Currently I have serious problems with my webapp, because it has strange behavior behind a web proxy ISA Server 2006. I found the problem was because I was using h:links to call some pages and ISA makes cache from that. I change the h:link to h:commandLink but the cache is the same. Doing debug of the request with firebug I find this:
POST currentPage
GET nextPage
The first is the page where i made click and the second one is the page I want to go. 1. I don't understand why there are 2 request? 2. I dont know why the command is sending a GET request?
Can anybody help me.... ????
Related
I am making a forum using Node, Express, EJS and MongoDB. Currently, I render the forum page and pass data from the database using Node and EJS. I use GET and POST requests. As soon as I add a comment, the page stores in the database and then redirects back to the same route. I am then able to scroll down and see my comment. However I am not happy with this and I want the comments and replies to be handled by Ajax so that as soon as I comment, without refreshing, I create a post request and again without refreshing the page I can load the new comment. Any suggestion on how can I bring this to live?
The project is available to view on https://github.com/Ibrahim40021974/Forum . (Sorry for the untidy code. Am still working on version control). All suggestions are welcomed!
Thanks in Advance.
What you wanna achieve, is generally called a single page application where you won't see the page refresh but the small component of that page is actually got updated with new data.
I have done using Reactjs, Nodejs which is pretty easy to do in Reactjs. If you are interested , I can share the repo.
Had looked into your project and few things I noted.
If I am referring the right one (https://github.com/Ibrahim40021974/Forum/blob/master/views/forum.ejs#L69) then you need to stop default form submit using e.preventDefault(). Default form submit always refresh the page which you don't want. Same form operation you have to do with ajax call.For exm.
handleFormSubmit(e) {
e.preventDefault();
// <add your ajax call here>
}
See once you do this if things work without page refresh.
See if this helps you with how to make ajax call. https://www.thetopsites.net/article/53326172.shtml
As #Ajay kumar said the best way is to create a single page app : framework like react/angular/vue are pretty good when it's about refreshing only part of your page when new data are inserted.
Yet you could do this without using any of this framework but it will be tricky.
You can, in your ejs template add the javascript logic that will, when you submit your comment, do the following :
Send a post request to submit the new comment
Send a get request to get comment affiliated to this post as soon as post request ended
update the DOM(vanillaJs or Jquery) to display the list of comment.
The first choice will ask you to change your project architecture, but will be easier to manage, the second will give you the possibiliy to keep using ejs but is a bit more complicated.
I am trying to scrape a oracle adf faces rich client webpage but I am not getting the best of luck, I login automatically using node.js request module but after that I can't get to any other page with request. I get stuck on redirects, the loop script or simply don't get information I expect to.
I am using Wireshark to view every page and the way it handles, I recreate the page to match headers and even size but everytime the framework denies me access.
Before you ask, it's legal and I am not breaking any terms of service. Just trying to make a web api to speed up a process. I have used phantomjs with casperjs but get stuck on ajax calls that don't show on page and php curl but it's much easier with java.
Any suggestions are really really appreciated.
My bad on this one, wireshark was displaying fields as truncated, if you want to see the full field you need to right click the packet and click follow TCP stream, rich clients have very long posts generated by the framework behind the rich client and it appears I was missing about half of them when I did the calls.
I've recently started using Restangular for making cross domain requests to a RESTful service, and so far everything works great.
But with IE10 when a make a GET request only for the first time it gets data from the Server, and for subsequent calls it does not hit the server, and returns probably cached data. I need to get the data refreshed from the Server. I tried setting defaultHttpFields cache to false, but no luck. Please help!
Thanks,
Lakshmi
I'm the creator of Restangular.
Could you please post an example? If you didn't set the cache to true in defaultHttpfields, Restangular shouldn't cache this at all.
Have you chcked if the requests are going out in the Network tab of the developers console? Does it work in other browsers? Check in restangular Library for RestangularResource to see if it's doing $http call.
Hope it helps!
I just hit this one too. Seems that IE10 is particularly keen on caching results from RESTful calls.
One workaround I used was to just provide some unique value as a parameter to each request and then IE10 seems happy not to cache it. I used the current timestamp in ms since I've seen jQuery use similar workarounds in the past.
var postsApi = Restangular.all("posts");
$scope.allPosts = postsApi.getList({ nocache : new Date().getTime() });
Works for now.
