国外主机测评 - 国外VPS，国外服务器，国外云服务器，测评及优惠码Oracle RPC代理：一种更高效的数据传输方式
Oracle数据库在很多企业应用中都扮演着重要角色，但是Oracle数据库的性能问题却也经常困扰着企业。其中一个主要问题就是数据传输效率问题。而Oracle RPC代理则是一种更高效的数据传输方式，能够显著提升Oracle数据库的性能。
RPC（Remote Procedure Call，远程过程调用）是一种常用的分布式计算模型。Oracle RPC代理就是在这个模型基础上实现的一种数据传输方式。它利用Oracle客户端的OCI（Oracle Call Interface）和Oracle服务器端的Pro*C编译器提供的远程过程调用功能，可以将数据直接从数据库的内存中传输到应用程序内存中，避免了频繁的磁盘IO操作，因此能够大大提升数据传输效率。
下面我们通过一个简单的示例来展示Oracle RPC代理的实现过程。
在Oracle服务器端，我们需要编写一个简单的Pro*C程序：
“`c
#include
#include
#include
#include
#include
#include
#define SERVICE_ID 301
#define PROG_ID 777
#define VERS_ID 1
#define USER “user”
#define PWD “pwd”
#define CONN_STR “tnsnames.ora”
struct remote_result {
char col1[20];
char col2[20];
};
struct remote_input {
char sql[256];
char param[256];
};
typedef struct {
struct remote_result (*query)(struct remote_input);
} query_prog_1_svc_args;
int
query_prog_1(struct remote_input input, struct remote_result result)
{
OCIEnv *envhp;
OCIError *errhp;
OCISession *authp;
OCISvcCtx *svchp;
OCIStmt *stmthp;
OCIDefine *defhp1, *defhp2;
OCIParam *parmp;
sword rc;
int errcode;
char buf[256];
if (rc = OCIEnvCreate(&envhp, OCI_DEFAULT, (dvoid *) 0, (dvoid * (*)(dvoid *, size_t)) malloc, (dvoid * (*)(dvoid *, dvoid *, size_t)) realloc, (void (*)(dvoid *, dvoid *)) free, (size_t) 0, (dvoid **) 0))
{
printf(“OCIEnvCreate() fled with return code %d\n”, rc);
return 1;
}
if (rc = OCIHandleAlloc(envhp, (dvoid **) &errhp, OCI_HTYPE_ERROR, (size_t) 0, (dvoid **) 0))
{
printf(“OCIHandleAlloc() fled with return code %d\n”, rc);
return 1;
}
if (rc = OCIInitialize((ub4) OCI_DEFAULT, (dvoid *) 0, (dvoid * (*)(dvoid *, size_t)) 0, (dvoid * (*)(dvoid *, dvoid *, size_t)) 0, (void (*)(dvoid *, dvoid *)) 0))
{
printf(“OCIInitialize() fled with return code %d\n”, rc);
return 1;
}
if (rc = OCIHandleAlloc(envhp, (dvoid **) &authp, OCI_HTYPE_SESSION, (size_t) 0, (dvoid **) 0))
{
printf(“OCIHandleAlloc() fled with return code %d\n”, rc);
return 1;
}
if (rc = OCIHandleAlloc(envhp, (dvoid **) &parmp, OCI_HTYPE_DESCRIBE, (size_t) 0, (dvoid **) 0)) {
printf(“OCIHandleAlloc() fled with return code %d\n”, rc);
return 1;
}
if (rc = OCIHandleAlloc(envhp, (dvoid **) &svchp, OCI_HTYPE_SVCCTX, (size_t) 0, (dvoid **) 0))
{
printf(“OCIHandleAlloc() fled with return code %d\n”, rc);
return 1;
}
if (rc = OCILogon2(envhp, errhp, &authp, (OraText *) USER, strlen(USER), (OraText *) PWD, strlen(PWD), (OraText *) CONN_STR, strlen(CONN_STR), OCI_LOGON2_DEFAULT))
{
printf(“OCILogon2() fled with return code %d\n”, rc);
return 1;
}
