This example MIB module defines a set of management objects for heating ventilation and air conditioning systems. It also includes objects that can be used to create policies that are applied to rooms. This eliminates the need to send per-instance configuration commands to the system.
Copyright (C) The Internet Society (2003). This version of this MIB module is part of RFC 3512; see the RFC itself for full legal notices.
This table is the representation and data control for building HVAC by each individual office. The table has rows for, and is indexed by a specific floor and office number. Each such row includes HVAC statistical and current status information for the associated office. The row also contains a bldgHVACCfgTemplate columnar object that relates the bldgHVACTable row to a row in the bldgHVACCfgTemplateTable. If this value is nonzero, then the instance in the row that has a value for how the HVAC has been configured in the associated template (bldgHVACCfgTeplateTable row). Hence, the bldgHVACCfgTeplateTable row contains the specific configuration values for the offices as described in this table.
bldgHVACFloor
1.3.6.1.3.122.1.1.1.1
Unsigned32 (1..1000)
This portion of the index indicates the floor of the building. The ground floor is considered the first floor. For the purposes of this example, floors under the ground floor cannot be controlled using this MIB module.
bldgHVACOffice
1.3.6.1.3.122.1.1.1.2
Unsigned32 (1..2147483647)
This second component of the index specifies the office number.
bldgHVACCfgTemplate
1.3.6.1.3.122.1.1.1.3
Unsigned32
The index (bldgHVACCfgTemplateIndex instance) of an entry in the 'bldgHVACCfgTemplateTable'. The bldgHVACCfgTable row instance referenced is a pre-made configuration 'template' that represents the configuration described by the bldgHVACCfgTemplateInfoDescr object. Note that not all configurations will be under a defined template. As a result, a row in this bldgHVACTable may point to an entry in the bldgHVACCfgTemplateTable that does not in turn have a reference (bldgHVACCfgTemplateInfo) to an entry in the bldgHVACCfgTemplateInfoTable. The benefit of this approach is that all configuration information is available in one table whether all elements in the system are derived from configured templates or not.
Where the instance value for this colunmar object is zero, this row represents data for an office whose HVAC status can be monitored using the read-only columnar object instances of this row, but is not under the configuration control of the agent.
bldgHVACFanSpeed
1.3.6.1.3.122.1.1.1.4
Gauge32 · revolutions per minute
Shows the revolutions per minute of the fan. Fan speed will vary based on the difference between bldgHVACCfgTemplateDesiredTemp and bldgHVACCurrentTemp. The speed is measured in revolutions of the fan blade per minute.
bldgHVACCurrentTemp
1.3.6.1.3.122.1.1.1.5
Gauge32 · degrees in celsius
The current measured temperature in the office. Should the current temperature be measured at a value of less than zero degrees celsius, a read of the instance for this object will return a value of zero.
bldgHVACCoolOrHeatMins
1.3.6.1.3.122.1.1.1.6
Counter32 · minutes
The total number of heating or cooling minutes that have been consumed since the row was activated. Notice that whether the minutes represent heating or cooling is a function of the configuration of this row. If the system is re-initialized from a cooling to heating function or vice versa, then the counter would start over again. This effect is similar to a reconfiguration of some network interface cards. When parameters that impact configuration are changed, the subsystem must be re-initialized. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of bldgHVACDiscontinuityTime.
bldgHVACDiscontinuityTime
1.3.6.1.3.122.1.1.1.7
TimeStampThe value of the sysUpTime object at which a specific occurrence happened. The specific occurrence must be
defined in the description of any object defined using this type.
If sysUpTime is reset to zero as a result of a re- initialization of the network management (sub)system, then the values of all TimeStamp objects are also reset. However, after approximately 497 days without a re- initialization, the sysUpTime object will reach 2^^32-1 and then increment around to zero; in this case, existing values of TimeStamp objects do not change. This can lead to ambiguities in the value of TimeStamp objects. · TimeTicks
The value of sysUpTime on the most recent occasion at which any heating or cooling operation for the office designated by this row instance experienced a discontinuity. If no such discontinuities have occurred since the last re- initialization of the this row, then this object contains a zero value.
bldgHVACOwner
1.3.6.1.3.122.1.1.1.8
SnmpAdminStringAn octet string containing administrative information, preferably in human-readable form.
To facilitate internationalization, this information is represented using the ISO/IEC IS 10646-1 character set, encoded as an octet string using the UTF-8 transformation format described in [RFC2279].
Since additional code points are added by amendments to the 10646 standard from time to time, implementations must be prepared to encounter any code point from 0x00000000 to 0x7fffffff. Byte sequences that do not correspond to the valid UTF-8 encoding of a code point or are outside this range are prohibited.
The use of control codes should be avoided.
When it is necessary to represent a newline, the control code sequence CR LF should be used.
The use of leading or trailing white space should be avoided.
For code points not directly supported by user interface hardware or software, an alternative means of entry and display, such as hexadecimal, may be provided.
For information encoded in 7-bit US-ASCII, the UTF-8 encoding is identical to the US-ASCII encoding.
UTF-8 may require multiple bytes to represent a single character / code point; thus the length of this object in octets may be different from the number of characters encoded. Similarly, size constraints refer to the number of encoded octets, not the number of characters represented by an encoding.
Note that when this TC is used for an object that is used or envisioned to be used as an index, then a SIZE restriction MUST be specified so that the number of sub-identifiers for any object instance does not exceed the limit of 128, as defined by [RFC3416].
