RFC 3998
Internet Printing Protocol (IPP): Job and Printer Administrative Operations
4. Definition of the Job Operations
All Job operations are directed at Job objects. A client MUST always supply some means to identify the Job object in order to select the correct target of the operation. That job identification MAY either be a single Job URI or a combination of a Printer URI and a Job ID. The IPP object implementation MUST support both forms of identification for every job. The Job Operations defined in this document are summarized in Table 4. Table 4. Job Operation Operation-Id Assignments Operation Name Operation-Id Brief description -------------------------------------------------------------------- Reprocess-Job 0x2C Creates a copy of a completed target job with a new Job ID and processes it. Cancel-Current- 0x2D Cancels the current job on the target Job Printer or the specified job if it is the current job.
Suspend- 0x2E Suspends the current processing job on Current-Job the target Printer or the specified job if it is the current job, allowing other jobs to be processed instead. Resume-Job 0x2F Resumes the suspended target job. Promote-Job 0x30 Promotes the pending target job to be next after the current job(s) complete. Schedule-Job- 0x31 Schedules the target job immediately After after the specified job, all other scheduling factors being equal.4.1. Reprocess-Job Operation
This OPTIONAL operation is a create job operation that allows a client to re-process a copy of a job that had been retained in the queue after processing was completed, canceled, or aborted (see [RFC2911], section 4.3.7.2). This operation is the same as the Restart-Job operation (see [RFC2911], section 3.3.7), except that the Printer creates a new job that is a copy of the target job and the target job is unchanged. New values are assigned to the "job-uri" and "job-id" attributes. The new job's Job Description attributes that track job progress, such as "job-impressions-completed", "job- media-sheets-completed", and "job-k-octets-processed", are initialized to 0, as with any create job operation. The target job moves to the Job History after a suitable period, independent of whether one or more Reprocess-Job operations have been performed upon it. If the Set-Job-Attributes operation is supported, then the "job- hold-until" operation attribute MUST be supported with at least the 'indefinite' value, so that a client can modify the new job before it is scheduled for processing by using the Set-Job-Attributes operation. After modifying the job, the client can release the job for processing by using the Release-Job operation specifying the newly assigned "job-uri" or "job-id" for the new job.4.2. Cancel-Current-Job Operation
This OPTIONAL operation allows a client to cancel the current job on the target Printer or the specified job if it is the current job on the Printer. See [RFC2911], section 3.3.3, for the semantics of canceling a job. Since a Job might already be marking by the time a Cancel-Current-Job is received, some media sheet pages might print before the job is actually terminated.
If the client does not supply a "job-id" operation attribute, the Printer MUST accept the request and cancel the current job if there is a current job in the 'processing' or 'processing-stopped' state; otherwise, it MUST reject the request and return the 'client-error- not-possible' status code. If more than one job is in the 'processing' or 'processing-stopped' state, the one that is marking is canceled, and the others are unaffected. Warning: On a shared printer, there is a race condition. Between the time when a user issues this operation and the time of its acceptance, the current job might change to a different job. If the user or operator is authenticated to cancel the new job, the wrong job is canceled. To prevent this race from canceling the wrong job, the client MAY supply the "job-id" operation attribute, which is checked against the current job's job-id. If the job identified by the "job-id" attribute is not the current job on the Printer (i.e., is not in the 'processing' or 'processing-stopped' state), the Printer MUST reject this operation and return the 'client-error-not- possible' status code. Otherwise, the Printer cancels the specified job. Access Rights: The authenticated user (see [RFC2911], section 8.3) performing this operation must either be the job owner (as determined in the Job Creation operation) or an operator or administrator of the Printer object (see [RFC2911], sections 1 and 8.5). The Cancel-Current-Job Request and Cancel-Current-Job Response have the same attribute groups and attributes as does the Resume-Printer operation (see [RFC2911], section 3.2.8), including the new "job- message-from-operator" operation attribute (see section 6), with the addition of the following Group 1 Operation attribute in the request: "job-id" (integer(1:MAX)): The client OPTIONALLY supplies this Operation attribute to verify that the identified job is still the current job on the target Printer object. The IPP object MUST support this operation attribute if it supports this operation.4.3. Suspend and Resume Job Operations
This section defines the Suspend-Current-Job and Resume-Job operations. These operations allow an operator or user to suspend a job while it is processing, allowing other jobs to be processed, and to resume the suspended job at a later point without losing any of the output.
