Abstract: An aerial work platform and a floating control system thereof, the system comprising a driving mechanism, a hydraulic oil tank, a hydraulic pump, a floating control valve, a floating mechanism, a boom function valve, an actuator, and an accumulator: the floating control valve comprises a first one-way valve, a second one-way valve, a pressure reducing valve, and a logic valve; and an oil inlet of the first one-way valve serves as the oil inlet of the floating control valve, an oil outlet of the first one-way valve is connected to a pipeline connecting the accumulator, the pressure reducing valve and the logic valve, the logic valve is connected to the second one-way valve, an oil outlet of the second one-way valve serves as the feedback oil port of the floating control valve, when the hydraulic pump is a variable displacement pump, a feedback oil port of the floating control valve and a feedback oil port of the boom function valve are connected to a feedback oil port of the variable displacement pump; when th

Abstract: A floating control system for a fixed displacement pump system is disclosed, which relates to the technical field of floating mechanisms and includes: a fixed displacement pump, floating control valves, a floating mechanism, boom function valves, an actuator and a control device, where the fixed displacement pump, the floating control valves and the floating mechanism are connected in sequence, the fixed displacement pump, the boom function valves and the actuator are connected in sequence, the floating control valves include a pressure reducing valve and a floating switching valve, and the boom function valves include a fixed differential overflow valve and a proportional directional valve; and the fixed differential overflow valve and the proportional directional valve are connected in parallel between the fixed displacement pump and an oil return tank, the floating switching valve and the fixed differential overflow valve are connected through a feedback oil path.

Abstract: Some embodiments provide a novel method for offloading firewall operations from a host computer executing a set of one or more virtual machines (VMs) to a physical network interface card (PNIC) connected to the host computer. The method configures, on the PNIC, a first firewall to determine actions to perform on flows associated with the set of VMs, and to offload processing of the flows to a flow-cache second firewall of the PNIC. The method configures, on the PNIC, the flow-cache second firewall to process a first set of flows based on a first set of actions determined by the first firewall, and to offload processing of a second set of flows to an embedded hardware switch of the PNIC. The method configures, on the PNIC, the embedded hardware switch to process the second set of flows based on a second set of actions determined by the first firewall.

Abstract: Some embodiments provide a novel method for updating firewall rules for data message flows processed at a physical network interface card (PNIC) connected to a host computer. A firewall of the PNIC receives an update to a particular firewall rule. The firewall identifies a particular data message flow that is processed at an embedded hardware switch of the PNIC using the particular firewall rule. The firewall updates a flow record associated with the particular data message flow to reflect the received update to the particular firewall rule. The firewall provides the updated flow record to the embedded hardware switch for the embedded hardware switch to process the particular flow according to the received update.

Abstract: Some embodiments provide a novel method for using connection tracking records to process data messages at a physical network interface card (PNIC) connected to a host computer. A first software firewall of the PNIC determines whether processing of a flow is passable to a second software firewall of the PNIC and to a third hardware firewall of the PNIC. The first software firewall creates a connection tracking record for the flow and data specifying whether processing of the flow is passable to the second software firewall and independently whether processing of the flow is passable to the third hardware firewall. The first software firewall provides the connection tracking record and said data to the second software firewall of the PNIC so that the second software firewall processes the flow or passes the connection tracking record and the data to the third hardware firewall if determination was that the flow is passable to the third hardware firewall.

Abstract: Some embodiments provide a novel method for migrating virtual machines (VMs) from a first host computer to a second host computer. The first host computer is connected to a physical network interface card (PNIC) that performs middlebox service operations for flows associated with the VMs. At the PNIC, the method receives a notification that a VM is to be migrated from the first to the second host computer. The method configures an embedded hardware switch of the PNIC to forward a set of flows associated with the VM to a firewall of the PNIC. The embedded hardware switch was initially programmed to process the set of flows instead of the firewall. The method synchronizes flow cache information regarding the set of flows from the embedded hardware switch to the firewall. The method processes the set of flows at the firewall until the VM is migrated to the second host computer.

