ASN.1及其PER编码在视频会议系统中的应用研究

抽象语法表符号1（ASN.1）在多媒体网络通信中起着非常重要的作用.ASN.1被用于描述基于H.323协议的视频会议系统的信令消息.介绍了ASN.1的基本概念、数据类型和数据表示方法,详细分析了ASN.1在网络传输编码中使用的分组编码规则（PER）,并结合H.323协议中所常用的数据类型举例说明了其信令消息的PER编码过程.     

DSRC协议ASN.1模块的设计与实现

通过研究专用短程通信（DSRC）协议栈中的应用层部分,针对其中的ASN.1 PER编解码模块,设计并实现了一种编解码框架,框架包括ASN.1映射规则、通用编解码流程以及符合小设备应用的内存管理机制。良好的模块划分使得此框架具有较好的通用性。测试结果表明,此实现框架具有良好的性能,满足协议的实时性要求。     

基于ASN.1的应用层协议的描述与开发

本文介绍了一种采用形式化描述语言ASN.1对应用层协议进行描述与开发的方法,协议的ASN.1描述具有简洁、可读性好、精确和无二义性等特点。在基于ASN.1的开发环境下对应用层协议的开发具有高效、可靠和易于维护等优点,解决了目前应用层协议开发中存在的许多问题。     

H.323协议栈中ASN.1模块的设计与实现

对ASN．1及PER编码规则作了简要介绍，接着提出了一种ASN．1编解码模块在H．323协议栈中的设计与实现的方案。     

LTE协议栈中ASN.1模块的设计与实现

开发长期演进(LTE)协议必须实现针对无线资源控制(RRC)消息的ASN.1编解码模块,但传统的ASN.1编解码方案函数调用频繁,编码效率较低。为此,分析LTE协议栈的软件需求,提出一种ASN.1编解码模块设计与实现方案。该方案采用模块化设计,从而简化函数调用、提高编码效率。在TD-LTE无线综合测试仪的协议栈软件中实现并进行测试,结果表明,该方案可实现对RRC消息的编解码。     

IP电话中ASN.1 PER编解码模块实现机制的研究

IP电话对ASN.1编解码模块的要求,提出一种优良的ASN.1PER编解码模块的实现机制,并分析其性能。     

基于CRT的证书状态服务的研究与实现

给出了CRT系统实现的逻辑结构模型;基于ASN.1的语法提出了一种证书状态证据（CRTbased Proof of Certificate Status,CRTPCS）请求协议,能够有效地实现用户-目录之间的证书CRTPCS请求服务,具有通用、高效的优点。针对协议实现的技术细节,介绍了利用OpenSSL实现ASN.1的DER编解码方法。     

基于Visual C++的MMSPDU编解码系统设计

采用ASN.1抽象语法描述的MMS PDU可读性好,但是传统ASN.1编译器有占用空间较大、运行效率不高的矛盾以及升级困难等缺点.本文采用面向对象的C++语言实现MMS PDU的编解码,利用一种新的、更为简单有效的方式来标识变电站通信报文的信息内容以及类型特征,从而大大提高编解码效率.     

基于面向对象方法的ASN.1编解码的设计与实现

随着计算机和通信技术的发展，ASN．1作为多种协议在表示层的抽象语法记法，它的作用在多媒体通信，协议测试等领域都非常重要。该文采用面向对象的设计方法实现了ASN．1标准X690，同时，通过比较各种编码规则的特点，在BER编解码实现的基础上，给出CER、DER及PER编码的实现方案，据此实现的ASN．1编解码对外提供了一致的接口，具有很好的通用性。     

ASN.1的编解码规则与应用层网络协议开发

本文首先简要介绍了ASN.1存在的意义。然后介绍ASN.1编解码规则。最后讲述一下在基于ASN.1的开发环境下对应用层网络协议的开发。     

EASE : A Software Environment for Automatic Implementation of Application Protocol

At present, ASN.1, and encoding and decoding rules, are not supported by Estelle. Estelle only specifies dynamic behaviours of protocols; and protocol data units of application layer protocol are specified in ASN.1. Hence, two standardized languages are required to specify an application protocol. In addition, Estelle and ASN.1 tools have been developed independently and do not support each other. As a result of these difficulties, the implementation of an application protocol is time consuming. To address this difficulty, we have proposed an approach which unified ASN.1 and Estelle specifications, and showed that the automatic implementation of an application protocol can be readily achieved by providing a software environment which supports this unified specification. This paper describes the detail of this software environment called EASE, and the results of using it to develop an implementation of the ISO FTAM protocol.     