(Using JEE6) Is it possible to have a webpage automatically update (or listen) to values from within a bean/class and display them on the JSF when these changes happen?
As KayKay mentioned you can implement some sort of polling methodology using javascript to ask the server periodically to send updates if there are any. And unless you use ajax you will have to be content with only complete page refreshes.
JSF as good as it is, sits on top of basic stateless web technology. As such unless you use Ajax or some custom code the server will only respond to a request from the client. Some libraries like icefaces have incorporated a "push" component that allows what you are looking for (from what I understand, this is a fundamental part of icefaxes). That is, to push server side changes to the client.
You have to set up a listener on your end so that your bean will be notified when a value change happens on the server (like in your backing bean which is on the server). When the change happens you can ask say, 'icefaces push' (or another library like primefaces, which you indicate you don't want to use) to send a notice to the client. The client side code (usually ajax/javascript) will process the notice and then send a request for the whole object per normal request response. That is the notice tells the client something it's interested in changed so the client can ask for an update. Aside from the notice, still request/response.
I mention icefaces push because it seems to be the favoured library for this now. But others have this as well. I don't believe the standard JSF 2.0 AJAX libraries have this.
Here are a couple of resources to look at:
(The video is a good start to get the idea of what is going on, then use the rest of the site)
http://www.icesoft.org/demos/icepush-demos.jsf
Older but I think still relevant IBM tutorial on what you want to do, using inventory changes as an example:
http://www.ibm.com/developerworks/web/library/wa-aj-dynamic/index.html
And another stack question related:
Is there a better Ajax Push for JSF 2.0 than Icefaces
Unfortunately it looks like you cannot do this with just JSF, you will have to use one of these libraries or even harder, roll your own push mechanism.
I don't know of a JSF feature to do so. I would simply do some javascript polling, using for example jquery load method to refresh the parts of the page where the values are displayed.
It would help to know what you want to do : refresh the whole page when there is a change, update somes values that are displayed from the start, or add new values to the page.
This is a dangerously easy thing I feel I should know more about - but I don't, and can't find much around.
The question is: How exactly does a browser know a web page has changed?
Intuitively I would say that F5 refreshes the cache for a given page, and that cache is used for history navigation only and has an expiration date - which leads me to think the browser never knows if a web page has changed, and it just reloads the page if the cache is gone --- but I am sure this is not always the case.
Any pointers appreciated!
Browsers will usually get this information through HTTP headers sent with the page.
For example, the Last-Modified header tells the browser how old the page is. A browser can send a simple HEAD request to the page to get the last-modified value. If it's newer than what the browser has in cache, then the browser can reload it.
There are a bunch of other headers related to caching as well (like Cache-Control). Check out: http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
Don't guess; read the docs. Here's a friendly, but authoritative introduction to the subject.
Web browsers send HTTP requests, and receive HTTP responses. They then displays the contents of the HTTP responses. Typically the HTTP responses will contain HTML. And many HTML elements may need new requests to receive the various parts of the page. For example each image is typically another HTTP request.
There are HTTP headers that indicate if a page is new or not. For example the last modified date. Web browsers typically use a conditional GET (conditional header field) or a HEAD request to detect the changes. A HEAD request receives only the headers and not the actual resource that is requested.
A conditional GET HTTP request will return a status of 304 Not Modified if there are no changes.
The page can then later change based on:
User input
After user input, changes can happen based on javascript code running without a postback
After user input, a new request to the server and get a whole new (possibly the same) page.
Javascript code can run once a page is already loaded and change things at any time. For example you may have a timer that changes something on the page.
Some pages also contain HTML tags that will scroll or blink or have other behavior.
You're getting along the right track, and as Jonathan mentioned, nothing is better than reading the docs. However, if you only want a bit more information:
There are HTTP response headers that let the server set the cacheability of a page, which falls into your expiration date system. However, one other important construct is the HTTP HEAD request, which essentially retrieves the MIME Type and Content-Length (if available) for a given page. Browsers can use the HEAD request to validate what is in their caches...
There is definitely more info on the subject though, so I would suggest reading the docs...