If either of these operations is supported, both MUST be supported. The Hold-Job and Release-Job operations ([RFC2911], section 3.3.5) are for holding and releasing held jobs, not suspending and resuming suspended jobs.4.3.1. Suspend-Current-Job Operation
This OPTIONAL operation allows a client to stop the current job on the target Printer or the specified job if it is the current job on the Printer, to allow other jobs to be processed instead. The Printer moves the current job or the target job to the 'processing- stopped' state and sets the 'job-suspended' value (see section 9.1) in the job's "job-state-reasons" attribute and processes other jobs. If the client does not supply a "job-id" operation attribute, the Printer MUST accept the request and suspend the current job if there is a current job in the 'processing' or 'processing-stopped' state. Otherwise, it MUST reject the request and return the 'client-error- not-possible' status code. If more than one job is in the 'processing' or 'processing-stopped' state, all of them are suspended. Warning: On a shared printer, there is a race condition. Between the time when a user issues this operation and the time of its acceptance, the current job might change to a different job. If the user or operator is authenticated to suspend the new job, the wrong job is suspended. To prevent this race from pausing the wrong job, the client MAY supply the "job-id" operation attribute, which is checked against the current job's job-id. If the job identified by the "job-id" attribute is not the current job on the Printer (i.e., is not in the 'processing' or 'processing-stopped' state), the Printer MUST reject this operation and return the 'client-error-not- possible' status code. Otherwise, the Printer suspends the specified job and processed other jobs. The Printer MUST reject a Suspend-Current-Job request (and return the 'client-error-not-possible') for a job that has been suspended, i.e., for a job in the 'processing-stopped' state, with the 'job-suspended' value in its "job-state-reasons" attribute. Access Rights: The authenticated user (see [RFC2911], section 8.3) performing this operation must be either the job owner (as determined in the Job Creation operation) or an operator or administrator of the Printer object (see [RFC2911], sections 1 and 8.5).
The Suspend-Current-Job Request and Suspend-Current-Job Response have the same attribute groups and attributes as does the Pause-Printer operation (see [RFC2911], section 3.2.8 ), including the new "job- message-from-operator" operation attribute (see section 6), with the addition of the following Group 1 Operation attribute in the request: "job-id" (integer(1:MAX)): The client OPTIONALLY supplies this Operation attribute to verify that the identified job is still the current job on the target Printer object. The IPP object MUST support this operation attribute if it supports this operation.4.3.2. Resume-Job Operation
This OPTIONAL operation allows a client to resume the target job at the point where it was suspended. The Printer moves the target job to the 'pending' state and removes the 'job-suspended' value from the job's "job-state-reasons" attribute. If the target job is not in the 'processing-stopped' state, with the 'job-suspended' value in the job's "job-state-reasons" attribute, the Printer MUST reject the request and return the 'client-error-not- possible' status code, since the job was not suspended. Access Rights: The authenticated user (see [RFC2911], section 8.3) performing this operation must be either the job owner (as determined in the Job Creation operation) or an operator or administrator of the Printer object (see [RFC2911], sections 1 and 8.5). The Resume-Job Request and Resume-Job Response have the same attribute groups and attributes as the Release-Job operation (see [RFC2911], section 3.3.6), including the new "job-message-from- operator" operation attribute (see section 6).4.4. Job Scheduling Operations
This section defines jobs that allow an operator to control the scheduling of jobs.4.4.1. Promote-Job Operation
This OPTIONAL operation allows a client to make the pending target job be processed next after the current job completes. This operation is especially useful in a production printing environment where the operator is involved in job scheduling.
If the target job is in the 'pending' state, this operation does not change the job's state but causes the job to be processed after the current job(s) complete. If the target job is not in the 'pending' state, the Printer MUST reject the request and return the 'client- error-not-possible' status code. If the Printer implements the "job-priority" Job Template attribute (see [RFC2911], section 4.2.1), the Printer sets the job's "job- priority" to the highest value supported (so that the job will print before any of the other pending jobs). The Printer returns the target job immediately after the current job(s) in a Get-Jobs response (see [RFC2911], section 3.2.6) for the 'not-completed' jobs. When the current job is completed, canceled, suspended (see section 4.3.1), or aborted, the target of this operation is processed next. If a client issues this request (again) before the target of the operation of the original request started processing, the target of this new request is processed first. IPP is specified not to require queues for job scheduling, as there are other implementation techniques for scheduling multiple jobs, such as re-evaluating a criteria function for each job on a scheduling cycle. However, if an implementation does implement queues for jobs, then the Promote-Job operation puts the specified job at the front of the queue. A subsequent Promote-Job operation prior to the processing of the first job puts that specified job at the front of the queue, so that it is "in front" of the previously promoted job. Access Rights: The authenticated user (see [RFC2911], section 8.3) performing this operation must be an operator or administrator of the Printer object (see [RFC2911], sections 1 and 8.5). The Promote-Job Request and Promote-Job Response have the same attribute groups and attributes as does the Cancel-Job operation (see [RFC2911], section 3.3.3), including the new "job-message-from- operator" operation attribute (see section 6).4.4.2. Schedule-Job-After Operation
This OPTIONAL operation allows a client to request that the Printer schedule the target job so that it will be processed immediately after the specified predecessor job, all other scheduling factors being equal. This operation is specially useful in a production printing environment where the operator is involved in job scheduling.
