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外链的论坛网站,外链购买平台,如何同步打开两个wordpress,广州最近发热病毒9 设计完整的EXI编解码库在第8节我们已经验证cbExiGen编解码库是完全可以信赖的，但是缺少输入输出层代码，无法对json格式的命令进行解析填充成结构体，解码后的数据结构也无法输出成json格式字符串。本节作者开始搭建一个完整的EXI编解码库框…

9 设计完整的EXI编解码库

在第8节我们已经验证cbExiGen编解码库是完全可以信赖的，但是缺少输入输出层代码，无法对json格式的命令进行解析填充成结构体，解码后的数据结构也无法输出成json格式字符串。本节作者开始搭建一个完整的EXI编解码库框架，目的是完美替换EXICodec.jar。新的的编解码库使用C语言编码，具备相同的encode、decode函数接口。

9.1 编解码库设计框架

作者对框架进行了深入思考，决定采用cjson+cbExiGen+转换层的结构，按照分层设计思想设计的框架如下图所示。

接口层：提供3个接口函数，version、encode、decode，函数原型与EXICodec.jar的调用接口一致。
分配层：编码时，根据域名参数区分-2/-20命令，根据命令参数区分片段编码、签名编码、命令编码。
表示层：编码时把命令cstring转换成cjson对象。解码时把cjson对象转换成cstring。
转换层：编码是根据cjson对象解析填充数据结构。解码时把数据结构填充到cjson对象。
编解码层：根据数据结构进行编码，根据exi数据进行解码。

接口定义：

extern EncodeResult encode(char * message, char * namespace);
extern char * decode(uint8_t * exidata, int len, char * namespace);
extern const char * getVersion();

9.2 编码流程

调用encode()接口，编码步骤如下：

1 检查namespace，确定是哪种协议或签名编码。这些命名空间定义如下：

char * AppProtocolNS = "urn:iso:15118:2:2010:AppProtocol";
char * MsgDefNS = "urn:iso:15118:2:2013:MsgDef";
char * CommonMessagesNS = "urn:iso:std:iso:15118:-20:CommonMessages";
char * ACNS = "urn:iso:std:iso:15118:-20:AC";
char * DCNS = "urn:iso:std:iso:15118:-20:DC";
char * WPTNS = "urn:iso:std:iso:15118:-20:WPT";
char * ACDPNS = "urn:iso:std:iso:15118:-20:ACDP";
char * XMLSIG = "http://www.w3.org/2000/09/xmldsig#";

2 对于-2/-20命令，检查是完整的V2G命令还是片段编码。

命令中包含“V2G_Message”一般是完整的V2G命令，否则就是片段编码。

识别片段编码的方法是查询预定义的命令表，-2命令中支持的片段编码命令全部罗列如下：

//解码函数映射
ISO2_MsgDefNS_FragmentFunction frag_MsgDefNS[] = {{"AuthorizationReq",                     ISO2_Frag_AuthorizationReq_J2S,                    ISO2_Frag_AuthorizationReq_S2J},{"CertificateInstallationReq",           ISO2_Frag_CertificateInstallationReq_J2S,          ISO2_Frag_CertificateInstallationReq_S2J},{"CertificateInstallationRes",           ISO2_Frag_CertificateInstallationRes_J2S,          ISO2_Frag_CertificateInstallationRes_S2J},{"CertificateUpdateReq",                 ISO2_Frag_CertificateUpdateReq_J2S,                ISO2_Frag_CertificateUpdateReq_S2J},{"CertificateUpdateRes",                 ISO2_Frag_CertificateUpdateRes_J2S,                ISO2_Frag_CertificateUpdateRes_S2J},{"ChargeParameterDiscoveryRes",          ISO2_Frag_ChargeParameterDiscoveryRes_J2S,         ISO2_Frag_ChargeParameterDiscoveryRes_S2J},{"ContractSignatureCertChain",           ISO2_Frag_ContractSignatureCertChain_J2S,          ISO2_Frag_ContractSignatureCertChain_S2J},{"ContractSignatureEncryptedPrivateKey", ISO2_Frag_ContractSignatureEncryptedPrivateKey_J2S,ISO2_Frag_ContractSignatureEncryptedPrivateKey_S2J},{"DHpublickey",                          ISO2_Frag_DHpublickey_J2S,                         ISO2_Frag_DHpublickey_S2J},{"MeteringReceiptReq",                   ISO2_Frag_MeteringReceiptReq_J2S,                  ISO2_Frag_MeteringReceiptReq_S2J},{"SalesTariff",                          ISO2_Frag_SalesTariff_J2S,                         ISO2_Frag_SalesTariff_S2J},{"eMAID",                                ISO2_Frag_eMAID_J2S,                               ISO2_Frag_eMAID_S2J},
};

