GB2349256A - Print job queue for arbitrary network topologies - Google Patents

Abstract

A single logical print job queue (17) is enabled for a network printer (20) to provide print queue information across complex networked (10) printing environments, regardless of network topology or layered spooling implementations. The single logical queue (17) is provided by: (i) employing a job ticket (65,85) with each print job (70,90), (ii) transmitting each job ticket directly to the destination network printer (20) via a first communication channel (75,95) over the network, (iii) queuing the job ticket on the printer (20) according to selected queuing criteria (15), (iii) transmitting each print job (70,90) to the printer (20) via a second communication channel (80,100) over the network (20) and via an intermediate spooling device (55,60), and (iv) processing the print job on the printer (20) according to the queued job ticket (65,85).

Description

PRINT JOB QUEUE FOR ARBITRARY NETWORK TOPOLOGIES FIELD OF THE INVENTION This invention relates in general to imaging device job management and, more particularly, to a single logical print job queue for arbitrary network topologies.

BACKGROUND OF THE INVENTION A queue is an ordered list of objects, where the ordering schema dictates that the object at the head of the queue will be provided some service before all other objects in the queue. The object at the tail of the queue receives services only after all preceding objects are serviced. The location at which an object is initially inserted in the queue is determined by an ordering algorithm which is independent of the queue structure. For example, a first-in first-out (FIFO) ordering algorithm schedules service for queue objects based upon their order of arriva. A priority ordering algorithm can also be used to determine an object's initial position in the queue. For example, using some evaluation criteria, an object can be inserted ahead of other objects in the queue to the extent of being placed directly at the head of the queue.

A print queue is an ordered list of print jobs scheduled to be printed by a printer or group of printers. A print job is a logical collection of pages which must be printed without interruption. Once a job begins printing, the job must complet printing before another job can begin. The printer provides service to the print jobs queued for printing. Generally jobs are printed in FIFO order but situations arise where priority jobs need to be printed before previously submitted print jobs.

The most common mechanism for implementing the ordered queuing of print jobs incorporates some form of print job spooling. A print spooler provides the queuing discipline for print jobs by buffering the print job in some manner until the printer becomes available for servicing the job. Print spooling can be implemented on a host computer, on the printer, on a dedicated device known as a print server whose principal function includes providing spooling services for the printer, or on a combination of these devices. As such, the spooling process may exist across many"layers"of devices in the printing environment.

To this regard, a printing environment can be quite simple or quite complex. A most simplistic environment includes a single printer directly connected to a host computer. A direct connect printer is not a shared device- because all print jobs sent to the printer come from the single host computer.

On the other hand, a networked printing environment approaches the complex end of the spectrum because multiple computers share a printer or printers through networked connections. Notably, an unwieldy network topology could incorporate multiple print servers providing many levels of print job spooling between a host computer and the shared printer.

From a user's initial perception, printing in a networked environment may be no different than printing to a directly connected printer.

However, submitted print jobs may not be immediately serviced by the network printer if other network users have submitted jobs to the same network printer which have yet to complete. As such, ascertaining the state of the print queue and providing that information to users is a printing function especially valued by users of shared printers. Generally, a user of a direct connect printer inherently knows the order in which print jobs are processed and is less incline to want a print queue status. However, networked printer users may use the print queue information to determine : (i) which printer is more readily available, (ii) when the print job would be processed if a priority scheduling algorithm is used, or (iii) the identity of a print job for removing it from the queue if so desired.

The difficulty in providing print queue information parallels the complexity of the networked printer configuration. The problem is compounded if multi-level print spooling exists in the networked print environment.

Conventionally, print spoolers external to a printer were developed to buffer print jobs until buffer memory on the printer became available to spool a respective job. Thus, external spoolers, such as found on print servers or host computers, prevent the overflowing of the printer's finite spooling capacity. In a complex networked printing environment, a print job may be stored in numerous spool buffers along the network path from the time the job leaves its host computer to the time it reaches the printer. In any case, the printer is only aware of jobs contained in its internal spool buffers and is not aware of print jobs spooled in external buffers. Thus, conventionally, there has not existed a single flexible solution for ascertaining print queue information across complexnetworked printing environments because, in part, of the multi-level spooling issues.