If the target job is in the 'pending' state, this operation does not change the job's state but causes the job to be processed after the preceding job completes. The preceding job can be in the target 'pending', 'processing', or 'processing-stopped' state. If the target job is not in the 'pending' state, or if the predecessor job is not in the 'pending', 'processing', or 'processing-stopped' state, the Printer MUST reject the request, and it returns the 'client- error-not-possible' status code, as the job cannot have its position changed. If the Printer implements the "job-priority" Job Template attribute (see [RFC2911], section 4.2.1), the Printer sets the job's "job- priority" to that of the predecessor job (so that the job will print after the predecessor job). The Printer returns the target job immediately after the predecessor in a Get-Jobs response (see [RFC2911], section 3.2.6) for the 'not-completed' jobs. When the predecessor job completes processing or is canceled or aborted while processing, the target of this operation is processed next. If the client does not supply a predecessor job, this operation has the same semantics as Promote-Job (see section 4.4). IPP is specified not to require queues for job scheduling, as there are other implementation techniques for scheduling multiple jobs, such as re-evaluating a criteria function for each job on a scheduling cycle. However, if an implementation does implement queues for jobs, then the Schedule-Job-After operation puts the specified job immediately after the specified job in the queue. A subsequent Schedule-Job-After operation specifying the same job will cause its target job to be placed after that job, even though it is between the first target job and the specified job. For example, suppose the job queue consisted of jobs A, B, C, D, and E, in that order. A Schedule-Job-After with job E as the target and B as the specified job would result in the following queue: A, B, E, C, D. A subsequent Schedule-Job-After with Job D as the target and B as the specified job would result in the following queue: A, B, D, E, C. In other words, the link between the two jobs in a Schedule-Job-After operation is not retained; i.e., there is no attribute on either job that points to the other job as a result of this operation. Access Rights: The authenticated user (see [RFC2911], section 8.3) performing this operation must be an operator or administrator of the Printer object (see [RFC2911], sections 1 and 8.5).
The Schedule-Job-After Request have the same attribute groups and attributes as does the Cancel-Job operation (see [RFC2911], section 3.3.3), plus the new "job-message-from-operator" operation attribute (see section 6). In addition, the following operation attribute is defined: "predecessor-job-id": The client OPTIONALLY supplies this attribute. The Printer MUST support it, if it supports this operation. This attribute specifies the job after which the target job is to be processed. If the client omits this attribute, the Printer MUST process the target job next, i.e., after the current job, if there is one. The Schedule-Job-After Response has the same attribute groups, attributes, and status codes as does the Cancel-Job operation (see [RFC2911], section 3.3.3). The following status codes have particular meaning for this operation: 'client-error-not-possible' - The target job was not in the 'pending' state, or the predecessor job was not in the 'pending', 'processing', or 'processing-stopped' state. 'client-error-not-found' - Either the target job or the predecessor job was not found.5. Additional Status Codes
This section defines new status codes used by the operations defined in this document.5.1. 'server-error-printer-is-deactivated' (0x050A)
The Printer has been deactivated by the Deactivate-Printer operation and is only accepting the Activate-Printer (see section 3.5.1), Get- Job-Attributes, Get-Jobs, Get-Printer-Attributes, and any other Get- Xxxx operations. An operator can perform the Activate-Printer operation to allow the Printer to accept other operations.6. Use of Operation Attributes That Are Messages from the Operator
This section summarizes the usage of the "printer-message-from- operator" and "job-message-from-operator" operation attributes [RFC3380] that set the corresponding Printer and Job Description attributes (see [RFC2911] for the definition of these). These operation attributes are defined for most of the Printer and Job operations that operators are likely to perform, respectively, so that operators can indicate the reasons for their actions.
