Windows RPC Demo实现
本文参考并整理以下相关文章
1. 《远程过程调用》 -百度百科
2. 《RPC 编程》 -http://www.ibm.com/developerworks/cn/aix/library/au-rpc_programming/
3. 《微软官方参考教程》 -http://blog.csdn.net/swanabin/article/details/18766209
1 概念
RPC：全称是“远程过程调用协议（Remote Procedure Call Protocol)”，它是一种通过网络从远程计算机程序上请求服务，而不需要了解底层网络技术的协议。RPC协议假定某些传输协议的存在，如TCP、UDP或者命名管道，为通信程序之间携带信息数据。在OSI网络通信模型中，RPC跨越了传输层和应用层。RPC使得开发包括网络分布式多程序在内的应用程序更加容易。
2 原理
RPC采用客户机/服务器模式。请求程序就是一个客户机，而服务提供程序就是一个服务器。首先，客户机调用进程发送一个有进程参数的调用信息到服务进程，然后等待应答信息。在服务器端，进程保持睡眠状态直到调用信息的到达为止。当一个调用信息到达，服务器获得进程参数，计算结果，发送答复信息，然后等待下一个调用信息，最后，客户端调用进程接收答复信息，获得进程结果，然后调用执行继续进行[1]。
不同的厂商实现了不同的RPC协议，显然我们此次用的是微软提供的。
3 实现
RPC的接口标准使用了IDL（Interface Description Language接口描述语言）语言标准描述，熟悉COM接口的用户应该一眼就能看出，因为它们的接口风格非常相似。相应微软的编译器是MIDL，通过IDL文件来定义RPC客户端与服务器之间的通信接口，只有通过这些接口客户端才能访问服务器。
下面我们就通过一个Demo来具体解释一下RCP编程的具体过程。
开发环境：Windows 7 SP1旗舰版
Visual Studio 2005
首先我们需要建立一个工程，我们选择Win32 Console程序RPCServer.exe，然后定义接口文件：IDL文件。
3.1 IDL文件
在工程中添加一个IDL文件，IDL文件由一个或多个接口定义组成，每一个接口定义都有一个接口头和一个接口体。接口头包含了使用此接口的信息，如UUID 。这此信息封装一对中括号之内。之后是interface关键字和接口名。接口体包含了C 风格的数据类型、函数原型和带属性的参数。这此参数的属性描述了数据如何在网络上传送。此例中，定义头中包含了uuid和版本号。版本号作兼容之用。客户端、服务端的版本只有兼容，才可以连接。
RPCServer.idl：
<span> 1</span> import <span>"</span><span>oaidl.idl</span><span>"</span><span>;
</span><span> 2</span> import <span>"</span><span>ocidl.idl</span><span>"</span><span>;
</span><span> 3</span> import <span>"</span><span>SelfDefine.h</span><span>"</span><span>;
</span><span> 4</span><span> 5</span><span>[
</span><span> 6</span> uuid( 551d88b0-b831-<span>4283</span>-a1cd-<span>276559e49f28 ),
</span><span> 7</span> version( <span>1.0</span><span> )
</span><span> 8</span><span>]
</span><span> 9</span><span>10</span><span>interface</span><span> RPCServer
</span><span>11</span><span>{
</span><span>12</span> error_status_t GetServerName( [<span>out</span>,size_is(len)]<span>char</span> *<span>pszName,
</span><span>13</span> [<span>in</span>]<span>long</span><span> len );
</span><span>14</span> error_status_t Add( [<span>in</span>]<span>long</span><span> num1,
</span><span>15</span> [<span>in</span>]<span>long</span><span> num2,
</span><span>16</span> [<span>out</span>]<span>long</span>*<span> rtn );
</span><span>17</span><span> error_status_t ShutDown();
</span><span>18</span> }
定义了IDL文件之后，可以直接编译该IDL文件，但是编译该文件之后并没有自动生成相应的服务端和客户端的C文件。如果要达到自动生成这些C文件的目的，需要配置ACF文件。
3.2 ACF文件
ACF文件可以使用户定义自己的客户端或服务端的RPC接口。例如，如果你的客户端程序包含了一个复杂的数据结构，此数据结构只在本地机上有意义，那么你就可以在ACF文件中指定如何描述独立于机器的数据结构，使用数据结构用于远程过程调用。下面我们在ACF文件中定义一个handle类型，用来代表客户端与服务端的连接。[implicit_handle]属性允许客户端程序为它的远程过程调用选择一个服务端。ACF定义了此句柄为handle_t类型(MIDL基本数据类型)。MIDL编译器将绑定ACF文件指定的句柄名字RPCServer_IfHandle，放在生成的头文件RPCServer.h中。
RPCServer.acf：
<span>1</span>
<span>[
</span>
<span>2</span>
<span> implicit_handle (handle_t RPCServer_IfHandle)
</span>
<span>3</span>
<span>]
</span>
<span>4</span>
<span>5</span>
<span>interface</span>
<span> RPCServer
</span>
<span>6</span>
<span>{
</span>
<span>7</span> }
当编译这些文件RPCServer.idl时，确保RPCServer.idl和RPCServer.acf在同一文件夹中。编译完成会生成三个文件：RPCServer.h、RPCServer_s.c、RPCServer_c.c，其中RPCServer.h、RPCServer_s.c供服务端使用，RPCServer_h.h、RPCServer_c.c供客户端使用。
3.3 SelfDefine.h文件
使用MIDL单独编译idl文件没有问题，但是在vs2005整个工程中编译时会提示如下所示错误：
fatal error C1189: #error : You need a Windows 2000 or later to run this stub because it uses these features:
该错误的官方原因现还不太清楚，解决该错误的就需要新建SelfDefine.h文件并定义如下宏：
#undef TARGET_IS_NT50_OR_LATER
#define TARGET_IS_NT50_OR_LATER 1
然后在idl文件中导入该头文件（import "SelfDefine.h";）。
SelfDefine.h：
<span>1</span>
<span>#ifndef _SELF_DEFINE_H_
</span>
