Yongqiang Zou

VegaWarden: A Uniform User Management System for Cloud Applications

In a virtual cluster based Cloud Computing environment, the sharing of infrastructure introduces two problems on user management: usability and security. Meanwhile, we observe that most conventional user management frameworks in the network environment are not fit for the scale expansion and interconnection of dynamic virtualization environment. In this paper, we propose VegaWarden, a uniform user management system to solve these problems. VegaWarden supplies a global user space for different virtual infrastructures and application services in one Cloud, and allows user system interconnection among homogeneous Cloud instances. A uniform authentication model enables the security isolation of different administrative domains, and a decentralized architecture ensures its scalability. We have implemented VegaWarden in an experimental Cloud-oriented infrastructure and a production Grid Computing environment. The functionality and performance of VegaWarden have been demonstrated.

Beyond Hadoop: Recent Directions in Data Computing for Internet Services

As a main subfield of cloud computing applications, internet services require large-scale data computing. Their workloads can be divided into two classes: customer-facing query-processing interactive tasks that serve hundreds of millions of users within a short response time and backend data analysis batch tasks that involve petabytes of data. Hadoop, an open source software suite, is used by many Internet services as the main data computing platform. Hadoop is also used by academia as a research platform and an optimization target. This paper presents five research directions for optimizing Hadoop; improving performance, utilization, power efficiency, availability, and different consistency constraints. The survey covers both backend analysis and customer-facing workloads. A total of 15 innovative techniques and systems are analyzed and compared, focusing on main research issues, innovative techniques, and optimized results.

ICOMC: Invocation Complexity Of Multi-Language Clients for Classified Web Services and its Impact on Large Scale SOA Applications

Theoretically, multi-language clients invocating web services is no longer a problem due to XML-based interface descriptions by WSDL, but the reality is not so good. Some implementation level difficulties still exist when invoking web services from clients in different programming languages. These difficulties are caused by involving complex data structures in the service interface, carrying additional information such as WS-security headers in the SOAP messages, missing language features such as Reflection in C/C++ and so on, which make large scale multi-language SOA application development a time-consuming and buggy work. This paper proposes a new complexity ICOMC, short for Invocation Complexity Of Multi-language Clients, to quantify these difficulties, introduces implementation cost and runtime performance metrics for ICOMC, and indentifies three factors dominating the ICOMC: service interface, message context, and language feature. Consequently, the problem is formulated as finding out the correlation of the three factors to ICOMC. To simplify the problem, web services are classified into four categories: SISM, SICM, CISM and CICM according to service interface complexity and message context complexity. Furthermore, micro-benchmark experiments are done in C/C++/Java for all four categories. This paper also takes the GOS System Software of the China National Grid as a real large scale application to implement its C/C++ client APIs and compare them with the original Java APIs. Evaluations based on micro-benchmarks and real application show the correlations between the factors and ICOMC. Our results benefit web service interface designing, appropriate language adoption, and implementation cost / runtime performance estimation.

A Layered Virtual Organization Architecture for Grid

Virtual organizations (VO) are widely accepted in the grid and other distributed computing environments. However, there are few effective VO implementations. This paper presents a layered architecture to construct Agora, an implementation of VO. Agora manages users, resources, and agora instances, provides policies to support a DAC/MAC-hybrid cross-domain access control mechanism, and maintains the context of operations. The Agora architecture consists of three layers. At the bottom is the physical layer containing external resources, then an abstraction RController is introduced to manipulate external resources. Above the physical layer, all the involved entities, including users, resources, and agoras, are abstracted as GNodes, and a naming layer is introduced to manage these GNodes. At the top, the logic layer implements all the Agora functionalities. This architecture has been implemented in Vega GOS and applied in the China National Grid and other grid platforms. The evaluation shows that the architecture provides minimal but sufficient VO functionalities while keeping decentralization, flexibility, simplicity, and effectiveness.