Table 5 shows the operation attributes defined for use with the Printer Operations. Table 5. Operation Attribute Support for Printer Operations Operation Attribute A B --------------------------------------------- attributes-charset REQ REQ attributes-natural-language REQ REQ printer-uri REQ REQ requesting-user-name REQ REQ printer-message-from-operator Note OPT Legend: A: Get-Printer-Attributes, Set-Printer-Attributes B: All other Printer administrative operations, including, but not limited to, Pause-Printer, Pause-Printer-After-Current- Job, Resume-Printer, Hold-New-Jobs, Release-Held-New-Jobs, Purge-Jobs, Enable-Print, Disable-Printer, Restart- Printer, Shutdown-Printer, and Startup-Printer. REQ: REQUIRED for a Printer to support. OPT: OPTIONAL for a Printer to support; the Printer ignores the attribute if it is not supported. Note: According to [RFC3380], the Client MUST NOT supply the "printer-message-from-operator" operation attribute in a Get-Printer-Attributes or Set-Printer-Attributes operation; the Printer MUST ignore this operation attribute in these two operations. Instead, when it is used by an operator, the client MUST supply the "printer-message-from-operator" as (one of the) explicit attributes being set on the Printer object with the Set-Printer-Attributes operation.
Table 6 shows the operation attributes defined for use with the Job operations. Table 6. Operation Attribute Support for Job Operations Operation Attribute A B C F --------------------------------------------------------- attributes-charset REQ REQ REQ REQ attributes-natural-language REQ REQ REQ REQ printer-uri REQ REQ REQ REQ job-uri REQ REQ REQ job-id REQ REQ REQ REQ requesting-user-name REQ REQ REQ REQ job-message-from-operator OPT OPT OPT Note message** OPT OPT OPT n/a job-hold-until n/a n/a OPT* n/a Legend: A: Cancel-Job, Resume-Job, Restart-Job, Promote-Job, Schedule-Job- After B: Cancel-Current-Job, Suspend-Current-Job C: Hold-Job, Release-Job, Reprocess-Job F: Get-Job-Attributes, Set-Job-Attributes REQ; REQUIRED for a Printer to support. OPT: OPTIONAL for a Printer to support; the Printer ignores the attribute if it is supplied, but not supported. n/a: not applicable for use with the operation; the Printer ignores the attribute. Note: According to [RFC3380], the Client MUST NOT supply the "job- message-from-operator" operation attribute in a Get-Job- Attributes or Set-Job-Attributes operation; the Printer MUST ignore this operation attribute in these two operations. Instead, when used by an operator, the client MUST supply the "job-message-from-operator" as (one of the) explicit attributes being set on the Job object with the Set-Job-Attributes operation. *: The Printer MUST support the "job-hold-until" operation attribute if it supports the "job-hold-until" Job Template attribute. For the Reprocess-Job operation, the client can hold the job and then modify the job before releasing it to be processed. **: In [RFC2911], the "message" operation attribute is defined to contain a message to the operator, but [RFC2911] does not define a Job Description attribute to store the message.
7. New Printer Description Attributes
The following new Printer Description attributes are needed to support the new operations defined in this document and the concepts of Printer Fan-Out (see section 10).7.1. subordinate-printers-supported (1setOf uri)
This Printer attribute is REQUIRED if an implementation supports Subordinate Printers (see section 10) and contains the URIs of the immediate Subordinate Printer object(s) associated with this Printer object. Each Non-Leaf Printer object MUST support this Printer Description attribute. A Leaf Printer object either does not support the "subordinate-printers-supported" attribute or does so with the 'no-value' out-of-band value (see [RFC2911], section 4.1), depending on the implementation. The precise format of the Subordinate Printer URIs is implementation dependent (see section 10.4). If the Printer object does not have an associated Output Device, the Printer MAY automatically copy the value of the Subordinate Printer object's "printer-name" attribute to the Job object's "output- device-assigned" attribute (see [RFC2911], section 4.3.13). The "output-device-assigned" Job attribute identifies the Output Device to which the Printer object has assigned a job; for example, when a single Printer object is supporting Device Fan-Out or Printer Fan- Out.7.2. parent-printers-supported (1setOf uri)
This Printer attribute is REQUIRED if an implementation supports Subordinate Printers (see section 10) and contains the URI of the Non-Leaf printer object(s) for which this Printer object is the immediate Subordinate; i.e., this Printer's immediate "parent" or "parents". Each Subordinate Printer object MUST support this Printer Description attribute. A Printer that has no parents either does not support the "parent-printers-supported" attribute or does so with the 'no-value' out-of-band value (see [RFC2911], section 4.1), depending on the implementation.8. Additional Values for the "printer-state-reasons" Printer Description Attribute
This section defines additional values for the "printer-state- reasons" Printer Description attribute.