For this discussion, the state of the print queue will be referred to as the logical print queue to differentiate it from the physical print queue (or queues) implemented with various levels of print spooling in a complex print environment.

The difficulty in determining the state of the logical print queue lies in the distributed nature of the print spooling system. For example, given an arbitrary network configuration, no single network component exists which has information pertaining to all submitted print jobs. Conventionally, a network configuration is layered with multiple print spoolers possibly residing on each host computer, print server, and/or printer. Thus, only the devices which are holding the submitted print jobs or have submitted the print jobs, have knowledge about the existence of those particular jobs. Accordingly, the difficulty of implementing a logical print queue in complex network environments arises in effectively and efficiently querying each network device for print job information, generating a single or master logical print queue, and distributing that print queue information to interested users. Additionally, for general network topologies there simply is no registry of networked devices, thus making a query model impractical.

Information technology managers can implement a network topology conducive to the generation of a logical print queue by implementing a single print server architecture on a network without multi-level spooling. In this context, every print job is spooled only on the single print server that is dedicated to spooling jobs for its client printer. Thus, the print server has the information required to generate a logical print queue.

Disadvantageously, single print servers disallow multi-level spooling and necessarily place a data flow bottleneck in the network topology. Although it is this bottleneck that conventionally provides the mechanism from which a logical print queue can be generated, network performance is inevitably impacted since all print jobs must pass through only one server/spooler device- en route to the printer.

Accordingly, an object of the present invention is to provide a tool and method for enabling logical print queue information and job control regardless of network topology.

SUMMARY OF THE INVENTION According to principes of the present invention in a preferred embodiment, a job queue manager provides a mechanism for enabling a single logical print job queue for a network printer for providing print queue information across complex networked printing environments, regardless of topology or layered spooling implementations. The single logical queue is provided by: (i) employing a job ticket with each print job, (ii) transmitting each job ticket directly to the destination printer via a first communication channel over the network, and (iii) transmitting each print job to the printer via a second communication channel over the network and via an intermediate spooling device.

According to further principles, a method of managing a job queue includes : (a) transmitting a job ticket over a first communication channel to a destination device coupled to a network; (b) transmitting a job identified by the job ticket over a second communication channel to an intermediate device coupled to the network; and, (c) queuing the job ticket on the destination device for managed processing of the job.

Other objects, advantages, and capabilities of the present invention will become more apparent as the description proceeds.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a communication network employing the present invention job queue manager and logical job queue.

FIG. 2 is a block diagram of a job ticket.

FIG. 3 is a block diagram of a logical job queue.

FIG. 4 is a flow chart depicting a preferred method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a schematic diagram of a communication network 10 including the present invention job queue manager 15 and logical queue 17 embodied in printer 20. Network 10 is any conventional communication network such as one employing the Transmission Control Protocol/Internet Protocol (TCP/IP) or Interne Packet Exchange (IPX) protocol for communication between devices coupled to the network. Network 10 may be a local area network, wide area network, plurality of interconnected networks, or even the Internet. Network 10 includes a plurality of devices communicating thereon that are coupled to the network, including printer 20, host computers 30,35,40,45 and 50, and network servers 55 and 60.

Clearly, FIG. 1 depicts only an exemplary configuration of devices coupled to network 10, and is also merely exemplary of devices that can be coupled to the network under principes of the present invention. Each device is coupled to network 10 using a hard wired connection, an infrared connection, radio frequency connection or other conventional coupling technology.

Server 55 is a computing device that"serves"the network in a conventional manner. Namely, in the example discussed herein and shown, server 55 offers services like file and print services for computers 30,35 and 40, and printer 20. To this regard, server 55 provides the queuing and spooling capabilities for enabling users at personal computers 30,35 and 40 to send print jobs to network printer 20. For example, if a user at computer 30 desires to send a print job to printer 20, the job is first transmitted from computer 30 to server 55 via network 10, and then server 55 spools the job over to printer 20 also via network 10.

