XMPP 的<message/>節是使用基本的”push”方法來從一個地方到另一個地方得到消息。因為消息通常是不告知的，它們是一種”fire-and-forget”(發射后自尋目的)的機制來從一個地方到另一個地方快速獲取信息
消息節有五種不同的類型，通過 type 屬性來進行區分：例如 chat 類型為 chat 的消息在兩個實體間的實時對話中交換，例如兩個朋友之間的即時通訊聊天。除了 type 屬性外，消息節還包括一個 to 和 from 地址，並且也可以包含一個用於跟蹤目的的 id 屬性（我們在使用更為廣泛的 IQ 節中詳細的討論 IDs）。to 地址是預期接收人的
JabberID，from 地址是發送者的JabberID。from 地址不由發送客戶端提供，而是由發送者的服務器添加郵戳，以避免地址欺騙。
消息節有五種不同的類型，通過 type 屬性來進行區分：例如 chat 類型為 chat 的消息在兩個實體間的實時對話中交換，例如兩個朋友之間的即時通訊聊天。除了 type 屬性外，消息節還包括一個 to 和 from 地址，並且也可以包含一個用於跟蹤目的的 id 屬性（我們在使用更為廣泛的 IQ 節中詳細的討論 IDs）。to 地址是預期接收人的
JabberID，from 地址是發送者的JabberID。from 地址不由發送客戶端提供，而是由發送者的服務器添加郵戳，以避免地址欺騙。
在Tigase中，有兩個重要的組成,一個組件,二是插件,可以去官方網去看下他的架構介紹 https://docs.tigase.net/tigase-server/7.1.4/Development_Guide/html/#writePluginCode
例如最著名的組件的一個例子是MUC或PubSub。在Tigase中，幾乎所有東西實際上都是一個組件:會話管理器、s2s連接管理器、消息路由器等等,組件是根據服務器配置加載的，新的組件可以在運行時加載和激活。您可以輕松地替換組件實現，唯一要做的更改是配置條目中的類名。
Tigase 中定義一個最簡單的消息組件,需要實現MessageReceiver或繼承 extends AbstractMessageReceiver 類, MessageReceiver 的抽象類: AbstractMessageReceiver 子類 :
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、當客戶端發送的message消息到tigase服務端，每個一SOCKET連接都會被包裝成IOService對象，IOService包含一系列操作socket的方法（接收發送數據等），processSocketData()接收網絡數據，由tigase.net處理解析成xml對象，並將packet放到接收隊列receivedPackets中再調用serviceListener.packetsReady(this)。由於ConnectionManager實現IOServiceListener接口，實現上調用的的是ConnectionManager中的packetsReady()來開始處理數據
此時的packet ：packetFrom=null，packetTo=null。
ClientConnectionManager.processSocketData方法中設置packet的一些屬性：
此時: packetFrom=c2s@llooper/192.168.0.33_5222_192.168.0.33_38624, packetTo=sess-man@llooper
此時: 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 設置為onnectionId p.setPacketTo(serv.getDataReceiver()); //packetTo 設置為sess-man --> SessionManager addOutPacket(p);//將會委托給父 MessageRouter 路由 }
//packet 被設置上一些源信息，和目的地信息，接下來，這個數據包將會委托給父 MessageRouter 幫忙路由到 SessionManager組件中進行處理
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 = (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)部分代碼如下：
//我們不會處理沒有目標地址的數據包,只是丟棄它們並寫一個日志消息 if (packet.getTo() == null) { log.log(Level.WARNING, "Packet with TO attribute set to NULL: {0}", packet); return; } //它不是一個服務發現包，我們必須找到一個處理組件 //下面的代碼塊是“快速”找到一個組件if //這個包TO 組件ID,格式在以下一項: // 1。組件名+“@”+默認域名 // 2。組件名+“@”+任何虛擬主機名 // 3。組件名+ "."+默認域名 // 4。組件名+ "."+任何虛擬主機名 ServerComponent comp = getLocalComponent(packet.getTo()); //SessionManager comp.processPacket(packet, results);
3、SessionManager.processPacket(final Packet packet)處理，有要代碼如下。 例如A->B,這樣做的目的是為了首先確定用戶A有權限發送packet，然后是確定用戶B有權限接收數據。如果用戶B不在線，那么離線消息處理器會把packet保存到數據庫當中。
//XMPPResourceConnection session——用戶會話保存所有用戶會話數據，並提供對用戶數據存儲庫的訪問。它只允許在會話的生命周期內將信息存儲在永久存儲或內存中。如果在分組處理時沒有聯機用戶會話，則此參數可以為空。 XMPPResourceConnection conn = getXMPPResourceConnection(packet); //現在要走SessionManager的處理函數,主要是走插件流程,插件在Tigase中也是一個重要的組成,入口就是在這里,SM plugin processPacket(packet, conn);
插入下SM plugin 流程說明 :
這個設計有一個驚人的結果。如果你看下面的圖片，顯示了兩個用戶之間的通信，你可以看到數據包被復制了兩次才送到最終目的地:
會話管理器(SessionManager)必須對數據包進行兩次處理。第一次以用戶A的名義將其作為傳出包進行處理，第二次以用戶B的名義將其作為傳入包進行處理。
這是為了確保用戶A有權限發送一個包，所有的processor都應用到packet上，也為了確保用戶B有權限接收packet，所有的processor都應用到packet了。例如，如果用戶B是脫機的，那么有一個脫機消息processor應該將包發送到數據庫，而不是用戶B。
protected XMPPResourceConnection getXMPPResourceConnection(Packet p) { XMPPResourceConnection conn = null; //首先根據這個包的發起者,來查找他的連接資源類,找不到則找接收者的資源類 JID from = p.getPacketFrom(); if (from != null) { conn = connectionsByFrom.get(from); if (conn != null) { return conn; } } //這個接收者它可能是這個服務器上某個用戶的消息,讓我們為這個用戶查找已建立的會話 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) { //授權匹配的processor處理packet walk(packet, conn); try { if ((conn != null) && conn.getConnectionId().equals(packet.getPacketFrom())) { handleLocalPacket(packet, conn); } } catch (NoConnectionIdException ex) { ... } } ... }
