| Essential COM

, , . , . , . , , ¹. , , . a (method remoting) , .

ORPC (Object Remote Procedure Call - ). ORPC MS-RPC ( Microsoft), DCE (Distributed Computing Environment - ). MS-RPC , ( DLL) ( Security Support Provider DLL). . - UDP (User Datagram Protocol - ), ². , .

, (marshaling), o , . , . (marshaled state) . , , , , (serialized) . , .

. , . , . , , , , . . API- CoMarshalInterface, .

CoMarshalInterface . , API- CoUnmarshalInterface , , , CoUnmarshalInterface. CoMarshalInterface , . :

 typedef enum tagMSHCTX {     MSHCTX_INPROC = 4,          // in-process/same host          //  /         MSHCTX_LOCAL  = 0,         // out-of-process/same host          //  /         MSHCTX_NOSHAREDMEM = 1,          // 16/32 bit/same host          // 16/32- /         MSHCTX_DIFFERENTMACHINE = 2          // off-host          //    } MSHCTX;

, , MSHCTX. CoMarshalInterface :

 typedef enum tagMSHLFLAGS {     MSHLFLAGS_NORMAL,          // marshal once, unmarshal once          //      ,          MSHLFLAGS_TABLESTRONG,          // marshal  , unmarshal many          //      .          MSHLFLAGS_TABLEWEAK,          // marshal once, unmarshal many          //      ,          MSHLFLAGS_NOPING = 4,          // suppress dist. garbage collection          //          } MSHLFLAGS;

(normal) , (call marshaling), , , , CoMarshalInterface. (table) , CoMarshalInterface. .

, CoMarshalInterface IStream, . IStream - Read Write. CoMarshalInterface Write IStream, , . IStream (raw) , API- CreateStreamOnHGlobal:

 HRESULT CreateStreamOnHGlobal(     [in] HGLOBAL hglobal,         // pass null to autoalloc          //                [in] BOOL bFreeMemoryOnRelease,      [out] IStream **ppStm);

IStream :

 void UseRawMemoryToPrintString(void)  {     void *pv = 0;         // alloc memory          //          pv = malloc(13);      if (pv != 0) {         // write a string to the underlying memory          //                  memcpy(pv, "Hello, World", 13);         printf((const char*)pv);          // free all resources          //                free (pv);      }  }

, IStream memcpy:

 void UseStreamToPrintString(void)  {     IStream *pStm = 0;         // alloc memory and wrap behind an IStream interface          //                 IStream      HRESULT hr = CreateStreamOnHGlobal(0, TRUE, &pStm);      if (SUCCEEDED(hr)) {         // write a string to the underlying memory          //                  hr = pStm->Write("Hello. World", 13, 0);          assert (SUCCEEDED (hr));              // suck out the memory              //              HGLOBAL hglobal = 0;         hr == GetHglobalFromStream(pStm, &hglobal);          assert(SUCCEEDED(hr));         printf((const char*)GlobalLock(hglobal));          // free all resources          //                GlobalUnlock(hglobal);          pStm->Release();      }  }

API- GetHGlobalFromStream (handle) , CreateStreamOnHGlobal. HGLOBAL .

API- CoMarshalInterface :

 HRESULT CoMarshalInterface(     [in] IStream *pStm,        // where to write marshaled state        //              [in] REFIID riid,       // type of ptr being marshaled        //            [in, iid_is(riid)] IUnknown *pItf,        // pointer being marshaled        //          [in] DWORD dwDestCtx,        // MSHCTX for destination apt.        // MSHCTX            [in] void *pvDestCtx,        // reserved, must be zero        //  ,            [in] DWORD dwMshlFlags        // normal, vs. table marshal        //          );

, :

 HRESULT WritePtr(IRacer *pRacer, HGLOBAL& rhglobal)  {      IStream *pStm = 0;       hglobal = 0;         // alloc and wrap block of memory          //                HRESULT hr = CreateStreamOnHGlobal(0, FALSE, &pStm);      if (SUCCEEDED(hr)) {         // write marshaled object reference to memory          //                      hr = CoMarshalInterface(pStm, IID_Iracer, pRacer,                                  MSHCTX_DIFFERENTMACHINE, 0,                                  MSHLFLAGS_NORMAL);          // extract handle to underlying memory          //                if (SUCCEEDED(hr))             hr = GetHGlobalFromStream(pStm, &rhglobal);          pStm->Release();      }      return hr; }

5.1 , . CoMarshalInterface . MSHCTX_DIFFERENTMACHINE, - .

, , , API- CoUnmarshalInterface:

 HRESULT CoUnmarshalInterface(   [in] IStream *pStm,     // where to read marshaled state      //          [in] REFIID riid,      // type of ptr being unma shaled      //        [out, iid_is(riid)] void **ppv      // where to put unmarshaled ptr      //          );

. 5.1.

CoUnmarshalInterface , . , , . - CoUnmarshalInterface , , . :

 HRESULT ReadPtr(HGLOBAL hglobal, IRacer * &rpRacer)  {     IStream *pStm = 0; rpRacer = 0;          // wrap block of existing memory passed on input          //            ,          //          HRESULT hr = CreateStreamOnHGlobal(hglobal, FALSE, &pStm);      if (SUCCEEDED(hr)) {             // get a pointer to the object that is legal in this apt.              //        ,                  hr = CoUnmarshalInterface(pStm, IID_Iracer, (void**)&rpRacer);          pStm->Release();     }     return hr;  }

Windows NT 4.0 . , , 1996 . . 5.2 . "MEOW" ( )³, ( , (standard), (custom)), IID , . , .

. 5.2.

" " (garbage collection) AddRef/Release, . (tuple) OXID/OID/IPID, . (Object Exporter Identifier OXID). OXID IPC- . (Object Identifier OID) CoUnmarshalInterface . (Interface Pointer Identifier - IPID) . IPID ORPC .

OXID , , - I . OXID IPC - , , OXID (OXID Resolver - OR). Windows NT 4.0 OR RPCSS. , OXID OR. , OR . , OR IPC- . CoUnmarshalInterface , OXID I OR. , , OR OXID OXID- IPC- . , , OR , OXID , , OXID . OXID , OR - , RPC. , - , , OR , .

OXID, OR - OXID ( 135 TCP UDP) . OXID , OXID. , . , OR - , I , . , OR OXID. OR , , . , . , (OXID), , . , ( TCP), . , - , .

¹ , , .

² UDP TCP (Transmission Control Protocol) - - - , TCP. , DCE RPC, , RPC. , UDP . , UDP, RPC / . .

³ Microsoft (Microsoft Program Manager), , , MEOW Microsoft Extended Object Wire ( Microsoft). , , .