Tigase 发送消息的流程源码分析

XMPP 的<message/>节是使用基本的”push”方法来从一个地方到另一个地方得到消息。因为消息通常是不告知的，它们是一种”fire-and-forget”(发射后自寻目的)的机制来从一个地方到另一个地方快速获取信息
消息节有五种不同的类型，通过 type 属性来进行区分：例如 chat 类型为 chat 的消息在两个实体间的实时对话中交换，例如两个朋友之间的即时通讯聊天。除了 type 属性外，消息节还包括一个 to 和 from 地址，并且也可以包含一个用于跟踪目的的 id  属性（我们在使用更为广泛的 IQ  节中详细的讨论 IDs）。to  地址是预期接收人的
JabberID，from 地址是发送者的JabberID。from 地址不由发送客户端提供，而是由发送者的服务器添加邮戳，以避免地址欺骗。

在Tigase中，有两个重要的组成,一个组件,二是插件,可以去官方网去看下他的架构介绍 https://docs.tigase.net/tigase-server/7.1.4/Development_Guide/html/#writePluginCode

例如最著名的组件的一个例子是MUC或PubSub。在Tigase中，几乎所有东西实际上都是一个组件:会话管理器、s2s连接管理器、消息路由器等等,组件是根据服务器配置加载的，新的组件可以在运行时加载和激活。您可以轻松地替换组件实现，唯一要做的更改是配置条目中的类名。

Tigase 中定义一个最简单的消息组件,需要实现MessageReceiver或继承 extends AbstractMessageReceiver 类, MessageReceiver 的抽象类: AbstractMessageReceiver 子类 :

一、ClientConnectionManager

二、SessionManager

三、 MessageRouter

public void setProperties(Map<String, Object> props){
    for (String name : msgrcv_names) {
        mr = conf.getMsgRcvInstance(name);
        if (mr instanceof MessageReceiver) {
            ((MessageReceiver) mr).setParent(this);
            ((MessageReceiver) mr).start();
        }
    }
}

1、当客户端发送的message消息到tigase服务端，每个一SOCKET连接都会被包装成IOService对象，IOService包含一系列操作socket的方法（接收发送数据等），processSocketData()接收网络数据，由tigase.net处理解析成xml对象，并将packet放到接收队列receivedPackets中再调用serviceListener.packetsReady(this)。由于ConnectionManager实现IOServiceListener接口，实现上调用的的是ConnectionManager中的packetsReady()来开始处理数据

此时的packet ：packetFrom=null，packetTo=null。

 

ClientConnectionManager.processSocketData方法中设置packet的一些属性：
此时: packetFrom=c2s@llooper/192.168.0.33_5222_192.168.0.33_38624, packetTo=sess-man@llooper

ClientConnectionManager.processSocketData(XMPPIOService<Object>serv)
    JID id = serv.getConnectionId(); //c2s@llooper/192.168.0.33_5222_192.168.0.33_38624
    p.setPacketFrom(id); //packetFrom 设置为onnectionId
    p.setPacketTo(serv.getDataReceiver()); //packetTo 设置为sess-man --> SessionManager 
    addOutPacket(p);//将会委托给父 MessageRouter 路由
    
}

//packet 被设置上一些源信息，和目的地信息，接下来，这个数据包将会委托给父 MessageRouter 帮忙路由到 SessionManager组件中进行处理
packet = (tigase.server.Message) from=c2s@llooper/192.168.0.33_5222_192.168.0.33_38624, to=sess-man@llooper, DATA=<message xmlns="jabber:client" id="44grM-176" type="chat" to="llooper@llooper"><thread>SWjZv5</thread><composing xmlns="http://jabber.org/protocol/chatstates"/></message>, SIZE=170, XMLNS=jabber:client, PRIORITY=NORMAL, PERMISSION=NONE, TYPE=chat

 

packet = from=c2s@llooper/192.168.0.33_5222_192.168.0.33_38624, to=sess-man@llooper, DATA=<message to="admin@llooper" type="chat" id="2jePE-253" xmlns="jabber:client"><thread>7VKMRq</thread><composing xmlns="http://jabber.org/protocol/chatstates"/></message>, SIZE=168, XMLNS=jabber:client, PRIORITY=NORMAL, PERMISSION=NONE, TYPE=chat

 

2、MessageRouter.processPacket(Packet packet)部分代码如下：

 

//我们不会处理没有目标地址的数据包,只是丢弃它们并写一个日志消息
if (packet.getTo() == null) {
    log.log(Level.WARNING, "Packet with TO attribute set to NULL: {0}", packet);
    return;
}   


//它不是一个服务发现包，我们必须找到一个处理组件
//下面的代码块是“快速”找到一个组件if

//这个包TO 组件ID,格式在以下一项:
// 1。组件名+“@”+默认域名
// 2。组件名+“@”+任何虚拟主机名
// 3。组件名+ "."+默认域名
// 4。组件名+ "."+任何虚拟主机名

