I want to develop an application where I want to push the messages (or data) to UI from backend Spring boot application.
I have the following requirement -
Consider there is a REST service that accepts the data from other applications using the POST method.
This data will be pushed to UI.
OR
Consider that there is a background process running which generate events and we want to push these events to UI.
For this, I came across about the WebSocket component that we can use in the Spring Boot application.
However, is there any other settings required to make it possible to push the incoming data to the UI?
Any help is appreciated.
Thanks,
Avinash Deshmukh
The backend cannot magically push updates to a client UI. The backend will have no way of knowing where the UI exists (i.e. what the UI's ip address is) and even if it did, it may not have access to establish a connection (due to firewalls or a NAT).
For this reason a client UI has to request updates. One way this could be done would be to have a timer in the UI application that polls for updates via REST. But this is essentially what websockets do - with much less overhead.
This is how common applications that you use everyday work all the time. So I'm not sure why you do not want to go down the websockets route.
...
Starting with Spring 5.0.5.RELEASE, it isn’t necessary to do any customization because of the improvement of #SendToUser annotation, that allows us to send a message to a user destination via “/user/{sessionId}/…” rather than “/user/{user}/…“.
That means the annotation works relying on the session id of the input message, effectively sending a reply to destination private to the session:
...
There is a good example over here:
https://www.baeldung.com/spring-websockets-sendtouser
Related
Is it possible to have one Laravel application listen for events triggered in another?
I've built a REST API to complement an existing web app. It uses the same database but I've built it as a separate application and there are certain events which clear some cached results. At the moment the events are not being shared between the two applications so I'm getting the cached results in spite of having updated the database. Is there a way for one app to pick up on events fired by the other? I haven't found anything about this in the docs.
Redis is completely agnostic about what application is listening to it. You can set your broadcast driver to redis and invoke your events in one application while listening on the other as long as they both use the same Redis instance. The other can then listen for those events. However, of note is that the way that Laravel handles the listeners is to bind to a specific class. So you would still have to make sure the class existed so you may define a listener for it.
I have created Web API which allows messages to be sent to the Queue. My Web API is designed with CQRS and DDD in mind. I want my message consumer to always be waiting for any messages on the queue to receive. Currently the way its done, this will only read messages if I make a request to the API to hit the method.
Is there a way of either using console application or something that will always be running to consume messages at anytime given without having to make a request from the Web Api. So more of a automation task ?
If so, how do I go about with it i.e. if its console app how would I keep it always running (IIS ?) and is there way to use Dependency Injection as I need to consume the message then send to my repository which lives on separate solution. ?
or a way to make EasyNetQ run at start up ?
The best way to handle this situation in your case is to subscribe to bus events using AMPQ through EasyNetQ library. The recommended way of hosting it is by writing a windows service using topshelf library and subscribe to bus events inside that service on start.
IIS processes and threads are not reliable for such tasks as they are designed to be recycled on a regular basis which may cause some instabilities and inconsistencies in your application.
and is there way to use Dependency Injection as I need to consume the message then send to my repository which lives on separate solution.
It is better to create a separate question for this, as it is obviously off-topic. Also, it requires a further elaboration as it is not clear what specifically you are struggling with.
We are designing an API for an application where the clients (external) can
interact with it synchronously to say:
a) request a plan
b) cancel a plan etc
However once the plan is made, the decision as to whether a plan is
approved or disapproved is done asynchronously. The application itself
can send other notifications to the clients asynchronously. This part has
been implemented using spring's stomp over websocket framework. This
work perfectly fine.
Now, coming to the synchronous part of the API, the plan is to provide
a RESTful interface for the interaction. If this is done this way, the
clients will have to build two different client API's, one using http
for making RESTful calls and another using a stomp client to consume notifications.
Should we rather make it accessible via one interface?
I am not convinced of using Stomp for synchronous calls since I think the REST framework
will address the use case well. However I am concerned about the need for the clients to do both, although it is for different functionality.
Will it be okay to support both? Is this a good design practice. Can someone please advice?
HTTP based clients could a) send requests ('simple polling), in long intervalls to limit bandwidth usage, or b) use HTTP long polling (blocking) to immediately return control to the client code when the server sends for a response
I have a project that is related to job postings. Consultants or employers register on my website and then start posting jobs. I want to make push notifications for all users. When a consultant or employer posts a job, all online users must get notified that an employer has posted this job without any page refreshes on jquery setInterval or timeout.
I am using Spring framework. I have searched for the solution but found nothing. I want to know whether Spring provided WebSockets in their latest version. Is this possible to do with WebSockets?
I want a proper resource so that I can implement it on my website.
There are two ways to satisfy your need;
First is polling in which you repeatedly send requests from client to the server. On server side you somehow need have a kind of message queue for each client to deliver the incidents on a request. There also is a different type of polling in which you send a request from client and never end the request on the server-side thus you have a kind of pipe between two ends. This is called long polling.
Disadvantage of polling is that you have to send requests to the server forever from the client and in many cases server sends empty messages as there is no events happened.
The real application of pushing messages is recently avaliable with websockets (thanks to html5). However this requires the application server to be capable of websocket functionality. afaik jetty and tomcat has this ability. Spring 4 has websocket here you can find the tutorial; http://syntx.io/using-websockets-in-java-using-spring-4/
You can find a related stackoverflow post here
I'm trying to understand whether the HTML5 Web Notifications API can help me out, but I'm falling short in understanding how it works.
I'd like user_a to be able to send user_b a message within my webapp.
I'd like user_b to receive a notification of this.
Can the web notifications API help here? Does it let me specifically target a user (rather than notify everyone the site has been updated_? I can't see how I would create an alert for one person.
Can anyone help me understand a little more?
The notifications API is client side, so it needs to get events from another client-side technology. Here, read THIS: http://nodejs.org/api/. Just kidding. Node.js+socket.io is probably the best way to go here, you can emit events to one or all clients (broadcast). That's a push scenario. Or each user could be pulling their notifications from the server.
HTML5 Web Notifications API gives you ability to display desktop notifications that your application has generated.
What you are trying to achieve is a different thing and web notification is just a part of your scenario.
Depending upon how you are managing your application, for chat and messaging purpose as humbolight mentioned, you should look into node.js. it will provide you the necessary back-end to manage sending and receiving messages between users.
To notify a user that (s)he has received a message, you can opt for ajax polling on client side.
Simply create a javascript that pings the server every x seconds and checks if there is any notification or new message available for this user.
If response is successful, then you can use HTML5 notification API to show a message to user that (s)he has a new message.
The main problem with long polling is server load, and bandwidth usage even when there are no messages, and if number of users are in thousands then you can expect your server always busy responding to poll calls.
An alternate is to use Server Sent Events API, where you send a request to server and then server PUSHES the notifications/messages to the client as soon as they are available.
This reduces the unnecessary client->server polling and seems much better option in your case.
To get started you can check a good tutorial at
HTML5Rocks
What you're looking for is WebSocket. It's the technology that allows a client (browser) to open a persistent connection to the server and receive data from it at the server's whim, rather than having to "poll" the server to see if there's anything new.
Other answers here have already mentioned node.js, but Node is simply one (though arguably the best) option for implementing websockets on your server. You might also be comfortable with Ratchet, which is a websocket server library for PHP, or Tornado which is in Python.
How you handle your real-time communication is up to you. Websockets are merely the underlying technology that you can use to pass data back and forth. The client side of this will be fairly easy, but on the server side, you'll need a mechanism for websocket handlers to get information from each other. Look at tools like ZeroMQ for handling queues, and Memcached or Redis to handle large swaths of data which don't need to be stored permanently.