Xerox Corporation

Fuji Xerox Co., Ltd.

David P Nesbitt

Jennifer D Thomas

Steve Atsushi Okamoto

Sang W Kim

Ton H Truong

Shee-Yen Tan

Joseph Z Fung

ShengKuo Fan

Larry Dean Bonham

Leslie B Nesbitt

Takeshi Nishizawa

Gilbert Kwock Keong Leong

Jennifer Y Yang

Temporary states are used transitionally in run-time situations and are unknown to the object database. A temporary state is created if, when an object is performing a requested event, interim work needs to be performed before the object reaches a permanent destination state. Use of a temporary state is transparent to the caller of the requested event.

State based object transition control and nested locking

A printing system for distributing print requests submitted by one or more clients includes a server that receives the print requests, generates a print job from one or more print requests, and extracts attributes of the print job. A database contains attributes of the logical printers and physical printers associated with the logical printers, the queues of a network and the attributes of the print job received from the clients. A database query is used to filter the attributes extracted from a print job against the attributes of the physical printers associated with the logical printer to which the print job was sent to determine whether the print job is printable by at least one of the associated physical printers. A queue stores print jobs that are determined to be acceptable. Each printer is capable of notifying the server when it is idle. A second database query, based on the attributes of an available physical printer, is used to filter against the attributes of the available printer against the attributes of the printable jobs in the associated queue, to determine which available jobs are printable on the available printer. One of the determined printable jobs is then output to the available physical printer.

System and method for distributing print jobs

A document printing system involves multi-threaded processing of a document object. A deadlock situation between a preprocessing thread and a cancellation thread can be averted with a time-out locking mechanism. After the cancellation thread has locked the document object, its sets a cancel flag, then waits for preprocessing to complete. Meanwhile, the preprocessing thread may request a lock of the document object. If so, it will specify a maximum time-out period. After expiration of the time-out period, a timed-out status response will be sent from the document object to the preprocessing thread. The preprocessing thread will then poll the document object for a cancel flag. A cancel flag will be set on the document object only if the cancellation thread has requested the document object perform a cancellation operation. If there is no cancel flag, the preprocessing thread will again request a lock of the document object with a maximum time-out period. If there is a cancel flag, the preprocessing thread will send a cancellation complete signal to the document object.

Avoiding deadlock situations in a printing system using a locking time-out mechanism

Temporary states are used transitionally in run-time situations and are unknown to the object database. A temporary state is created if, when an object is performing a requested event, interim work needs to be performed before the object reaches a permanent destination state. Use of a temporary state is transparent to the caller of the requested event. Within a single flow of control, an unlimited number of nested locks may be acquired. A request to unlock an object will only truly unlock the object if the unlock requester is at the highest level of locking. For recursive or embedded functions, no knowledge of the previous locking condition is necessary. Attribute-based locking provides a mechanism for allowing only certain members of the system to lock an object for writing while the object is in a predetermined state. However, any thread may obtain a read lock on an object in order to examine its attributes. This may be expanded to state that the system may restrict locking of an object or entity based upon any attribute in the database or upon any combination or logical expression of these attributes.

State-based object transition control and nested locking

A method and apparatus are provided for storing non-persistent attributes separately from persistent attributes in a print management system. The system server may register callback functions with the object database which allow an attribute to be stored non-persistently, yet be obtained from the object database as if they were stored as one of the persistent attributes. The server attempts to retrieve the attribute from an object database. The object database may then determine whether the requested attribute has been registered as non-persistent in a separate virtual memory. If the requested attribute is registered as non-persistent, the object database invokes the callback function. Otherwise, if the requested attribute is not registered as non-persistent, the object database retrieves the information from disk using a database application program.

Database management system and method for storing persistent and non-persistent attributes

A method and apparatus are provided to enable other system elements to obtain configuration attribute modifications from a print management system. An attribute broker provides two methods, register and advertise, to facilitate necessary configuration changes. The register method is called by other system elements to indicate an interest in a particular attribute. In registering interest in an attribute, the system element provides a callback function. The attribute broker maintains a list of all attributes that have been registered and keeps the set of callback functions for each registered attribute. Whenever a server configuration attribute is modified, the server object uses the advertise method to provide the attribute information to any system element that has registered interest in that attribute. Upon receiving the advertisement of an attribute, the attribute broker checks to see if any callback functions have been registered for that attribute. If so, the attribute broker calls each callback function. The callback function implementation then stores the configuration attribute value in a virtual memory to be used by the system elements whenever required.

Dynamic system configuration using an object-based client-server system

A method and apparatus for parallel processing of remote procedure call (RPC) requests from clients includes placing the remote procedure call requests in a queue and storing them in a memory. A response is immediately returned to the client indicating receipt of the processing request. The RPC requests are retrieved from the queue and processed in parallel. Notification of the completed processing is provided to a notification client. In the event of a server fault or system failure, the processing requests are retrieved from the memory upon system restoration, and replaced into the queue in the order they were received by the server.

Multi-thread processing with queuing and recovery

A utility that defines additional attributes that would cater to a user's needs provides dynamically extended printing capabilities. The system architecture allows the information to be pushed down transparently to the receiving end, which understands the semantics of the given information. One possible function of the system administrators can be to define information to monitor for accounting purposes. The utility allows additional printer features to be incorporated without disrupting the existing system.

Dynamic extension of print capabilities

A distributed printing system that more optimally distributes job requests within a distributed printing system based on more detailed information about the particular attributes of each output device. In particular, additional printer attributes are used that allow greater utilization of a plurality of attached printers having differing capabilities. These attributes include 'max-concurrent-jobs-processing' (MCJP), 'number-of-jobs-on-device' (NJOD) and 'number-of-cascaded-jobs' (NCJ), and a attribute value 'saturated' for the attribute 'printer-state'. The attribute MCJP is an integer value that is based on the capabilities of the printer. NJOB and NCJ attributes allow monitoring of jobs sent to each printer for supported and unsupported printers. If NJOB or NCJ are greater than MCJP, then the attribute 'printer-state' is set to 'saturated', prohibiting further spooling of print jobs to that particular printer.

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Redondo Beach, CA, United States of America

David P Nesbitt