Sipdroid实现SIP(四): 传输层和应用层之间的枢纽SipProvider

一. 概述

在整套Sipdroid源码中, 类SipProvider是最靠近TCP/UDP的一层, 在Sipdroid实现的SIP协议栈中扮演底层枢纽的角色(前一篇文章中介绍的SipdroidEngine扮演的是上层枢纽), 这一角色也可以从该类是Configurable, TransportListener, TcpServerListener的继承体现出来.

向下层, SipProvider和通信传输层进行交互, 包括接收Transport的回调, 向Transport传递要发送的msg

向上层, SipProvider和UI交互, 包括根据msg触发指定Transaction回调, 从而通知Call再到UserAgent

二. 主要变量

2.1 监听标识之一: ANY

如果接收到的msg, 没有与其匹配的method_id, transaction_id或dialog_id, 就用ANY标识

public static final Identifier ANY = new Identifier("ANY");

2.2 监听标识之二: PROMISQUE

public static final Identifier PROMISQUE = new Identifier("PROMISQUE");

2.3 监听对象哈希表

在SipProviderListener中, 简单的接口定义和回调方法声明, 接口的对象listeners将会在SipProvider类中发挥重要的作用.

public void onReceivedMessage(SipProvider sip_provider, Message message);

listeners对象很关键, SipProvider提供的上下层枢纽功能都是要经过对应listener的被动触发和任务派发, Indentifier的值会在下面介绍.

Hashtable<Identifier, SipProviderListener> listeners = null;

2.4 通信协议相关

/*TCP/UDP相关*/

String[] transport_protocols = null;

boolean transport_udp = false;

boolean transport_tcp = false;

static UdpTransport udp = null;

TcpServer tcp_server = null;

/*Socket相关*/

SocketAddress outbound_proxy = null;

private String outbound_addr = null;

private int outbound_port = -1;

三. 主要方法

3.1 初始化SipProvider

首先, 从宏观上了解SipProvider类, 需要明确以下三个问题:

1. SipProvider的生命周期伴随Sipdroid核心引擎的全过程

　　SipdroidEngine.StartEngine(): 在Sipdroid应用"引擎"初始化的时候初始化

　　SipdroidEngine.halt(): 在Sipdroid应用"引擎"终止的时候终止

2. 初始化SipProvider要完成哪些事情

　　SipProvider具有连接传输层和UA,RA的功能, 所以需要初始化和传输, 监听相关的变量, 比如传输协议, IP和端口, 服务器地址, 监听对象的哈希表

    public SipProvider(String via_addr, int port, String[] protocols, String ifaddr) {

        init(via_addr, port, protocols, ifaddr);

        initlog();

        startTrasport();

    }

3. 初始化SipProvider后程序发生的变化

　　根据全局变量LINES的值, 确定了每个应用中初始化的sip_providers对象数组的大小.

3.2 应用启动时SipProvider监听者列表的变化过程(注册成功):

我删掉了和SipProviderListener无关的代码, 这样就能够显著看到Listener HashTable的变化情况: 在注册前逐个增加listeners, 当注册成功后, 和Register有关的listeners都被删除.

I/System.out: SipProvider: adding SipProviderListener: 412269425175@10.15.3.73-1-REGISTER-null-z9hG4bK26975

I/System.out: SipProvider: SipProviderListener:  size=1, listeners=412269425175@10.15.3.73-1-REGISTER-null-z9hG4bK26975,

I/System.out: SipProvider: adding SipProviderListener: INVITE

I/System.out: SipProvider: SipProviderListener:  size=2, listeners=INVITE, 412269425175@10.15.3.73-1-REGISTER-null-z9hG4bK26975,

I/System.out: SipProvider: adding SipProviderListener: OPTIONS

I/System.out: SipProvider: SipProviderListener:  size=3, listeners=INVITE, OPTIONS, 412269425175@10.15.3.73-1-REGISTER-null-z9hG4bK26975,

I/System.out: SipProvider: adding SipProviderListener: 412269425175@10.15.3.73-2-REGISTER-null-z9hG4bK84870

I/System.out: SipProvider: SipProviderListener:  size=4, listeners=INVITE, OPTIONS, 412269425175@10.15.3.73-1-REGISTER-null-z9hG4bK26975, 412269425175@10.15.3.73-2-REGISTER-null-z9hG4bK84870, 
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

I/System.out: SipProvider: removing SipProviderListener: NOTIFY

I/System.out: SipProvider: WARNING: trying to remove a missed SipProviderListener.

