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。     

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.     

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。     

Extending EASE with new ASN.1 encoding rules

EASE (R. Lai, A. Lo, EASE: a software environment for automatic implementation of application protocol, Software—Practice and Experience, 26(1) (1996) 83–103) is a software tool that integrates Estelle and ASN.1 (Abstract Syntax Notation One) specifications to produce an integrated specification for application layer protocol, from which an automatic implementation can be generated. EASE, though a new tool, is already outdated because of the recent changes, including new syntaxes, and additions of encoding rules, to the 1994 ASN.1 standard. Building a complete compiler that supports the full ASN.1:94 standard is a huge task; many researchers and developers only implement a subset of the standard that meets their requirements, while others use tools for building certain stages of such a compiler. For EASE to keep in line with the 1994 standard, it is a big task and requires a major rewrite; the only two encoding rules that could be added to EASE without implementing the full 1994 ASN.1 syntaxes are the canonical encoding rules (CER) and the distinguished encoding rules (DER). This paper describes how EASE has been extended to include these new rules, and aims to provide researchers and developers with the lessons learned from this work, and with some pointers to developing an ASN.1 compiler that complies with the 1994 standard.     

OSI／MMS系统中ASN.1编／解码器的设计与实现

ＡＳＮ．１是一种标准的抽象语法定义描述语言，它提供了定义复杂数据类型以及确定这些数据类型值的方法，许多ＯＳＩ应用协议标准都采用ＡＳＮ．１作为数据结构定义描述工具，尤其用来定义各各应用协议数据单元的结构。本文首先介绍ＡＳＮ．１数据类型和基本编码规则，接着详细讨论ＭＭＳ通信系统中ＡＳＮ．１编／解码器的设计与实现，此编／解码器用于ＭＭＳ协议数据单元的ＡＳＮ．１抽象语法和传送语法之间的转换，以实现ＭＭＳ在     

Advanced multimedia service provisioning based on efficient interoperability of adaptive streaming protocol and high efficient video coding

The popularity of the new standard H.265 (High Efficiency Video Coding) depends on two factors: the rapidity of deploying clients for the most outstanding platforms and the capacity of service providers to develop efficient encoders for serving demanding multimedia services such as Live TV. Both encoders and decoders should inter-operate efficiently with the streaming protocols to limit the risks of implementation incompatibilities.This paper presents a synergy framework between High Efficiency Video Coding (HEVC) and Dynamic Adaptive Streaming over HTTP (DASH) that increases the compression capabilities of the encoder and opens new parallel encoding points for accelerating the video content coding and formatting processes. The synergy takes advantage of inter-motion prediction in HEVC for delimiting the segments of DASH protocol, which increases the motion compensation in each segment. Moreover, the impact of encoding multiple DASH representations is limited due to the parallel encoding presented in this paper.     

基于BER的ASN.1语法编译器及编解码器实现与应用

介绍了ASN.1标记语言和BER基本编码规则。结合其在移动通信国际漫游话单中的应用场景,详细介绍了应用于移动通信国际漫游话单处理系统中的ASN.1语法编译器和BER编解码模块的设计与实现。     

网络电话中ASN.1编解码器的实现研究

简要介绍了抽象语法标记语言ASN.1,以及BER和PER编码规则,阐述了网络电话中H.323协议栈的ASN.1编解码器的设计与实现。     

抽象形式语法对象封装与BER编码实现

抽象形式语法标注的网络协议数据单元可读性好,但是用传统的过程调用方法实现这些协议单元的编解码将是一件复杂而繁重的工作,因此,本文使用面向对象的思想对象抽象形式语法的基本数据类型进行封 达到如简化目的：“在对抽象形式语法标注的协议数据单元不作改动或稍作改动的情况下,直接利用原有的协议数据单元定义完成这些协议数据单元的编码解码工作。”。本文描述的对象封装形式不仅仅适合Ｘ．６９０ＢＥＲ编码,而且也适合Ｘ     

