Showing papers on "Server published in 1997"

Self-similarity in World Wide Web traffic: evidence and possible causes

Abstract: The notion of self-similarity has been shown to apply to wide-area and local-area network traffic. We show evidence that the subset of network traffic that is due to World Wide Web (WWW) transfers can show characteristics that are consistent with self-similarity, and we present a hypothesized explanation for that self-similarity. Using a set of traces of actual user executions of NCSA Mosaic, we examine the dependence structure of WWW traffic. First, we show evidence that WWW traffic exhibits behavior that is consistent with self-similar traffic models. Then we show that the self-similarity in such traffic can be explained based on the underlying distributions of WWW document sizes, the effects of caching and user preference in file transfer, the effect of user "think time", and the superimposition of many such transfers in a local-area network. To do this, we rely on empirically measured distributions both from client traces and from data independently collected at WWW servers.

Simple object access protocol

Abstract: An application layer protocol is provided on top of HTTP 1.0/1.1 to allow for COM Automation objects to be invoked over the Internet through IIS/ISAPI servers. The format essentially encodes the automation object's name, method to invoke, and any [in], [out], [in, out] parameters that the method signature requires, packages them up into a custom MIME type and marshals it to the ISAPI dynamic link library (DLL) on the IIS/HTTP server. There, the ISAPI DLL contains the logic to unpack the SOAP request, parses it, creates the Automation object, invokes the method with the marshaled parameters, and then returns any [out] parameters to the caller/client using the SOAP protocol. It is a stateless protocol, meaning that object lifetimes only extend to one method, and are recreated between multiple calls to the object.

System and method for delivering consumer product related information to consumers within retail environments using internet-based information servers and sales agents

Abstract: A system and method are disclosed for finding and serving consumer product-related information over the Internet to consumers in retail shopping environments, as well as at home and work, and on the road. The system includes Internet information servers which store information pertaining to Universal Product Number (e.g. UPC number) preassigned to each consumer product registered with the system, along with a list of Uniform Resource Locators (URLs) that point to the location of one or more information resources on the Internet, e.g. World Wide Web-sites, which related to such registered consumer products. Upon entering the UPC number into the system using a conventional Internet browser program running on any computing platform or system, the menu of URLs associated with the entered UPC number is automatically displayed for user selection. The displayed menus of URLs are categorically arranged according to specific types of product information such as, for example: product specifications and operation manuals; product wholesalers and retailers; product advertisements and promotions; product endorsements; product updates and reviews; product warranty/servicing; related or complementary products; product incentives including rebates, discounts and/or coupons; manufacturer's annual report and 10K information; electronic stock purchase; etc. Web-based techniques are disclosed for collecting the UPC/URL information from manufacturers and transmitting the same to the Internet-based databases of the system.

Internet Web servers: workload characterization and performance implications

Abstract: This paper presents a workload characterization study for Internet Web servers. Six different data sets are used in the study: three from academic environments, two from scientific research organizations, and one from a commercial Internet provider. These data sets represent three different orders of magnitude in server activity, and two different orders of magnitude in time duration, ranging from one week of activity to one year. The workload characterization focuses on the document type distribution, the document size distribution, the document referencing behavior, and the geographic distribution of server requests. Throughout the study, emphasis is placed on finding workload characteristics that are common to all the data sets studied. Ten such characteristics are identified. The paper concludes with a discussion of caching and performance issues, using the observed workload characteristics to suggest performance enhancements that seem promising for Internet Web servers.

