Websocket support

[decebals]

It's the successor of #279. All information presented in #279 are available.

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Coverage decreased (-0.4%) to 18.635% when pulling edc37fd on web_socket_2 into a7bb328 on master.

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Coverage decreased (-0.4%) to 18.635% when pulling f680d12 on web_socket_2 into a7bb328 on master.

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Coverage decreased (-0.4%) to 18.647% when pulling 0bdc296 on web_socket_2 into a7bb328 on master.

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Coverage decreased (-0.4%) to 18.661% when pulling 361b603 on web_socket_2 into a7bb328 on master.

[decebals]

• inject WebSocketFilter automatically in Pippo launcher

See #279 (comment) for more details.
Resolved in a smooth way by 7c4c069.

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Coverage decreased (-0.4%) to 18.639% when pulling 7c4c069 on web_socket_2 into a7bb328 on master.

[mhagnumdw]

Hello, Decebals!

The dependency org.eclipse.jetty.websocket:websocket-server is optional after your commit 7c4c069. How to tell maven to add this dependency so that JettyServer.java add the JettyWebSocketFilter filter instead of PippoFilter?

[decebals]

@mhagnumdw
It's made automatically by JettyServer in createPippoFilter method.
All you have to do is just add Jetty's websocket-server as dependency in your pom.xml:

<!-- Enable websocket support -->
<dependency>
    <groupId>org.eclipse.jetty.websocket</groupId>
    <artifactId>websocket-server</artifactId>
    <version>${jetty.version}</version>
</dependency>

The advantages are:

• Jetty server is minimal for non websocket application, as in present
• JettyServer class from Pippo adds automatically JettyWebSocketFilter instead of PippoFilter (via createPippoFilter method) if it "feels" that you added in your classpath (via pom.xml) a dependency to websocket implementation from Jetty

A new pippo-demo-websocket module is prepared already and it will be available in pippo-demo project.

You can see parts from this demo in this Gist.

The websocket support is implemented only for Jetty in this moment.
The implementation is finished, the API is stable. I will add a little bit more documentation in this PR and after this we can remove a new Pippo version that contains the websocket support.

[mhagnumdw]

@decebals

Thanks for the answer. I had already done so. I just find it a bit strange because the developer can specify a version for the org.eclipse.jetty.websocket: websocket-server that conflicts with the version of the Jetty server shipped in Pippo, right? Is there a way for the developer not to specify the version so that it is obtained from the Jetty server version used by Pippo? I went crazy? :)

Other inquiries,

1. Is it possible to send a message to a group? From what I've seen (and already tested!) It's only possible to send a message to a single user and to all (brodcast);
2. Is it possible to send a message from an asynchronous process?

PS: Is it better to address these issues here or in the mailing list?

[decebals]

They are some situations when you want to access some details information in your WebSocketHandler. For example, I want to find the remote address, the request URI, the HTTP method or the parameter map.
For this situation we have a very simple solution (see below the code):

addWebSocket("/ws-debug", (webSocketContext, message) -> {
    WebSocketConnection connection = webSocketContext.getConnection();
    // cast WebSocketConnection to JettyWebSocketConnection
    JettyWebSocketConnection jettyConnection = (JettyWebSocketConnection) connection;
    String remoteAddress = jettyConnection.getRemoteAddress().toString();
    System.out.println("remoteAddress = " + remoteAddress);
    org.eclipse.jetty.websocket.api.Session session = jettyConnection.getSession();
    String protocolVersion = session.getProtocolVersion();
    System.out.println("protocolVersion = " + protocolVersion);
    org.eclipse.jetty.websocket.api.UpgradeRequest upgradeRequest = session.getUpgradeRequest();
//    upgradeRequest.getCookies();
//    upgradeRequest.getHeaders();
//    upgradeRequest.getParameterMap();
    String query = upgradeRequest.getQueryString();
    System.out.println("query = " + query);
});

Now, if I make a request from a websocket client (I used Simple WebSocket Client extension for Chrome) with the url ws://localhost:8338/ws-debugt?param1=a&param2=b, I obtain the below result in console:

remoteAddress = /127.0.0.1:35594
protocolVersion = 13
query = param1=a&param2=b

That it's all, simple and straightforward 😄

[decebals]

@mhagnumdw
I am not a Maven expert, so I don't know if it's possible to not specify the jetty version in your pom.xml. I putted in my demo the same version as in pippo-jetty module. I think that it's important/mandatory to have the same version.
I feel that my approach with websocket-server as optional is correct, because the majority of applications will be non websocket and I don't want to add extra dependency, but it's a possibility that I may be wrong.

Is it possible to send a message to a group? From what I've seen (and already tested!) It's only possible to send a message to a single user and to all (brodcast)

I think that you can. WebSocketContext contains all clients connections, the current client connection and two helper methods for sending a message (to current client or to all clients - broadcast). You can create a method that filters your clients according some criteria (the group) and to send the message only to these clients. I will expose the connections field from WebSocketContext via getConnections method to have access to all connections for that websocket.

Is it possible to send a message from an asynchronous process?

I don't know what involves this. Can you add more details about your use case?

[coveralls]

Coverage decreased (-0.4%) to 18.636% when pulling bfc6d4b on web_socket_2 into a7bb328 on master.

[decebals]

@mhagnumdw

Is it possible to send a message to a group? From what I've seen (and already tested!) It's only possible to send a message to a single user and to all (brodcast)

Other solution is to use the websocket hook methods onOpen and onClose from WebSocketHandler and to keep a map in your Application with all connections grouped on a criteria. In onOpen method you add a new entry and onClose method you delete an existed entry. If you have this map it's super easy to send a message for all clients from a group.

[mhagnumdw]

@decebals

Is it possible to send a message from an asynchronous process?

I don't know what involves this. Can you add more details about your use case?

I have a periodic schedule made by java.util.concurrent.ScheduledExecutorService. This asynchronous task collects some data that application users should be aware of. To achieve this, I imagined this asynchronous task to post the messages and get them to the client via websocket (so the client / user does not have to keep giving F5 on the screen for news!).

[decebals]

@mhagnumdw
I don't see a problem. The approach described by me in comment #360 (comment) is a good start point.

[mhagnumdw]

@decebals
Thank you very much! I'll be working on proofs of concept in the coming days.