, if you want to read more, send a request again.
Twitter does it too - the infinite scroll.
Icing on the cake
This approach benefits you in two ways:
It reduces server load - less chances of crashing a website.
It decreases your website's page-load time since you'll be passing less data i.e. the data required at that moment. Thus making your website faster. (Yes, it can outrun Flash, too!)
Food for thought
If you've got some cool technologies around such as AJAX, why not use it? Your server is not a donkey, for God's sake!
P.S. By Facebook and Twitter, I mean the engineers behind them.
Well It would depend on the following:
A. Whether you want to Display that number on Page load itself or when user clicks to see it* ?
If you want to show the the numbers at the time of Page load Itself than it is preferable to get them at time of Template response itself.
Why do you would want your Site Visitors to wait till those numbers populate (if the intention is to display them) ?
If it is to be displayed on User's click only then Ajax should be preferred
B. How much Time is this Query going to take and Can the query be optimized to minimal time ?
If the Query you are making takes a Lot of time than first effort should be made to optimize that query to be as fast as possible,
If the query can give result in minimal time than it is futile to do another Request to Server via Ajax.
But if you know the Query will take a lot of Time than Ajax is fine.
I have a site developed in codeigniter.
In the page search I have a form that when I compile It I send a request to a servere with CURL and return me an xml.
This query and the print date is about 15seconds because I have to make more query with many server and this time is necessary.
But the problem is: I have a list of element, when I click on an element I make a query to retrieve the data of the element.
But if I click back or click to go back to all element searched I don't want to make an other query that takes 15second.
When I search the element I have a get request and I have a link like this:
http://myurl/backend/hotel/hotel_list?nation=94&city=1007&check-in=12%2FApr%2F2013&check-out=13%2FApr%2F2013&n_single_rooms=1&n_double_rooms=0&n_triple_rooms=0&n_extra_beds=0
I load the page and I can have more elements. i click on some of this in a simple link like this:
http://myurl/backend/hotel/hotel_view?id_service=tra_0_YYW
When I enter into this page I have to go back to the previous url (the first) without remake the query that takes more seconds.
I can't cache the result because is a realtime database and change every minutes or second but I thinked to cache the page search when I enter on it and if i go back to it reload from cache if the time is minor than 2 minutes for example.
Is this a good way or there is a more perfmormant way to do this in codeigniter?
I can't put in session because there is large data.
The other solution are:
- cache page (but every minutes I have to delete it)
- cache result (but every minutes I have to delete it)
- create sessionflashdata (but I have a large amount of data)
is there a way with the browser when I go back to don't remake the page?
Thanks
cache page (but every minutes I have to delete it)
I think you can easily implement it with codeigniter's page caching function "$this->output->cache(1);"
cache result (but every minutes I have to delete it)
You will have to use codeigniter's object caching method to implement it.
create sessionflashdata (but I have a large amount of data)
Its not a good idea to save huge data in session. Rather use 'database session' instead, which will help you handling similar way and codeigniter has its integrated support.
Hope this helps. You can read more about all kind of codeigniter caching if you are just starting with it.
I need to measure load time on a page navigation. Here is my situation:
When I navigate, the page laod is taking variable time as the ajax elements load. How to be certain that the page is fully loaded to measure its load time correctly?
I cannot be specific that locating a particular element(text, table, or image...) indicate the complete page load as page load depends on data.
Please help me deal with this situation.
Thanks
Do you want to be able to test this on an "as needed" basis or do you want to instrument the pages so that you gather data from all your users?
If you just need to do it on an ad-hoc basis then http://webpagetest.org will help you - providing there's not too long a gap between the AJAX requests it will include them.
If you want to look gather data across all AJAX calls then you will need to instrument the success and failure callbacks to store the time they finish and calculate the difference between the last one and the page start. Then once you've got this push the value to Google Analytics or something else.
If all your AJAX calls are designed to complete before onload fires then the existing SiteSpeed numbers in Google Analytics might be good enough for you.