3 调用具体命令的转换函数

这一步设计成函数指针，调用函数指针dispatchMessage派发到对应的处理函数进行处理。

4 字符串转成cjson对象

在处理函数内首先把命令字符串转换成cjson对象。如果出错，表示字符串格式非法。

5 根据该命令的数据结构，解析cjson对象正确填充数据结构

读取cjson每一个字段，填充到对应的数据结构体中。尤其要注意可选项，如果存在就必须正确填充。

6 对数据结构编码，返回exi数据

调用cbExigen编码函数，完成编码。

9.3 解码流程

调用decode()接口，解码步骤如下：

1 检查namespace，确定是哪种协议。实际上，在解码过程中只有三种namaspace：

char * AppProtocolNS = "urn:iso:15118:2:2010:AppProtocol";
char * MsgDefNS = "urn:iso:15118:2:2013:MsgDef";
char * CommonMessagesNS = "urn:iso:std:iso:15118:-20:CommonMessages";

2 调用cbExigen解码函数

3 根据解码后的数据结构，识别出是哪一个命令。

4 调用对应命令的转换函数，把数据结构转成cjson

5 把cjson转成字符串，返回。

9.4 转换层设计

转换层函数需要实现数据结构和cjson之间的双向转换，针对每一个命令都需要实现一步步一层层解析到底。这些转换层代码行数总共5W+，作者付出最多精力的也正是这一层代码。因为V2G命令定义特别复杂，最多时候结构嵌套13层以上，写程序时直接让人坠入十八层地狱，烧的脑子都冒烟了。

针对-2协议编写的转换文件如下：

\src\Json2Schema\iso15118-2 的目录2024/03/14  11:09             7,249 J2S_AuthorisationReq.c
2023/11/14  13:47             6,635 J2S_CableCheckReq.c
2025/01/16  17:56            21,999 J2S_CertificateInstallationReq.c
2025/01/17  11:08            49,141 J2S_ChargeParameterDiscoveryReq.c
2023/11/08  17:16             8,130 J2S_ChargingStatusReq.c
2023/11/14  09:50            12,546 J2S_common.c
2025/02/07  14:42            40,545 J2S_createHeaderWithSignedInfo.c
2023/11/14  14:56            16,961 J2S_CurrentDemandReq.c
2024/03/14  11:10             2,859 J2S_Frag_AuthorizationReq.c
2024/03/13  15:38             3,799 J2S_Frag_CertificateInstallationReq.c
2024/03/13  18:22             8,988 J2S_Frag_CertificateUpdateReq.c
2024/03/13  13:27             1,671 J2S_Frag_ChargeParameterDiscoveryRes.c
2024/03/13  11:22             1,542 J2S_Frag_ContractSignatureCertChain.c
2024/03/13  11:22             1,762 J2S_Frag_ContractSignatureEncryptedPrivateKey.c
2024/03/13  11:20             1,471 J2S_Frag_DHpublickey.c
2024/03/13  11:20             1,301 J2S_Frag_eMAID.c
2024/03/13  16:46             1,507 J2S_Frag_MeteringReceiptReq.c
2024/03/14  09:47             1,434 J2S_Frag_SalesTariff.c
2025/01/15  16:57            12,197 J2S_MeteringReceiptReq.c
2023/11/14  15:26             7,880 J2S_PaymentDetailsReq.c
2023/11/02  10:08             8,988 J2S_PaymentServiceSelectionReq.c
2025/01/22  17:22            24,762 J2S_PowerDeliveryReq.c
2023/11/14  15:10             7,709 J2S_PreChargeReq.c
2023/11/02  10:09            12,901 J2S_ServiceDetailReq.c
2024/05/20  10:33            18,174 J2S_ServiceDiscoveryReq.c
2025/02/07  17:13             6,104 J2S_SessionSetupReq.c
2023/11/08  17:59             5,808 J2S_SessionStopReq.c
2023/11/30  16:13             1,429 J2S_SignedInfo.c
2023/11/08  09:27             5,232 J2S_supportedAppProtocolReq.c
2023/11/14  13:52             7,075 J2S_WeldingDetectionReq.c30 个文件        307,799 字节