Server 60 is also a computing device that"serves"the network in a conventional manner. Namely, in the example discussed herein and shown, server 60 offers services like file and print services for computers 45 and 50 and printer 20. To this regard, server 60 provides the queuing and spooling capabilities for enabling users at personal computers 45 and 50 to send printjobs to printer 20. For example, if a user at computer 45 desires to send a print job to printer 20, the job is first transmitted from computer 45 to server 60 via network 10, and then server 60 spools the job over to printer 20 also via network 10.

Printer 20 is a laser printer employing electrophotographic imaging technology as conventional in the art in addition to embodying the present invention job queue manager 15 and logical queue 17. Although job queue manager 15 will be described herein in association with printer 20, it will be understood that job queue manager 15 may similarly be employed in other network computing devices, such as for example, an inkjet printer, digital copier, facsimile machine and the like, each of which may process a job on network 10.

It should also be noted here that job queue manager 15 may similarly be employed on any other device coupled to network 10, such as on server 55 or 60, or even on any host computer 30,35,40,45 or 50, so long as that device is the sole gateway through which all print jobs must pass to printer 20, regardless of any other layers of spooling employed on network 10.

Computers 30,35,40,45 and 50 (30-50) each represent a computer having memory, storage, processing and networking technologies as conventional in the art. Additionally, each computer 30-50 includes a copy of printer driver firmware 25 for operative communication with job queue manager 15. However, to simplify the drawing and for ease of discussion purposes, printer driver 25 is only depicted in association with computers 30 and 45.

Moreover, it is understood that printer driver 25 may similarly reside on other networked computing devices, such as server 55 or 60, depending on respective imaging needs relative to printer 20.

Although in a preferred embodiment printer driver 25 and job queue manager 15 are each enabled in firmware, it is similarly feasible to enable each in software or"hardwired"in circuitry on the respective device.

Importantly, the present invention job queue manager 15 and printer driver 25 provide a mechanism for enabling a single logical print job queue 17 for printer 20 and for providing print queue information across complex networked printing environments, regardless of topology or layered spooling implementations. In short, a single logical queue 17 is provided by: (i) employing a job ticket 65 with each print job 70, (ii) transmitting each job ticket 65 to printer 20 via a first communication channel 75 over network 10, and (iii) transmitting each print job 70 to printer 20 via a second communication channel 80 over network 10. Importantly, job ticket 65 is network addressed directly to printer 20 when transmitted from its respective host computer 30, but the associated print job 70 is spooled to printer 20 through its respective network spooling device 55.

Advantageously, logical queue 17 is provided by job queue manager 15 even where multi-level spooling is employed in complex networked topologies. Namely, in addition to a user at computer 30 seeing and using logical queue 17 as discussed, all other computers on the network also similarly see and use the same logical queue 17. For example, when a print job is initiated from computer 45, job ticket 85 defining print job 90 is transmitted to printer 20 via first communication channel 95 over network 10, and print job 90 is transmitted to printer 20 via second communication channel 100 over network 10. Importantly, again, job ticket 85 is network addressed directly to printer 20 when sent from its respective host computer 45, but the associated print job 90 is spooled through (addressed to) its respective network spooling device 60.

Although multiple communication channels 75,80,95,100 are depicted in FIG. 1 for discussion purposes, it will be understood that in a preferred embodiment each job ticket channel 75,95 are one and the same, and each print job channel 80, 100 are one and the same, all relative to network 10.

Additionally, although communication channels 75,80,95,100 are shown separately from network 10, it will be understood that they exist in cooperation with network 10.

FIG. 2 is a block diagram of an exemplary job ticket 155 and will be discussed also in context of FIG. 1. Job ticket 155 is representative of job- tickets 65 and 85 in FIG. 1 after printer 20 has assigned a respective job id 160.

