OGSA(Open Grid Services Architecture) is called the next generation grid architecture. It evolves from theearly five levels hourglass model architecture. OGSA consists of two key technologies: grid technology and Web ...OGSA(Open Grid Services Architecture) is called the next generation grid architecture. It evolves from theearly five levels hourglass model architecture. OGSA consists of two key technologies: grid technology and Web Ser-vice technology. OGSA gives emphasis to services and all things in OGSA are services. After explaining the basic ideaof OGSA,this paper introduces the composition of OGSA-based hosting environment and virtual organization. Todemonstrate the process of how an application is executed in an OGSA-based environment,the paper gives an exampleof data mining which illustrates the basic functions and working mechanism of OGSA. A brief comparison to relatedgrid architecture is also given in the paper. The paper concludes that OGSA is not mature and it needs improvementtogether with related technology and grid applications.展开更多
XML is a promising technology developed in recent years. Due to its superiority in extensibility and flexibility,XML has become the language over the internet. With more and more XML documents produced,the problem exi...XML is a promising technology developed in recent years. Due to its superiority in extensibility and flexibility,XML has become the language over the internet. With more and more XML documents produced,the problem exists to transform them to other documents of various structures. This paper discusses and compares four methods to transform XML documents,then introduces XSLT,a W3C recommendation, by giving examples and outlining a project in brief.展开更多
超大型天文观测技术的出现不仅能够让研究人员观测到新的天文现象,更能用于验证已有物理模型的正确性.这些最新天文成果的发现是建立在海量天文数据的近乎实时产生、管理与分析的基础上,因此给目前的数据管理系统带来了新的挑战.以我国...超大型天文观测技术的出现不仅能够让研究人员观测到新的天文现象,更能用于验证已有物理模型的正确性.这些最新天文成果的发现是建立在海量天文数据的近乎实时产生、管理与分析的基础上,因此给目前的数据管理系统带来了新的挑战.以我国自主研发的地基广角相机阵(the ground-based wide-angle camera array,GWAC)天文望远镜为例,15s的采样和处理周期都处于短时标观测领域的世界前列,但却对数据管理系统提出了很多问题,包括多镜头并行输出数据管理、实时瞬变源发现、当前观测夜数据的秒级查询、数据持久化和快速离线查询等.基于上述问题,设计了分布式GWAC数据模拟生成器用于模拟真实GWAC数据产生场景,并基于产生的数据特性,提出一种两级缓存架构,使用本地内存解决多镜头并行输出、实时瞬变源发现,使用分布式共享内存实现秒级查询.为了平衡持久化和查询效率,设计一种星表簇结构将整个星表数据划分后聚集存储.根据天文需求特点,设计基于索引表的查询引擎能从缓存和星表簇以较小的代价对星表数据查询.通过实验验证,当前方案能够满足GWAC的需求.展开更多
文摘OGSA(Open Grid Services Architecture) is called the next generation grid architecture. It evolves from theearly five levels hourglass model architecture. OGSA consists of two key technologies: grid technology and Web Ser-vice technology. OGSA gives emphasis to services and all things in OGSA are services. After explaining the basic ideaof OGSA,this paper introduces the composition of OGSA-based hosting environment and virtual organization. Todemonstrate the process of how an application is executed in an OGSA-based environment,the paper gives an exampleof data mining which illustrates the basic functions and working mechanism of OGSA. A brief comparison to relatedgrid architecture is also given in the paper. The paper concludes that OGSA is not mature and it needs improvementtogether with related technology and grid applications.
文摘XML is a promising technology developed in recent years. Due to its superiority in extensibility and flexibility,XML has become the language over the internet. With more and more XML documents produced,the problem exists to transform them to other documents of various structures. This paper discusses and compares four methods to transform XML documents,then introduces XSLT,a W3C recommendation, by giving examples and outlining a project in brief.
文摘超大型天文观测技术的出现不仅能够让研究人员观测到新的天文现象,更能用于验证已有物理模型的正确性.这些最新天文成果的发现是建立在海量天文数据的近乎实时产生、管理与分析的基础上,因此给目前的数据管理系统带来了新的挑战.以我国自主研发的地基广角相机阵(the ground-based wide-angle camera array,GWAC)天文望远镜为例,15s的采样和处理周期都处于短时标观测领域的世界前列,但却对数据管理系统提出了很多问题,包括多镜头并行输出数据管理、实时瞬变源发现、当前观测夜数据的秒级查询、数据持久化和快速离线查询等.基于上述问题,设计了分布式GWAC数据模拟生成器用于模拟真实GWAC数据产生场景,并基于产生的数据特性,提出一种两级缓存架构,使用本地内存解决多镜头并行输出、实时瞬变源发现,使用分布式共享内存实现秒级查询.为了平衡持久化和查询效率,设计一种星表簇结构将整个星表数据划分后聚集存储.根据天文需求特点,设计基于索引表的查询引擎能从缓存和星表簇以较小的代价对星表数据查询.通过实验验证,当前方案能够满足GWAC的需求.