<span>2</span>
<span>#define</span> _SELF_DEFINE_H_
<span>3</span><span>4</span><span>#undef</span> TARGET_IS_NT50_OR_LATER
<span>5</span><span>#define</span> TARGET_IS_NT50_OR_LATER 1
<span>6</span><span>7</span> typedef <span>long</span><span> MyHandle;
</span><span>8</span><span>9</span><span>#endif</span>
SelfDefine.h文件中还多了一句typedef long MyHandle;，如果不加入类似语句，MIDL编译器就会提示如下错误，真不知道这是什么原因。
error MIDL2183 : unexpected end of file found : SelfDefine.h
有了RPC接口文件，我们就可以编写服务程序，提供接口中定义的服务。
3.4 服务器端
根据用户的编码风格，可以在一个或多个独立的文件中实现这些远程过程。Demo中使用RPCServer.cpp源文件编写主要的服务端代码。
服务端调用RPC运行库函数RpcServerUseProtseqEp和RpcServerRegisterIf来建立有效的服务端。
服务端必须包含两个内存分配函数。这两个函数被服务端程序调用：midl_user_allocate和midl _user_free。这两个函数在服务端分配和释放内存，一般情况下midl _user_allocate和midl_user_free都会简单地封装C库函数malloc和free。
RPCServer.cpp：
<span> 1</span> #include <span>"</span><span>stdafx.h</span><span>"</span><span> 2</span> #include <Windows.h>
<span> 3</span> #include <stdlib.h>
<span> 4</span> #include <stdio.h>
<span> 5</span> #include <span>"</span><span>RPCServer_h.h</span><span>"</span><span> 6</span><span> 7</span><span>#pragma</span> comment(lib, "Rpcrt4.lib")
<span> 8</span><span> 9</span><span>long</span><span> StartService();
</span><span>10</span><span>11</span><span>int</span> main( <span>int</span> argc, <span>char</span>*<span> argv[] )
</span><span>12</span><span>{
</span><span>13</span><span> StartService();
</span><span>14</span><span>return</span><span>0</span><span>;
</span><span>15</span><span>}
</span><span>16</span><span>17</span><span>void</span> __RPC_FAR *<span> __RPC_USER midl_user_allocate( size_t len )
</span><span>18</span><span>{
</span><span>19</span><span>return</span> (<span>malloc</span><span>(len) );
</span><span>20</span><span>}
</span><span>21</span><span>void</span> __RPC_USER midl_user_free( <span>void</span> __RPC_FAR *<span>ptr )
</span><span>22</span><span>{
</span><span>23</span><span>free</span><span>( ptr );
</span><span>24</span><span>}
</span><span>25</span><span>26</span><span>long</span><span> StartService()
</span><span>27</span><span>{
</span><span>28</span> unsigned <span>char</span> pszProtocolSequence[] = <span>"</span><span>ncacn_np</span><span>"</span><span>;
</span><span>29</span> unsigned <span>char</span> *pszSecurity =<span> NULL;
</span><span>30</span> unsigned <span>char</span> pszEndPoint[] = <span>"</span><span>pipeRPCServer</span><span>"</span>; <span>//</span><span>命名管道</span><span>31</span><span>32</span> RPC_STATUS rpcStats =<span> RpcServerUseProtseqEp( pszProtocolSequence,
</span><span>33</span><span> RPC_C_LISTEN_MAX_CALLS_DEFAULT,
</span><span>34</span><span> pszEndPoint,
</span><span>35</span><span> pszSecurity );
</span><span>36</span><span>if</span><span> ( rpcStats )
</span><span>37</span><span> exit( rpcStats );
</span><span>38</span><span>39</span> rpcStats =<span> RpcServerRegisterIf( RPCServer_v1_0_s_ifspec, NULL, NULL );
</span><span>40</span><span>if</span><span> ( rpcStats )
</span><span>41</span><span> exit( rpcStats );
</span><span>42</span><span>43</span> unsigned <span>int</span> fDontWait = <span>false</span><span>;
</span><span>44</span> rpcStats = RpcServerListen( <span>1</span><span>, RPC_C_LISTEN_MAX_CALLS_DEFAULT, fDontWait );
</span><span>45</span><span>if</span><span> ( rpcStats )
</span><span>46</span><span> exit( rpcStats );
</span><span>47</span><span>48</span><span>return</span><span>0</span><span>;
</span><span>49</span><span>}
</span><span>50</span><span>51</span><span>void</span><span> StopService()