The present invention enables logical print queue 17 within job queue manager 15 by employing a job ticket 155 for each print job to be processed by printer 20. Job ticket 1 55 is simply a data packet which describes a corresponding print job. The job ticket contains information about the job which, minimally, includes job identification (id) indicia 160. In a preferred embodiment, job id 160 is assigned by job queue manager 15 in printer 20 upon request from an originating host computer 30-50. Job id 160 provides the basis for the generation of logical print queue 17. In an alternate embodiment, job id 160 is assigned by a respective originating host 30,45.

Importantly, in either case, the job id must be unique to enable printer 20 to clearly distinguish it from other queued jobs.

Also in a preferred embodiment, job ticket data includes more information than just job id 160 for improving the quality of information provided to the user via logical print queue 17 as well as affecting the processing of the print job by the printer. For example, preferably, page count information 165 is included and transmitted by host 30,45 as part of job ticket 155 to be included in the logical print queue 17 information. Page count information 165 helps a user determine the print load queued for a particular printer 20 which can drive the decision as to which printer to submit a job to. Although only printer 20 is shown coupled to network 10 for ease of discussion purposes, it is understood that other printers or imaging devices may similarly be coupled to network 10 and served by any one or more of print servers 55 and 60. In this context, each user on each computer 30-50 would have a choice as to which printer to use (as is common in many large business computing environments).

As another example of further preferred job ticket information, a priority based printing system includes a requested priority indicator 170 in the job ticket 155 from which printer 20 synchronizes jobs arriving at its internal spool buffers with the actual order in which jobs are to be printed. In this context, knowing that a higher priority job is en route, printer 20 buffers jobs to its fullest capacity while waiting for the actual print job corresponding to the highest priority print job ticket.

These examples of job ticket information are merely exemplary and are not meant to be all inclusive. Obviously, other job information may also be included in the ticket depending upon design criteria, including for example, information indicative of duplexing requirements, copies, color, fonts, or other resource matching criteria.

Typically, a user requests print services in the desk top computing environment 30-50 via print drivers 25 accessed through an application program. However, communication with printer 20 may not necessarily take place immediately, depending upon the designated intermediate spooling devices 55,60 present on network 10 between the computer 30,45 and printer 20. It is precisely at this time, however, that the job ticket 155 needs to be transmitted to printer 20. Immediate communication of a job ticket by the originating host computer 30,45 to printer 20 is critical for enabling the printer to become job-aware at the onset of the print process and for developing logical print queue 17. However, job tickets 65,85 cannot be transmitted over the same communication channel on network 10 as the print jobs 70,90 because of the serial nature of the communication channel. Namely, a job ticket can't leap frog over print jobs previously submitted in the channel which have yet to reach the printer. Additionally, job tickets 65,85 cannot afford to be buffered by external spoolers 55,60. Consequently, under the present invention, a secondary direct communication channel 75,95 is provided between the host computer 30,45 and the destination printer 20. For example, in LaserJet printers provided by Hewlett-Packard Company, the Peripheral Management Language (PML) port provides a secondary communication channel capable of handling the job ticket data packet 65,85. To this regard, FIG. 1 visibly differentiates the print job communication channel 80,100 from the PML communication channel 75,95. With this configuration, job tickets are directly transmitted to the destination printer 20 over the secondary communication channel 75,95 by being addressed directly to printer 20 itself rather than to the intermediate print server 55,60. In contrast, the actual print job 70,90 is addressed to its respective intermediate print server 55,60 over conventional print channel 80,100 on network 10.

Referring now to FIG. 3, a block diagram depicts a logical print queue 17 (as established by job queue manager 15) comprising five exemplary job tickets 205,210,215,220,225. In this example, each job ticket includes a job id, job priority, and job page count. Additionally, in this example, the highest priority jobs ("1"being highest) are located at the head of the queue and the lower priority jobs are placed at the tail of the queue. Similar priority jobs are ordered according to job id. Page counts are provided so that users can quickly determine the load associated with the corresponding printer. Clearly, this queuing criteria is merely exemplary, and it is understood that other queuing criteria are also feasible and obviously design implementation specific.