I'm using AbstractAjaxWicketBehavior in my Wicket application and it seems to have a descending performance over time when more AJAX calls appear. When a page is refreshed without AJAX, the performance is fine again. I would like to know if this is a normal thing or can be a memory leak of some kind present? I can't simply attach the code as it's spread over more classes and it would require too much effort to understand, but in short I want to do this:
create and start the timer
repeat some code 10x
stop the timer
set some values to attributes
ajax refresh (causes show/hide of some components)
and do the same again (hypotetically infinite times).
Every repetition of this flow is slower even though I use constant updating interval of 100ms.
As the timer is a behavior and does not allow to be restarted or reused, it is created every time as a new instance and attached to the Form component.
The timer looks like this:
static int count = 0
new AbstractAjaxTimerBehavior(Duration.milliseconds(100)) {
// do some code
count++
if(count == 10) {
stop();
// do some code
}
}
This behavior is attached to a Form inside a Panel and upon a click on an AjaxLink the Form is refreshed (added to AjaxRequestTarget). Every time I remove the old timer from the Form component before adding the new behavior.
Everything works fine, but every repetition of this procedure runs slower (The first one is perfect, the second one is also around 100ms, but then it gets slower (after 10 or 15 repetitions, the refresh interval is about 1 second) and all other AJAX calls in the app also go significantly slower), so I suspect there is a memory leak... any obvious reasons? Or any ways how to make a wicket timer better for my purpose? Any advice appreciated. Thanks.
Our wicket applications also tend to get slower with every AJAX-Request. I'm not sure if this is the exact same problem or if it relates to the AjaxTimerBehavior in particular, but:
We found that one reason for this are pseudo leaks in the browser that occur due to HTML replacement. Obviously the nrowser cannot free memory until the page is reloaded.
You can monitor Browser Memory with the Task manager (or another Tool) and watch Memory raise with every AJAX-request and how it reliefs on a full page reload (F5). Especially in IE.
We replace alot of HTML with our AJAX-requests though.
I run a Symfony 1.4 project with very large amount of data. The main page and category pages are using pagers which need to know how much rows are available. I'm passing a query which contains joins to the pager which leads to a loading-time of 1 minute on these pages.
I configured cache.yml for the respective actions. But I think the workaround is insufficient and here are my assumptions:
Symfony rebuilds the cache within a single request which is made by a user. Let's call this user "cache-victim" to simplify things.
In our case, the data needs to be up-to-update - a lifetime of 10 minutes would be sufficient. Obviously, the cache won't be rebuilt, if no user is willing to be the "cache-victim" and therefore just cancels the request. Are these assumptions correct?
So, I came up with this idea:
Symfony should fake the http-request after rebuilding the cache. The new cache-entries should be written on a temporary file/directory and should be swapped with the previous cache-entries, as soon as cache rebuilding has finished.
Is this possible?
In my opinion, this is similar to the concept of double buffering.
Wouldn't it be silly, if there was a single "gpu-victim" in a multiplayer game who sees the screen building up line by line? (This is a lop-sided comparison, I know ... ;) )
Edit
There is no "cache-victim" - Every 10 minutes page reloading takes 1 minute for every user.
I think your problem is due to some missing or wrong indexes. I've a sf1.4 project for a large soccer site (i.e. 2M pages/day) and pagers aren't going so slow even if our database has more than 1M rows these days. Take a look at your query with EXPLAIN and check where it is going bad...
Sorry for necromancing (is there a badge for that?).
By configuring cache.yml you are just caching the view layer of your app (that is, css, js and html) for REQUESTS WITHOUT PARAMETERS. Navigating the pager obviously has a ?page=X on the GET request.
Taken from symfony 1.4 config.yml documentation:
An incoming request with GET parameters in the query string or submitted with the POST, PUT, or DELETE method will never be cached by symfony, regardless of the configuration. http://www.symfony-project.org/reference/1_4/en/09-Cache
What might help you is to cache the database results, but its a painful process on symfony/doctrine. Refer to:
http://www.symfony-project.org/more-with-symfony/1_4/en/08-Advanced-Doctrine-Usage#chapter_08_using_doctrine_result_caching
Edit:
This might help you as well:
http://www.zalas.eu/symfony-meets-apc-alternative-php-cache