I/System.out: SipProvider: SipProviderListener:  size=4, listeners=INVITE, OPTIONS, 412269425175@10.15.3.73-1-REGISTER-null-z9hG4bK26975, 412269425175@10.15.3.73-2-REGISTER-null-z9hG4bK84870,

I/System.out: SipProvider: adding SipProviderListener: NOTIFY

I/System.out: SipProvider: SipProviderListener:  size=5, listeners=INVITE, OPTIONS, NOTIFY, 412269425175@10.15.3.73-1-REGISTER-null-z9hG4bK26975, 412269425175@10.15.3.73-2-REGISTER-null-z9hG4bK84870,

I/System.out: SipProvider: removing SipProviderListener: 412269425175@10.15.3.73-1-REGISTER-null-z9hG4bK26975

I/System.out: SipProvider: SipProviderListener:  size=4, listeners=INVITE, OPTIONS, NOTIFY, 412269425175@10.15.3.73-2-REGISTER-null-z9hG4bK84870,

I/System.out: SipProvider: removing SipProviderListener: 412269425175@10.15.3.73-2-REGISTER-null-z9hG4bK84870

I/System.out: SipProvider: SipProviderListener:  size=3, listeners=INVITE, OPTIONS, NOTIFY,

3.3 呼叫请求时监听者列表的变化过程(呼叫失败)

I/System.out: SipProvider: removing SipProviderListener: INVITE

I/System.out: SipProvider: SipProviderListener:  size=2, listeners=OPTIONS, NOTIFY,

I/System.out: SipProvider: adding SipProviderListener: 847642009035@10.15.3.73-z9hG4bK06452429-null

I/System.out: SipProvider: SipProviderListener:  size=3, listeners=OPTIONS, NOTIFY, 847642009035@10.15.3.73-z9hG4bK06452429-null,

I/System.out: SipProvider: adding SipProviderListener: 847642009035@10.15.3.73-1-INVITE-null-z9hG4bK26053

I/System.out: SipProvider: SipProviderListener:  size=4, listeners=OPTIONS, NOTIFY, 847642009035@10.15.3.73-z9hG4bK06452429-null, 847642009035@10.15.3.73-1-INVITE-null-z9hG4bK26053,

I/System.out: SipProvider: adding SipProviderListener: 847642009035@10.15.3.73-2-INVITE-null-z9hG4bK50097

I/System.out: SipProvider: SipProviderListener:  size=5, listeners=OPTIONS, NOTIFY, 847642009035@10.15.3.73-z9hG4bK06452429-null, 847642009035@10.15.3.73-1-INVITE-null-z9hG4bK26053, 847642009035@10.15.3.73-2-INVITE-null-z9hG4bK50097, 
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

I/System.out: SipProvider: removing SipProviderListener: 847642009035@10.15.3.73-z9hG4bK06452429-null

I/System.out: SipProvider: SipProviderListener:  size=4, listeners=OPTIONS, NOTIFY, 847642009035@10.15.3.73-1-INVITE-null-z9hG4bK26053, 847642009035@10.15.3.73-2-INVITE-null-z9hG4bK50097,

I/System.out: SipProvider: adding SipProviderListener: INVITE

I/System.out: SipProvider: SipProviderListener:  size=5, listeners=INVITE, OPTIONS, NOTIFY, 847642009035@10.15.3.73-1-INVITE-null-z9hG4bK26053, 847642009035@10.15.3.73-2-INVITE-null-z9hG4bK50097,

I/System.out: SipProvider: adding SipProviderListener: OPTIONS

I/System.out: SipProvider: WARNING: trying to add a SipProviderListener with a id that is already in use.

I/System.out: SipProvider: SipProviderListener:  size=5, listeners=INVITE, OPTIONS, NOTIFY, 847642009035@10.15.3.73-1-INVITE-null-z9hG4bK26053, 847642009035@10.15.3.73-2-INVITE-null-z9hG4bK50097,

I/System.out: SipProvider: removing SipProviderListener: 847642009035@10.15.3.73-1-INVITE-null-z9hG4bK26053

I/System.out: SipProvider: SipProviderListener:  size=4, listeners=INVITE, OPTIONS, NOTIFY, 847642009035@10.15.3.73-2-INVITE-null-z9hG4bK50097,

I/System.out: SipProvider: removing SipProviderListener: 847642009035@10.15.3.73-2-INVITE-null-z9hG4bK50097

I/System.out: SipProvider: SipProviderListener:  size=3, listeners=INVITE, OPTIONS, NOTIFY,

3.4 从"哈希监听者列表"删除一个SipProvider监听

四. 在Sipdroid中的应用

就像每个产品会配一个产品经理一样, 每个UA和RA都会配一个sip_provider, 负责这个UA或RA的消息监听, 接收和处理.