Of course we can do this, but is it alright to do so? Are there any downsides of this approach?
What do you mean by session data? What programming language on the server (if you are referring to session data on the server)?
If you are using PHP, then you'll need to just call a PHP file with AJAX and delete using unset() (such as unset($_SESSION['user_id']) what ever you need to. I see this as just as risky as doing it with a normal request.
There's no reason you can't do this. The only concern would be that you'd need to handle any page state changes (like removing the 'account' links, etc).
Related
From my understanding, AJAX requires the use of the XMLHttpRequest object. What I am confused on is the source of where the XMLHttpRequest object is connected to? In the school projects, I have connected it to XML and mySQL and was told that I am doing AJAX. What if I connect the XMLHttpRequest object to a PHP script which contains an array of data? Would that count as AJAX?
The reason why I ask is because I was thinking of adding AJAX to my resume, but since this area seems so broad and I have had limited experience with it, I want to make sure I have a clear understanding of this technology.
The AJAX part is just how the request is made from the client. If it happens asynchronously using XmlHttpRequest, it doesn't matter where the request is going :-) It could be a request to an server side script in PHP, a JSON file, an xml file, or anything else.
It's not broad at all. Any time you do an async web request (actually, it doesn't even have to be async, but that's really the best way to to use it) via javascript (rather than through a Form submit) you're using AJAX. What you connect to or what you retrieve is irrelevant.
Without being rude, I'd like to point out that if you state on a resume that you possess "a clear understanding of this technology" then you're not being honest, since you're asking this question, which indicates that your understanding of the technology isn't "clear".
If, however, you're totally confortable with the use of Ajax and were simply not entirely clear on it's lexical definition... well... now you should be.
yes ,the ajax can used for all language,soever java or asp and php
So I have a framework we've built on codeigniter. It uses regular codeigniter sessions by default which allows up to 4kb storage encrypted on a cookie.
Its for general apps that require a registration process, which can vary in size as questions are generated dynamically through an admin panel. Registration process relies on session data as it redirects throughout process.
I have used db_sessions in the past when I knew this would be an issue on the framework, however, I'm now considering the possibility to always have registration process using db_session and the rest of the site use the 4kb cookie session.
Is this possible. It seems like it could be a really bad idea, but I don't really want to rework the dynamic registration process or really use db_session for whole site as it will eventually make the site run very slow if too many users are online at once.
so I'm think I can just set the variable in config to be true only when the registration controller is loaded(by checking the url via $_SERVER or the uri helper if I can load it in the config which I'm guessing I cant).
Does this seem plausible?
It seems like it could be a really bad idea
You answered your own question :) You'll have issues when the user switches from one page to another. What happens if they open multiple windows, press a 'back' button etc. You'll need to switch the cookie over when they start registration, and switch it back at the end. It will be very very messy for basically no gain.
but I don't really want to rework the dynamic registration process or
really use db_session for whole site as it will eventually make the
site run very slow if too many users are online at once.
The reality is; your website has to be huge to have ANY real performance issues by using a DB for your sessions. Any if you are not using the DB, then you are relying on the cookie stored on the users computer. Depending on your site, this means they might have the ability to edit that cookie and change "admin = true" or something.
Just use the DB session - I think you are overcomplicating the situation.
If I have Ajax code on my website:
1) Is it still necessary to check if a user's browser supports Ajax? Don't they all?
2) if so, is there an non-ActiveX approach to check this? I'd really like to avoid ActiveX as some security filters could flag it as potential malware.
It's not a question of if browsers support 'ajax', this is just a pithy term used to describe the process of a client retreiving data from a server via Javascript, typically asynchronously, and typically using the XMLHttpRequest object.
This object is not defined by IE 5-6, so you have to write code to compensate, or use a library such as jQuery which encapsulates this.
So, what you should be asking is whether your site gracefully degrades if Javascript is not available on the client. i.e. can users still get to the content without Javascript?
I'm still pretty new to AJAX and javascript, but I'm getting there slowly.
