Use grails-events-push in grails to implement ajax/Comet/websocket message push

> The push technology on the browser side is very mature. The grails Events push plug-in is used here.
>
> Events push is an extension of grails-platform-Core Based on http://grailsrocks.github.com/grails-platform-core/guide/ and https://github.com/Atmosphere/atmosphere.
> Here we use the Events push example and make some addendum to it.

# Create a grails project first.

# Install the plug-in events-push. Version 1.0.m7 is used here.

# Modify buildconfig. grooy
Add the atmosphere-runtime MVN repository to repositories

Repositories {
...
Mavenrepo http://mvn.atns.de/repository/internal"
...
}

### Add in plugins

Plugins {
...
Complie "'org. Atmosphere: Atmosphere-runtime: 1.1.0-Snapshot '"
Compile ": events-push: 1.0.m7"
...
}

### The events-push.1.0.M7 references atmosphere-runtime: 1.1.0-snapshot.

# Create myevents. Groovy In the config directory

Events = {
// The browser must receive the notification "msgfromserver ".
'Msgfromserver' namespace: 'browser ', browser: True, browserfilter: {data, request->
Println "browserfilter after service"
Println "browserfilter data: $ data"
Return false
}

// The browser sends the notification named msgtoserver.
'Msgtoserver' namespace: 'browser ', browser: True, filter: {println "msgtoserver filter"; return true}
}

### In the above Code
##### 'Msgtoserver' message label and message name
##### Namespace message group, group name
##### Whether the Browser allows the browser to accept the message. The grails-platform-core plug-in is mainly used for pushing events on the server. Events push integrates it with atmosphere, so we have this parameter.
##### Filter access filter closure, equivalent to xxfilters. Groovy in config, which usually performs some permission checks or something. After using atmosphere, Ajax/comet access will not go through xxxfilters. groovy, you need to make a judgment here. Of course, just write the closure like filters. The return value determines whether to intercept messages from the browser to the server.
##### After the service processes the messages pushed by the browser, browserfilter will execute the following command to accept the message content sent by the event () method in the data: Service parameter, request: Servlet request. Like filters, the return value determines whether to intercept messages from the server to the browser.

# Create a service named myservice. Groovy

// The Listener annotation specifies the message that this method accepts. If namespace is not specified, all messages are accepted. Here, messages named browser group are accepted.
// Note that the method name must be the Tag Name Defined in myevents. Groovy
@ Listener (namespace = 'browser ') def msgtoserver (Map Data ){
Println "MSG from browser MSG: $ data"
Println "service send 'msgfromserver' MSG"
// Send the "msgfromserver" Event
Event ('msgfromserver', [MSG :"! This is MSG! "], [Namespace: 'browser '])
}

# Modify a GSP by yourself and add the event push listener and message sender

HTML:

### The transport parameter accepted in grails. events is supported by atmosphere and basically contains various ajax/Comet/websocket protocols.
### Supported polling, long-polling, streaming, jsonp, SSE, and websocket

# Output result of println for the entire processing process:

##### 1. msgtoserver filter> filter of myevents. Groovy msgtoserver tag
##### 2. MSG from browser MSG: [MSG: MSG from browser]> myservice. Groovy msgtoserver Method
##### 3. service send 'msgfromserver' MSG> myservice. Groovy msgtoserver Method
##### 4. browserfilter after service> browserfilter of myevents. Groovy msgtoserver tag
##### 5. browserfilter data: [MSG :! This is MSG!] > Myevents. Groovy msgtoserver tag browserfilter Filter

***
# Reference:
##### Server Response push technology such as ajax/comet, IBM article series http://www.ibm.com/developerworks/cn/views/web/libraryview.jsp? View_by = SEARCH & sort_by = Date & sort_order = DESC & view_by = SEARCH & search_by = % E5 % 8f % 8d % E5 % 90% 91 + Ajax + % E9 % 83% A8 % E5 % 88% 86 & dwsearch. X = 14 & dwsearch. y = 15
##### Using browser pushes in grails http://java.dzone.com/articles/using-browser-push-grails
##### Grails-Atmosphere-plugin framework https://bitbucket.org/bgoetzmann/grails-atmosphere-plugin/wiki/Home
##### Jquery. Atmosphere. js API https://github.com/Atmosphere/atmosphere/wiki/jQuery.atmosphere.js-API
##### Grails-events-push https://github.com/smaldini/grails-events-push
##### Grails plugin platform http://grailsrocks.github.com/grails-platform-core/guide/

### PS: It is too painful to read the source code of goovy language. There are only a few documents, and too many languages are involved ......