I Have a requirement like below :
Get invoked a particular action repeatedly without user interaction.For example, I have a message status page which displayed JMS message status.Message status can be changed by a number of application components.What I wanted is, my status UI has to pick latest message status.I need the action which displays status UI to be called repeatedly in an interval of 5 seconds or so, so that UI will get displayed with latest status.
How can I achieve this in spring.Is it something,Polling an action?
Any help highly appreciated
The easiest thing to do is to ask the server every few seconds using JavaScript and AJAX (pseudo-code using jquery):
function askServerForStatus() {
$.getJSON('/your-app/jms-status', function(response) {
$('#status').text(response.status);
}
}
setInterval(askServerForStatus, 5000); //every 5 seconds
Very simple example, it asks Spring MVC controllers mapped to /jms-status and expects the following JSON response:
{"status": "Processing..."}
Consider using setTimeout().
More general, reliable and robust approach is to use websockets, servlet-3.0 asynchronous support or comet. Also have a look at atmosphere.
Related
I have some async form validation code that I'd like to put under test using Cypress. The code is pretty simple -
on user input, enter async validation UI state (or stay in that state if there are previous validation requests that haven't been responded to)
send a request to the server
receive a response
if there are no pending requests, leave async validation UI state
Step 1 is the part I want to test. Right now, this means checking if some element has been assigned some class -- but the state changes can happen very fast, and most of the time (not always!) Cypress times out waiting for something that has ALREADY happened (in other words, step 4 has already occurred by the time we get around to seeing if step 1 happened).
So the failing test looks like:
cy.get("#some-input").type("...");
cy.get("#some-target-element").should("have.class", "class-to-check-for");
Usually, by the time Cypress gets to the second line, step 4 has already ran and the test fails. Is there a common pattern I should know about to solve this? I would naturally prefer not to have change the code under test.
Edit 1:
I'm not certain that I've 100% solved the "race" condition here, but if I use the underlying native elements (discarding the jQuery abstraction), I haven't had a failure yet.
So, changing:
cy.get("#some-input").type("...")
to:
cy.get("#some-input").then(jQueryObj => {
let nativeElement = jQueryObj[0];
nativeElement.value = "...";
nativeElement.dispatchEvent(new Event("input")); // make sure the app knows this element changed
});
And then running Cypress' checks for what classes have / haven't been added has been effective.
You can stub the server request that happens during form validation - and slow it down, see delay parameter https://docs.cypress.io/api/commands/route.html#Use-delays-for-responses
While the request is delayed, your app's validation UI is showing, you can validate it and then once the request finishes, check if the UI goes away.
I'm trying to integrate the schedule component from Syncfusion. The component has a URL adaptor to connect to the controller; GetData() and Batch() for Crud Operations. Batch has a payload indicating what actions to perform. At the end, the Batch method would requery the database and send data identical to GetData() back.
Unfortunately, there is no built-in method to notify clients of anything going wrong - whether there is an exception, server-side validation kicks in or similar.
What I'd like to do is to add a placeholder outside the compentent to receive and display server messages (be it a notification popup, a or whatever.
Since I can't influence the Ajax call itself, I was wondering if I had to get started with SignalR (still in beta for .Net Core 2 as far as I know), or if I may have missed something more obvious? I have read a lot about push notifications etc - but these are not quite what I'm after, it'd be slightly over the top I think.
To summarise, let's say I have
<div id="messages"></div>
<div id="component">HereGoesTheScheduleWhichICantDoMuchWith</div>
Now in the Batch() method, it would be great to call a SendMessage("Sorry,you can't do this") - the text of which would ideally then appear in the messages-div.
How would you go about this?
I have now solved this, using SignalR (currently 1.0.0-alpha2-final) and for a nice view on the Client, PNotify.
Presently, it only works if the client is authenticated, if it needs to work anonymously you'd need to figure out a way to track SignalR's connection id.
On the page with the Syncfusion Schedule component, I connect to SignalR.
let connection = new signalR.HubConnection("/signalr", { transport: signalR.TransportType.ServerSentEvents });
connection.on("Notify",
(title, message) => {
new PNotify({
title: title,
text: message
});
});
connection.start();
The Hub (SignalRHub : Hub) creates a notification group for the user connecting:
public override Task OnConnectedAsync()
{
Groups.AddAsync(Context.ConnectionId, Context.User.Identity.Name);
return base.OnConnectedAsync();
}
The associated controller gets IHubContext<SignalRHub> signalRHub injected.
Now in the Batch-Method for the Syncfusion component, which returns Json and can't itself carry messages or notifications, you can notify the user:
_signalRHub.Clients.Group(User.Identity.Name).InvokeAsync("Notify", "A title", "A message");
In my particular case, I'm sending over an object to control layout, animation and popup duration for PNotify (e.g. longer for an exception to allow copy/paste etc) - as you please. Returning an object could be done using:
_signalRHub.Clients.Group(User.Identity.Name).InvokeAsync("Notify", JsonConvert.SerializeObject(new { title = "Some Title", message = "notification", type = "notice"}););
Obviously, connection.on("Notify"... needs to be changed accordingly.
I hope this is clear enough and might help someone else.
I'm doing a blog-app currently, and I'm struggling to find a way to redirect/send a specific status and then act accordingly.
