I have a REST API made with Spring Boot. I can add entities (Persons) to a database using HTTP requests.
I would like to have a web page display those entities dynamically: whenever a new Person is stored in the database, the page displays it on top of the list. No need to refresh the page.
What are the ways to achieve this? Would JSP be enough? Do I need javascript?
The simpler the better.
What are the ways to achieve this? Would JSP be enough? Do I need
javascript?
Yes you need javascript. But you can embed it in JSP too.
This is a solved problem, you will find numerous examples in the web if you search for "websocket spring". Example https://spring.io/guides/gs/messaging-stomp-websocket/
If you are not stuck in JVM-land and RDBMS, I would encourage you to take a look at firebase-angular stack (3-way binding)
Further read
Read this https://stackoverflow.com/a/12855533/6785908
Shameless copy since posting just a link is not advisable as link may break in future
In the examples below the client is the browser and the server is the webserver hosting the website.
Before you can understand these technologies, you have to understand
classic HTTP web traffic first.
Regular HTTP:
A client requests a webpage from a server.
The server calculates the response
The server sends the response to the client.
Ajax Polling:
A client requests a webpage from a server using regular HTTP (see HTTP above).
The client receives the requested webpage and executes the JavaScript on the page which requests a file from the server at
regular intervals (e.g. 0.5 seconds).
The server calculates each response and sends it back, just like normal HTTP traffic.
Ajax Long-Polling:
A client requests a webpage from a server using regular HTTP (see HTTP above).
The client receives the requested webpage and executes the JavaScript on the page which requests a file from the server.
The server does not immediately respond with the requested information but waits until there's new information available.
When there's new information available, the server responds with the new information.
The client receives the new information and immediately sends another request to the server, re-starting the process.
HTML5 Server Sent Events (SSE) / EventSource:
A client requests a webpage from a server using regular HTTP (see HTTP above).
The client receives the requested webpage and executes the JavaScript on the page which opens a connection to the server.
The server sends an event to the client when there's new information available.
Real-time traffic from server to client, mostly that's what you'll need
You'll want to use a server that has an event loop
Not possible to connect with a server from another domain
If you want to read more, I found these very useful: (article), (article), (article), (tutorial).
HTML5 Websockets:
A client requests a webpage from a server using regular http (see HTTP above).
The client receives the requested webpage and executes the JavaScript on the page which opens a connection with the server.
The server and the client can now send each other messages when new data (on either side) is available.
Real-time traffic from the server to the client and from the client to the server
You'll want to use a server that has an event loop
With WebSockets it is possible to connect with a server from another domain.
It is also possible to use a third party hosted websocket server, for example Pusher or others. This way you'll only have to
implement the client side, which is very easy!
If you want to read more, I found these very useful: (article), (article) (tutorial).
Comet:
Comet is a collection of techniques prior to HTML5 which use streaming
and long-polling to achieve real time applications. Read more on
wikipedia or this article.
Related
I need some advice in the following matter:
I have two machines that are connected via ethernet.
One machine (lets call it ServerSide) is also connected to the Internet via LAN. The second machine (ClientSide) is offline, in the beginning.
So ServerSide is creating a webserver with Jetty on port XY. ClientSide opens a webbrowser and requests some page (e.g. stackoverflow.com). The request will be forwarded to port XY and the webserver. ServerSide would have to send the request to the internet and then back over ServerSide to ClientSide, so the webbrowser should display the requested webpage.
Is it even possible to do that this way?
Thanks in advance
Yes. What you need on server side is an HTTP Proxy and there are plenty of existing solutions in the market.
Check out the Wikipedia article about proxies. Bear in mind that the client might require some configuration (Proxy settings) so that it forwards the requests to the proxy rather than attempting to reach the final host.
I am trying to simulate a response from a web server login confirmation to a windows application. I have the captured packets that detail the conversation between the server and the application for successful login already as it is my application, this is for debugging and MIME simulation to test application and network security. communications create what I hope can be a custom foolproof way to prevent a MIME but I dont have a way to test it, so here I am to ask for guidance.
