Abstract: The disclosure relates to an airway maintenance device, such as an endotracheal tube, tracheostomy tube, or supraglottic airway device, and in particular to an airway maintenance device having a sensor for measuring capillary blood flow and/or pressure. The device includes an airway maintenance device with an airway lumen having a proximal end and a distal end, a distal end portion incorporating an optical sensor configured to measure capillary blood flow in tissue surrounding the distal end when in position within a patient's airway. The optical sensor may include a portion of an optical fibre extending to the distal end portion along the lumen.

Abstract: The disclosure relates to an airway maintenance device, such as an endotracheal tube, tracheostomy tube, or supraglottic airway device, and in particular to an airway maintenance device having a sensor for measuring capillary blood flow and/or pressure. The device includes an airway maintenance device with an airway lumen having a proximal end and a distal end, a distal end portion incorporating an optical sensor configured to measure capillary blood flow in tissue surrounding the distal end when in position within a patient's airway. The optical sensor may include a portion of an optical fibre extending to the distal end portion along the lumen.

Abstract: A multi-stage login procedure and system involves a first stage in which a login ID and a public key (encrypted) is transmitted from a client computer to a server computer and a key-exchange key (encrypted) is provided from the server computer to the client computer. In a second stage, a first split symmetric key and a server authentication string is generated and encrypted by the client computer and then transmitted to the server computer. In addition, the server computer generates a second split symmetric key and combines the same with the first split symmetric key to obtain a complete symmetric key for encrypting further communications from the server to the client computer. The server also generates a client authentication string, encrypts the same and transmits the encrypted string, the server authentication string (encrypted and incremented) and the second split symmetric key (encrypted) to the client computer.

Abstract: A multi-stage login procedure and system involves a first stage in which a login ID and a public key (encrypted) is transmitted from a client computer to a server computer and a key-exchange key (encrypted) is provided from the server computer to the client computer. In a second stage, a first split symmetric key and a server authentication string is generated and encrypted by the client computer and then transmitted to the server computer. In addition, the server computer generates a second split symmetric key and combines the same with the first split symmetric key to obtain a complete symmetric key for encrypting further communications from the server to the client computer. The server also generates a client authentication string, encrypts the same and transmits the encrypted string, the server authentication string (encrypted and incremented) and the second split symmetric key (encrypted) to the client computer.

Abstract: A multi-stage login procedure and system involves a first stage in which a login ID and a public key (encrypted) is transmitted from a client computer to a server computer and a key-exchange key (encrypted) is provided from the server computer to the client computer. In a second stage, a first split symmetric key and a server authentication string is generated and encrypted by the client computer and then transmitted to the server computer. In addition, the server computer generates a second split symmetric key and combines the same with the first split symmetric key to obtain a complete symmetric key for encrypting further communications from the server to the client computer. The server also generates a client authentication string, encrypts the same and transmits the encrypted string, the server authentication string (encrypted and incremented) and the second split symmetric key (encrypted) to the client computer.

Abstract: A process is described in which a user enters ID and password information at a network client computer terminal. This information is combined with an asymmetric key stored in a persistent storage directly accessible to the client's computer terminal. This "combined" information is communicated through a communication network to one or more server computers for authentication of the client. A similar identification and authentication process may be used to authenticate the server computer. Upon authentication of the client, the server provides the client computer with three symmetric keys, in encrypted format. The first key is for encrypting and decrypting persistent information associated with the client computer's control program. The second key is used to encrypt and decrypt persistent information associated with the login ID. The third key is used to encrypt and decrypt communication between the client computer and the server computer.

Abstract: A distributed data processing system and method in which locks on a file are supported by a data structure that resides on either a client machine or on the file's server. When only a single client's processes are locking a file, the data structure can reside on that client. Whenever a plurality of client machines attempt to place locks on a file, the data structure is moved to the server; this forces the clients locking the file to communicate with the server when performing lock operations. When a client requests a lock from the server that cannot be granted because of an existing blocking lock, the client is informed that it should put the requesting process asleep awaiting a retry notification. When there is a change in the locks on the file that might allow such a client's now sleeping process to acquire the lock, the server sends a retry notice to the client. This awakens the sleeping process at the client, and the process then reattempts the lock operation by sending a message to the server.