Note that the size of an SnmpAdminString object is measured in octets, not characters. SIZE (0..255) · OCTET STRING · hint 255t
The identity of the operator/system that last modified this entry. When a new entry is created, a valid SnmpAdminString must be supplied. If, on the other hand, this entry is populated by the agent 'discovering' unconfigured rooms, the empty string is a valid value for this object.
bldgHVACStorageType
1.3.6.1.3.122.1.1.1.9
StorageType1 = other2 = volatile3 = nonVolatile4 = permanent5 = readOnlyDescribes the memory realization of a conceptual row. A row which is volatile(2) is lost upon reboot. A row which is either nonVolatile(3), permanent(4) or readOnly(5), is backed up by stable storage. A row which is permanent(4) can be changed but not deleted. A row which is readOnly(5) cannot be changed nor deleted.
If the value of an object with this syntax is either permanent(4) or readOnly(5), it cannot be written. Conversely, if the value is either other(1), volatile(2) or nonVolatile(3), it cannot be modified to be permanent(4) or readOnly(5). (All illegal modifications result in a 'wrongValue' error.)
Every usage of this textual convention is required to specify the columnar objects which a permanent(4) row must at a minimum allow to be writable. · Integer32
The persistence of this row of the table in system storage, as it pertains to permanence across system resets. A columnar instance of this object with value 'permanent' need not allow write-access to any of the columnar object instances in the containing row.
bldgHVACStatus
1.3.6.1.3.122.1.1.1.10
RowStatus1 = active2 = notInService3 = notReady4 = createAndGo5 = createAndWait6 = destroyThe RowStatus textual convention is used to manage the creation and deletion of conceptual rows, and is used as the value of the SYNTAX clause for the status column of a conceptual row (as described in Section 7.7.1 of [2].)
The status column has six defined values:
- `active', which indicates that the conceptual row is available for use by the managed device;
- `notInService', which indicates that the conceptual row exists in the agent, but is unavailable for use by the managed device (see NOTE below); 'notInService' has no implication regarding the internal consistency of the row, availability of resources, or consistency with the current state of the managed device;
- `notReady', which indicates that the conceptual row exists in the agent, but is missing information necessary in order to be available for use by the managed device (i.e., one or more required columns in the conceptual row have not been instanciated);
- `createAndGo', which is supplied by a management station wishing to create a new instance of a conceptual row and to have its status automatically set to active, making it available for use by the managed device;
- `createAndWait', which is supplied by a management station wishing to create a new instance of a conceptual row (but not make it available for use by the managed device); and, - `destroy', which is supplied by a management station wishing to delete all of the instances associated with an existing conceptual row.
Whereas five of the six values (all except `notReady') may be specified in a management protocol set operation, only three values will be returned in response to a management
protocol retrieval operation: `notReady', `notInService' or
`active'. That is, when queried, an existing conceptual row
has only three states: it is either available for use by
the managed device (the status column has value `active'); it is not available for use by the managed device, though the agent has sufficient information to attempt to make it so (the status column has value `notInService'); or, it is not available for use by the managed device, and an attempt to make it so would fail because the agent has insufficient information (the state column has value `notReady').
NOTE WELL
This textual convention may be used for a MIB table, irrespective of whether the values of that table's conceptual rows are able to be modified while it is active, or whether its conceptual rows must be taken out of service in order to be modified. That is, it is the responsibility of the DESCRIPTION clause of the status column to specify whether the status column must not be `active' in order for the value of some other column of the same conceptual row to be modified. If such a specification is made, affected columns may be changed by an SNMP set PDU if the RowStatus would not be equal to `active' either immediately before or after processing the PDU. In other words, if the PDU also contained a varbind that would change the RowStatus value, the column in question may be changed if the RowStatus was not equal to `active' as the PDU was received, or if the varbind sets the status to a value other than 'active'.
Also note that whenever any elements of a row exist, the RowStatus column must also exist.
To summarize the effect of having a conceptual row with a status column having a SYNTAX clause value of RowStatus, consider the following state diagram:
STATE +--------------+-----------+-------------+-------------
| A | B | C | D
| |status col.|status column|
|status column | is | is |status column
ACTION |does not exist| notReady | notInService| is active
--------------+--------------+-----------+-------------+-------------
set status |noError ->D|inconsist- |inconsistent-|inconsistent-
column to | or | entValue| Value| Value
createAndGo |inconsistent- | | |
| Value| | |
--------------+--------------+-----------+-------------+-------------
set status |noError see 1|inconsist- |inconsistent-|inconsistent-
column to | or | entValue| Value| Value
createAndWait |wrongValue | | |
--------------+--------------+-----------+-------------+-------------
set status |inconsistent- |inconsist- |noError |noError
column to | Value| entValue| |
active | | | |
| | or | |
| | | |
| |see 2 ->D|see 8 ->D| ->D
--------------+--------------+-----------+-------------+-------------
set status |inconsistent- |inconsist- |noError |noError ->C
column to | Value| entValue| |
notInService | | | |
| | or | | or
| | | |
| |see 3 ->C| ->C|see 6
--------------+--------------+-----------+-------------+-------------
set status |noError |noError |noError |noError ->A
column to | | | | or
destroy | ->A| ->A| ->A|see 7
--------------+--------------+-----------+-------------+-------------
set any other |see 4 |noError |noError |see 5
column to some| | | |
value | | see 1| ->C| ->D
--------------+--------------+-----------+-------------+-------------
(1) goto B or C, depending on information available to the agent.
(2) if other variable bindings included in the same PDU, provide values for all columns which are missing but required, and all columns have acceptable values, then return noError and goto D.
(3) if other variable bindings included in the same PDU, provide legal values for all columns which are missing but required, then return noError and goto C.
(4) at the discretion of the agent, the return value may be either:
inconsistentName: because the agent does not choose to
create such an instance when the corresponding RowStatus instance does not exist, or
inconsistentValue: if the supplied value is
inconsistent with the state of some other MIB object's value, or
noError: because the agent chooses to create the instance.