</span><span>52</span><span>{
</span><span>53</span><span> RPC_STATUS rpcStatus;
</span><span>54</span> rpcStatus =<span> RpcMgmtStopServerListening( NULL );
</span><span>55</span> rpcStatus =<span> RpcServerUnregisterIf( NULL, NULL, FALSE );
</span><span>56</span><span>}
</span><span>57</span><span>58</span><span>error_status_t GetServerName(
</span><span>59</span><span>/*</span><span> [size_is][out] </span><span>*/</span> unsigned <span>char</span> *<span>pszName,
</span><span>60</span><span>/*</span><span> [in] </span><span>*/</span><span>long</span><span> len)
</span><span>61</span><span>{
</span><span>62</span> strncpy( (<span>char</span>*)pszName, <span>"</span><span>RPCServer</span><span>"</span><span>, len );
</span><span>63</span> pszName[len-<span>1</span>] = <span>‘</span><span> </span><span>‘</span><span>;
</span><span>64</span> printf( <span>"</span><span>服务已经启动！
</span><span>"</span><span> );
</span><span>65</span><span>return</span><span>0</span><span>;
</span><span>66</span><span>}
</span><span>67</span><span>68</span><span>error_status_t Add(
</span><span>69</span><span>/*</span><span> [in] </span><span>*/</span><span>long</span><span> num1,
</span><span>70</span><span>/*</span><span> [in] </span><span>*/</span><span>long</span><span> num2,
</span><span>71</span><span>/*</span><span> [out] </span><span>*/</span><span>long</span> *<span>rtn)
</span><span>72</span><span>{
</span><span>73</span> *rtn = num1 +<span> num2;
</span><span>74</span><span>return</span><span>0</span><span>;
</span><span>75</span><span>}
</span><span>76</span><span>77</span> error_status_t ShutDown( <span>void</span><span>)
</span><span>78</span><span>{
</span><span>79</span><span> StopService();
</span><span>80</span> printf( <span>"</span><span>服务已经关闭！
</span><span>"</span><span> );
</span><span>81</span><span>return</span><span>0</span><span>;
</span><span>82</span> }
3.5 客户端
类似服务器，我们也需要新建一个Win32 Console程序-RPCClient.exe，作为客户端。
客户端程序调用运行时函数来建立一个指向服务端的句柄，在远程过程调用完成后，释放这个句柄。函数RpcStringBindingCompose()生成一个以字符串表示的绑定句柄(bindinghandle)并为此字符串分配内存。因为服务指定了使用本地命名管道作为网络通信介质，所以客户端在建立于服务器的连接时也必须指定相同的管道参数。
函数RpcBindingFromStringBinding()从字符串表示的绑定句柄，创建了一个服务绑定句柄RPCServer_IfHandle。绑定之后客户端便可以请求服务器的服务（调用服务器的函数）。
RPCClient.cpp：
<span> 1</span> #include <span>"</span><span>stdafx.h</span><span>"</span><span> 2</span> #include <windows.h>
<span> 3</span> #include <stdlib.h>
<span> 4</span> #include <stdio.h>
<span> 5</span> #include <span>"</span><span>..RPCServerRPCServer_h.h</span><span>"</span><span> 6</span> #include <span>"</span><span>..RPCServerRPCServer_c.c</span><span>"</span><span> 7</span><span> 8</span><span>#pragma</span> comment( lib, "Rpcrt4.lib" )
<span> 9</span><span>10</span><span>void</span><span> CallServerFuntions();
</span><span>11</span><span>12</span><span>int</span> main(<span>int</span> argc, <span>char</span>*<span> argv[])
</span><span>13</span><span>{
</span><span>14</span> unsigned <span>char</span> *pszUuid =<span> NULL;
</span><span>15</span> unsigned <span>char</span> pszProtocolSequence[] = <span>"</span><span>ncacn_np</span><span>"</span><span>;
</span><span>16</span> unsigned <span>char</span> *pszNetworkAddress =<span> NULL;
</span><span>17</span> unsigned <span>char</span> pszEndpoint[] = <span>"</span><span>pipeRPCServer</span><span>"</span><span>;
</span><span>18</span> unsigned <span>char</span> *pszOptions =<span> NULL;
</span><span>19</span> unsigned <span>char</span> *pszStringBinding =<span> NULL;