Cluster-based scalable network services

Abstract: We identify three fundamental requirements for scalable network services: incremental scalability and overflow growth provisioning, 24x7 availability through fault masking, and cost-effectiveness. We argue that clusters of commodity workstations interconnected by a high-speed SAN are exceptionally well-suited to meeting these challenges for Internet-server workloads, provided the software infrastructure for managing partial failures and administering a large cluster does not have to be reinvented for each new service. To this end, we propose a general, layered architecture for building cluster-based scalable network services that encapsulates the above requirements for reuse, and a service-programming model based on composable workers that perform transformation, aggregation, caching, and customization (TACC) of Internet content. For both performance and implementation simplicity, the architecture and TACC programming model exploit BASE, a weaker-than-ACID data semantics that results from trading consistency for availability and relying on soft state for robustness in failure management. Our architecture can be used as an off the shelf infrastructural platform for creating new network services, allowing authors to focus on the content of the service (by composing TACC building blocks) rather than its implementation. We discuss two real implementations of services based on this architecture: TranSend, a Web distillation proxy deployed to the UC Berkeley dialup IP population, and HotBot, the commercial implementation of the Inktomi search engine. We present detailed measurements of TranSend's performance based on substantial client traces, as well as anecdotal evidence from the TranSend and HotBot experience, to support the claims made for the architecture.

A mechanism for retrieving information using data encoded on an object

Abstract: A client computer (102) with a scanner (118) capable of scanning objects (115) for a code (117). The client computer (102) scans the object (115) of interest and translates the code (117) into a URL (Uniform Ressource Locator) that specifies both a server computer (122, 160) and the location within the server of information that is relevant to the object (115). The client computer (102) transmits the URL to the server computer (122, 160), receives the information related to the object (115) from the server computer (122, 160), and communicates the information to the customer.

Method of redirecting a client service session to a second application server without interrupting the session by forwarding service-specific information to the second server

Abstract: An on-line services network includes application servers and Gateway microcomputers that are interconnected by a LAN. The Gateway microcomputers receive service requests which are transmitted over a WAN from client microcomputers operated by end users. Upon receiving a request to open a service, the Gateway microcomputers access a periodically-updated service map to locate the replicated application servers that are currently running the corresponding service application, and then apply a load balancing method (using server load data contained within the service map) to select an application server that has a relatively low processing load. A communications protocol between the client and Gateway microcomputers enables users to access multiple services simultaneously. A hot redirection technique allows a user service session to be transferred from one application server to another (replicated) application server without termination of the service session. Various mechanisms are provided for efficiently reallocating application servers to different on-line services, and for allowing additional servers to be efficiently added to the network.

Start-time fair queueing: a scheduling algorithm for integrated services packet switching networks

Abstract: We present a start-time fair queueing (SFQ) algorithm that is computationally efficient and achieves fairness regardless of variation in a server capacity. We analyze its single server and end-to-end deadline guarantee for variable rate fluctuation constrained (FC) and exponentially bounded fluctuation (EBF) servers. To support heterogeneous services and multiple protocol families in integrated services networks, we present a hierarchical SFQ scheduler and derive its performance bounds. Our analysis demonstrates that SFQ is suitable for integrated services networks since it: (1) achieves low average as well as maximum delay for low-throughput applications (e.g., interactive audio, telnet, etc.); (2) provides fairness which is desirable for VBR video; (3) provides fairness, regardless of variation in server capacity, for throughput-intensive, flow-controlled data applications; (4) enables hierarchical link sharing which is desirable for managing heterogeneity; and (5) is computationally efficient.

Frangipani: a scalable distributed file system

Abstract: The ideal distributed file system would provide all its users with coherent, shared access to the same set of files, yet would be arbitrarily scalable to provide more storage space and higher performance to a growing user community. It would be highly available in spite of component failures. It would require minimal human administration, and administration would not become more complex as more components were added. Frangipani is a new file system that approximates this ideal, yet was relatively easy to build because of its two-layer structure. The lower layer is Petal (described in an earlier paper), a distributed storage service that provides incrementally scalable, highly available, automatically managed virtual disks. In the upper layer, multiple machines run the same Frangipani file system code on top of a shared Petal virtual disk, using a distributed lock service to ensure coherence. Frangipani is meant to run in a cluster of machines that are under a common administration and can communicate securely. Thus the machines trust one another and the shared virtual disk approach is practical. Of course, a Frangipani file system can be exported to untrusted machines using ordinary network file access protocols. We have implemented Frangipani on a collection of Alphas running DIGITAL Unix 4.0. Initial measurements indicate that Frangipani has excellent single-server performance and scales well as servers are added.