Investigating, Modeling, and Ranking Interface Complexity of Web Services on the World Wide Web

Analyzing factors of affecting Web Service invocation performance is a hot topic. Among the factors, service interface complexity is a key one investigated by much research work. However, these researches mainly analyze the impact on the performance of primitives, some simple data structures like mesh interface object, or array of them. For the complex data structures, these works lack of a systematic approach to characterize the impact. This paper firstly makes a detailed statistics of service interface complexity based on a large sample space (10K+ WSDL files) on the World Wide Web, and we find about 41.6% services contain complex data structures. The statistic results guide us to conduct many experiments for finding out the correlation of service interface complexity to invocation performance. We discover an interesting feature on commonly used Web Service platforms (Axis/gSOAP/.Net), called Data Structural Form Unaware. As each parameter or return value can be represented as a tree with two kinds of nodes, structure type node and primitive type node, then the feature means that the overhead caused by parameters or return values is independent of the organization of nodes in the trees, but it is only related with the number and the type of nodes. By this feature, we present a simple model to quantify the impact of service interface complexity. Using our model, a Service Interface Performance Vector can be calculated by parsing a WSDL file to estimate the overhead of service interface design. This vector, together with the invocation probability of each operation, generates the Service Interface Performance Score, a comprehensive complexity indicator which can be used to evaluate and rank the service interfaces. At last, a rank report of services on the WWW is shown. Our work can play a guiding role in service interface designing, service interface performance predicting, and ranking.

GOS Security: Design and Implementation

Grid technology has being widely accepted in distributed resources sharing and high performance computing cross multi administrative domains. In this paper, we analysis the security issues in grid computing environments, and propose a security framework for VegaGOS[1] which is a Service Oriented Architecture middleware developed for the China National Grid. We address mutual authentication using certificate with digital signature. We address authorization through combining VO level access control decision and resource level enforcement. Communication security is guaranteed by TLS/SSL at transport level and WS-Security at message level. This security framework has been implemented in VegaGOS and deployed in China National Grid Environment.

A Login Shell for Computing Grid

Shell is a most important user interface for HPC users in scientific computing. This paper presents a login shell for computing grid, called GShell, which provides an integrated and uniform environment for constructing, running and managing grid applications. Besides conventional functionality of shell, GShell provides grid-level functionality including grid context maintenance, grid application management interfaces, and extended pipe and redirection semantics. Grid contexts avoid repeat information input when a grid application is started. All the grid applications started in GShell are managed in the grid system, and they can be monitored or stopped in a global scope. Extended shell scripts allow constructing new grid applications using existing tools. At present, GShell has been implemented and applied in the CNGrid project, and is proved to be a simple and flexible command-line tool for most scientists to work in the grid.

An Experimental Analysis for Memory Usage of GOS Core

As grid software and grid applications grow in size and complexity, memory usage experiment and analysis have become more and more essential. In this paper, we investigate an antitestcase-based approach to analyze the memory usage of GOS core software, and present a set of anti-testcases, which describe predefined memory problems of GOS core. This approach is applied with a set of automated test tools in controlled experiments including basic memory requirements, memory errors and memory usage of GOS core. With the experiment and analysis, we find several memory usage results of GOS core and they are valuable for other systems based on JVM, Tomcat and Axis. We also give some JVM memory configuration suggestions for better performance in the production server.

PGOS: An Architecture of a Personal Net Computing Platform

The development of web has brought rich applications and services, giving users convenience, but also causing that the user’s information is locked and isolated, the users’ resource are disperse, and the operation granularity is not uniform, which ultimately harm the end-users. This paper presents PGOS,Personal Grid Operation System, a general-purpose software for controlled sharing of cross-domain resources in personal net computing [1]. It accesses disperse resources uniformly from web client in order to connect the information islands formed by the companies, and it provides uniform fine-grained sharing mechanism, in addition, we can build new applications by combining the integrated resources in PGOS. The article proposes PGOS Core to complete decentralized user authentication, authorization and access control, Funnel is used to abstract the resource and make decentralized resource discovery, simultaneously PGSML, the Personal Grid Service Markup Language, is put forward to construct PGOS applications.