OCIAttrSet(svchp, OCI_HTYPE_SVCCTX, authp, 0, OCI_ATTR_SESSION, errhp);
OCIStmtPrepare2(svchp, &stmthp, errhp, (text*) input.sql, strlen(input.sql), (text*) NULL, 0, OCI_NTV_SYNTAX, OCI_DEFAULT);
if (rc = OCIStmtExecute(svchp, stmthp, errhp, 0, 0, NULL, NULL, OCI_DEFAULT))
{
printf(“OCIStmtExecute() fled with return code %d\n”, rc);
return 1;
}
rc = OCIParamGet(stmthp, OCI_HTYPE_STMT, errhp, (dvoid **)&parmp, 1);
if (rc != OCI_SUCCESS) {
printf(“OCIParamGet() fled with code %d\n”, rc);
return 1;
}
rc = OCIAttrGet(parmp, OCI_DTYPE_PARAM, &defhp1, 0, OCI_ATTR_DATA_TYPE, errhp);
if (rc != OCI_SUCCESS) {
printf(“OCIAttrGet() fled with code %d\n”, rc);
return 1;
}
rc = OCIAttrGet(parmp, OCI_DTYPE_PARAM, &defhp2, 0, OCI_ATTR_DATA_SIZE, errhp);
if (rc != OCI_SUCCESS) {
printf(“OCIAttrGet() fled with code %d\n”, rc);
return 1;
}
memset(&result, 0, sizeof(struct remote_result));
while (rc != OCI_NO_DATA) {
rc = OCIStmtFetch2(stmthp, errhp, 1, OCI_FETCH_NEXT, 0, OCI_DEFAULT);
if (rc == OCI_SUCCESS)
{
memset(buf, 0, sizeof(buf));
rc = OCIAttrGet(defhp1, OCI_DTYPE_PARAM, buf, 0, OCI_ATTR_TYPE_NAME, errhp);
if (rc != OCI_SUCCESS) {
printf(“OCIAttrGet() fled with code %d\n”, rc);
return 1;
}
if (strcasecmp(buf, “VARCHAR2”) == 0)
{
rc = OCIDefineByPos(stmthp, &defhp1, errhp, 1, result.col1, sizeof(result.col1), SQLT_STR, NULL, NULL, NULL, OCI_DEFAULT);
rc = OCIDefineByPos(stmthp, &defhp2, errhp, 2, result.col2, sizeof(result.col2), SQLT_STR, NULL, NULL, NULL, OCI_DEFAULT);
}
}
}
OCIHandleFree(errhp, OCI_HTYPE_ERROR);
OCIHandleFree(authp, OCI_HTYPE_SESSION);
OCIHandleFree(svchp, OCI_HTYPE_SVCCTX);
OCIHandleFree(stmthp, OCI_HTYPE_STMT);
OCIHandleFree(parmp, OCI_HTYPE_DESCRIBE);
OCIHandleFree(envhp, OCI_HTYPE_ENV);
return 0;
}
int
mn(int argc, char **argv)
{
if (pmap_unset(PROG_ID, VERS_ID))
{
fprintf(stderr, “unable to unset RPC parameters for service %d \n”, SERVICE_ID);
return 1;
}
if (!svc_register(NULL, PROG_ID, VERS_ID, query_prog_1, IPPROTO_TCP))
{
fprintf(stderr, “unable to register (PROG_ID, VERS_ID, tcp).”);
return 1;
}
pmap_unset(PROG_ID, VERS_ID);
return 0;
}
这个程序的作用是接收来自客户端的SQL语句，然后在Oracle数据库中执行这个SQL语句，并将执行结果返回给客户端。
接下来，在客户端，我们可以编写一个简单的C程序，使用RPC协议将SQL语句发送给服务器端，然后接收执行结果：
```c
#include
#include
#include
#include
#include "rpc_proxy.h"
int mn(int argc, char **argv)
{
char *server;
CLIENT *cl;
struct remote_input input;
struct remote_result *result;
char *sql = "SELECT col1, col2 FROM table1 WHERE col3 = :1";
char *param = "param1";
if (argc != 2)
{
fprintf(stderr, "usage: %s server_name\n",