If noError is returned, then the instance of the status column must also be created, and the new state is B or C, depending on the information available to the agent. If inconsistentName or inconsistentValue is returned, the row remains in state A.
(5) depending on the MIB definition for the column/table, either noError or inconsistentValue may be returned.
(6) the return value can indicate one of the following errors:
wrongValue: because the agent does not support notInService (e.g., an agent which does not support createAndWait), or
inconsistentValue: because the agent is unable to take the row out of service at this time, perhaps because it is in use and cannot be de-activated.
(7) the return value can indicate the following error:
inconsistentValue: because the agent is unable to remove the row at this time, perhaps because it is in use and cannot be de-activated.
(8) the transition to D can fail, e.g., if the values of the conceptual row are inconsistent, then the error code would be inconsistentValue.
NOTE: Other processing of (this and other varbinds of) the set request may result in a response other than noError being returned, e.g., wrongValue, noCreation, etc.
Conceptual Row Creation
There are four potential interactions when creating a
conceptual row: selecting an instance-identifier which is
not in use; creating the conceptual row; initializing any objects for which the agent does not supply a default; and, making the conceptual row available for use by the managed device.
Interaction 1: Selecting an Instance-Identifier
The algorithm used to select an instance-identifier varies for each conceptual row. In some cases, the instance- identifier is semantically significant, e.g., the destination address of a route, and a management station selects the instance-identifier according to the semantics.
In other cases, the instance-identifier is used solely to distinguish conceptual rows, and a management station without specific knowledge of the conceptual row might examine the instances present in order to determine an unused instance-identifier. (This approach may be used, but it is often highly sub-optimal; however, it is also a questionable practice for a naive management station to attempt conceptual row creation.)
Alternately, the MIB module which defines the conceptual row might provide one or more objects which provide assistance in determining an unused instance-identifier. For example, if the conceptual row is indexed by an integer-value, then an object having an integer-valued SYNTAX clause might be defined for such a purpose, allowing a management station to issue a management protocol retrieval operation. In order to avoid unnecessary collisions between competing management stations, `adjacent' retrievals of this object should be different.
Finally, the management station could select a pseudo-random number to use as the index. In the event that this index
was already in use and an inconsistentValue was returned in response to the management protocol set operation, the management station should simply select a new pseudo-random number and retry the operation.
A MIB designer should choose between the two latter algorithms based on the size of the table (and therefore the efficiency of each algorithm). For tables in which a large number of entries are expected, it is recommended that a MIB object be defined that returns an acceptable index for creation. For tables with small numbers of entries, it is recommended that the latter pseudo-random index mechanism be used.
Interaction 2: Creating the Conceptual Row
Once an unused instance-identifier has been selected, the management station determines if it wishes to create and activate the conceptual row in one transaction or in a negotiated set of interactions.
Interaction 2a: Creating and Activating the Conceptual Row
The management station must first determine the column requirements, i.e., it must determine those columns for which it must or must not provide values. Depending on the complexity of the table and the management station's knowledge of the agent's capabilities, this determination can be made locally by the management station. Alternately, the management station issues a management protocol get operation to examine all columns in the conceptual row that it wishes to create. In response, for each column, there are three possible outcomes:
- a value is returned, indicating that some other management station has already created this conceptual row. We return to interaction 1.
- the exception `noSuchInstance' is returned, indicating that the agent implements the object-type associated with this column, and that this column in at least one conceptual row would be accessible in the MIB view used by the retrieval were it to exist. For those columns to which the agent provides read-create access, the `noSuchInstance' exception tells the management station that it should supply a value for this column when the conceptual row is to be created.
- the exception `noSuchObject' is returned, indicating that the agent does not implement the object-type associated with this column or that there is no conceptual row for which this column would be accessible in the MIB view used by the retrieval. As such, the management station can not issue any management protocol set operations to create an instance of this column.
Once the column requirements have been determined, a management protocol set operation is accordingly issued. This operation also sets the new instance of the status column to `createAndGo'.
When the agent processes the set operation, it verifies that it has sufficient information to make the conceptual row available for use by the managed device. The information
available to the agent is provided by two sources: the
management protocol set operation which creates the conceptual row, and, implementation-specific defaults supplied by the agent (note that an agent must provide implementation-specific defaults for at least those objects which it implements as read-only). If there is sufficient information available, then the conceptual row is created, a `noError' response is returned, the status column is set to `active', and no further interactions are necessary (i.e., interactions 3 and 4 are skipped). If there is insufficient information, then the conceptual row is not created, and the set operation fails with an error of `inconsistentValue'. On this error, the management station can issue a management protocol retrieval operation to determine if this was because it failed to specify a value for a required column, or, because the selected instance of the status column already existed. In the latter case, we return to interaction 1. In the former case, the management station can re-issue the set operation with the additional information, or begin interaction 2 again using `createAndWait' in order to negotiate creation of the conceptual row.
NOTE WELL
Regardless of the method used to determine the column requirements, it is possible that the management station might deem a column necessary when, in fact, the agent will not allow that particular columnar instance to be created or written. In this case, the management protocol set operation will fail with an error such as `noCreation' or `notWritable'. In this case, the management station decides whether it needs to be able to set a value for that particular columnar instance. If not, the management station re-issues the management protocol set operation, but without setting a value for that particular columnar instance; otherwise, the management station aborts the row creation algorithm.
Interaction 2b: Negotiating the Creation of the Conceptual Row
The management station issues a management protocol set operation which sets the desired instance of the status column to `createAndWait'. If the agent is unwilling to process a request of this sort, the set operation fails with an error of `wrongValue'. (As a consequence, such an agent must be prepared to accept a single management protocol set operation, i.e., interaction 2a above, containing all of the
columns indicated by its column requirements.) Otherwise,
the conceptual row is created, a `noError' response is returned, and the status column is immediately set to either `notInService' or `notReady', depending on whether it has sufficient information to (attempt to) make the conceptual row available for use by the managed device. If there is sufficient information available, then the status column is set to `notInService'; otherwise, if there is insufficient information, then the status column is set to `notReady'. Regardless, we proceed to interaction 3.