HTTP distributed remote user authentication system

Abstract: The present invention relates to the field of data and computer network security. Data and computer network security is of the utmost importance to most organizations that possess such networks. One of the difficulties that users and managers of these networks face is that the users have to provide a user ID and password every time they wish to access one of the organization's secured HTTP servers or URLs. This creates a problem for users and managers since lists of numerous user IDs and passwords need to be maintained and therefore can easily be lost or their confidentiality compromised. This invention addresses these problems by providing a transparent, scalable, single point of authentication for remote users across any number of HTTP servers anywhere on a data network, such as an Intranet, using any user ID and password scheme implemented by a main authentication HTTP server.

An empirical model of HTTP network traffic

Abstract: The workload of the global Internet is dominated by the Hypertext Transfer Protocol (HTTP), an application protocol used by World Wide Web clients and servers. Simulation studies of IP networks require a model of the traffic patterns of the World Wide Web, in order to investigate the effects of this increasingly popular application. We have developed an empirical model of network traffic produced by HTTP. Instead of relying on server or client logs, our approach is based on packet traces of HTTP conversations. Through traffic analysis, we have determined statistics and distributions for higher-level quantities such as the size of HTTP files, the number of files per "Web page", and user browsing behavior. These quantities form a model can then be used by simulations to mimic World Wide Web network applications.

Recovery from failure of a data processor in a network server

Abstract: A network file server includes a first set of data processors for receiving requests from clients, and a second set of data processors for accessing read-write file systems. A respective data processor in the second set is assigned to each file system for exclusive management of locks on the file system. The file server can detect failure of a failed data processor and automatically recover from the failure. When a failure of a data processor in the first set is detected, a spare data processor is programmed with the logical and physical network addresses of the failed data processor so that the spare data processor assumes the network identity of the failed data processor. When a failure of a data processor in the second set is detected, responsibility for management of the locks on each file system managed by the failed data processor is transferred to an operational data processor. Preferably the responsibility is transferred to the operational data processors in such a way as to balance loading on the operational data processors. The data processors can be commodity digital computers for low cost, and a cached disk storage subsystem or file system caches and remote dual copy techniques can be used to ensure high performance and high data availability.

Subscription access system for use with an untrusted network

Abstract: A system and method is disclosed for controlling access to computer resources using an untrusted network. The system preferably uses a hardware key connected to each subscriber client computer and adds software to the subscriber client computer and to the existing server computer. A clearinghouse is provided to store client and server identification data, including demographic data, including URL data, usage data and billing information. The clearinghouse authenticates the subscriber and server computers before an operating session occurs. For every new client session, a login mechanism requires the client computer to supply appropriate identification data, including a digital identification generated by the hardware key. The login parameters are verified by the clearinghouse and a session is then started. The system is adapted to protect preselected content from being printed or copied by a client using a web browser. The system architecture permits a geographical distributed system of multiple subscriber client computers, multiple server computers and multiple clearinghouses which can interact with each other.

Hierarchical packet fair queueing algorithms

Abstract: We propose to use the idealized hierarchical generalized processor sharing (H-GPS) model to simultaneously support guaranteed real-time, rate-adaptive best-effort, and controlled link-sharing services. We design hierarchical packet fair queueing (H-PFQ) algorithms to approximate H-GPS by using one-level variable-rate PFQ servers as basic building blocks. By computing the system virtual time and per packet virtual start/finish times in unit of bits instead of seconds, most of the PFQ algorithms in the literature can be properly defined as variable-rate servers. We develop techniques to analyze delay and fairness properties of variable-rate and hierarchical PFQ servers. We demonstrate that in order to provide tight delay bounds with an H-PFQ server, it is essential for the one-level PFQ servers to have small worst-case fair indices (WFI). We propose a new PFQ algorithm called WF/sup 2/Q+ that is the first to have all the following three properties: (1) providing the tightest delay bound among all PFQ algorithms; (2) having the smallest WFI among all PFQ algorithms; and (3) having a relatively low asymptotic complexity of O(log N). Simulation results are presented to evaluate the delay and link-sharing properties of H-WF/sup 2/Q+, H-WFQ, H-SFQ, and H-SCFQ.

