An initiator agent and target agent exchange measurement and response messages to determine the performance of a network supporting communication between the initiator agent and the target agent. The initiator agent creates and transmits measurement packets in a measurement packet group to the target agent. The measurement packet include one or more performance metrics created by the initiator agent such as timestamp information and sequencing information. The target agent receives the measurement packets, perform calculations of network performance metrics in generates corresponding response packets that are forwarded back to the initiator agent. The initiator agent receives the response packets and uses parameter information contained therein to calculate network link performance metrics such as one-way and round-trip packet latency of measurement and response packets as well as packet loss performance metrics for one-way and round-trip packet propagation between the initiator and target agents. Payload data within the measurement and response packets simulates application data traffic.

To lower risks of overhead on management of an access log and of a loss of the access log due to a default and to prevent deterioration in service providing performance caused by access concentration to a specific Web server in an access relaying apparatus including a plurality of proxy servers. An access relaying apparatus has a plurality of proxy servers 23, an administration server 24 for statistic processing, and a shared disk 25 accessible from them. Each of the proxy servers outputs an access log to the shared disk, and the administration server reads the access logs from the shared disk and performs statistic processing. An access limit to a specific Web server is determined based on a result of the statistic processing, it is notified to each of the proxy servers, and a number of accesses to the Web server is controlled.

An infrastructure "insurance" mechanism enables a Web site to fail over to a content delivery network (CDN) upon a given occurrence at the site. Upon such occurrence, at least some portion of the site's content is served preferentially from the CDN so that end users that desire the content can still get it, even if the content is not then available from the origin site. In operation, content requests are serviced from the site in the usual manner, e.g., by resolving DNS queries to the site's IP address, until detection of the given occurrence. Thereafter, DNS queries are managed by a CDN dynamic DNS-based request routing mechanism so that such queries are resolved to optimal CDN edge servers. After the event that caused the occurrence has passed, control of the site's DNS may be returned from the CDN back to the origin server's DNS mechanism.

A system for managing a JMS message store in a clustered network includes an object acting as a message store for Java Message Service (JMS). A lead server is selected from several clustered servers. The lead server uses a distributed consensus algorithm to select a host server, utilizing multicast messaging while executing rounds of the algorithm. The selected host server hosts the JMS message store, providing sole access to JMS. The other servers are notified of the new host by multicast messaging. All servers in the cluster can use JMS, but they must send messages to the message store on the host and pick up any messages from the message store.

A system for managing objects in a clustered network includes a file system containing at least one copy of a data object. The system can include several clustered servers in communication with the file system. A distributed consensus algorithm is used to select a host server. The selected host server can contain a copy of the data object, such as in local cache, providing access to the local copy to any other server in the cluster. Any change made to an item hosted by the host server can also be updated in the file system. If the host server becomes unable to host the object, a new host can be chosen using the distributed consensus algorithm. The other servers are then notified of the new host by multicast messaging.