针对-20编写的文件如下：

\src\Json2Schema\iso15118-20 的目录2023/11/29  17:24             1,539 J2S_AbsolutePriceSchedule_20.c
2023/12/03  12:55            99,497 J2S_AC_ChargeLoopReq_20.c
2023/12/08  11:30            35,753 J2S_AC_ChargeParameterDiscoveryReq_20.c
2023/10/26  11:27             8,176 J2S_ac_common_20.c
2025/01/15  17:00            30,967 J2S_AC_createHeaderWithSignedInfo_20.c
2024/03/11  23:49            10,848 J2S_AuthorizationReq_20.c
2024/03/12  00:07             9,814 J2S_AuthorizationSetupReq_20.c
2025/01/17  09:20            26,533 J2S_CertificateInstallationReq_20.c
2024/03/13  18:25            13,356 J2S_common_20.c
2025/01/15  17:34            41,991 J2S_createHeaderWithSignedInfo_20.c
2023/12/04  16:56             4,113 J2S_DC_CableCheckReq_20.c
2024/02/28  16:22            77,415 J2S_DC_ChargeLoopReq_20.c
2023/12/06  13:26            26,368 J2S_DC_ChargeParameterDiscoveryReq_20.c
2023/12/04  16:25             4,785 J2S_dc_common_20.c
2025/01/15  17:26            35,233 J2S_DC_createHeaderWithSignedInfo_20.c
2023/12/04  19:07             5,280 J2S_DC_PreChargeReq_20.c
2023/12/04  19:08             4,701 J2S_DC_WeldingDetectionReq_20.c
2025/01/15  17:26            18,721 J2S_MeteringConfirmationReq_20.c
2024/04/19  10:30             1,549 J2S_OEMProvisioningCertificateChain_20.c
2023/11/29  15:19             1,451 J2S_PnC_AReqAuthorizationMode_20.c
2024/03/14  17:41            13,564 J2S_PowerDeliveryReq_20.c
2023/11/01  16:03             1,149 J2S_PreChargeReq_20.c
2023/12/06  13:44            68,086 J2S_ScheduleExchangeReq_20.c
2023/11/02  10:16            10,893 J2S_ServiceDetailReq_20.c
2023/11/02  10:16             8,582 J2S_ServiceDiscoveryReq_20.c
2023/11/02  10:16             7,293 J2S_ServiceSelectionReq_20.c
2025/02/05  13:23             4,801 J2S_SessionSetupReq_20.c
2023/11/06  15:57             5,840 J2S_SessionStopReq_20.c
2023/11/29  15:55             1,297 J2S_SignedInfo_20.c
2023/11/29  15:48             1,275 J2S_SignedInstallationData_20.c30 个文件        580,870 字节