基于BER的ASN．1编解码原理与设计实现

本文介绍了ASN．1和BER基本编码规则，分析了7号信令协议栈的TCAP层消息结构和ASN．1之间的关系，详细介绍了应用于信令中继系统中的ASN．1编解码模块的设计和实现。     

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。     

ASN_EZE: An Analgesic for Writers of ASN.1 Applications

Many programmers find that the logical structure of data defined in ASA.1 is simple enough, but the physical representation requires painfully careful attention to lots of detail. ASN.1 'compilers' which we had used required a programmer ot know the intricacies of both ASN.1 and the generated code. Furthermore those which generated 'C' code were prone to 'memory leaks' and produced bulky code. Two features of object orientiation led us to develop a code generator that procues 'C++'. First Class inheritance permits a small number of functions to operate on objects of any derived class. Second, the destructors of such objects can be designed to prevent memory leaks automatically. Our own use of the system shows that within a few days programmers withh no pair exposure to ASN.1 can start writing applications using only the ASN.1 specification for reference. The generated code is compact and well protected anainst memory leaks. This paper describes the capabilies of the code generator, the library of functions for handling all ASN.1 objects so generated, and the interior structure of these objects which allows the library functions to navigate any hierarchy. The las section discusses our experience in using the system.     

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.     

Distributed Average Consensus in Multi-agent Networks with Limited Bandwidth and Time-delays

This paper studies the distributed average consensus problem of multi-agent digital networks with time-delays. For the network, each agent can only exchange symbolic data with its neighbours. We provide a distributed average consensus protocol which uses the quantized and time-delay information. We consider two types of dynamic encoders/decoders in our protocol. One uses inverse proportion function as scaling function, while the other uses exponential function as scaling function. All agents can reach average consensus asymptotically with our protocol. Furthermore, we show that the average consensus protocol is robust to finite symmetric time-delays, but is sensitive to asymmetric time-delays that will destroy the average consensus of the networks. Finally, simulations are presented to illustrate validity of our theoretical results.      

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。     

Columbia's VoD and Multimedia Research Testbed with Heterogeneous Network Support

This paper reports our progress in developing an advanced video-on-demand (VoD) testbed, which will be used to accommodate various multimedia research and applications such as Electronic News on Demand, Columbia's Video Course Network, and Digital Libraries. The testbed supports delivery of MPEG-2 audio/video stored as transport streams over various types of networks, e.g., ATM, Ethernet, and wireless. Both software and hardware video encoders/decoders are used in the testbed. A real-time video pump and a distributed application control protocol (MPEG-2's DSM-CC) have been incorporated. Hardware decoders and set-tops are being used to test wide-area video interoperability. Our VoD testbed also provides an advanced platform for implementing proof-of-concept prototypes of related research. Our current research focus covers video transmission with heterogeneous quality-of-service (QoS) provision, variable bitrate (VBR) traffic modeling, VBR server scheduling, video over Internet, and video transmission over IP-ATM hybrid networks. An important aim is to enhance interoperability. Accommodation of practical multimedia applications and interoperability testing with external VoD systems has also been undertaken.     

X.400协议测试环境中的ASN.1工具

Ｘ．４００协议是ＯＳＩ应用层最为成熟的一套关于信报处理的应用协议，目前已涌现大量的Ｘ．４００协议实现。为了验证了这些协议实正确性及相互连接。相互操作的能力。需要对Ｘ．４００协议实现进行一致性测试。抽象语法表示法－ＡＳＮ．１作为ＯＳＩ应用层协议描述所使用的一种形式化语言，不仅在Ｘ．４００议实现中不可缺少，而且在对Ｘ．４００进行一致性测试中扮演举足轻重的作用。本文旨在分析ＡＳＮ．１工具的应用，并提出“     

嵌入式VOIP系统中ASN.1编解码器的实现

抽象语法描述ASN.1已经被广泛地运用于协议通信。在VOIP应用中,同样也要用到ASN.1编解码。但是由于H.323协议栈本身的asn描述文件较大,使得传统的ASN.1编解码方案在资源有限的嵌入式系统中并不适用。文章在实际开发项目的基础上,提出了一个适用于嵌入式系统的解决方案。