Hardware and software failover services for a file server

Abstract: A file server includes stream server computers linking a cached disk array storage subsystem to a data network, and at least two controller servers for receiving requests for file access from network clients. At any given time one of the controller servers is active and another is inactive in servicing client requests. The active controller server selects one of the stream servers to service each request. A controller server failover mechanism is provided for recovering from a failure of the active controller server, and a stream server failover mechanism is provided for recovering from a failure of a stream server. The inactive controller server becomes active when it fails to receive a signal periodically transmitted by the active controller server. The active controller server begins stream server failover when it fails to receive a signal periodically transmitted by each stream server. To resume automatically an interrupted task, the tasks are organized as a series of transactions, and each transaction includes operations which can be duplicated without substantial disruption. The active controller server commits results of each transaction to memory of the cached disk array. Before becoming active, the inactive controller recovers the committed state of the interrupted tasks from the cached disk array.

Querying the World Wide Web

Abstract: The World Wide Web is a large, heterogeneous, distributed collection of documents connected by hypertext links. The most common technology currently used for searching the Web depends on sending information retrieval requests to "index servers". One problem with this is that these queries cannot exploit the structure and topology of the document network. The authors propose a query language, WebSQL, that takes advantage of multiple index servers without requiring users to know about them, and that integrates textual retrieval with structure and topology-based queries. They give a formal semantics for WebSQL using a calculus based on a novel "virtual graph" model of a document network. They propose a new theory of query cost based on the idea of "query locality," that is, how much of the network must be visited to answer a particular query. Finally, they describe a prototype implementation of WebSQL written in Java.

Implementation of charging in a telecommunications system

Abstract: The invention concerns a method for the implementation of charging in a telecommunications system including customer terminals used by customers for ordering services and servers for providing services to customers. In order to implement the charging of services easily especially in a multimedia environment, at least one separate billing server is used in the network so that each customer terminal has a dedicated billing server. A contract message is sent to the customer terminal stating that the customer must make a contact on the selected service, and the customer's acceptance of the contact is sent from the customer terminal to the billing server in the network. The billing servers of the network are used for transferring charging records to the billing system so that the transfer of the charging record(s) concerning the selected service involves at least one billing server.

Loading balancing across servers in a computer network

Abstract: A dynamic routing of object requests among a collection or cluster of servers factors the caching efficiency of the servers and the load balance or just the load balance The routing information on server location can be dynamically updated by piggybacking meta information with the request response To improve the cache hit at the server, the server selection factors the identifier (eg URL) of the object requested A partitioning method can map object identifiers into classes; and requester nodes maintain a server assignment table to map each class into a server selection The class-to-server assignment table can change dynamically as the workload varies and also factors the server capacity The requester node need only be informed on an “on-demand” basis on the dynamic change of the class-to-server assignment (and thus reduce communication traffic) In the Internet, the collection of servers can be either a proxy or Web server cluster and can include a DNS and/or TCP-router The PICS protocol can be used by the server to provide the meta information on the “new” class-to-server mapping when a request is directed to a server based on an invalid or obsolete class-to-server mapping DNS based routing for load balancing of a server cluster can also benefit By piggybacking meta data with the returned object to reassign the requester to another server for future requests, adverse effects of the TTL on the load balance are overcome without increasing traffic

Server-group messaging system for interactive applications

Abstract: A method for deploying interactive applications over a network containing host computers and group messaging servers is disclosed. The method operates in a conventional unicast network architecture comprised of conventional network links and unicast gateways and routers. The hosts send messages containing destination group addresses by unicast to the group messaging servers. The group addresses select message groups maintained by the group messaging servers. For each message group, the group messaging servers also maintain a list of all of the hosts that are members of the particular group. In its most simple implementation, the method consists of the group server receiving a message from a host containing a destination group address. Using the group address, the group messaging server then selects a message group which lists all of the host members of the group which are the targets of messages to the group. The group messaging server then forwards the message to each of the target hosts. In an interactive application, many messages will be arriving at the group server close to one another in time. Rather than simply forward each message to its targeted hosts, the group messaging server aggregates the contents of each of messages received during a specified time period and then sends an aggregated message to the targeted hosts. The time period can be defined in a number of ways. This method reduces the message traffic between hosts in a networked interactive application and contributes to reducing the latency in the communications between the hosts.

