Abstract: In one aspect of the invention, a method of dynamically switching message logging schemes to improve performance of a distributed system is provided. The distributed system includes a client device and a server device that communicate by sending and receiving messages across a network. The method includes measuring a system load for the server and a network delay for the messages transmitted between the client and the server. The method further includes selecting at least one of a client-side message logging scheme and a server-side message logging scheme based on a determination of whether the system load is greater than a system load threshold and whether the network delay is greater than a network delay threshold.

Abstract: In one aspect of the invention, a method of dynamically switching among a plurality of fault tolerance schemes is provided. The fault tolerance schemes are associated with a fault tolerance mechanism that executes in a distributed system. The method comprises obtaining a wait time of at least one user interface event occurring in the distributed system. The wait time includes at least one of a communications time, a service time and a fault tolerance time. The method further comprises determining whether a mean of the wait time is greater than a predetermined mean wait time threshold. The method also comprises determining whether the communications time, the service time and the fault tolerance time are mutually independent when the mean of the wait time is greater than the predetermined mean wait time threshold.

Abstract: In one aspect of the invention, a method for load balancing a plurality of servers is provided. The method comprises intercepting a request from a requestor client forming part of a client group for a service provided by the plurality of servers, determining wait times for servicing prior requests from at least one member client of the client group by at least one of the plurality of servers, and selecting an execution server from among the plurality of servers for responding to the request dynamically based on a computation of the wait times.

Abstract: In one aspect of the invention, a method of dynamically switching among a plurality of fault tolerance schemes is provided. The fault tolerance schemes are associated with a fault tolerance mechanism that executes in a distributed system. The method comprises obtaining a wait time of at least one user interface event occurring in the distributed system. The wait time includes at least one of a communications time, a service time and a fault tolerance time. The method further comprises determining whether a mean of the wait time is greater than a predetermined mean wait time threshold. The method also comprises determining whether the communications time, the service time and the fault tolerance time are mutually independent when the mean of the wait time is greater than the predetermined mean wait time threshold.

Abstract: A method and system for preserving application session states among multiple terminals. An application session state is captured from a first terminal. The application session state is stored on a central storage device or repository server. The application session state is then retrieved from the central storage device with a second terminal. At least one application on the second terminal is then placed in the application session state using the information that is retrieved from the central storage device.

Abstract: In one aspect of the invention, a mobile application environment for a mervlet application is provided. The mobile application environment forms part of a mobile communication network comprising at least one access network. The environment comprises the mervlet, which includes instructions to create a web page with dynamically generated content. The mervlet is capable of executing on at least one of a local node and a remote node of the network. The environment also comprises a set of application attributes for the mervlet, including performance attributes characterizing the user interface of the mervlet. The environment further comprises a set of security attributes for the mervlet defining a security context in which to execute the mervlet. In addition, the environment comprises a mervlet engine that is operative to manage a lifecycle of the mervlet. The engine includes a core interpreter module operative to execute the mervlet in the security context defined by its security attributes.

Abstract: In one aspect of the invention, a method for load balancing a mobile application among a plurality of devices forming part of at least one communication network is provided. The method includes storing the application on a server device of the network. The method also includes requesting the application from a client computing device of the network. The method further includes provisioning execution of the application on one of the server and client devices to optimize the user perceived performance of the application based on a set of application attributes. The application attributes includes performance attributes relating to wait times for user interface events of the application.

Abstract: In one aspect of the invention, a fault tolerant system for recovering from transient faults in a mobile computing environment is provided. The fault tolerant system comprises a configurable reliable messaging system, which includes a client computer operative to generate a message and a server computer operative to receive the message and to generate a reply in response to the message across a communication network. The messaging system also includes a client logging agent on the client operative to buffer the message in a persistent storage on the client and to transmit the message to the server until the reply is received. The client logging agent executes in response to a client logging signal. The messaging system further includes a server logging agent on the server operative to buffer the received message and the reply in a persistent storage on the server and to transmit the reply to the client. The server logging agent executes in response to a server logging signal.

Abstract: A browser state repository (BSR) service allows a user to save and restore independent browser states of active sessions between browsers and sites. Each independent browser state may be associated with the user and stored as a browser snapshot. The user may later retrieve any saved browser snapshot on any browser and/or any device and restore the corresponding active session with the corresponding site. The BSR service decouples the traditional association between the browser state and a device, in favor of an association between the browser state and a user that is independent of any browser or device.

Abstract: A method, apparatus and computer product that enables one or more computing devices to discover and use services over a network, which may be ad-hoc when the computing device is mobile. Service discovery is based on periodic multicasting of exported service descriptions to nearby devices over the (ad-hoc) network. Middleware enables a device to discover, advertise and use services. This enables software clients on the same device to share a service implementation (in the case of a local service) or to share an implementation proxy (in the case of a remote service). Each device being aware of the services (and service locations) that are currently available generally reduces the response time associated with accessing available services. While service descriptors are multicast and discovered, the service software is only downloaded on the device when the service is used. This enables economical resource management that is particularly useful for mobile devices.

Abstract: A server complex including at least one hit server with item cache, used to process read and write operations relating to cached items from clients, and at least one miss server, serving as a link to other servers (e.g., web servers, file system servers, and databases) for receiving requests relayed from the hit server(s) which relate to non-cached items and for responding to same. The hit server is a general-purpose, generic, component, which is independent of concrete applications and is basically responsible for the performance; while a miss server is a highly-customizable component, which is responsible for flexibility, and is application specific. The inventive architecture provides improved performance whereby a server complex achieves exceptionally high throughput rates for local services (i.e.