Interaction 3: Initializing non-defaulted Objects
The management station must now determine the column requirements. It issues a management protocol get operation to examine all columns in the created conceptual row. In the response, for each column, there are three possible outcomes:
- a value is returned, indicating that the agent implements the object-type associated with this column and had sufficient information to provide a value. For those columns to which the agent provides read-create access (and for which the agent allows their values to be changed after their creation), a value return tells the management station that it may issue additional management protocol set operations, if it desires, in order to change the value associated with this column.
- the exception `noSuchInstance' is returned, indicating that the agent implements the object-type associated with this column, and that this column in at least one conceptual row would be accessible in the MIB view used by the retrieval were it to exist. However, the agent does not have sufficient information to provide a value, and until a value is provided, the conceptual row may not be made available for use by the managed device. For those columns to which the agent provides read-create access, the `noSuchInstance' exception tells the management station that it must issue additional management protocol set operations, in order to provide a value associated with this column.
- the exception `noSuchObject' is returned, indicating that the agent does not implement the object-type associated with this column or that there is no conceptual row for which this column would be accessible in the MIB view used by the retrieval. As such, the management station can not issue any management protocol set operations to create an instance of this column.
If the value associated with the status column is `notReady', then the management station must first deal with all `noSuchInstance' columns, if any. Having done so, the value of the status column becomes `notInService', and we proceed to interaction 4.
Interaction 4: Making the Conceptual Row Available
Once the management station is satisfied with the values associated with the columns of the conceptual row, it issues a management protocol set operation to set the status column to `active'. If the agent has sufficient information to make the conceptual row available for use by the managed device, the management protocol set operation succeeds (a `noError' response is returned). Otherwise, the management protocol set operation fails with an error of `inconsistentValue'.
NOTE WELL
A conceptual row having a status column with value `notInService' or `notReady' is unavailable to the managed device. As such, it is possible for the managed device to create its own instances during the time between the management protocol set operation which sets the status column to `createAndWait' and the management protocol set operation which sets the status column to `active'. In this case, when the management protocol set operation is issued to set the status column to `active', the values held in the agent supersede those used by the managed device.
If the management station is prevented from setting the status column to `active' (e.g., due to management station or network failure) the conceptual row will be left in the `notInService' or `notReady' state, consuming resources indefinitely. The agent must detect conceptual rows that have been in either state for an abnormally long period of time and remove them. It is the responsibility of the DESCRIPTION clause of the status column to indicate what an abnormally long period of time would be. This period of time should be long enough to allow for human response time (including `think time') between the creation of the conceptual row and the setting of the status to `active'. In the absence of such information in the DESCRIPTION clause, it is suggested that this period be approximately 5 minutes in length. This removal action applies not only to newly-created rows, but also to previously active rows which are set to, and left in, the notInService state for a prolonged period exceeding that which is considered normal for such a conceptual row.
Conceptual Row Suspension
When a conceptual row is `active', the management station may issue a management protocol set operation which sets the instance of the status column to `notInService'. If the agent is unwilling to do so, the set operation fails with an error of `wrongValue' or `inconsistentValue'. Otherwise, the conceptual row is taken out of service, and a `noError' response is returned. It is the responsibility of the DESCRIPTION clause of the status column to indicate under what circumstances the status column should be taken out of service (e.g., in order for the value of some other column of the same conceptual row to be modified).
Conceptual Row Deletion
For deletion of conceptual rows, a management protocol set operation is issued which sets the instance of the status column to `destroy'. This request may be made regardless of the current value of the status column (e.g., it is possible to delete conceptual rows which are either `notReady',
`notInService' or `active'.) If the operation succeeds,
then all instances associated with the conceptual row are immediately removed. · Integer32
Controls and reflects the creation and activation status of a row in this table.
No attempt to modify a row columnar object instance value in the bldgHVACTable should be issued while the value of bldgHVACStatus is active(1). Should an agent receive a SET PDU attempting such a modification in this state, an inconsistentValue error should be returned as a result of the SET attempt.
bldgHVACCfgTemplateInfoTable
1.3.6.1.3.122.1.2
Index: bldgHVACCfgTemplateInfoIndex
This table provides unique string identification for HVAC templates in a network. If it were necessary to configure rooms to deliver a particular quality of climate control with regard to cooling or heating, the index string of a row in this table could be the template name. The bldgHVACCfgCfgTemplateInfoDescription contains a brief description of the template service objective such as: provides summer cooling settings for executive offices. The bldgHVACCfgTemplateInfo in the bldgHVACCfgTemplateTable will contain the pointer to the relevant row in this table if it is intended that items that point to a row in the bldgHVACCfgTemplateInfoTable be identifiable as being under template control though this mechanism.
bldgHVACCfgTemplateInfoIndex
1.3.6.1.3.122.1.2.1.1
Unsigned32 (1..2147483647)
The unique index to a row in this table.
bldgHVACCfgTemplateInfoID
1.3.6.1.3.122.1.2.1.2
SnmpAdminStringAn octet string containing administrative information, preferably in human-readable form.
To facilitate internationalization, this information is represented using the ISO/IEC IS 10646-1 character set, encoded as an octet string using the UTF-8 transformation format described in [RFC2279].
Since additional code points are added by amendments to the 10646 standard from time to time, implementations must be prepared to encounter any code point from 0x00000000 to 0x7fffffff. Byte sequences that do not correspond to the valid UTF-8 encoding of a code point or are outside this range are prohibited.