Notably, these job tickets 205,210,215,220,225 could have originated from any computer on network 10. Advantageously, with the present invention, users can easily see the total logical queue 17 for printer 20 to determine whether a job should be sent to that printer, or to determine when a pending job will be imaged, regardless of the topology of devices and spooling layers employed on network 10. Additionally, users can communicate to printer 20 actions to take pertaining to a specific print job, before the actual print job reaches the printer. For example, a job cancel or a modification in print job priority are changes which a user may effectuate before a job actually prints.

Referring now to FIG. 4, a flow chart depicts a preferred method of the present invention. First, 255, in response to a print initiation by a host 30, printer driver 25 transmits a job ticket packet 65 directly to printer 20 over a first communication channel 75. Next, 260, host 30 transmits print job 70 associated with job ticket 65 to the appropriate network print server 55 over a second communication channel 80. When job queue manager 15 of printer 20 receives job ticket packet 65, a job id 160 is assigned 265 to the job ticket 65.

Additionally, job queue manager 15 records the job ticket packet information, such as job page length 165 and job priority 170, into the logical print queue 1-7, Printer 20 then transmits the job ticket 65 back to the originating host 30 as a confirmation of the queued job.

Finally, 270, job queue manager 15 receives print job 70 from network spooler (server) device 55 on second communication channel 80 according to logical print queue 17 criteria. When received, print job 70 is buffered on printer 20 until processed 275 according to logical print queue 17 criteria.

In summary, the present invention provides a tool and method for enabling and managing a logical print job queue in a complex networked environment. It will be obvious to one of ordinary skill in the art that the present invention is easily implemented utilizing any of a variety of components and tools existing in the art. Moreover, while the present invention has been described by reference to specific embodiments, it will be apparent that other alternative embodiments and methods of implementation or modification may be employed without departing from the true spirit and scope of the invention.

Claims (10)

CI What is claimed is:

1. A method of managing a job queue (15,17), comprising: (a) transmitting a job ticket (65, 85) over a first communication channel (75,95) to a destination device (20) coupled to a network (10) ; (b) transmitting a job (70,90) identified by the job ticket (65,85) over a second communication channel (80,100) to an intermediate device (55,60) coupled to the network (10); and, (c) queuing (17) the job ticket (65,85) on the destination device (20) for managed processing (15) of the job (70,90).

2. The method of claim 1 wherein the job (70,90) includes data for processing on an imaging device (20) coupled to the network (10).

3. The method of claim 1 or 2 wherein the destination device (20) includes an imaging device (20).

4. The method of claim 1 or 2 wherein the destination device (20) includes a server device.

5. The method of claim 1,2,3 or 4 wherein the intermediate device (55,60) includes a server device.

6. The method of claim 1,2,3,4 or 5 wherein the job ticket (65,85) on the destination device (20) includes identification indicia for the job, the identification indicia being selected from the group consisting of job ID (160) job priority (170), and job size (165).

7. The method of claim 1,2,3,4,5 or 6 wherein the first communication channel (75,95) includes a printer management langage (PML) channel, and the second communication channel (80,100) includes a printer channel.

8. An imaging system, comprising: (a) means for transmitting (30,45) a job ticket (65,85)over a first communication channel (75,95) to a destination device (20) coupled to a network (10); (b) means for transmitting (30,45) a job (70,90) identified by the job ticket over a second communication channel (80,100) to an intermediate device (55,60) coupled to the network; and, (c) means for queuing (17) the job ticket (65,85) on the destination device (20) for managed processing (15) of the job (70,90).

9. The imaging system of claim 8 wherein the job (70,90) includes data for processing on an imaging device (20) coupled to the network.

10. The imaging system of claim 13 wherein the job ticket (65,85) on the destination device (20) includes identification indicia for the job, the identification indicia being selected from the group consisting of job ID (160), job priority (170), and job size (165).