Integrated Estelle and ASN.1 specification approach to automatic implementation of application protocol

Estelle currently does not support ASN.1 and encoding and decoding rules. Tools developed for Estelle and ASN.1 have been developed independently of each other. As such, ASN.1 tools do not support Estelle and vice versa. At present, due to these two separate specifications, implementation is time consuming. It is imperative to find a way for ASN.1 and Estelle specifications to be efficiently integrated to facilitate fully automatic implementation. This paper describes how Estelle and ASN.1 can be integrated to give a unified specification which can then be fed into a software environment to produce a truly automatic implementation of an application protocol, including encoding and decoding of protocol data units, when application layer protocols are specified in Estelle and in ASN.1. The integration approach is based on the powerful programming concept, Data Abstraction. The software that implements this integrated specification approach to automatic implementation of application protocol is called EASE (Estelle and ASN.1 Software Environment). To demonstrate the viability of the approach, the unified specification of the ISO ACSE and Presentation protocols are also presented.     

优化TLV编码规则

抽象语法标记ASN．1是一种ISO／ITU-T标准,描述了一种对数据进行表示、编码、传输和解码的数据格式。ISO协议体系中的应用层协议使用了ASN．1来描述它们所传输的协议数据单元。ASN．1取得成功的一个主要原因是它与几个标准化编码规则（如基本编码规则BER）相关。TLV编码是指先对Tag编码,再对Length编码,最后对Value编码。BER编码确定的编码方式就是这样的。在实际的通信中,通常特定类型编码中数据的长度是已知的,在数据字典中有明确的标识。提出了一种优化TLV编码的方法,使用一个比特的标志位,将长度字段作为编码中一个可选择的项目,而不是必须存在的项目,以此来缩短TLV编码的长度。在满足需求的前提下,优化后的TLV编码可以大幅度地提高数据传输效率。     

T.38协议栈中ASN.1模块的设计与实现

T.38协议栈作为IP网络传真代理的核心部分必须具有同时处理多个用户传真消息的能力,可见一个高效的ASN.1模块对T.38协议栈来说是十分重要的.然而,传统的ASN.1模块实现方案无法满足T.38协议栈在效率上的要求.本文在改进传统ASN.1实现方案的基础上,提出了一种T.38协议栈中ASN.1模块的设计方案.     

ASN.1在网络管理中的应用研究

ASN.1语言定义了网络管理信息结构、网络管理信息库、简单网络管理协议。以这些网络管理相关RFC文档为例,对应用于网络管理中的常用ASN.1语法进行了总结性研究。     

ASN.1支持工具与应用层网络协议开发环境

抽象语法表示ASN.1在OSI网络高层协议的描述与开发方面起着重要的作用,本文介绍了ASN.1支持工具的构成及基于ASN.1的OSI网络应用层协议的开发环境,并给出了开发实例。     

3G移动通信系统安全协议的描述及实现

在对3G通信系统安全相关算法和协议研究的过程中,采用ASN.1来描述相关的协议,通过VC++来实现相关的安全算法和ASN.1的编解码器。相关信令消息的传输码基于串行线仿真和传输。文中所提到的协议描述及实现方法,可广泛应用于通信协议的研究及测试。     

The design and implementation of an ASN.1-C compiler

Abstract syntax notation one (ASN.1) has been widely used in international standard specification: its transfer-syntax, the basic encoding rules (BER), is used as the external data representation. A BER implementation called the ED library is presented. The ED library includes a number of encoding and decoding routines that may be used as primitive functions to compose encoders and decoders for arbitrarily complicated ASN.1 data types. Based on the ED library an ASN.1-C compiler, called CASN1, is designed and implemented to free the protocol implementers from the arduous work of translating protocol-defined data-types and constructing their encoders and decoders. Given an ASN.1 protocol specification, CASN1 automatically translates the input ASN.1 modules into C and generates the BER encoders and decoders for the protocol defined data-types. The CASN1 design principles, user interface, and some example applications are discussed. The performance of the ED library and generated CASN1 code is also measured and discussed     

ASN.1编解码器的JAVA实现

作为一个国际标准,ASN.1主要应用在通信协议的具体表示上。文章介绍了ASN.1的基本特点,以及用Java语言实现ASN.1编解码器时的一些设计思想和注意事项。