Method and system for providing a networked collaborative work environment

Abstract: A system and method for providing a collaborative work environment includes servers and client workstations. Client workstations receive data objects from one or more servers and combine the received data objects with stored templates to render HTML pages representing at least a portion of a common project. Users may view, edit, and create common documents for the projects and upload them to the server using a drag-and-drop interface. Additionally, since all file transfers take place using HTTP, project groups can span corporate organizations as well as time zones and geographic boundaries.

Method and apparatus for balancing the process load on network servers according to network and server based policies

Abstract: According to the present invention, a method and system provides the ability to assign requests for data objects made by clients among multiple network servers. The invention provides a distributed computing system and methods to assign user requests to replicated servers contained by the distributed computing system in a manner that attempts to meet the goals of a particular routing policy. Policies may include minimizing the amount of time for the request to be completed.

Disk-directed I/O for MIMD multiprocessors

Abstract: Many scientific applications that run on today's multiprocessors, such as weather forecasting and seismic analysis, are bottlenecked by their file-I/O needs. Even if the multiprocessor is configured with sufficient I/O hardware, the file system software often fails to provide the available bandwidth to the application. Although libraries and enhanced file system interfaces can make a significant improvement, we believe that fundamental changes are needed in the file server software. We propose a new technique, disk-directed I/O, to allow the disk servers to determine the flow of data for maximum performance. Our simulations show that tremendous performance gains are possible both for simple reads and writes and for an out-of-core application. Indeed, our disk-directed I/O technique provided consistent high performance that was largely independent of data distribution and obtained up to 93% of peak disk bandwidth. It was as much as 18 times faster than either a typical parallel file system or a two-phase-I/O library.

Controlled transfer of information in computer networks

Abstract: The present invention relates to techniques for controlling transfers of information in computer networks. One technique involves transmitting from a server computer to a client computer a document containing a channel object corresponding to a communication service, and storing an access ticket that indicates that a user of the client computer permits the information source computer to communicate with the user over a specified channel. Another technique involves transmitting smart digital offers based on information such as coupons and purchasing histories stored at the computer receiving the offer. Another technique involves transmitting from a server computer to a client computer a request for a user's personal profile information, and activating a client avatar that compares the request for personal profile information with a security profile of the user limiting access to personal profile information. Another technique involves transmitting from a server computer to a client computer a document containing an embedded link, activating the embedded link at the client computer and recording activation of the embedded link in a metering log.

Network server platform for internet, JAVA server and video application server

Abstract: A new architecture capable of utilizing the existing twisted pair interface between the customer services equipment and the local office is used to provide a vast array of new services to customers. Using an intelligent services director (ISD) at the customer services equipment and a facilities management platform (FMP) at the local office, new services such as simultaneous, multiple calls (voice analog or digital), facsimile, Internet traffic and other data can be transmitted over the existing single twisted pair using xDSL transmission schemes. New services such as the implementation of Internet connectivity, videophone, utility metering, broadcasting, multicasting, bill viewing, information pushing in response to a user profile, directory look-up and other services can be implemented via a network server platform via this architecture. A network server platform for hosting a plurality of services comprises, for example, a memory for storing a user profile, the user profile containing interests of a user, and for storing information related to their interests and a controller for controlling the collection of information from information servers and for pushing the collected information to the user in accordance with their defined priority.

Anti-virus agent for use with databases and mail servers

Abstract: A software agent for detecting and removing computer viruses located in attachments to e-mail messages. A client-server computer network includes a server computer and a plurality of client computers. A message system, located at the server computer, controls the distribution of e-mail messages. An anti-virus module, located at the server computer, scans files for viruses. The agent is located at the server computer and provides an interface between the anti-virus module and the message system. The agent can operate both on a real-time basis and at preset period intervals. E-mail messages that are sent internally within the network can be scanned, e.g., Intranet e-mail messages. In addition, e-mail messages received over the Internet can be scanned.