</span><span>20</span><span>21</span> RPC_STATUS rpcStatus =<span> RpcStringBindingCompose( pszUuid,
</span><span>22</span><span> pszProtocolSequence,
</span><span>23</span><span> pszNetworkAddress,
</span><span>24</span><span> pszEndpoint,
</span><span>25</span><span> pszOptions,
</span><span>26</span> &<span>pszStringBinding );
</span><span>27</span><span>if</span><span> ( rpcStatus )
</span><span>28</span><span> exit( rpcStatus );
</span><span>29</span><span>30</span> rpcStatus =<span> RpcBindingFromStringBinding( pszStringBinding,
</span><span>31</span> &<span>RPCServer_IfHandle );
</span><span>32</span><span>if</span><span> ( rpcStatus )
</span><span>33</span><span> exit( rpcStatus );
</span><span>34</span><span>35</span><span> RpcTryExcept
</span><span>36</span><span> {
</span><span>37</span><span> CallServerFuntions();
</span><span>38</span><span> }
</span><span>39</span> RpcExcept( <span>1</span><span> )
</span><span>40</span><span> {
</span><span>41</span> unsigned <span>long</span> ulCode =<span> RpcExceptionCode();
</span><span>42</span> printf( <span>"</span><span>抛出异常0x%lx = %ld。
</span><span>"</span><span>, ulCode, ulCode );
</span><span>43</span><span> }
</span><span>44</span><span> RpcEndExcept
</span><span>45</span><span>46</span> rpcStatus = RpcStringFree( &<span>pszStringBinding );
</span><span>47</span><span>if</span><span> ( rpcStatus )
</span><span>48</span><span> exit( rpcStatus );
</span><span>49</span><span>50</span> rpcStatus = RpcBindingFree( &<span>RPCServer_IfHandle );
</span><span>51</span><span>if</span><span> ( rpcStatus )
</span><span>52</span><span> exit( rpcStatus );
</span><span>53</span><span>return</span><span>0</span><span>;
</span><span>54</span><span>55</span><span>return</span><span>0</span><span>;
</span><span>56</span><span>}
</span><span>57</span><span>58</span><span>void</span> __RPC_FAR *<span> __RPC_USER midl_user_allocate( size_t len )
</span><span>59</span><span>{
</span><span>60</span><span>return</span> (<span>malloc</span><span>(len) );
</span><span>61</span><span>}
</span><span>62</span><span>void</span> __RPC_USER midl_user_free( <span>void</span> __RPC_FAR *<span>ptr )
</span><span>63</span><span>{
</span><span>64</span><span>free</span><span>( ptr );
</span><span>65</span><span>}
</span><span>66</span><span>67</span><span>void</span><span> CallServerFuntions()
</span><span>68</span><span>{
</span><span>69</span> unsigned <span>char</span> pszName[<span>64</span>] = {<span>0</span><span>};
</span><span>70</span> GetServerName( pszName, <span>64</span> ); <span>//</span><span>获取服务名称</span><span>71</span> printf( <span>"</span><span>Server Name is: %s
</span><span>"</span><span>, pszName );
</span><span>72</span><span>73</span><span>long</span> num1 = <span>2</span><span>;
</span><span>74</span><span>long</span> num2 = <span>2</span><span>;
</span><span>75</span><span>long</span> nSum = <span>0</span><span>;
</span><span>76</span> Add( num1, num2, &nSum ); <span>//</span><span>加法求值c</span><span>77</span> printf( <span>"</span><span>%d + %d = %d
</span><span>"</span><span>, num1, num2, nSum );
</span><span>78</span><span>79</span> ShutDown(); <span>//</span><span>关闭服务</span><span>80</span> }
具体函数的详细解释还需要参考MSDN，参政正确掌握RPC变成技巧。
3.6 运行结果
客户端分别调用了服务器的GetServerName()、Add()和Shutdown()函数，获取了服务器的名称、计算了两个数据的和，最后关闭了服务器。小小的Demo完成了RPC通信的整个过程，下图是Demo运行的效果图。
原文：http://www.cnblogs.com/wanghaiyang1930/p/4469222.html
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