I have a web-based application that relies heavily on mySQL and there are individual user accounts that are accessed and the UI is populated with user specific data.
I'm working on getting rid of a tabbed navigation bar that currently loads new pages because all that changes from page to page is information within one box.
The thing is that box needs to reload info from the database, etc.
I have had great help from users here showing that I need to call the database within the php page that ajax is calling.
OK-so pardon the lengthy intro-what I'm wondering is are there any specific limitations to what ajax can call that I need to know about? IE: someone mentioned that it's best not to call script files and that I should remove scripts from the php page that is being called and keep those in the 'parent' page. Any other things like this I need to keep in mind?
To clarify: I'm not looking to discuss the merits/drawbacks of the technology. I'm wondering about specific coding implementation that I need to be aware of (for example-I didn't until yesterday realize that if even if I had established a mySQL connection on the page, that I would need to re establish that connection in my called page as well...makes perfect sense now).
XMLHttpRequest which powers ajax has a number of limitations. I recommend brushing up on the same origin policy. This is a pivotal rule because it limits where AJAX calls can be made.
First, you can't have Javascript embedded in the HTTP response to an AJAX call. That's a security issue.
No mention of the dynamics of the database, but if the data to be displayed in tabs doesn't have to be real-time, why not cache it server-side?
I find that like any other protocol, Ajax works best in tightly controlled conditions. It wouldn't make much sense for updating nearly the whole page, unless you find that the user experience is improved with an on-page 'loader'. Without going into workarounds, disadvantages will include losing the browser back button / history, issues such as the one your friend mentioned, and also embedded resources and other rich content can suffer as well, and just having an extra layer of complexity to deal with in your app. Don't treat it as magic sauce for your app - make sure every use delivers specific results that benefit your client / audience.
IMHO, it's best to put your client side javascript in a separate page and then import it - neater container. one thing I've faced before is how to call xml back which contains code to run such as more javascript - it's worth checking if this is likely earlier on and avoiding, than having to look at evals.
Mildly interesting.
From http://en.wikipedia.org/wiki/AJAX, I get a fairly good grasp of what AJAX is. However, it looks like in order to learn it, I'd have to delve into multiple technologies at the same time to get any benefit out of it. So two questions:
What are resources that can help me understand/use AJAX?
What sort of website would benefit from AJAX?
If you aren't interested in the nitty gritty, you could use a higher-level library like JQuery or Prototype to create the underlying Javascript for you. The main benefit is a vastly more responsive user interface for web-based applications.
There are many libraries out there that can help you get benefit out of AJAX without learning about implementing callbacks, etc.
Are you using .NET? Look at http://ajax.asp.net. If you're not, then take a look at tools like qcodo for PHP, and learn about prototype.js, jquery, etc.
As far as websites that would benefit: Every web application ever. :) Anything you interact with by exchanging information, not just by clicking a link and reading an article.
Every website can benefit from AJAX, but in my opinion the biggest benefit to AJAX comes in data entry sections - forms basically. I have done entire sites where the front end - the part the user sees had almost no AJAX functionality in it. All the AJAX stuff was in the administration control panel for assisting in (correct!) data entry.
There is nothing worse than submitting a form and getting back an error, using AJAX you can pretty much prevent this for everything but file uploads.
I find it easiest to just stay away from all the frameworks and other helpers and just do basic Javascript. This not only lets you understand what's going on under the covers, it also lets you do it in the simplest way possible. There's really not much to it. User the JS XML DOM objects to create an xml document client side. Sent it to the server with XMLHTTPRequest, and then process the result, again using the JS XML DOM objects. Start with something simple. Just try sending one piece of information to the server, and getting a small piece of information back.
The Mozilla documentation is good. Sites that benefit from it the most are ones that behave almost like a desktop application and need high interactivity. You can usually improve usability on almost any site by using it, however.
Ajax should be thought of as a means to alter some content on a page without reloading the entire page.
So when do you need to do this? Really only when you have some user interactions or form information that you want to keep intact while you change some content on the page.