The use of control codes should be avoided.
When it is necessary to represent a newline, the control code sequence CR LF should be used.
The use of leading or trailing white space should be avoided.
For code points not directly supported by user interface hardware or software, an alternative means of entry and display, such as hexadecimal, may be provided.
For information encoded in 7-bit US-ASCII, the UTF-8 encoding is identical to the US-ASCII encoding.
UTF-8 may require multiple bytes to represent a single character / code point; thus the length of this object in octets may be different from the number of characters encoded. Similarly, size constraints refer to the number of encoded octets, not the number of characters represented by an encoding.
Note that when this TC is used for an object that is used or envisioned to be used as an index, then a SIZE restriction MUST be specified so that the number of sub-identifiers for any object instance does not exceed the limit of 128, as defined by [RFC3416].
Note that the size of an SnmpAdminString object is measured in octets, not characters. SIZE (0..255) · OCTET STRING · hint 255t
Textual identifier for this table row, and, consequently the template. This should be a unique name within an administrative domain for a particular template so that all systems in a network that are under the same template can have the same 'handle' (e.g., 'Executive Offices', 'Lobby Areas').
bldgHVACCfgTemplateInfoDescr
1.3.6.1.3.122.1.2.1.3
SnmpAdminStringAn octet string containing administrative information, preferably in human-readable form.
To facilitate internationalization, this information is represented using the ISO/IEC IS 10646-1 character set, encoded as an octet string using the UTF-8 transformation format described in [RFC2279].
Since additional code points are added by amendments to the 10646 standard from time to time, implementations must be prepared to encounter any code point from 0x00000000 to 0x7fffffff. Byte sequences that do not correspond to the valid UTF-8 encoding of a code point or are outside this range are prohibited.
The use of control codes should be avoided.
When it is necessary to represent a newline, the control code sequence CR LF should be used.
The use of leading or trailing white space should be avoided.
For code points not directly supported by user interface hardware or software, an alternative means of entry and display, such as hexadecimal, may be provided.
For information encoded in 7-bit US-ASCII, the UTF-8 encoding is identical to the US-ASCII encoding.
UTF-8 may require multiple bytes to represent a single character / code point; thus the length of this object in octets may be different from the number of characters encoded. Similarly, size constraints refer to the number of encoded octets, not the number of characters represented by an encoding.
Note that when this TC is used for an object that is used or envisioned to be used as an index, then a SIZE restriction MUST be specified so that the number of sub-identifiers for any object instance does not exceed the limit of 128, as defined by [RFC3416].
Note that the size of an SnmpAdminString object is measured in octets, not characters. SIZE (0..255) · OCTET STRING · hint 255t
A general description of the template. One example might be - Controls the cooling for offices on higher floors during the summer.
bldgHVACCfgTemplateInfoOwner
1.3.6.1.3.122.1.2.1.4
SnmpAdminStringAn octet string containing administrative information, preferably in human-readable form.
To facilitate internationalization, this information is represented using the ISO/IEC IS 10646-1 character set, encoded as an octet string using the UTF-8 transformation format described in [RFC2279].
Since additional code points are added by amendments to the 10646 standard from time to time, implementations must be prepared to encounter any code point from 0x00000000 to 0x7fffffff. Byte sequences that do not correspond to the valid UTF-8 encoding of a code point or are outside this range are prohibited.
The use of control codes should be avoided.
When it is necessary to represent a newline, the control code sequence CR LF should be used.
The use of leading or trailing white space should be avoided.
For code points not directly supported by user interface hardware or software, an alternative means of entry and display, such as hexadecimal, may be provided.
For information encoded in 7-bit US-ASCII, the UTF-8 encoding is identical to the US-ASCII encoding.
UTF-8 may require multiple bytes to represent a single character / code point; thus the length of this object in octets may be different from the number of characters encoded. Similarly, size constraints refer to the number of encoded octets, not the number of characters represented by an encoding.
Note that when this TC is used for an object that is used or envisioned to be used as an index, then a SIZE restriction MUST be specified so that the number of sub-identifiers for any object instance does not exceed the limit of 128, as defined by [RFC3416].
Note that the size of an SnmpAdminString object is measured in octets, not characters. SIZE (0..255) · OCTET STRING · hint 255t
The identity of the operator/system that last modified this entry.
bldgHVACCfgTemplateInfoStatus
1.3.6.1.3.122.1.2.1.5
RowStatus1 = active2 = notInService3 = notReady4 = createAndGo5 = createAndWait6 = destroyThe RowStatus textual convention is used to manage the creation and deletion of conceptual rows, and is used as the value of the SYNTAX clause for the status column of a conceptual row (as described in Section 7.7.1 of [2].)
The status column has six defined values:
- `active', which indicates that the conceptual row is available for use by the managed device;
- `notInService', which indicates that the conceptual row exists in the agent, but is unavailable for use by the managed device (see NOTE below); 'notInService' has no implication regarding the internal consistency of the row, availability of resources, or consistency with the current state of the managed device;
- `notReady', which indicates that the conceptual row exists in the agent, but is missing information necessary in order to be available for use by the managed device (i.e., one or more required columns in the conceptual row have not been instanciated);
- `createAndGo', which is supplied by a management station wishing to create a new instance of a conceptual row and to have its status automatically set to active, making it available for use by the managed device;
- `createAndWait', which is supplied by a management station wishing to create a new instance of a conceptual row (but not make it available for use by the managed device); and, - `destroy', which is supplied by a management station wishing to delete all of the instances associated with an existing conceptual row.
