Abstract: A distributed system comprises one or more computers implementing a downstream server configured to determine whether it is overloaded and in response, to indicate to one or more upstream servers that the downstream server is in a hotspot situation. The system comprises one or more computers implementing one or more upstream servers configured to respond to receiving the indication of the hotspot situation by shielding the downstream server from subsequent requests, the shielding including serving one or more client requests without requesting service from the downstream server and reporting one or more measures of the shielded requests to the downstream server. The downstream server is further configured to determine whether the hotspot situation still exists, dependent on one or more of the reported measures.

Abstract: Disclosed are various embodiments for a hybrid networked application. An application context communicates with a thin client application. The application context maintains a navigation state and manages previously loaded content to simulate a native application experience. Navigation contexts facilitate the search and discovery of information. Overlays facilitate the discovery and rendering of item details.

Abstract: Disclosed are various embodiments for a hybrid networked application. An application context communicates with a thin client application. The application context maintains a navigation state and manages previously loaded content to simulate a native application experience. Navigation contexts facilitate the search and discovery of information. Overlays facilitate the discovery and rendering of item details.

Abstract: Disclosed are various embodiments for a hybrid networked application. An application context communicates with a thin client application. The application context maintains a navigation state and manages previously loaded content to simulate a native application experience. Navigation contexts facilitate the search and discovery of information. Overlays facilitate the discovery and rendering of item details.

Abstract: A computer system that provides services to clients may adaptively throttle incoming service requests in order to reach and then maintain operation at an ideal request rate. An ideal request rate may be a maximum rate at which incoming service requests can be serviced such that client-specified quality of service (QoS) expectations are met for most or all incoming service requests, or a rate within a range of rates defined by that maximum rate. Determining whether the system is operating at an ideal request rate may include determining the minimum difference between the expected and actual QoS for a group of recently serviced requests. The system may gradually modify a throttle multiplier value in order to reach or maintain an ideal request rate. Maintaining operation at an ideal request rate may allow the system to avoid entering an overloaded state, and/or oscillating between an overloaded state and a non-overloaded state.

Abstract: A computer system that provides services to clients may be configured to determine whether it is operating in an overloaded state based on the percentage of client-specified quality of service (QoS) expectations that are not met. For example, if the percentage of service requests in a group of recently serviced requests for which client-specified expectations of a maximum response time were not met is greater than a pre-determined overload threshold, the system may be considered to be in an overloaded state. The overload threshold may be configurable. The overload state may be determined periodically by determining the percentage of service requests in a moving window of time for which client-specified QoS expectations were not met. In response to determining that the system is operating in an overloaded state, it may be configured to throttle at least a portion of incoming service requests in an attempt to exit the overloaded state.

Abstract: A computer system that provides services to clients may be configured to adaptively throttle incoming service requests. It may modify throttle parameters to aggressively increase throttling in response to detecting that the system is in an overloaded state. For example, a throttle multiplier value may be increased by a large amount in an attempt to quickly exit the overloaded state. The throttle multiplier value may be increased multiple times before the system exits the overloaded state. The percentage of incoming requests that are throttled and/or the particular requests that are throttled may be dependent on the throttle multiplier value and/or on a request priority rank. Some time after the system returns to a non-overloaded state, the system may gradually reduce throttling by iteratively decreasing the throttle multiplier value until it is zero. Gradually reducing throttling may allow the system to avoid oscillating between an overloaded state and a non-overloaded state.