8.1. 'hold-new-jobs' Value
'hold-new-jobs': The operator has issued the Hold-New-Jobs operation (see section 3.3.1) or other means, but the output-device(s) are taking an appreciable time to stop. Later, when all output has stopped, the "printer-state" becomes 'stopped', and the 'paused' value replaces the 'moving-to-paused' value in the "printer- state-reasons" attribute. This value MUST be supported if the Hold-New-Jobs operation is supported and the implementation takes significant time to pause a device in certain circumstances.8.2. 'deactivated' Value
'deactivated': A client has issued a Deactivate-Printer operation for the Printer object (see section 3.4.1), and the Printer is in the process of becoming deactivated or has become deactivated. The Printer MUST reject all requests except for Activate-Printer, queries (Get-Printer-Attributes, Get-Job-Attributes, Get-Jobs, etc.), Send-Document, and Send-URI (so that partial job submission can be completed; see section 3.1.1), and then return the 'server-error-service-unavailable' status code.9. Additional Values for the "job-state-reasons" Job Description Attribute
This section defines additional values for the "job-state-reasons" Job Description attribute.9.1. 'job-suspended' Value
'job-suspended': While job processing has been suspended by the Suspend-Current-Job operation, other jobs can be processed on the Printer. The Job can be resumed with the Resume-Job operation, which removes this value.10. Use of the Printer Object to Represent IPP Printer Fan-Out and IPP Printer Fan-In
This section defines how the Printer object MAY be used to represent IPP Printer Fan-Out and IPP Printer Fan-In. In Fan-Out, an IPP Printer is used to represent other IPP Printer objects. In Fan-In, several IPP Printer objects are used to represent another IPP Printer object.
10.1. IPP Printer Fan-Out
The IPP/1.1 Model and Semantics introduces the semantic concept of an IPP Printer object that represents more than one Output Device (see [RFC2911], section 2.1). This concept is called "Output Device Fan- Out". However, with Fan-Out there was no way to represent the individual states of the Output Devices or to perform operations on a specific Output Device. This document generalizes the semantics of the Printer object to represent Subordinate Fan-Out Output Devices such as IPP Printer objects. This concept is called "Printer object Fan-Out". A Printer object that has a Subordinate Printer object is called a Non-Leaf Printer object. Thus, a Non-Leaf Printer object supports one or more Subordinate Printer objects in order to represent Printer object Fan-Out. A Printer object that does not have any Subordinate Printer objects is called a Leaf Printer object. Each Non-Leaf Printer object submits jobs to its immediate Subordinate Printers and otherwise controls the Subordinate Printers by using IPP or other protocols. Whether pending jobs are kept in the Non-Leaf Printer until a Subordinate Printer can accept them or are kept in the Subordinate Printers depends on implementation and/or configuration policy. Furthermore, a Subordinate Printer object MAY, in turn, have Subordinate Printer objects. Thus a Printer object can be both a Non-Leaf Printer and a Subordinate Printer. A Subordinate Printer object MUST be a conforming Printer object, so it MUST support all of the REQUIRED [RFC2911] operations and attributes. However, with access control, the Subordinate Printer MAY be configured so that end-user clients are not permitted to perform any operations (or just Get-Printer-Attributes) while one or more Non-Leaf Printer object(s) are permitted to perform any operation.10.2. IPP Printer Fan-In
The IPP/1.1 Model and Semantics did not preclude the semantic concept of multiple IPP Printer objects that represent a single Output Device (see [RFC2911], section 2.1). However, there was no way for the client to determine whether there was a Fan-In configuration; nor was there a way to perform operations on the Subordinate device. This specification generalizes the semantics of the Printer object to allow several Non-Leaf IPP Printer objects to represent a single Subordinate Printer object. Thus a Non-Leaf Printer object MAY share a Subordinate Printer object with one or more other Non-Leaf Printer objects in order to represent IPP Printer Fan-In. As with Fan-Out (see section 10.1), when a Printer object is a Non- Leaf Printer, it MUST NOT have an associated Output Device. As with