Abstract: The system and method of this invention controls how client data processing systems in a distributed networking environment can efficiently extend files and write into regions of the files previously unoccupied by data. The server data processing system manages the distributed allocation of new file blocks by sending nascent zeros in addition to real bytes that have been requested by the client data processing system. Nascent zeros are logically zero bytes that have never been stored to or written to, and may be outside the current extent of the file. The server determines whether or not this additional range of nascent zeros will be sent to a client depending upon the amount of physical storage available at the server, and whether or not other client data processing systems require access to this range of blocks. Likewise, the client data processing system has the option of writing to this additional range of nascent zeros.

Abstract: A communication protocol for direct communications between operating system kernels of a plurality of processors in a clustered-type, shared virtual memory, multi-processor data processing system is disclosed. Each processor unit includes a intermachine communications software system ("IMCS") which may-be used by a trusted kernel of the operating system of the processor to communicate with a service in another processor, either directly or through an intermediate processor. Communications are initiated when a user prepares a message in accordance with pre-programmed instructions from the IMCS in a standard format. Once the message is prepared, the user calls IMCS which selects a route for the transmission of the message over a serial communications link to the receiving processor using a "request to send immediate" serial link level protocol. The message is initially directed to a common buffer pool.

Abstract: A method for minimizing I/O mechanical assess operations on secondary storage devices in a data processing system having a plurality of processor units interconnected in a cluster configuration to permit each processor unit to request and obtain data that is resident only on a secondary storage device of one processor unit. The method involves the steps of maintaining at each processor unit information about each copy of data that has been sent from the unit to another unit to permit a second request to the unit to be serviced by transferring a copy of the data from the main memory which is storing the data to the requesting unit rather than servicing the request with a relatively slow I/O accessing operation to a secondary storage device.

Abstract: A distributed data processing system and method in which locks on a file are supported by a data structure that resides on either a client machine or on the file's server. When only a single client's processes are locking a file, the data structure can reside on that client. Whenever a plurality of client machines attempt to place locks on a file, the data structure is moved to the server; this forces the clients locking the file to communicate with the server when performing lock operations. When a client requests a lock from the server that cannot be granted because of an existing blocking lock, the client is informed that it should put the requesting process asleep awaiting a retry notification. When there is a change in the locks on the file that might allow such a client's now sleeping process to acquire the lock, the server sends a retry notice to the client. This awakens the sleeping process at the client, and the process then reattempts the lock operation by sending a message to the server.

Abstract: A system for maintaining the reliability of shared data structures, such as message queues, in a multi-processor data processing system is disclosed. The system includes a plurality of virtual memory-type processor units in which the processors share virtual memory and can access each one of a plurality of virtual memory segments by the same virtual memory address. The system assures the reliability of system-wide shared data structures in the event of a failure of one of the processors by maintaining at least two copies of each data structure and by maintaining two copies of a table used in locating such data structures. The system updates copies of such shared data structures that are stored in at least two different processing units with the results of a specified data processing transaction, which may have affected the information in such data structures, in a manner to insure that either identical updates occur or no update occurs.

Abstract: A system and method in which client access to data at a server is synchronized to keep the data consistent by ensuring that each portion of the data accessible for modification at a node is not accessible for reading or modification by any other node, while allowing portions of the data accessible only for reading to be accessible by any number of nodes. If a conflicting request arises from a different client the server must revoke data that has been previously distributed to a client. For a revoke.sub.-- bytes request, all outstanding get.sub.-- bytes are marked so that the bytes that are being requested to be revoked will be discarded when they do arrive at the client. To insure that read and write system calls on a file are performed in a serializable fashion throughout a distributed environment, each machine at which a read is being performed must acquire a read token and each machine at which a write is being performed must acquire a read/write token from the server for the file.

Abstract: A data processing method for storing groups of related information in a storage subsystem of a data processing system in which the storage subsystem includes one or more storage devices having a plurality of block addressable storage locations (blocks or sectors) each of which stores a predetermined fixed number of bytes of said information. The method includes the step of establishing allocatable increments of storage, called physical partitions, which comprise a predetermined number of contiguous addressable blocks, and initially allocating, in response to a request to the operating system, a preselected number of partitions for each group of related information, where the partitions in each group are not necessarily physically contiguous and where the number that is selected is the minimum number of partitions required to store the group of related information.

Abstract: The system and method of this invention maintains the latest file attributes such as file size, modify time, and access time, at the server data processing system in a distributed data processing system. The server data processing system combines information requested from the client data processing system that has permission to write to the file with information periodically received from other client data processing systems that may be extending the same file by mapping the file into their own virtual address space. In this way, the server can maintain the latest file size attribute even when some clients are extending the file through system calls and other clients are extending the file through mapped access. To maintain a latest modify time and access time, the server keeps a modify count and access count.