How would I go about simulating the response from the server to the application?
I have some idea in the direction I would possibly need to go to achieve my desired outcome:
Utilizing my network:
I have a Linux machine set up as a dynamic router, dhcp, routing, and my Linksys router just acts as an access point and ethernet switch.
1: Set up web server on Linux machine.
2: redirect traffic from application port to Linux server.
3: run server-side script to respond to application request using packets captured to establish replay successful login to server.
So, I am kinda new to using Linux tools. I have setup a Linux router, captured basic information utilizing Wireshark, and am able to program in VB, javascript, some java. I have not done much network-oriented programming other than some simple communication for authentication I have successfully established.
Any information to point me in the right direction I am grateful for!
Most logins use encryption (https / TLS) so capturing the packets won't help.
If not, the packets will form a http request, and you should be able to see the format of the request, whether the login credentials are part of the URL for GET or part of the http body for POST. It is not hard to create your own http request.
How are parameters sent in an HTTP POST request?
Each http request will be followed by an http response from the server, and the format of the headers or body will contain the login result (http requests and responses are similar in format, but the headers are not the same).
More sophisticated logins may involve a series of requests/responses.
You will need to write a simpler server to receive the requests and send the responses. Java is probably your best choice, given the languages you know, plus there will be plenty of examples online. With JS it may be possible but for the most part JS is used in browsers, so not a great choice. VB is a Windows language not supported on Linux.
I am trying to write a simple client-server application in Java using HTTP request/response. I would like the client to be a desktop program which sends (posts) a request to a server. The server is a web page which will be hosted on Apache Tomcat server. The server must be able to read the information and display it on the browser and must be able to respond to the client with a status code 200. I am using eclipse and Apache tomcat server. I have so far tried various resources, but all I could find is a client which could request response from an already existing web server. Could someone please give me an example or some insight on how to make the client request the our own server which runs on the local machine.
Good question, though in your case, I won't recommend you implement a simple HTTP request/response approach as you will end up implementing a timer, heartbeat or Comet. You might wanna try javax or jetty WebSocket API. All you need is to create three parts:
a websocket.server
a websocket.client (desktop application)
a javascript websocket client (browser agent)
Your server and both clients will become full-duplex via onMessage and send events.
Here's an example which I believe is a bit relevant one.
https://dzone.com/articles/sample-java-web-socket-client
I am looking for some guidelines as to how to secure requests from android client to server
How can i prevent un autenthic (users which initiate requests not from the android app) requests to be accepted and processed by the server?
Waybe generate token at user registration and use it somehow at each call?
My server is a lite instance and performance is top issue in the implementation of the server client communication.
Appreciate any help!
You could use Google Cloud Messaging as a via medium to make sure messages that reach your server are from the app, without getting too involved in details. Check the documentation here:
https://developer.android.com/google/gcm/index.html
Or else, as you said, create a unique id on registration and send it back to the client. Store it at both client and server. Now with each request from the client, add an extra field in the request and send the id also. Check this id serverside and make sure it is valid (this check could eventually become heavy on time).
I am practicing some web-apps technology. I setup Apache HTTP server which provides HTTP page with JNLP/FlashFX file with simple data-form to fill by the user. My first idea was to send/receive the data from JNLP with help of UDP (I just serialize object inside datagrams). To be more specific:
Apache provides a static HTTP and JNLP/FlashFX (HTTP is just to deploy JNLP)
JNLP communicates via UDP with server
server runs simple Java program to send/receive UDP packets to JNLP
My problem is when I access the page from 'client' browser machine a firewall asking if I want to allow/deny the access to network from 'java'. No doubts this is normal, but I think no one is expecting this from a web page.... I want to change this approach and use existing HTTP protocol.
QUESTION UPDATE
As far as I understood with HTTP protocol we have couple of methods which are used to communicate with the server (GET, PUT, POST .... ) and provided by Apache service.
I would like to use this for data exchange like this:
JNLP sends some serialized data with HTTP methods
Apache will redirect some (or full) traffic to my Java program
My Java program will answers via Apache to my JNLP
How can I do that?