packetTo被設置為組件ID（sess-man@llooper），其值原先也是這個。
其中walk(packet, conn)方法，匹配處理器（授權）。對於message，此處匹配到的processor是amp和message-carbons，message-carbons沒有怎么處理，主要是amp在處理,packet被塞amp的隊列中等待處理。
private void walk(final Packet packet, final XMPPResourceConnection connection) { for (XMPPProcessorIfc proc_t : processors.values()) { XMPPProcessorIfc processor = proc_t; //根據element和xmlns，授權匹配成功的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)授權了的processor的隊列 if (pt.addItem(processor, packet, connection)) { packet.processedBy(processor.id()); } else { ... } } else { ... } } }
WorkerThread.run() 從隊列中取出packet，由SessionManager.process(QueueItem item)給amp處理。
SessionManager.pocess(QueueItem item) 如下：
@Override public void process(QueueItem item) { XMPPProcessorIfc processor = item.getProcessor(); try { //由授權的 processor 處理 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 { ... // 在比較JIDs之前，記住要去除資源部分 id = (packet.getStanzaFrom() != null) ? packet.getStanzaFrom().getBareJID() : null; // 檢查這是否是來自客戶端的數據包 if (session.isUserId(id)) { // 這是來自這個客戶端的數據包，最簡單的操作是轉發到它的目的地: // 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 }
檢查stanzaFfrom與session匹配通過后，將packet.copyElementOnly()放到results中，作后續投遞，原來的packet 就丟棄了。
此時投遞的packet ：packetFrom=null，packetTo=null。
此時投遞的packet ：packetFrom=null，packetTo=null。
packet在SessionManager.addOutPacket(Packet packet)中判斷packetFrom是否為空，為空則將其設置為ComponentId（此處為sess-man@llooper），然后調用父類（AbstractMessageReceiver.java) 的addOutPacket(packet)方法塞到out_queue 隊列中。
此時packet:：packetFrom=sess-man@llooper，packetTo=null。
此時packet:：packetFrom=sess-man@llooper，packetTo=null。
4、上層組件MessageRouter處理,把packet塞到in_queues. 又回到了MessageRouter.processPacket(Packet packet)處理:
不同的是 PacketTo為空，packet.getTo()的返回值是stanzaTo。
getLocalComponent(packet.getTo());方法根據stanzaTo與compId、comp name、Component都匹配不到。
此時packet會給組件SessionManager處理，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、第二次來到SessionManager.processPacket(final Packet packet)處理。不同的是在getXMPPResourceConnection(packet)方法中，
conn = connectionsByFrom.get(from)返回值是null，所以是根據stanzaTo取獲取接收方的session，返回接收方連接的Connection。
conn = connectionsByFrom.get(from)返回值是null，所以是根據stanzaTo取獲取接收方的session，返回接收方連接的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、如同步驟3,此時packet作為一個以用戶B的名義將其作為傳入包進行處理。
然后packetTo被設置為組件ID（sess-man@llooper)
此時packet: packetFrom = sess-man@llooper，packetTo =sess-man@llooper。
之后packet又經walk(packet, conn)方法，匹配處理器（授權），扔給amp處理。
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 }
檢查stanzaTo與session匹配通過后，根據session拿到接收方所有的連接（可能多端登陸），然后Packet result = packet.copyElementOnly()生成新的packet（原packet丟棄了），並將packetTo設置為接收方連接的ConnectionId（例如：c2s@llooper/192.168.0.33_5222_192.168.0.33_38624），通過addOutPacket()方法塞到out_queue隊列。
此時packet：packetFrom = sess-man@llooper，packetTo =c2s@llooper/192.168.0.33_5222_192.168.0.33_38624。
7、 如同前面步驟2,不同的是根據packetTo匹配到組件 c2s@llooper
8、 組件 c2s@llooper 從queue中取出packet，分發到目的地
public void processPacket(final Packet packet) { ... if (packet.isCommand() && (packet.getCommand() != Command.OTHER)) { ... } else { // 把packet 發送給客戶端 if (!writePacketToSocket(packet)) { ... } } // end of else }
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