Fan-Out, a Leaf Printer object has one or more associated Output Devices. As with Fan-Out, the Non-Leaf Printer objects submit jobs to their Subordinate Printer objects and otherwise control the Subordinate Printer. As with Fan-Out, whether pending jobs are kept in the Non-Leaf Printers until the Subordinate Printer can accept them or are kept in the Subordinate Printer depends on the implementation and/or configuration policy.10.3. Printer Object Attributes Used to Represent Printer Fan-Out and Printer Fan-In
The following Printer Description attributes are defined to represent the relationship between Printer object(s) and their Subordinate Printer object(s): 1. "subordinate-printers-supported" (1setOf uri) - Contains the URI of the immediate Subordinate Printer object(s). 2. "parent-printers-supported (1setOf uri) - Contains the URI of the Non-Leaf printer object(s) for which this Printer object is the immediate Subordinate; i.e., this Printer's immediate "parent" or "parents".10.4. Subordinate Printer URI
Each Subordinate Printer object has a URI used as the target of each operation on the Subordinate Printer. The means to configure URIs for Subordinate Printer objects is implementation-dependent, as are all URIs. However, there are two distinct approaches: a. When the implementation seeks to make sure that no operation on a Subordinate Printer object "sneaks by" the parent Printer object (or that no Subordinate Printer is fronting for a device that is not networked), the host part of the URI specifies the host of the parent Printer. Then the parent Printer object can easily reflect the state of the Subordinate Printer objects in the parent's Printer object state and state reasons as the operation passes "through" the parent Printer object. b. When the Subordinate Printer is networked and the implementation allows operations to go directly to the Subordinate Printer (with proper access control) without knowledge of the parent Printer object, the host part of the URI is different from the host part of the parent Printer object. In this a case, the parent Printer object MAY keep its "printer-state" and "printer-state-reasons" up to date, either by polling the Subordinate Printer object or by subscribing to events with the Subordinate Printer object (see [RFC3995] for
means to subscribe to event notification when the Subordinate
Printer object supports IPP notification). Alternatively, the
parent Printer MAY wait until its "printer-state" and
"printer-state-reasons" attributes are queried and then query
all its Subordinate Printers in order to return the correct
values.
10.5. Printer Object Attributes Used to Represent Output Device Fan-Out
Only Leaf IPP Printer objects are allowed to have one or more
associated Output Devices. Each Leaf Printer object MAY support the
"output-devices-supported" (1setOf name(127)) to indicate the user-
friendly name(s) of the Output Device(s) that the Leaf Printer object
represents. It is RECOMMENDED that each Leaf Printer object have
only one associated Output Device, so that the individual Output
Devices can be represented completely and controlled completely by
clients. In other words, the Leaf Printer's "output-devices-
supported" attribute SHOULD have only one value.
Non-Leaf Printer MUST NOT have associated Output Devices. However, a
Non-Leaf Printer SHOULD support an "output-devices-supported" (1setOf
name(127)) Printer Description attribute that contains all the values
of its immediate Subordinate Printers. As these Subordinate Printers
MAY be Leaf or Non-Leaf, the same rules apply to them. Thus any
Non-Leaf Printer SHOULD have an "output-devices-supported" (1setOf
name(127)) attribute that contains all the values of the Output
Devices associated with Leaf Printers of its complete sub-tree.
When a configuration of Printers and Output Devices is added, moved,
or changed, there can be moments when the tree structure is not
consistent; i.e., times when a Non-Leaf Printer's "subordinate-
printers-supported" does not agree with the Subordinate Printer's
"parent-printers-supported". Therefore, the operator SHOULD first
Deactivate all Printers being configured in this way, update all
pointer attributes, and then reactivate them. A useful client tool
would validate a tree structure before Activating the Printers
involved.
10.6. Figures to Show All Possible Configurations
Figures 1, 2, and 3 are taken from [RFC2911] to show the
configurations possible with IPP/1.0 and IPP/1.1 where all Printer
objects are Leaf Printer objects. The remaining figures show
additional configurations using Non-Leaf and Leaf Printer objects.
Legend:
----> indicates a network protocol with the direction of its requests
##### indicates a Printer object that is either
embedded in an Output Device, or
hosted in a server.
The Printer object might or might not be capable
of queuing/spooling.
any indicates any network protocol or direct
connect, including IPP.