Whereas five of the six values (all except `notReady') may be specified in a management protocol set operation, only three values will be returned in response to a management
protocol retrieval operation: `notReady', `notInService' or
`active'. That is, when queried, an existing conceptual row
has only three states: it is either available for use by
the managed device (the status column has value `active'); it is not available for use by the managed device, though the agent has sufficient information to attempt to make it so (the status column has value `notInService'); or, it is not available for use by the managed device, and an attempt to make it so would fail because the agent has insufficient information (the state column has value `notReady').
NOTE WELL
This textual convention may be used for a MIB table, irrespective of whether the values of that table's conceptual rows are able to be modified while it is active, or whether its conceptual rows must be taken out of service in order to be modified. That is, it is the responsibility of the DESCRIPTION clause of the status column to specify whether the status column must not be `active' in order for the value of some other column of the same conceptual row to be modified. If such a specification is made, affected columns may be changed by an SNMP set PDU if the RowStatus would not be equal to `active' either immediately before or after processing the PDU. In other words, if the PDU also contained a varbind that would change the RowStatus value, the column in question may be changed if the RowStatus was not equal to `active' as the PDU was received, or if the varbind sets the status to a value other than 'active'.
Also note that whenever any elements of a row exist, the RowStatus column must also exist.
To summarize the effect of having a conceptual row with a status column having a SYNTAX clause value of RowStatus, consider the following state diagram:
STATE +--------------+-----------+-------------+-------------
| A | B | C | D
| |status col.|status column|
|status column | is | is |status column
ACTION |does not exist| notReady | notInService| is active
--------------+--------------+-----------+-------------+-------------
set status |noError ->D|inconsist- |inconsistent-|inconsistent-
column to | or | entValue| Value| Value
createAndGo |inconsistent- | | |
| Value| | |
--------------+--------------+-----------+-------------+-------------
set status |noError see 1|inconsist- |inconsistent-|inconsistent-
column to | or | entValue| Value| Value
createAndWait |wrongValue | | |
--------------+--------------+-----------+-------------+-------------
set status |inconsistent- |inconsist- |noError |noError
column to | Value| entValue| |
active | | | |
| | or | |
| | | |
| |see 2 ->D|see 8 ->D| ->D
--------------+--------------+-----------+-------------+-------------
set status |inconsistent- |inconsist- |noError |noError ->C
column to | Value| entValue| |
notInService | | | |
| | or | | or
| | | |
| |see 3 ->C| ->C|see 6
--------------+--------------+-----------+-------------+-------------
set status |noError |noError |noError |noError ->A
column to | | | | or
destroy | ->A| ->A| ->A|see 7
--------------+--------------+-----------+-------------+-------------
set any other |see 4 |noError |noError |see 5
column to some| | | |
value | | see 1| ->C| ->D
--------------+--------------+-----------+-------------+-------------
(1) goto B or C, depending on information available to the agent.
(2) if other variable bindings included in the same PDU, provide values for all columns which are missing but required, and all columns have acceptable values, then return noError and goto D.
(3) if other variable bindings included in the same PDU, provide legal values for all columns which are missing but required, then return noError and goto C.
(4) at the discretion of the agent, the return value may be either:
inconsistentName: because the agent does not choose to
create such an instance when the corresponding RowStatus instance does not exist, or
inconsistentValue: if the supplied value is
inconsistent with the state of some other MIB object's value, or
noError: because the agent chooses to create the instance.
If noError is returned, then the instance of the status column must also be created, and the new state is B or C, depending on the information available to the agent. If inconsistentName or inconsistentValue is returned, the row remains in state A.
(5) depending on the MIB definition for the column/table, either noError or inconsistentValue may be returned.
(6) the return value can indicate one of the following errors:
wrongValue: because the agent does not support notInService (e.g., an agent which does not support createAndWait), or
inconsistentValue: because the agent is unable to take the row out of service at this time, perhaps because it is in use and cannot be de-activated.
(7) the return value can indicate the following error:
inconsistentValue: because the agent is unable to remove the row at this time, perhaps because it is in use and cannot be de-activated.
(8) the transition to D can fail, e.g., if the values of the conceptual row are inconsistent, then the error code would be inconsistentValue.
NOTE: Other processing of (this and other varbinds of) the set request may result in a response other than noError being returned, e.g., wrongValue, noCreation, etc.
Conceptual Row Creation
There are four potential interactions when creating a
conceptual row: selecting an instance-identifier which is
not in use; creating the conceptual row; initializing any objects for which the agent does not supply a default; and, making the conceptual row available for use by the managed device.
Interaction 1: Selecting an Instance-Identifier
The algorithm used to select an instance-identifier varies for each conceptual row. In some cases, the instance- identifier is semantically significant, e.g., the destination address of a route, and a management station selects the instance-identifier according to the semantics.
In other cases, the instance-identifier is used solely to distinguish conceptual rows, and a management station without specific knowledge of the conceptual row might examine the instances present in order to determine an unused instance-identifier. (This approach may be used, but it is often highly sub-optimal; however, it is also a questionable practice for a naive management station to attempt conceptual row creation.)
Alternately, the MIB module which defines the conceptual row might provide one or more objects which provide assistance in determining an unused instance-identifier. For example, if the conceptual row is indexed by an integer-value, then an object having an integer-valued SYNTAX clause might be defined for such a purpose, allowing a management station to issue a management protocol retrieval operation. In order to avoid unnecessary collisions between competing management stations, `adjacent' retrievals of this object should be different.
Finally, the management station could select a pseudo-random number to use as the index. In the event that this index
was already in use and an inconsistentValue was returned in response to the management protocol set operation, the management station should simply select a new pseudo-random number and retry the operation.
A MIB designer should choose between the two latter algorithms based on the size of the table (and therefore the efficiency of each algorithm). For tables in which a large number of entries are expected, it is recommended that a MIB object be defined that returns an acceptable index for creation. For tables with small numbers of entries, it is recommended that the latter pseudo-random index mechanism be used.