Abstract: Some embodiments provide a novel method for processing flows at an embedded hardware switch of a physical network interface card (PNIC) connected to a host computer. A firewall of the PNIC detects an end of a particular data message flow associated with a particular VM of the host computer. Processing of the particular data message flow was offloaded from the firewall to an embedded hardware switch of the PNIC. After detecting the end of the particular data message flow, the firewall ends offloading of the particular data message flow by deleting a first flow record stored at the embedded hardware switch for the particular data message flow. The firewall deletes a second flow record stored at the first firewall for the particular data message flow.

Abstract: An emergency descent system for an aerial work platform includes a telescopic hydraulic cylinder provided a piston rod inside, a counterbalance valve, an oil return pipe and a proportional valve. An interior of the telescopic hydraulic cylinder is divided into a cavity with rod and a cavity with non-rod. An inlet of the counterbalance valve is connected to the cavity with non-rod, and an outlet of the counterbalance valve is connected to an oil supply pipe. The oil return pipe is connected to the cavity with rod and a control port of the counterbalance valve, the oil return pipe is connected to an emergency oil source which is used for providing hydraulic oil to the oil return pipe. An inlet of the proportional valve is connected to the cavity with non-rod, and an outlet of the proportional valve is connected to the oil return pipe.

Abstract: An example method of packet processing in a host cluster of a virtualized computing system includes: receiving traffic at packet processing software of a hypervisor executing on a host of the host cluster; processing the traffic using a network service of the packet processing software in the hypervisor; redirecting the traffic to a service virtual machine (VM) in the host cluster through a virtual network interface card (vNIC) of the service VM; sending metadata from the network service of the packet processing software to the service VM; processing the traffic and the metadata through at least one network service executing in the service VM; returning the traffic from the service VM to the packet processing software of the hypervisor; and forwarding, by the packet processing software, the traffic to a destination.

Abstract: Some embodiments provide novel methods for providing a set of services for a logical network associated with an edge forwarding element acting between a logical network and an external network. In some embodiments, the services are provided using a logical service forwarding plane that connects the edge forwarding element to a set of service nodes that each provide a service in the set of services. The service classification operation of some embodiments identifies a chain of multiple service operations that has to be performed on the data message. In some embodiments, identifying the chain of service operations includes selecting a service path to provide the multiple services. After selecting the service path, the data message is sent along the selected service path to have the services provided.

Abstract: Some embodiments provide novel methods for providing a set of services for a logical network associated with an edge forwarding element acting between a logical network and an external network. In some embodiments, the services are provided using a logical service forwarding plane that connects the edge forwarding element to a set of service nodes that each provide a service in the set of services. The service classification operation of some embodiments identifies a chain of multiple service operations that has to be performed on the data message. In some embodiments, identifying the chain of service operations includes selecting a service path to provide the multiple services. After selecting the service path, the data message is sent along the selected service path to have the services provided.

Abstract: Some embodiments provide novel methods for providing different types of services for a logical network associated with an edge forwarding element acting between the logical network and an external network. The edge forwarding element receives data messages for forwarding and performs a service classification operation to select a set of services of a particular type for the data message. The particular type of service is one of multiple types of services that use different transport mechanisms to forward the data to a set of service nodes (e.g., service virtual machines, or service appliances, etc.) that provide the service. The edge forwarding element receives the data message after the selected set of services has been performed and performs a forwarding operation to forward the data message. In some embodiments, the method is also performed by edge forwarding elements that are at the edges of logical network segments within the logical network.

Abstract: Some embodiments configure an edge forwarding element to perform service insertion operations to identify stateful services to perform for data messages received for forwarding by the edge forwarding element at multiple virtual interfaces of the edge forwarding element. The service insertion operation, in some embodiments, includes applying a set of service insertion rules. The service insertion rules (1) specify a set of criteria and a corresponding action to take for data messages matching the criteria and (2) are associated with a set of interfaces to which the service insertion rules are applied. In some embodiments, the action is specified using a universally unique identifier (UUID) that is then used as a matching criteria for a subsequent policy lookup that identifies a type of service insertion and a set of next hop data.