Output Device
+---------------+
| ########### |
O +--------+ | # (Leaf) # |
/|\ | client |------------IPP-----------------># Printer # |
/ \ +--------+ | # Object # |
| ########### |
+---------------+
Figure 1. Embedded Printer Object
########### Output Device
O +--------+ # (Leaf) # +---------------+
/|\ | client |---IPP----># Printer #---any->| |
/ \ +--------+ # object # | |
########### +---------------+
Figure 2. Hosted Printer Object
+---------------+
| |
+->| Output Device |
########### any/ | |
O +--------+ # (Leaf) # / +---------------+
/|\ | client |---IPP----># Printer #--*
/ \ +--------+ # Object # \ +---------------+
########### any\ | |
+->| Output Device |
| |
+---------------+
Figure 3. Output Device Fan-Out
########### ########### O +--------+ # Non-Leaf# # subord. # /|\ | client |---IPP----># Printer #---IPP----># Printer # / \ +--------+ # object # # object # ########### ########### The Subordinate Printer can be a Non-Leaf Printer, as in Figures 4 through 6, or can be a Leaf Printer, as in Figures 1 through 3. Figure 4. Chained IPP Printer Objects +------IPP--------------------->########### / +---># subord. # / / # Printer # / ########### IPP # object # O +--------+ # Non-Leaf# / ########### /|\ | client |---IPP----># Printer #--* / \ +--------+ # object # \ \ ########### IPP ########### \ \ # subord. # \ +---># Printer # +------IPP---------------------># object # ########### The Subordinate Printer can be a Non-Leaf Printer, as in Figures 4 through 6, or can be a Leaf Printer, as in Figures 1 through 3. Figure 5. IPP Printer Object Fan-Out
########### # Non-Leaf# +---># Printer #-+ / # object # \ IPP ########### \ ########### O +--------+ / +-IPP-># subord. # /|\ | client |--+-----------IPP---------------># Printer # / \ +--------+ \ +-IPP-># object # IPP ########### / ########### \ # Non-Leaf# / +---># Printer #-+ # object # ########### The Subordinate Printer can be a Non-Leaf Printer, as in Figures 4 through 6, or can be a Leaf Printer, as in Figures 1 through 3. Figure 6. IPP Printer Object Fan-In10.7. Forwarding Requests
This section describes the forwarding of Job and Printer requests to Subordinate Printer objects.10.7.1. Forwarding Requests that Affect Printer Objects
In Printer Fan-Out, Printer Fan-In, and Chained Printers, the Non- Leaf IPP Printer object MUST NOT forward the operations that affect Printer objects to its Subordinate Printer objects. If a client seeks to explicitly target a Subordinate Printer, the client MUST specify the URI of the Subordinate Printer. The client can determine the URI of any Subordinate Printers by querying the Printer's "subordinate-printers-supported (1setOf uri) attribute (see section 7.1). Table 7 lists the operations that affect Printer objects and the forwarding behavior that a Non-Leaf Printer MUST exhibit to its immediate Subordinate Printers. Operations that affect jobs have a different forwarding rule (see section 10.7.2 and Table 8):
Table 7. Forwarding Operations that Affect Printer Objects Printer Operation Non-Leaf Printer Action --------------------------------------------------------------- Printer Operations: Enable-Printer MUST NOT forward to any of its Subordinate Printers Disable-Printer MUST NOT forward to any of its Subordinate Printers Hold-New-Jobs MUST NOT forward to any of its Subordinate Printers Release-Held-New- MUST NOT forward to any of its Subordinate Jobs Printers Deactivate-Printer MUST NOT forward to any of its Subordinate Printers Activate-Printer MUST NOT forward to any of its Subordinate Printers Restart-Printer MUST NOT forward to any of its Subordinate Printers Shutdown-Printer MUST NOT forward to any of its Subordinate Printers Startup-Printer MUST NOT forward to any of its Subordinate Printers IPP/1.1 Printer See [RFC2911] Operations: Get-Printer- MUST NOT forward to any of its Subordinate Attributes Printers Pause-Printer MUST NOT forward to any of its Subordinate Printers Resume-Printer MUST NOT forward to any of its Subordinate Printers Set Operations: See [RFC3380] Set-Printer- MUST NOT forward to any of its Subordinate Attributes Printers
10.7.2. Forwarding Requests that Affect Jobs
Unlike Printer Operations that only affect Printer objects (see section 10.7.1), a Non-Leaf Printer object MUST forward operations that directly affect jobs to the appropriate Job object(s) in one or more of its immediate Subordinate Printer objects. Forwarding is REQUIRED since the purpose of this Job operation is to affect the indicated job, which may have been forwarded itself. This forwarding MAY be immediate or queued, depending on the operation and the implementation. For example, a Non-Leaf Printer object MAY queue/spool jobs, feeding a job at a time to its Subordinate Printer(s), or MAY forward jobs immediately to one of its Subordinate Printers. In either case, the Non-Leaf Printer object forwards Job Creation operations to one of its Subordinate Printers. Only the time of forwarding of the Job Creation operations depends on whether the policy is to queue/spool jobs in the Non-Leaf Printer or the Subordinate Printer. When a Non-Leaf Printer object creates a Job object in its Subordinate Printer, whether that Non-Leaf Printer object keeps a fully formed Job object or just keeps a mapping from the "job-ids" that it assigned to those assigned by its Subordinate Printer object is IMPLEMENTATION-DEPENDENT. In either case, the Non-Leaf Printer MUST be able to accept and carry out future Job operations that specify the "job-id" that the Non-Leaf Printer assigned and returned to the job submitting client. Table 8 lists the operations that directly affect jobs and the forwarding behavior that a Non-Leaf Printer MUST exhibit to its Subordinate Printers.
