Modules are discrete units of software (binary and source). Binary modules are instantiated at run time and these instantiations are commonly called components and connectors. A given module may contain the specifications for several component types and connector types. The component (instances) may be of a fixed number in some situations. For example, a Web server executable, when launched, results in a single Web server component instance. The Web server module is the binary code that exists as a set of program files. The Web server component is a running instance of the Web server.

I have seen some confusion over the use of the terms module, component, and connector. A module is a discrete unit of design that is composed of a hidden set of elements and a set of shared elements. Modules have high internal cohesion and low external coupling. Modules may represent the physical packaging of the application's binary code, which can be described further by component types and connector types. Components and connectors describe the physical instantiation of a system. The term component is often used to mean a component type or module. A module refers to a unit of software that can be designed, implemented, and compiled into a deliverable executable system or subsystem; it is a unit of execution. A component is a runtime entity, the definition of which exists in a module. A classic modular architecture is a client-server system. The client and the server are two modules. The server exports some elements such as a set of publicly visible relational database tables and views. The client knows about this publicly visible schema. The client and server are unaware of the internal composition of the other.

           1. 把原有使用openh323的程序升级到h323plus,利用其h.460.18 ,19 或其上的Nat功能,配合公网的GnuGK来实现内外网的穿透.

           2. 用另一个MCU直接放到公网上代理内网会议.
          
（部门还有人提出什么修改openh323底层通信部分以用自己的连接发送h323数据，或另写一套能完全代理h323的协议用自己创建的TCP ，UDP来传输之类的方案。我觉得对于人手有限的小团队来说都不现实。看上头怎么决定吧;( ）

比较这两方案，前者 h323plus对h460.18,19的支持虽然是有了，但它给的例子在我们实验室里跑起来就出错，我觉得它目前好像不是很完善，估计到他完善起立还需些时间。而第二种方案比较方便,不必要改动过多代码即可在短时间内实现.
       具体做法如下:

                1.内网MCU  (以后称为mcuA ) 召开一个会议,内网的EP参加该 MCU上的会议.
                2. mcuA 通过邀请 外网MCU(以后称为mcuB) 参加该会议.
                          这个时候会发生以下通信过程:
                                       1) 信令通道建立:mcuA呼叫mcuB ,他们间建立了点对点的h.225及h.245通信.
                                       2) 媒体逻辑通道建立: 这里的Rtp通道其实是由UDP来实现的,所以只要mcuA先发起对mcuB的数据传输,网关上的pinhold就开了，那么反方向的数据即可由mcuB到mcuA.

                                       3) T120通道建立:T120是条TCP通道,通常建立时mcuA,B 双方都会同时试图创建到对方的这条通道,只要其中一条建立成功即可,一般情况下只有mcuA的建立过程能通过防火墙或网关.
                3. 这时内外网的音频视频数据都可互相传输了。
                4. 外网的EP只要拨到公网的mcuB即可参加mcuA上召开的会议了。
                5. 至于会议管理，可以在mcuA和B间用扩展h.245来实现，这点就不难了。
            


 估计很多同行也都有为h.323内外网穿透和防火墙的问题伤脑筋,我想这个方案可以给大家一点帮助吧.

OPAL VOIP： 保留Opal现有H323功能，但重点明显是要向兼容SIP方向发展；其网站介绍为：

OPAL implements the commonly used protocols used to send voice, video and fax data over IP networks. Originally part of the OpenH323 project, OpalVoip has grown to include SIP and IAX2.

h323plus：在原有OpenH323基础上继续完善ITU的H323系列的协议，其介绍为：

            The H.323 Plus project intends to do much more than simply provide a new home for open source H.323 developers. Developers have told us they intend to work to provide significant new enhancements to the very successful H.323 systems deployed worldwide. For example, NAT/FW traversal, instant messaging, presence, and many other enhancements are already in progress or being planned. Further, the open source community has expressed interest to us to enable more collaborative features to H.323, including such things as application sharing, whiteboarding, and other capabilities.（可惜，这些功能OPAL将不能用到了）

至于底层的pwlib（即ptlib）估计暂时还会保持一致。

分家后期邮件列表也将分开：

https://lists.sourceforge.net/lists/listinfo/opalvoip-devel

http://lists.packetizer.com/mailman/listinfo/h323plus

网站地址分别：

http://www.h323plus.org/

http://www.opalvoip.org/

对于我们可能会更关心OpenH323的主要开发者 Simon 的以下言论：  

The following projects are currently planned to be supported within H323plus.

OpenMCU (including remote conference controls) OpenAM  (upgraded to support VoiceMail support to GnuGk) MyPhone OhPhone

The Library is almost drop-in replacable with the existing OpenH323 and contains numerous enhancements including video plugins (compatible with

Opal) and large amount of new work not currently supported in Opal.

Some of the new work now available in h323plus H.230  Conference Controls (incl tunneling GCC (T.124))

H.239  Application Sharing

H.249  Extended user inputs

H.341  SNMP support

H.350  LDAP WhitePages

H.460  Numerous custom Extensibility features

        Text Messaging (working doc ITU),

        Follow Me,

        PDI (Personal Data Interchange)

H.460.9 RealTime QoS Measurements

Video Plugins (fully compatible with Opal)

H.235 Plugins (for external Biometric and smartcard authenticators) QoS Capability negotiation Conference Controls capability advertisement.

New work planned/proposed

H.460.presence

H.460.18/19 Nat Traversal

Video on Demand project (using H.239/H.249)

We can also provide full consulting service support for existing openH323 based projects as well as provide assistance in migration of these projects to h323plus.