FMS之Multi-point publishing技术

采用该技术，能large-scale你的直播系统，结构如图所示：

A. Live Video B. Server 1 (New York City)  C. Server 2 (Chicago) and Server 3 (Los Angeles) D. Users

1.客户端代码：ns.publish("localnews", "live");

2.LiveVideo代码：

// Called when the client publishes
application.onPublish = function(client, myStream) {
    trace(myStream.name + " is publishing into application " + application.name);
    // This is an example of using the multi-point publish feature to republish
    // streams to another application instance on the local server.
    if (application.name == "livestreams/_definst_"){
        trace("Republishing the stream into livestreams/anotherinstance");
        nc = new NetConnection();
        nc.connect( "rtmp://localhost/livestreams/anotherinstance" );
        ns = new NetStream(nc);
        // called when the server NetStream object has a status
        ns.onStatus = function(info) {
            trace("Stream Status: " + info.code)
            if (info.code == "NetStream.Publish.Start") {
                trace("The stream is now publishing");
            }
        }
        ns.setBufferTime(2);
        ns.attach(myStream);
        ns.publish( myStream.name, "live" );
    }
}

ns.onStatus = function(info) {
    trace("Stream Status: " + info.code)
    if (info.code == "NetStream.Publish.Start") {
        trace("The stream is now publishing");
    }
}

application.onUnpublish = function( client, myStream ) {
    trace(myStream.name + " is unpublishing"  );
}

3.Server1 和 Server2采用正常服务器流程

　　需要说明的是，FMS分为FMSS/FMIS/FMES/FMDS，FMSS因为不能配置成edge服务器，不适合提供运营级别的高性能/高分布的视频应用方案FMIS/FMES/FMDS除了都能配置成edge服务器外，还是有些区别的，FMDS是试用版本，有10个连接数的现在，FMES除了具备FMIS功能外，还多了P2P的功能；通过edge服务器，用户连接到的是edge服务器，而不是origin服务器，Edge分为是聚合大量的来自客户端的请求，并发送到源服务器，这样可以将负载的请求连接分布化，保证了流媒体高并发情况下的带宽及系统资源分配合理性，他管理连接，缓存内容，推送数据到客户端，文件缓存在edge端，降低了访问源服务器文件存储的需求量，突破了大规模视频应用的服务器瓶颈

　　上述的结构解决了S->C的问题，C->S的问题是需要采用Edge服务器，就要对Edge服务器进行配置，修改<RootInstall>/conf/_defaultRoot_/_defaultVHost_/Vhost.xml中的Mode/Anonymous/CacheDir/LocalAddress/RouteTable/RouteEntry；比如有以下两个服务器：

Edge服务器为edge1.adobe.com
Origin服务器为fms.adobe.com

Client连接Edge服务器就可以采用以下两中方式：

1).Explicit显式：Anonymous字段为false，直接将edgeURL作为originURL的前缀
rtmp://edge1.adobe.com/?rtmp://fms.adobe.com/app/instance
2).Implicit隐式：Anonymous字段为true，修改RouteTable/RouteEntry值为Edge/Origin的IP和Port
<RouteTable protocol="">
<RouteEntry>edge1.adobe.com:*;fms.adobe.com:1935</RouteEntry>
</RouteTable>
如果是多级就以此类推，比如Edge1->Edge2->Origin，注意哥没写错
<RouteEntry>edge1.adobe.com:*;edge2.adobe.com:1935</RouteEntry>
<RouteEntry>edge1.adobe.com:*;fms.adobe.com:1935</RouteEntry>