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diff --git a/sca-java-2.x/tags/2.0.1-RC1/samples/learning-more/binding-websocket/weather-webapp/README b/sca-java-2.x/tags/2.0.1-RC1/samples/learning-more/binding-websocket/weather-webapp/README new file mode 100644 index 0000000000..eb195bc4dc --- /dev/null +++ b/sca-java-2.x/tags/2.0.1-RC1/samples/learning-more/binding-websocket/weather-webapp/README @@ -0,0 +1,89 @@ +Tuscany - Learning More - Binding Websocket - Weather Monitor Webapp +----------------------------------------------------------------- + +This sample demonstrates how Tuscany can expose services via websockets as well +as how to interact with them using Tuscany's javascript API. It also demonstrates +how to push multiple responses for a single request using SCA callbacks. + +This project contains multiple services that once called will push notifications +to the client regarding certain weather parameters according to the location of +the user. Of course, the service implementation is a mock that generates random +numbers at a fixed interval of time as weather parameters. + +By adding <tuscany:binding.websocket port="8090"/> to a service definition, the +Tuscany runtime will start a websocket server listening for requests coming +in for the exposed service at the specified port. If no port is specified, the +runtime will use port 9000 as a default. + +The websocket binding uses embedded Jetty instances as websocket servers. At the +moment, Jetty 8.0.0-M3 is used which has support for the 00, 01, 06 and 07 +versions of the websocket protocol drafts. + +IN ORDER TO RUN THIS SAMPLE SUCCESSFULLY PLEASE CHECK IF YOUR BROWSER SUPPORTS +THE ABOVE WEBSOCKET PROTOCOL VERSIONS AND THAT THE WEBSOCKET SUPPORT IS ENABLED. + +In order to enable callbacks to push multiple responses, you need to declare the +WebsocketBindingCallback in the service definition as follows: + + <interface.java interface="sample.ChatService" + callbackInterface="org.apache.tuscany.sca.binding.websocket.runtime.WebsocketBindingCallback" /> + <tuscany:binding.websocket /> + <callback> + <tuscany:binding.websocket /> + </callback> + +The callback object has methods that facilitate sending messages back to the +calling client. It can be injected in the service implementation using the @Callback +annotation. + +One requirement that service methods have to meet to enable multiple response +support is that they have to be annotated with @OneWay to enable non-blocking +support. Without it, methods are treated synchronously sending a single response +which is the object returned by the method call. + +The websocket binding also features a javascript API to simulate SCA in the +browser. In order to use it, the following script has to be included in the +client page: + <script type="text/javascript" + src="org.apache.tuscany.sca.WebsocketComponentContext.js"> + </script> + +This will inject proxies for all services defined in the composite that are +using binding.websocket. All invocation and connection management is handled +under the hood so in order to invoke a websocket service, the following should +be called: + Tuscany.WebsocketComponentContext.<component name>.<service name>.<operation name>(<parameters>); + +Given the asynchornous nature of websockets, a function should be defined in +order to handle responses received for a certain service operation. This should +be done as follows: + Tuscany.WebsocketComponentContext.<component name>.<service name>.<operation name>.responseHandler = function(response) { + // handle response + }; + +Note that the data exchange is automatically handled by the binding, so parameters +will be mapped to the data types defined in the method definition. Also, the response +will have the same data type as the server side object used to wrap the response. +Objects are passed over the wire in JSON format. + +Another detail worth mentioning is that the binding will use a single persistent +websocket connection to handle communication between a browser client and all services +defined using binding.websocket on the same port. Requests and responses will get +multiplexed via the same channel and get routed to the appropriate service +implementation, respectively javascript function. + +In order to run the sample, you can execute "mvn jetty:run" which will start a Jetty +instance automatically or use "mvn package" and deploy the resulting war to the +application server of your choice. + +Next, point your browser at + http://localhost:8080/sample-binding-websocket-weather-webapp/ + +You can now set a location and register for various weather parameters. Notifications +will be pushed to the browser when weather parameters change. You can see the persistent +websocket connection handling all the communication using the developer tools provided +by your browser. + +The websocket binding is an experimental binding so community feedback is much +appreciated. Feel free to send comments or suggestions on the Apache Tuscany +dev mailing list (dev@tuscany.apache.org).
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