Abstract: The invention provides the mechanism, hereinafter referred to as Flexible Dynamic Partitioning (FDP), to allocate and reallocate resources among scheduling schemes of many types for multicomputing environments. Resources can include, but are not limited to, processors, disks and communications connections. Partitioning of resources can be initiated by both application and system triggers. Once dynamic partitioning is triggered, FDP allows a partition to invoke a set of resource allocation functions associated with its partition. The reallocation function performs a set of resource matchings and determine the necessary resource movement among partitions.

Abstract: A system and method whereby a gang scheduling entity assembles a schedule of application tasks to be run on a plurality of distributed parallel processors for pre-set time intervals. The scheduling information, including an ordered set of applications and the length of the time interval, are provided to each of the node level schedulers for the relevant processors, and the node level schedulers assure that the tasks of the applications are executed, with context switching between tasks being controlled at the node level. Tasks from multiple applications can be scheduled simultaneously, with time sharing and space sharing being utilized in the schedule. The inventive system is dynamically scalable, with the gang scheduling entity restructuring the matrix schedule should dynamic re-partitioning result in addition or deletion of processors.

Abstract: A cache system in accordance with the present invention consists of one or more cache components and a set of one or more consistency-replacement functions. A cache component caches one or more items in its one or more cache entries. Items that hit in the cache can result in corresponding cache entries being read or written. Any valid entry in a cache component includes status information reflecting whether the entry has been accessed and whether it has been modified, and is linked to a consistency-action matrix that, in correspondence with the entry's status information and access type (i.e. read or write), determines what consistency action has to be executed in conjunction with the current entry access. Consistency actions and the consistency-action matrix are the inventive mechanisms for implementing cache-coherency and cache-replacement policies. Any valid entry in a cache is linked to a consistency-replacement function that implements one or more consistency and/or replacement policies.

Abstract: An open architecture for arbitrarily combining data analysis algorithms and databases on the Internet where the data analysis algorithm and database may be from different vendors or suppliers. At the request of a customer, the two are combined on the fly while maintaining proper security and while enforcing some agreed upon payment from the customer to both the algorithm and database suppliers. In one embodiment, a message including an identifier of a user selected independent content provider and an identifier of a particular service associated with a service provider is sent to the service provider on a communication network. The user selected independent content provider is separate from the service provider. In response to the message, a computer executable code, which when executed by the content provider will cause the particular service to be performed against content controlled by the content provider, is sent from the service provider to the content provider.

Abstract: A dynamic derivation mechanism is defined which enables limited permissions to be dynamically and flexibly derived for executables based upon their authenticated description. The dynamic derivation mechanism uses the authenticated description to determine the maximal permissions that individual principals can delegate to the content. A principal's maximal permissions for content define a superset of the rights that that principal will actually delegate to that content. Although the maximal permissions are derived from predefined specifications, the specifications can be sensitive to runtime state on the downloader's system or previous delegations to enable the dynamic (i.e., runtime) derivation. Multiple principals can delegate a subset of their maximal permissions for the executable content. The mechanism uses policy for combining the delegated permissions into the content's runtime permissions.

Abstract: A cache system in accordance with the present invention consists of one or more cache components and a set of one or more consistency-replacement functions. A cache component caches one or more items in its one or more cache entries. Items that hit in the cache can result in corresponding cache entries being read or written. Any valid entry in a cache component includes status information reflecting whether the entry has been accessed and whether it has been modified, and is linked to a consistency-action matrix that, in correspondence with the entry's status information and access type (i.e. read or write), determines what consistency action has to be executed in conjunction with the current entry access. consistency actions and the consistency-action matrix are the inventive mechanisms for implementing cache-coherency and cache-replacement policies. Any valid entry in a cache is linked to a consistency-replacement function that implements one or more consistency and/or replacement policies.

Abstract: A mechanism for creating links and services on the Internet to reduce the bottlenecks at service providers by associating code with links to make them intelligent and a special protocol between the links and the back end servers to maintain scalableness and performance. Scalableness is supported by moving much of the functionality of searching onto the client side.

Abstract: An object oriented application comprising an hierarchy of application classes, each having a plurality of class methods, is created from a toolkit having a static class hierarchy including a number of standard classes, a number of public interface methods with interfacing attributes and a list for chaining class private methods to the public interface methods, a plurality of class definition source and header files defining the extended application classes, a plurality of class method source and header files implementing the class methods of the extended classes, and a plurality of object user source and header files implementing the object users, using a traditional programming language that provides no support for object oriented programming. Together, the various files cooperate to achieve data abstraction and inheritance of object oriented programming, when the various files are compiled, linked, executed.

Abstract: In the system of the present invention, an event driven journaling mechanism which is not dependent on the timing of execution of processes is implemented. Special events, referred to as synchronization events, mark locations, referred to as synchronization points, in the journal file of events where previously initiated processing must be completed before initiating the subsequent process. The synchronization points are located between processes which are exchanging state. The synchronization events are put into the journal file during the recording phase. On playback, the journaling mechanism waits for a synchronization event to occur before proceeding to the next action in the journal file and initiating subsequent execution of the process.