Abstract: Some embodiments provide stateful services in a chain of services identified for some data messages. The edge forwarding element receives a data message at a particular interface of the edge forwarding element that is traversing the edge forwarding element in a forward direction between two machines. The edge forwarding element identifies (1) a set of stateful services for the received data message and (2) a next hop associated with the identified set of stateful services in the forward direction and a next hop associated with the identified set of stateful services in the reverse direction. Based on the identified set of services and the next hops for the forward and reverse directions, the edge forwarding element generates and stores first and second connection tracking records for the forward and reverse data message flows, respectively used to forward data messages received subsequently for the flow.

Abstract: Some embodiments facilitate the provision of a service reachable at a virtual internet protocol (VIP) address. The VIP address is used by clients to access a set of service nodes in the logical network. Facilitating the provision of the service, in some embodiments, includes returning a serviced data message to a load balancer that selected a service node to provide the service for the load balancer to track the state of the connection using the service logical forwarding element. To use the service logical forwarding element, some embodiments configure an egress datapath of the service nodes to intercept the serviced data message before being forwarded to a logical forwarding element in the datapath from the client to the service node, and determine if the serviced data message requires routing by the routing service provided as a service by the edge forwarding element.

Abstract: Some embodiments provide a method of performing stateful services that keeps track of changes to states of service nodes to update connection tracker records when necessary. At least one global state value indicating a state of the service nodes is maintained at the edge device. The method generates a record in a connection tracker storage including the current global state value as a flow state value for a first data message in a data message flow. Each time a data message is received for the data message flow, the stored state value (i.e., a flow state value) is compared to the relevant global state value to determine if the stored action may have been updated. After a change in the global state value relevant to the flow the method examines a flow programming table to determine if the flow has been affected by a flow programming instruction(s) that caused the global state value to change.

Abstract: Example methods and systems for failure handling for service chaining with service path monitoring. One example may comprise a first computer system detecting a data packet that is being forwarded along a first service path. The first computer system may configure a liveness check query and send the liveness check query along with the data packet towards a service virtualized computing instance to cause a liveness check response. In response to detecting the liveness check response from the service virtualized computing instance, the first computer system may determine that the service virtualized computing instance is available. Otherwise, report information may be generated and sent to trigger a switch from the first service path to a second service path that excludes the service virtualized computing instance.

Abstract: Example methods and systems for failure handling for service chaining with service path monitoring. One example may comprise a first computer system detecting a data packet that is being forwarded along a first service path. The first computer system may configure a liveness check query and send the liveness check query along with the data packet towards a service virtualized computing instance to cause a liveness check response. In response to detecting the liveness check response from the service virtualized computing instance, the first computer system may determine that the service virtualized computing instance is available. Otherwise, report information may be generated and sent to trigger a switch from the first service path to a second service path that excludes the service virtualized computing instance.

Abstract: For traffic exiting a logical network through a particular VTI, some embodiments perform a service classification operation for different data messages to identify different VTIs that connect the edge forwarding element to a service node to provide services required by the data messages. Each data message, in some embodiments, is then forwarded to the identified VTI to receive the required service. The identified VTI does not perform a service classification operation. The service node then returns the serviced data message to the edge forwarding element. In some embodiments, the identified VTI is not configured to perform the service classification operation and is instead configured to mark all traffic directed to the edge forwarding element as having been serviced. The marked serviced data message is received at the edge forwarding element and forwarded to a destination of the data message through the particular VTI.

Abstract: For traffic exiting a logical network through a particular VTI, some embodiments perform a service classification operation for different data messages to identify different VTIs that connect the edge forwarding element to a service node to provide services required by the data messages. Each data message, in some embodiments, is then forwarded to the identified VTI to receive the required service. The identified VTI does not perform a service classification operation. The service node then returns the serviced data message to the edge forwarding element. In some embodiments, the identified VTI is not configured to perform the service classification operation and is instead configured to mark all traffic directed to the edge forwarding element as having been serviced. The marked serviced data message is received at the edge forwarding element and forwarded to a destination of the data message through the particular VTI.