举个一般的命令转换文件iso15118-2\J2S_AuthorisationReq.c，说明下关键的代码

/*
* J2S_AuthorisationReq.c
*
*  Created on: 2023-10-10
*      Author: Tom
*/#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>#include "cJSON.h"#include "iso2_msgDefDatatypes.h"
#include "iso2_msgDefEncoder.h"
#include "iso2_msgDefDecoder.h"#include "J2S_header.h"#include "base64Codec.h"
#include "printHex.h"/*--------------------------------------------------------------------------------*/static cJSON * ISO2_create_cJSON_Body_AuthorizationRes(struct iso2_AuthorizationResType cmd);/*--------------------------------------------------------------------------------*/// transform json to Schema Struct
struct iso2_exiDocument ISO2_AuthorizationReq_J2S(cJSON *cjson) {//读取V2G_MessagecJSON *json_V2G_Message = cJSON_GetObjectItem(cjson, "V2G_Message");//读取HeadercJSON *json_Header = cJSON_GetObjectItem(json_V2G_Message, "Header");//读取Body对象cJSON *json_Body = cJSON_GetObjectItem(json_V2G_Message, "Body");cJSON *json_AuthorizationReq = cJSON_GetObjectItem(json_Body, "AuthorizationReq");//填充Schema数据结构// init for structsstruct iso2_exiDocument exiDoc;struct iso2_V2G_Message V2G_Message;struct iso2_MessageHeaderType Header;struct iso2_BodyType Body;struct iso2_AuthorizationReqType AuthorizationReq;// fill Headerinit_iso2_MessageHeaderType(&Header);Header = create_Header_WithSignedInfo(json_Header);// fill Bodyinit_iso2_AuthorizationReqType(&AuthorizationReq);// Attribute: Id, ID (base: NCName)cJSON * json_Id = cJSON_GetObjectItem(json_AuthorizationReq,"Id");if(json_Id){strcpy(AuthorizationReq.Id.characters, json_Id->valuestring);AuthorizationReq.Id.charactersLen = strlen(json_Id->valuestring);AuthorizationReq.Id_isUsed = 1u;}// GenChallenge, genChallengeType (base: base64Binary)cJSON * json_GenChallenge = cJSON_GetObjectItem(json_AuthorizationReq,"GenChallenge");if(json_GenChallenge){AuthorizationReq.GenChallenge_isUsed = 1u;base64_decode((uint8_t *)json_GenChallenge->valuestring, strlen(json_GenChallenge->valuestring),AuthorizationReq.GenChallenge.bytes, &AuthorizationReq.GenChallenge.bytesLen);}init_iso2_BodyType(&Body);Body.AuthorizationReq = AuthorizationReq;Body.AuthorizationReq_isUsed = 1u;init_iso2_V2G_Message(&V2G_Message);V2G_Message.Header = Header;V2G_Message.Body = Body;init_iso2_exiDocument( &exiDoc );exiDoc.V2G_Message = V2G_Message;return exiDoc;
}// transform Schema Struct to json
cJSON * ISO2_AuthorizationReq_S2J(struct iso2_exiDocument *exiDoc){cJSON * root   =  cJSON_CreateObject();cJSON * json_V2G_Message   =  cJSON_CreateObject();cJSON_AddItemToObject(root, "V2G_Message", json_V2G_Message);//----------Header--------cJSON * json_Header = create_cJSON_Header_WithSignedInfo(exiDoc->V2G_Message.Header);cJSON_AddItemToObject(json_V2G_Message, "Header", json_Header);//----------Body-----------cJSON * json_Body   =  cJSON_CreateObject();cJSON_AddItemToObject(json_V2G_Message, "Body", json_Body);if(exiDoc->V2G_Message.Body.AuthorizationReq_isUsed){cJSON * json_AuthorizationReq   =  cJSON_CreateObject();if(json_AuthorizationReq){cJSON_AddItemToObject(json_Body, "AuthorizationReq", json_AuthorizationReq);struct iso2_AuthorizationReqType cmd = exiDoc->V2G_Message.Body.AuthorizationReq;// Attribute: Id, ID (base: NCName)if(cmd.Id_isUsed){char *Id = (char *)malloc(cmd.Id.charactersLen+1);memset(Id,0, cmd.Id.charactersLen+1);memcpy(Id, cmd.Id.characters, cmd.Id.charactersLen);cJSON_AddItemToObject(json_AuthorizationReq, "Id", cJSON_CreateString(Id));free(Id);}// GenChallenge, genChallengeType (base: base64Binary)if(cmd.GenChallenge_isUsed){char * encode = (char *)base64_encode2Str(cmd.GenChallenge.bytes, (int)cmd.GenChallenge.bytesLen);if(encode){cJSON_AddItemToObject(json_AuthorizationReq, "GenChallenge", cJSON_CreateString(encode));free(encode);}}}}return root;
