I just want to know what is the difference between sending parameter with ajax(post/get) to a servlet and sending them with "submit" .
Thanks for your help.
A standard form submit sends a new HTTP request (POST or GET) and loads the new page in the browser. In Ajax, the data is sent to the server (POST or GET) in the background, without affecting the page at all, and the response is then received by javascript in the background, again without affecting the page at all.
(The javascript can, of course, then use the data received from the server to update some of the page content.)
Ajax is generally useful where only a small section of the page content will change.
At the simplest, with ajax, you don't witness page refresh while submitting form data. And if you don't use it eg you use submit buttons, you witness page refresh. Both submit the data.
Server side handling of both are exactly the same. The server is not concerned about how the post request is made.
The difference is in how the browser (client side) responds to both the actions. The browser usually decides to make a request for an entire page if it is a form submit; otherwise, it just updates a part of the page.
From the servlet's point of view there is no difference. For the client, a submit will load a new page, while an Ajax request will parse the response with javascript code and act accordingly.
The form submit will reload the page that you are working on client side.,while in ajax call the call was made to server will not reload your client side page
Related
I just started studying Ajax and I totally have not idea what AJAX is. What is the difference between asynchronous and synchronous request? I would like to seek a very simple example demonstrating their differences.
AJAX short for Asynchronous JavaScript And XML is a programming language. It typically involves sending HTTP requests from client to server and processing the server's response, without reloading the entire page. This process is asynchronous. Comparing to synchronous request which blocks the client until operation completes, asynchronous HTTP is more efficient and user-friendly.
Take very simple example, when you are signing up on a commercial website, you can know whether your username is available or not once you finish typing the name. If the username was used already, the website will give you a reminder that your username is used on the same web page. This is the application of AJAX, so you don't need to complete the whole form and click the submit button to know that your username is not available.
AJAX uses two components for request process and display:
A browser built-in XMLHttpRequest object (to request data from a web server)
JavaScript and HTML DOM (to display or use the data)
It begins with an event occurs in a web page, such as a button is clicked. Then an XMLHttpRequest object is created by JavaScript, followed by sending a request to a web server. Once the web server receives the request, it will process it and send a response back to the web page. Then the webpage utilizes JavaScript to perform update of the web page without reloading the whole page.
AJAX stands for Asynchronous JavaScript And XML
Ajax main purpose is the loading data from the server without refreshing the web page
It's works in the background thread without interrupting UI thread
AJAX allows web pages to be updated asynchronously by exchanging data with a web server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.
A browser built-in XMLHttpRequest object which is used to request data from a web server
Example
when you are filling any kind of online form that time observe one thing there is option for country,state,district.
In this country drop down initially filled with data but state and district's are empty.
when you select a country like India then Asynchronous call goes to server and fetch the data of state drop down respective to selected country and so on.
when AJAX request fetching the data for the state drop down you are eligible to work with other parts of the form.
I'm trying to scrape a website created with the ICEfaces web framework via a node.js script. I've managed to handle the login just fine, and then get some data from the main page (namely ice.session and ice.view, along with the JSESSIONID cookie returned by the login response).
The problem I've run into is when I try to do an AJAX POST request to the /block/ URLs. If I do the request by itself, it returns some data (just not the data I need), but if I do it after any other request, I get <session-expired/> as a result. It doesn't even matter which of the ICEfaces /block/ URLs I send the request to (I've tried with /send-receive-updates, /dispose-views, and even /ping). I've even tried the same request twice in a row just for kicks, and I always get a <session-expired/> response in return on the second one. I've monitored the requests when I browse the page with Chrome, and as far as I know I'm sending all the correct form data (as well as the correct headers). The page works just fine when I load it in the browser, so there must be something I'm not doing right.
Apparently, the order in which you do the requests matters in ICEfaces (i.e. it's not stateless, which kind of makes sense I guess). I just moved the requests around and finally got the response I desired.
IceWindow, IceView and ViewState
Need to be passed as a parameter whenever you do an ajax submit.
Managed bean takes the previous instance of the current view view using ViewState value.
Say I have a web page, and it has a websocket chat running on it. Now, my plan is, when the user clicks on any of the links of the page, the page is not refreshed. Instead, I send the request to the websocket (the same one on which the chat is running), and it returns the new page.
So, is this a good idea? Or should I go for Ajax?
Ajax would be easier. You don't need branching inside the chat websocket listener this way, just request the needed page and put the response into the page body.
I would like to integrate some Ajax techniques into an existing struts application.
How do I send the requested data back server side to the client without causing the page to reload?
If you called the server side with Ajax, the page will not reload. You don't have to do anything special on the server side. Although, obviously, you should do your Ajax request to a different page made for that purpose, not to the same page.
Is there a way that a MVC Action, initiated by an AJAX request, can redirect the response directly to another page/View without sending a JavaScript “window.location=…” to the client first? In other words, directly transferring the response on the server side and avoiding the roundtrip to the client.
This is a more general question about the possibility to transfer directly an AJAX call, but here is a more specific scenario:
The browser sends an AJAX request to the server and based on the request data the controller's logic performs some operations.
For the majority of the cases, the controller needs to return back a result (JSON) to the same page. However, for few cases it needs to redirect to another page and it returns back a script to redirect the page, but this causes another roundtrip to the browser. The flow is: Page – Server – Page – Server – New Page, and the question is if this can be optimized to Page – Server – New Page .
This isn't really possible, no.
The browser has two options to choose between:
Go to a page
Make an AJAX call to a page
It can't make an AJAX call and automatically redirect based on what the server decides because the client (browser) doesn't know what the server has decided on before the response is even received by the browser.
The traditional approach (which you're avoiding) is:
The browser makes an asynchronous request to the server
The server responds with data informing the client to redirect
The client makes a new request to the server via window.location
The server responds with the new page
However you want to skip a step by doing:
The browser makes an asynchronous request to the server
The client makes a new request to the server via window.location
The server responds with the new page
But the client doesn't know that it needs to redirect and/or it doesn't know how to.
One (ugly) possibility
One idea that comes to mind to pseudo-achieve what you want is to have MVC render the required view and send the whole thing back to the client via JSON rather than a redirection approach. Let me explain.
The browser makes an asynchronous request to the server
The server determines which page needs to be displayed and renders the view (Generating a view without a controller in MVC)
The server serialises the resulting HTML as JSON
The client receives the JSON, and re-renders the entire page with the new markup (i.e. completely replace)
You can also alter the URL and history of the browser to make it "feel" like a redirect by manipulating the browser history.
However I would like to point out that this "solution" is more of an amusing/interesting approach. This isn't really a good way to go about the problem.