ServerComponent comp = getLocalComponent(packet.getTo()); //SessionManager
comp.processPacket(packet, results);

 3、SessionManager.processPacket(final Packet packet)处理，有要代码如下。 例如A->B,这样做的目的是为了首先确定用户A有权限发送packet，然后是确定用户B有权限接收数据。如果用户B不在线，那么离线消息处理器会把packet保存到数据库当中。

//XMPPResourceConnection session——用户会话保存所有用户会话数据，并提供对用户数据存储库的访问。它只允许在会话的生命周期内将信息存储在永久存储或内存中。如果在分组处理时没有联机用户会话，则此参数可以为空。
XMPPResourceConnection conn = getXMPPResourceConnection(packet);
//现在要走SessionManager的处理函数,主要是走插件流程,插件在Tigase中也是一个重要的组成,入口就是在这里,SM plugin
processPacket(packet, conn);

   插入下SM plugin 流程说明 :

这个设计有一个惊人的结果。如果你看下面的图片，显示了两个用户之间的通信，你可以看到数据包被复制了两次才送到最终目的地: 

会话管理器(SessionManager)必须对数据包进行两次处理。第一次以用户A的名义将其作为传出包进行处理，第二次以用户B的名义将其作为传入包进行处理。
这是为了确保用户A有权限发送一个包，所有的processor都应用到packet上，也为了确保用户B有权限接收packet，所有的processor都应用到packet了。例如，如果用户B是脱机的，那么有一个脱机消息processor应该将包发送到数据库，而不是用户B。

 

protected XMPPResourceConnection getXMPPResourceConnection(Packet p) {
        XMPPResourceConnection conn = null;
        
        //首先根据这个包的发起者,来查找他的连接资源类,找不到则找接收者的资源类
        JID    from = p.getPacketFrom();
        if (from != null) {
            conn = connectionsByFrom.get(from);
            if (conn != null) {
                return conn;
            }
        }

        //这个接收者它可能是这个服务器上某个用户的消息,让我们为这个用户查找已建立的会话
        JID to = p.getStanzaTo();

        if (to != null) {
            if (log.isLoggable(Level.FINEST)) {
                log.finest("Searching for resource connection for: " + to);
            }
            conn = getResourceConnection(to);
        } else {

            // Hm, not sure what should I do now....
            // Maybe I should treat it as message to admin....
            log.log(Level.INFO,
                    "Message without TO attribute set, don''t know what to do wih this: {0}", p);
        }    // end of else

        return conn;
    }
    
    
protected void processPacket(Packet packet, XMPPResourceConnection conn) {

    ...
    packet.setPacketTo(getComponentId()); //sess-man@llooper
    ...

    if (!stop) {
        //授权匹配的processor处理packet
        walk(packet, conn);
        try {
            if ((conn != null) && conn.getConnectionId().equals(packet.getPacketFrom())) {
                handleLocalPacket(packet, conn);
            }
        } catch (NoConnectionIdException ex) {
            ...
        }
    }
    
    ...
}

packetTo被设置为组件ID（sess-man@llooper），其值原先也是这个。
其中walk(packet, conn)方法，匹配处理器（授权）。对于message，此处匹配到的processor是amp和message-carbons，message-carbons没有怎么处理，主要是amp在处理,packet被塞amp的队列中等待处理。

private void walk(final Packet packet, final XMPPResourceConnection connection) {

        for (XMPPProcessorIfc proc_t : processors.values()) {
            XMPPProcessorIfc processor = proc_t;
            //根据element和xmlns，授权匹配成功的processor
            Authorization    result    = processor.canHandle(packet, connection);

            if (result == Authorization.AUTHORIZED) {
                ....
            
                ProcessingThreads pt = workerThreads.get(processor.id());

                if (pt == null) {
                    pt = workerThreads.get(defPluginsThreadsPool);
                }
                //packet 放到(addItem)授权了的processor的队列
                if (pt.addItem(processor, packet, connection)) {
                    packet.processedBy(processor.id());
                } else {

                    ...
                }
            } else {
                ...
            }
        }   
    }

WorkerThread.run() 从队列中取出packet，由SessionManager.process(QueueItem item)给amp处理。

SessionManager.pocess(QueueItem item) 如下：

@Override
public void process(QueueItem item) {
    
    XMPPProcessorIfc processor = item.getProcessor();

    try {
        //由授权的 processor 处理 packet
        processor.process(item.getPacket(), item.getConn(), naUserRepository,local_results, plugin_config.get(processor.id()));
        if (item.getConn() != null) {
            setPermissions(item.getConn(), local_results);
        }
        addOutPackets(item.getPacket(), item.getConn(), local_results);
    } catch (PacketErrorTypeException e) {
        ...
    } catch (XMPPException e) {
        ...
    }
}


//其中processor.process（）------> MessageAmp.process()，如下：

@Override
public void process(Packet packet, XMPPResourceConnection session,
        NonAuthUserRepository repo, Queue results, Map settings) throws XMPPException {
    if (packet.getElemName() == "presence") {
        ...
        