For example, I have a function that saves data in mongodb using mongoose. Then if no errors occurred 200 status.
newArticle.save(function(err){
if (err) throw err;
else {
res.sendStatus(200);
}
});
I want to be able to "fetch" this status (I'm using react for my views and routes and superagent for my ajax request), and then do something, for example, If my article is successfully added then load a certain component on the page that will have an h1 saying : Great job on posting an article.
So this is the first part.
The second part is, for everything 404 or 500 errors I want express to redirect me from for example : myblog.com -> myblog.com/something and then with my react router simply render some basic 404 pages, I do not know how to do that, I'm searching a lot and couldn't find something...
And, since I lack knowledge in the HTTP basics like how server and client talk to each other, if you have any good article/books to recommend I'd like to know about.
For first part. Depending on if you are using state or data library like flux or redux, if not, you can just have ajax response will have the HTTP status from your server. Using that, you can use setState to set a state property called something like isArticleSaveSucessful. Then simply render your success message component if that key is true.
Second part. For the better user experience which is I think what you intended, the url should still be what the user intended, ie, blog.com/bad-article-name but the page should render a 404. Very similar to above, when the API response comes back, setState accordingly, something like articleNotFound. Then in your render function, do an if check on the the state and if it is true, then render your error component.
It's Google Chrome extension development. I'm using content script to inject into webpages. However some webpages have their own ajax scripts that change the content dynamically. How do I wait until such scripts are completed, since before their completion my script cannot obtain the correct content?
For example,
1- on Google search result page,
2- I want to append "text" to title of every search result item, which could be easily done by calling,
$('h3').append("text");
3- then listen to the search query change, done by
$('input[name="q"]').change( function(eventObj){
console.log("query changed");
// DOESN'T work
$('h3').append("text");
});
The last line doesn't work probably because at the time it's executed the page is still refreshing and $('h3') is not available. Google uses ajax to refresh the search result when the query is changed on the page.
So the question is how to capture this change and still be able to append "text" every time successfully?
EDIT:
Have tried and didn't work either:
$('h3[class="r"]').delay(1000).append("text");
and using .delay() is not really preferred.
EDIT:
.delay() is simply not designed to solve pause the execution of scripts other than UI effects. An workaround is
$('input[name="q"]').change(function(eventObj) {
setTimeout(function() {
$('h3[class="r"]').append(" text");
}, 1000);
});
But as I argued before, setTimeout() is connection-speed dependent, not preferred because I have to manually balance the time of waiting and the speed of response (of my script).
Although this post is down-voted for god-knows-why I'll still be waiting for an elegant answer.
Maybe with jQuery 1.7+ (or with older version using "live" or "delegate")
$('form').on( "change", 'input[name="q"]', function(eventObj){
console.log("query changed");
$('h3').append("text");
});
If form is another element, change it accordingly.
i am working on status update and commenting application in asp.net mvc3 like Facebook wall and comment. User can comment my wall and all stuff like Facebook.
http://demos.99points.info/facebook_wallpost_system/
like above demo, i want to create my application.
how can i do that using mvc3 and ajax?
i successfully updated user status to database but cant get all status updates of same user, i want to use partial view to display all status of user below the status textarea.
and if user write some status and share status that time status message saved in database and again reflect to same view Asynchronously.
how can i do that using ajax?
I'm going to answer this in broad terms as I don't have any knowledge of asp.net or mvc3. However, it seems to me that you're looking for more architectural direction.
You will need to setup an endpoint which generates the status page, call it /status.asp. This will create the text area and load the existing status messages from your database.
Then create a second endpoint, say /api/status.asp. This is not a view, but an API in your application that let's a user create (and, if you want, retrieve/modify/delete?) a status.
When a user hits enter in the textarea, fire off an XHR request to /api/status.asp with the new status. It is common, but not required, to do this as a POST request (read up on REST - http://en.wikipedia.org/wiki/Representational_State_Transfer). This API should then save the new status to your DB, and return the uid of the status along with the status message, perhaps as JSON (or XML or YAML if you prefer, it's up to you). For example, in JSON:
{
status: [
{
uid: '1234567890987654321'
msg: 'Hello World'
}
]
}
(To send the XHR request it's easiest to use a JS library like Dojo ( http://dojotoolkit.org/reference-guide/dojo/xhr.html#dojo-xhr ) or JQuery ( http://api.jquery.com/jQuery.ajax/ ).)
When your XHR request returns, check the status is a 200 (everything went OK), then read the data returned. Write some Javascript to create a new DOM node, inject the status message into that DOM node and add it to the bottom of the previous status nodes.
Bonus Points:
If you want person B to be looking at person A's /status.asp page and for that page to auto-update when person A posts a new status, you'll need to do a little more work. Firstly, modify /api/status.asp to return a list of the last x (say, 10?) status updates when called via HTTP GET. Include the UID of each status along with the status text.
Call your /api/status.asp API repeatedly* (perhaps with a timestamp of the last time you called it, and get your API to only return status posts after that time), loop over the the results and check to see if that post is already included in the users page (perhaps by having an id on each DOM node matching the UID of the status). If not, add it to the page.
*you have a number of options for doing this. For example, simply setup a JS timeout (easy, but not very efficient), or use Comet (eg http://cometd.org/) or WebSockets ( http://websocket.org/ ). I'd go for a timeout first, get it working and then figure out if a better technology is required.