Interaction 2: Creating the Conceptual Row
Once an unused instance-identifier has been selected, the management station determines if it wishes to create and activate the conceptual row in one transaction or in a negotiated set of interactions.
Interaction 2a: Creating and Activating the Conceptual Row
The management station must first determine the column requirements, i.e., it must determine those columns for which it must or must not provide values. Depending on the complexity of the table and the management station's knowledge of the agent's capabilities, this determination can be made locally by the management station. Alternately, the management station issues a management protocol get operation to examine all columns in the conceptual row that it wishes to create. In response, for each column, there are three possible outcomes:
- a value is returned, indicating that some other management station has already created this conceptual row. We return to interaction 1.
- the exception `noSuchInstance' is returned, indicating that the agent implements the object-type associated with this column, and that this column in at least one conceptual row would be accessible in the MIB view used by the retrieval were it to exist. For those columns to which the agent provides read-create access, the `noSuchInstance' exception tells the management station that it should supply a value for this column when the conceptual row is to be created.
- the exception `noSuchObject' is returned, indicating that the agent does not implement the object-type associated with this column or that there is no conceptual row for which this column would be accessible in the MIB view used by the retrieval. As such, the management station can not issue any management protocol set operations to create an instance of this column.
Once the column requirements have been determined, a management protocol set operation is accordingly issued. This operation also sets the new instance of the status column to `createAndGo'.
When the agent processes the set operation, it verifies that it has sufficient information to make the conceptual row available for use by the managed device. The information
available to the agent is provided by two sources: the
management protocol set operation which creates the conceptual row, and, implementation-specific defaults supplied by the agent (note that an agent must provide implementation-specific defaults for at least those objects which it implements as read-only). If there is sufficient information available, then the conceptual row is created, a `noError' response is returned, the status column is set to `active', and no further interactions are necessary (i.e., interactions 3 and 4 are skipped). If there is insufficient information, then the conceptual row is not created, and the set operation fails with an error of `inconsistentValue'. On this error, the management station can issue a management protocol retrieval operation to determine if this was because it failed to specify a value for a required column, or, because the selected instance of the status column already existed. In the latter case, we return to interaction 1. In the former case, the management station can re-issue the set operation with the additional information, or begin interaction 2 again using `createAndWait' in order to negotiate creation of the conceptual row.
NOTE WELL
Regardless of the method used to determine the column requirements, it is possible that the management station might deem a column necessary when, in fact, the agent will not allow that particular columnar instance to be created or written. In this case, the management protocol set operation will fail with an error such as `noCreation' or `notWritable'. In this case, the management station decides whether it needs to be able to set a value for that particular columnar instance. If not, the management station re-issues the management protocol set operation, but without setting a value for that particular columnar instance; otherwise, the management station aborts the row creation algorithm.
Interaction 2b: Negotiating the Creation of the Conceptual Row
The management station issues a management protocol set operation which sets the desired instance of the status column to `createAndWait'. If the agent is unwilling to process a request of this sort, the set operation fails with an error of `wrongValue'. (As a consequence, such an agent must be prepared to accept a single management protocol set operation, i.e., interaction 2a above, containing all of the
columns indicated by its column requirements.) Otherwise,
the conceptual row is created, a `noError' response is returned, and the status column is immediately set to either `notInService' or `notReady', depending on whether it has sufficient information to (attempt to) make the conceptual row available for use by the managed device. If there is sufficient information available, then the status column is set to `notInService'; otherwise, if there is insufficient information, then the status column is set to `notReady'. Regardless, we proceed to interaction 3.
Interaction 3: Initializing non-defaulted Objects
The management station must now determine the column requirements. It issues a management protocol get operation to examine all columns in the created conceptual row. In the response, for each column, there are three possible outcomes:
- a value is returned, indicating that the agent implements the object-type associated with this column and had sufficient information to provide a value. For those columns to which the agent provides read-create access (and for which the agent allows their values to be changed after their creation), a value return tells the management station that it may issue additional management protocol set operations, if it desires, in order to change the value associated with this column.
- the exception `noSuchInstance' is returned, indicating that the agent implements the object-type associated with this column, and that this column in at least one conceptual row would be accessible in the MIB view used by the retrieval were it to exist. However, the agent does not have sufficient information to provide a value, and until a value is provided, the conceptual row may not be made available for use by the managed device. For those columns to which the agent provides read-create access, the `noSuchInstance' exception tells the management station that it must issue additional management protocol set operations, in order to provide a value associated with this column.
- the exception `noSuchObject' is returned, indicating that the agent does not implement the object-type associated with this column or that there is no conceptual row for which this column would be accessible in the MIB view used by the retrieval. As such, the management station can not issue any management protocol set operations to create an instance of this column.
If the value associated with the status column is `notReady', then the management station must first deal with all `noSuchInstance' columns, if any. Having done so, the value of the status column becomes `notInService', and we proceed to interaction 4.
Interaction 4: Making the Conceptual Row Available
Once the management station is satisfied with the values associated with the columns of the conceptual row, it issues a management protocol set operation to set the status column to `active'. If the agent has sufficient information to make the conceptual row available for use by the managed device, the management protocol set operation succeeds (a `noError' response is returned). Otherwise, the management protocol set operation fails with an error of `inconsistentValue'.
NOTE WELL
A conceptual row having a status column with value `notInService' or `notReady' is unavailable to the managed device. As such, it is possible for the managed device to create its own instances during the time between the management protocol set operation which sets the status column to `createAndWait' and the management protocol set operation which sets the status column to `active'. In this case, when the management protocol set operation is issued to set the status column to `active', the values held in the agent supersede those used by the managed device.