    } else {
        Element amp = packet.getElement().getChild("amp", XMLNS);

        if ((amp == null) || (amp.getAttributeStaticStr("status") != null)) {
            messageProcessor.process(packet, session, repo, results, settings);
        } else {
            ...
    }
}

// 其中messageProcessor.process（） --------> Message.process()，如下


@Override
public void process(Packet packet, XMPPResourceConnection session,
        NonAuthUserRepository repo, Queue results, Map settings) throws XMPPException {

    ...
    try {
        ...
        // 在比较JIDs之前，记住要去除资源部分
        id = (packet.getStanzaFrom() != null)
                ? packet.getStanzaFrom().getBareJID()
                : null;

        // 检查这是否是来自客户端的数据包
        if (session.isUserId(id)) {
            // 这是来自这个客户端的数据包，最简单的操作是转发到它的目的地:
            // Simple clone the XML element and....
            // ... putting it to results queue is enough
            results.offer(packet.copyElementOnly());

            return;
        }

        
    } catch (NotAuthorizedException e) {
        ...
    }    // end of try-catch
}

检查stanzaFfrom与session匹配通过后，将packet.copyElementOnly()放到results中，作后续投递，原来的packet 就丢弃了。
此时投递的packet ：packetFrom=null，packetTo=null。

packet在SessionManager.addOutPacket(Packet packet)中判断packetFrom是否为空，为空则将其设置为ComponentId（此处为sess-man@llooper），然后调用父类（AbstractMessageReceiver.java) 的addOutPacket(packet)方法塞到out_queue 队列中。
此时packet:：packetFrom=sess-man@llooper，packetTo=null。

 

4、上层组件MessageRouter处理,把packet塞到in_queues. 又回到了MessageRouter.processPacket(Packet packet)处理:

 
不同的是 PacketTo为空，packet.getTo()的返回值是stanzaTo。
getLocalComponent(packet.getTo());方法根据stanzaTo与compId、comp name、Component都匹配不到。
此时packet会给组件SessionManager处理，Packet will be processed by: sess-man@llooper，由AbstractMessageReceiver的非阻塞性方法addPacketNB(Packet packet)加入到in_queues。

 

 5、第二次来到SessionManager.processPacket(final Packet packet)处理。不同的是在getXMPPResourceConnection(packet)方法中，
conn = connectionsByFrom.get(from)返回值是null，所以是根据stanzaTo取获取接收方的session，返回接收方连接的Connection。

protected XMPPResourceConnection getXMPPResourceConnection(Packet p) {
    XMPPResourceConnection conn = null;
    JID                    from = p.getPacketFrom();

    if (from != null) {
        conn = connectionsByFrom.get(from);
        if (conn != null) {
            return conn;
        }
    }

    // It might be a message _to_ some user on this server
    // so let's look for established session for this user...
    JID to = p.getStanzaTo();

    if (to != null) {
        ...
        conn = getResourceConnection(to);
    } else {

        ...
    }    // end of else

    return conn;
}

 6、如同步骤3,此时packet作为一个以用户B的名义将其作为传入包进行处理。

然后packetTo被设置为组件ID（sess-man@llooper)

此时packet: packetFrom = sess-man@llooper，packetTo =sess-man@llooper。

之后packet又经walk(packet, conn)方法，匹配处理器（授权），扔给amp处理。

 如同前面: 直到Message.process()，如下：

@Override
public void process(Packet packet, XMPPResourceConnection session,
        NonAuthUserRepository repo, Queue<Packet> results, Map<String, Object> settings) throws XMPPException {

    // For performance reasons it is better to do the check
    // before calling logging method.
    if (log.isLoggable(Level.FINEST)) {
        log.log(Level.FINEST, "Processing packet: {0}, for session: {1}", new Object[] {
                packet,
                session });
    }

    // You may want to skip processing completely if the user is offline.
    if (session == null) {
        processOfflineUser( packet, results );
        return;
    }    // end of if (session == null)
    try {

        // Remember to cut the resource part off before comparing JIDs
        BareJID id = (packet.getStanzaTo() != null)
                ? packet.getStanzaTo().getBareJID()
                : null;