}//---------------------------------------------------------------------------------------------------------------
// transform json to Schema Struct
struct iso2_exiDocument ISO2_AuthorizationRes_J2S(cJSON *cjson) {//读取V2G_MessagecJSON *json_V2G_Message = cJSON_GetObjectItem(cjson, "V2G_Message");//读取HeadercJSON *json_Header = cJSON_GetObjectItem(json_V2G_Message, "Header");//读取Body对象cJSON *json_Body = cJSON_GetObjectItem(json_V2G_Message, "Body");cJSON *json_AuthorizationRes = cJSON_GetObjectItem(json_Body, "AuthorizationRes");//填充Schema数据结构// init for structsstruct iso2_exiDocument exiDoc;struct iso2_V2G_Message V2G_Message;struct iso2_MessageHeaderType Header;struct iso2_BodyType Body;struct iso2_AuthorizationResType AuthorizationRes;// fill Headerinit_iso2_MessageHeaderType(&Header);Header = create_Header_WithSignedInfo(json_Header);// fill Bodyinit_iso2_AuthorizationResType(&AuthorizationRes);//ResponseCodecJSON *json_ResponseCode = cJSON_GetObjectItem(json_AuthorizationRes, "ResponseCode");if(json_ResponseCode){AuthorizationRes.ResponseCode = ResponseCode_Str2Int(json_ResponseCode->valuestring);}// EVSEProcessing, EVSEProcessingType (base: string)cJSON * json_EVSEProcessing = cJSON_GetObjectItem(json_AuthorizationRes,"EVSEProcessing");if(json_EVSEProcessing){AuthorizationRes.EVSEProcessing  = EVSEProcessing_Str2Int(json_EVSEProcessing->valuestring);}init_iso2_BodyType(&Body);Body.AuthorizationRes = AuthorizationRes;Body.AuthorizationRes_isUsed = 1u;init_iso2_V2G_Message(&V2G_Message);V2G_Message.Header = Header;V2G_Message.Body = Body;init_iso2_exiDocument( &exiDoc );exiDoc.V2G_Message = V2G_Message;return exiDoc;
}// transform Schema Struct to json
cJSON * ISO2_AuthorizationRes_S2J(struct iso2_exiDocument *exiDoc){cJSON * root   =  cJSON_CreateObject();cJSON * json_V2G_Message   =  cJSON_CreateObject();cJSON_AddItemToObject(root, "V2G_Message", json_V2G_Message);//----------Header--------cJSON * json_Header = create_cJSON_Header_WithSignedInfo(exiDoc->V2G_Message.Header);cJSON_AddItemToObject(json_V2G_Message, "Header", json_Header);//----------Body-----------cJSON * json_Body   =  cJSON_CreateObject();cJSON_AddItemToObject(json_V2G_Message, "Body", json_Body);if(exiDoc->V2G_Message.Body.AuthorizationRes_isUsed){cJSON * json_AuthorizationRes = ISO2_create_cJSON_Body_AuthorizationRes(exiDoc->V2G_Message.Body.AuthorizationRes);cJSON_AddItemToObject(json_Body, "AuthorizationRes", json_AuthorizationRes);}return root;
}static cJSON * ISO2_create_cJSON_Body_AuthorizationRes(struct iso2_AuthorizationResType cmd){cJSON *json_Res = cJSON_CreateObject();//ResponseCodechar * ResponseCode = ResponseCode_Int2Str(cmd.ResponseCode);if(ResponseCode){cJSON_AddItemToObject(json_Res, "ResponseCode", cJSON_CreateString(ResponseCode));}// EVSEProcessing, EVSEProcessingType (base: string)char *EVSEProcessing = EVSEProcessing_Int2Str(cmd.EVSEProcessing);if(EVSEProcessing){cJSON_AddItemToObject(json_Res, "EVSEProcessing", cJSON_CreateString(EVSEProcessing));}return json_Res;
}

转换函数入口：

struct iso2_exiDocument ISO2_AuthorizationReq_J2S(cJSON *cjson)       // AuthorizationReq:   编码时把cjson解析成数据结构iso2_exiDocument
cJSON * ISO2_AuthorizationReq_S2J(struct iso2_exiDocument *exiDoc)    // AuthorizationReq：  解码时把iso2_exiDocument转换成cjsonstruct iso2_exiDocument ISO2_AuthorizationRes_J2S(cJSON *cjson)       // AuthorizationRes:   编码时把cjson解析成数据结构iso2_exiDocument
cJSON * ISO2_AuthorizationRes_S2J(struct iso2_exiDocument *exiDoc)    // AuthorizationRes:   解码时把iso2_exiDocument转换成cjson

下节预告：

9.5 cjson库缺陷改进

9.6 cbExiGen库bug及改进

9.7 编解码库稳定性测试

9.8 编解码库兼容性测试

9.9 编解码库性能测试

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