Data distribution techniques for load-balanced fault-tolerant web access

Abstract: A server system for processing client requests received over a communication network includes a cluster of N document servers and at least one redirection server The redirection server receives a client request from the network and redirects it to one of the document servers, based on a set of pre-computed redirection probabilities Each of the document servers may be an HTTP server that manages a set of documents locally and can service client requests only for the locally-available documents A set of documents are distributed across the document servers in accordance with a load distribution algorithm which may utilize the access rates of the documents as a metric for distributing the documents across the servers and determining the redirection probabilities The load distribution algorithm attempts to equalize the sum of the access rates of all the documents stored at a given document server across all of the document servers In the event of a server failure, the redirection probabilities may be recomputed such that the load of client requests is approximately balanced among the remaining document servers The redirection probabilities may also be recomputed periodically in order to take into account changes in document access rates and changes in server capacity The recomputation may be based on a maximum-flow minimum-cost solution of a network flow problem

System and method for automatic configuration of home network computers

Abstract: In a distributed computer system, an automated configuration system and method for configuring home network client computers, including determining local service provider information, the configuration performed without any user assistance The distributed computer network comprising of unconfigured network home dient computers, and at least one autoconfiguration server The network may also include sales servers and local service provider servers The home network client computer determines on power on time if it possesses the requisite configuration information If the requisite configuration information is lacking, the home network client computer sends a configuration request along with client computer identifying information to the autoconfiguration server On receiving the configuration request from a home network client computer, the autoconfiguration server uses the client identifying information to determine the local service provider information and client computer specific data The autoconfiguration server determines the local service provider information by looking up a directory of local service providers, the directory being stored on the autoconfiguration server or on some local service provider server The autoconfiguration server determines the client computer specific data by accessing a database containing client computer information for each home network client computer, the database being stored either on the autoconfiguration server itself or on some sales server The client computer specific data is stored in the database at time of sale/purchase/shipment of the home network computer to the user The local service provider information and the client computer specific data is then downloaded to the requesting home network client computer The home network client computer uses the configuration information downloaded by the autoconfiguration server to configure itself and establish connection to the local service provider

Network request distribution based on static rules and dynamic performance data

Abstract: A system and method for the distribution of client requests received from a digital computer network provides an intermediary between the client and one or more content servers that actually service the client request. Client requests are distributed amongst groups of content servers according to a one or more static rules. These static rules are applied to determine which group of content servers will service each client request. Content servers may be grouped without regard to hardware configuration and without regard to where the content server resides within the network. Client requests may be distributed amongst the content servers within each group according to a dynamic metric. The dynamic metric includes time-varying measurements of the available processing capacity of each content server within a group. Client requests may then be distributed to those content servers within a group that are best able to handle additional processing burdens. The available processing capacity of each content server is measured without requiring special software to be installed in the content servers, and without unduly increasing network message traffic. Connections may be established with content servers in one of two modes: a proxy mode where the present invention acts on behalf of the client by having the client request serviced, and a redirect mode where the present invention returns to the client whatever information is required to enable the client to establish a direct connection with the content server.

Systems for providing large arena games over computer networks

Abstract: The gaming systems according to the invention include hardware and software systems that allow a large arena of participants to interactively play a game of chance or skill. Generally, the invention can be understood game servers that generate page signals, such as HTML pages, that are representative of a hand being played, or dealt to a participant in a large arena game. For example, the game server can generate for each participant in a large arena game a page that is representative of a bingo card dealt to that participant. Each of the pages generated by the server includes a control mechanism, such as a check box or radio button, that allows the server to collect information from the participant to determine the moves being played by that participant. The gamer server collects from each participant the moves being played by the participant and as a function of the moves played and the hand dealt, the game server generates a new page that shows the progression of the participant through the game.

Apparatus, method and article of manufacture for servicing client requests on a network

Abstract: A server services client requests in an improved manner by a utilizing a combination of sending an id of the last article that has been previously sent to the client, load balancing servers to provide efficient servicing of clients and providing redundant servers so that a failure of any one server does not result in the termination of server services to clients.