        // Checking if this is a packet TO the owner of the session
        if (session.isUserId(id)) {
            if (log.isLoggable(Level.FINEST)) {
                log.log(Level.FINEST, "Message 'to' this user, packet: {0}, for session: {1}",
                        new Object[] { packet,
                        session });
            }

            if (packet.getStanzaFrom() != null && session.isUserId(packet.getStanzaFrom().getBareJID())) {
                JID connectionId = session.getConnectionId();
                if (connectionId.equals(packet.getPacketFrom())) {
                    results.offer(packet.copyElementOnly());
                    // this would cause message packet to be stored in offline storage and will not
                    // send recipient-unavailable error but it will behave the same as a message to
                    // unavailable resources from other sessions or servers
                    return;
                }
            }

            // Yes this is message to 'this' client
            List<XMPPResourceConnection> conns = new ArrayList<XMPPResourceConnection>(5);

            // This is where and how we set the address of the component
            // which should rceive the result packet for the final delivery
            // to the end-user. In most cases this is a c2s or Bosh component
            // which keep the user connection.
            String resource = packet.getStanzaTo().getResource();

            if (resource == null) {

                // If the message is sent to BareJID then the message is delivered to
                // all resources
                conns.addAll(getConnectionsForMessageDelivery(session));
            } else {

                // Otherwise only to the given resource or sent back as error.
                XMPPResourceConnection con = session.getParentSession().getResourceForResource(
                        resource);

                if (con != null) {
                    conns.add(con);
                }
            }

            // MessageCarbons: message cloned to all resources? why? it should be copied only
            // to resources with non negative priority!!

            if (conns.size() > 0) {
                for (XMPPResourceConnection con : conns) {
                    Packet result = packet.copyElementOnly();

                    result.setPacketTo(con.getConnectionId());

                    // In most cases this might be skept, however if there is a
                    // problem during packet delivery an error might be sent back
                    result.setPacketFrom(packet.getTo());

                    // Don't forget to add the packet to the results queue or it
                    // will be lost.
                    results.offer(result);
                    if (log.isLoggable(Level.FINEST)) {
                        log.log(Level.FINEST, "Delivering message, packet: {0}, to session: {1}",
                                new Object[] { packet,
                                con });
                    }
                }
            } else {
                // if there are no user connections we should process packet
                // the same as with missing session (i.e. should be stored if
                // has type 'chat'
                processOfflineUser( packet, results );
            }

            return;
        }    // end of else

        // Remember to cut the resource part off before comparing JIDs
        id = (packet.getStanzaFrom() != null)
                ? packet.getStanzaFrom().getBareJID()
                : null;

        // Checking if this is maybe packet FROM the client
        if (session.isUserId(id)) {

            // This is a packet FROM this client, the simplest action is
            // to forward it to is't destination:
            // Simple clone the XML element and....
            // ... putting it to results queue is enough
            results.offer(packet.copyElementOnly());

            return;
        }

        // Can we really reach this place here?
        // Yes, some packets don't even have from or to address.
        // The best example is IQ packet which is usually a request to
        // the server for some data. Such packets may not have any addresses
        // And they usually require more complex processing
        // This is how you check whether this is a packet FROM the user
        // who is owner of the session:
        JID jid = packet.getFrom();

        // This test is in most cases equal to checking getElemFrom()
        if (session.getConnectionId().equals(jid)) {

            // Do some packet specific processing here, but we are dealing
            // with messages here which normally need just forwarding
            Element el_result = packet.getElement().clone();

            // If we are here it means FROM address was missing from the
            // packet, it is a place to set it here:
            el_result.setAttribute("from", session.getJID().toString());

            Packet result = Packet.packetInstance(el_result, session.getJID(), packet
                    .getStanzaTo());

            // ... putting it to results queue is enough
            results.offer(result);
        }
    } catch (NotAuthorizedException e) {
        log.log(Level.FINE, "NotAuthorizedException for packet: " + packet + " for session: " + session, e);
        results.offer(Authorization.NOT_AUTHORIZED.getResponseMessage(packet,
                "You must authorize session first.", true));
    }    // end of try-catch
}

检查stanzaTo与session匹配通过后，根据session拿到接收方所有的连接（可能多端登陆），然后Packet result = packet.copyElementOnly()生成新的packet（原packet丢弃了），并将packetTo设置为接收方连接的ConnectionId（例如：c2s@llooper/192.168.0.33_5222_192.168.0.33_38624），通过addOutPacket()方法塞到out_queue队列。
此时packet：packetFrom = sess-man@llooper，packetTo =c2s@llooper/192.168.0.33_5222_192.168.0.33_38624。

7、 如同前面步骤2,不同的是根据packetTo匹配到组件 c2s@llooper

8、 组件 c2s@llooper 从queue中取出packet，分发到目的地

public void processPacket(final Packet packet) {
    ...
    if (packet.isCommand() && (packet.getCommand() != Command.OTHER)) {
        ...
    } else {
        // 把packet 发送给客户端
        if (!writePacketToSocket(packet)) {

            ...
            
        }
    }    // end of else
}

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