Table 8. Forwarding Operations that Affect Jobs Objects Operation Non-Leaf Printer action --------------------------------------------------------------- Job operations: Reprocess-Job MUST forward to the appropriate Job in one of its Subordinate Printers Cancel-Current- MUST NOT forward Job Resume-Job MUST forward to the appropriate Job in one of its Subordinate Printers Promote-Job MUST forward to the appropriate Job in one of its Subordinate Printers IPP/1.1 Printer operations: Print-Job MUST forward immediately or queue to the appropriate Subordinate Printer Print-URI MUST forward immediately or queue to the appropriate Subordinate Printer Validate-Job MUST forward to the appropriate Subordinate Printer Create-Job MUST forward immediately or queue to the appropriate Subordinate Printer Get-Jobs MUST forward to all its Subordinate Printers Purge-Jobs MUST forward to all its Subordinate Printers IPP/1.1 Job operations: Send-Document MUST forward immediately or queue to the appropriate Job in one of its Subordinate Printers Send-URI MUST forward immediately or queue to the appropriate Job in one of its Subordinate Printers Cancel-Job MUST forward to the appropriate Job in one of its Subordinate Printers Get-Job- MUST forward to the appropriate Job in one of Attributes its Subordinate Printers if the Non-Leaf Printer doesn't know the complete status of the Job object Hold-Job MUST forward to the appropriate Job in one of its Subordinate Printers Release-Job MUST forward to the appropriate Job in one of its Subordinate Printers
Restart-Job MUST forward to the appropriate Job in one of its Subordinate Printers IPP Set operations: See [RFC3380] Set-Job- MUST forward to the appropriate Job in one of Attributes its Subordinate Printers When a Printer receives a request that REQUIRES forwarding, it does so on a "best efforts basis" and returns a response to its client without waiting for responses from any of its Subordinate Printers. Such forwarded requests could fail.10.8. Additional Attributes to Help with Fan-Out
The following operation and Job Description attributes are defined to help represent Job relationships for Fan-Out and forwarding of jobs.10.8.1. output-device-assigned (name(127)) Job Description Attribute - from [RFC2911]
[RFC2911] defines "output-device-assigned" as follows: "This attribute identifies the Output Device to which the Printer object has assigned this job. If an Output Device implements an embedded Printer object, the Printer object NEED NOT set this attribute. If a print server implements a Printer object, the value MAY be empty (zero-length string) or not returned until the Printer object assigns an Output Device to the job. This attribute is particularly useful when a single Printer object supports multiple devices (so called "Device Fan-Out" see [RFC2911] section 2.1)." See also section 10.1 in this specification.10.8.2. original-requesting-user-name (name(MAX)) Operation and Job Description Attribute
The operation attribute containing the user name of the original user; i.e., corresponding to the "requesting-user-name" operation attribute (see [RFC2911], section 3.2.1.1) that the original client supplied to the first Printer object. The Printer copies the "original-requesting-user-name" operation attribute to the corresponding Job Description attribute.
10.8.3. requesting-user-name (name(MAX)) Operation Attribute - Additional Semantics
The IPP/1.1 "requesting-user-name" operation attribute (see [RFC2911] section 3.2.1.1) is updated by each client to be itself on each hop; i.e., the "requesting-user-name" represents the client forwarding the request, not the original client.10.8.4. job-originating-user-name (name(MAX)) Job Description Attribute - Additional Semantics
The "job-originating-user-name" Job Description attribute (see [RFC2911], section 4.3.6) remains as the authenticated original user, not the parent Printer's authenticated host, and is forwarded by each client without changing the value.
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