If the management station is prevented from setting the status column to `active' (e.g., due to management station or network failure) the conceptual row will be left in the `notInService' or `notReady' state, consuming resources indefinitely. The agent must detect conceptual rows that have been in either state for an abnormally long period of time and remove them. It is the responsibility of the DESCRIPTION clause of the status column to indicate what an abnormally long period of time would be. This period of time should be long enough to allow for human response time (including `think time') between the creation of the conceptual row and the setting of the status to `active'. In the absence of such information in the DESCRIPTION clause, it is suggested that this period be approximately 5 minutes in length. This removal action applies not only to newly-created rows, but also to previously active rows which are set to, and left in, the notInService state for a prolonged period exceeding that which is considered normal for such a conceptual row.
Conceptual Row Suspension
When a conceptual row is `active', the management station may issue a management protocol set operation which sets the instance of the status column to `notInService'. If the agent is unwilling to do so, the set operation fails with an error of `wrongValue' or `inconsistentValue'. Otherwise, the conceptual row is taken out of service, and a `noError' response is returned. It is the responsibility of the DESCRIPTION clause of the status column to indicate under what circumstances the status column should be taken out of service (e.g., in order for the value of some other column of the same conceptual row to be modified).
Conceptual Row Deletion
For deletion of conceptual rows, a management protocol set operation is issued which sets the instance of the status column to `destroy'. This request may be made regardless of the current value of the status column (e.g., it is possible to delete conceptual rows which are either `notReady',
`notInService' or `active'.) If the operation succeeds,
then all instances associated with the conceptual row are immediately removed. · Integer32
The activation status of this row.
No attempt to modify a row columnar object instance value in the bldgHVACCfgTemplateInfo Table should be issued while the value of bldgHVACCfgTemplateInfoStatus is active(1). Should an agent receive a SET PDU attempting such a modification in this state, an inconsistentValue error should be returned as a result of the SET attempt.
bldgHVACCfgTemplateInfoStorType
1.3.6.1.3.122.1.2.1.6
StorageType1 = other2 = volatile3 = nonVolatile4 = permanent5 = readOnlyDescribes the memory realization of a conceptual row. A row which is volatile(2) is lost upon reboot. A row which is either nonVolatile(3), permanent(4) or readOnly(5), is backed up by stable storage. A row which is permanent(4) can be changed but not deleted. A row which is readOnly(5) cannot be changed nor deleted.
If the value of an object with this syntax is either permanent(4) or readOnly(5), it cannot be written. Conversely, if the value is either other(1), volatile(2) or nonVolatile(3), it cannot be modified to be permanent(4) or readOnly(5). (All illegal modifications result in a 'wrongValue' error.)
Every usage of this textual convention is required to specify the columnar objects which a permanent(4) row must at a minimum allow to be writable. · Integer32
The persistence of this row of the table in system storage, as it pertains to permanence across system resets. A columnar instance of this object with value 'permanent' need not allow write-access to any of the columnar object instances in the containing row.
bldgHVACCfgTemplateTable
1.3.6.1.3.122.1.3
Index: bldgHVACCfgTemplateIndex
This table contains the templates, which can be used to set defaults that will be applied to specific offices. The application of those values is accomplished by having a row instance of the bldgHVACTable reference a row of this table (by the value of the former's bldgHVACCfgTemplate columnar instance). Identifying information concerning a row instance of this table can be found in the columnar data of the row instance of the bldgHVACCfgTemplateInfoTable entry referenced by the bldgHVACCfgTemplateInfo columnar object of this table.
bldgHVACCfgTemplateIndex
1.3.6.1.3.122.1.3.1.1
Unsigned32 (1..2147483647)
A unique value for each defined template in this table. This value can be referenced as a row index by any MIB module that needs access to this information. The bldgHVACCfgTemplate will point to entries in this table.
bldgHVACCfgTemplateDesiredTemp
1.3.6.1.3.122.1.3.1.2
Gauge32 · degrees in celsius
This is the desired temperature setting. It might be changed at different times of the day or based on seasonal conditions. It is permitted to change this value by first moving the row to an inactive state, making the change and then reactivating the row.
bldgHVACCfgTemplateCoolOrHeat
1.3.6.1.3.122.1.3.1.3
BldgHvacOperation1 = heat2 = coolOperations supported by a heating and cooling system. A reference to underlying general systems would go here. · Integer32
This controls the heating and cooling mechanism and is set-able by building maintenance. It is permitted to change this value by first moving the row to an inactive state, making the change and then reactivating the row.
bldgHVACCfgTemplateInfo
1.3.6.1.3.122.1.3.1.4
Unsigned32
This object points to a row in the bldgHVACCfgTemplateInfoTable. This controls the heating and cooling mechanism and is set-able by building maintenance. It is permissible to change this value by first moving the row to an inactive state, making the change and then reactivating the row. A value of zero means that this entry is not associated with a named template found in the bldgHVACCfgTemplateInfoTable.
bldgHVACCfgTemplateOwner
1.3.6.1.3.122.1.3.1.5
SnmpAdminStringAn octet string containing administrative information, preferably in human-readable form.
To facilitate internationalization, this information is represented using the ISO/IEC IS 10646-1 character set, encoded as an octet string using the UTF-8 transformation format described in [RFC2279].
Since additional code points are added by amendments to the 10646 standard from time to time, implementations must be prepared to encounter any code point from 0x00000000 to 0x7fffffff. Byte sequences that do not correspond to the valid UTF-8 encoding of a code point or are outside this range are prohibited.
The use of control codes should be avoided.
When it is necessary to represent a newline, the control code sequence CR LF should be used.
The use of leading or trailing white space should be avoided.
For code points not directly supported by user interface hardware or software, an alternative means of entry and display, such as hexadecimal, may be provided.
For information encoded in 7-bit US-ASCII, the UTF-8 encoding is identical to the US-ASCII encoding.
UTF-8 may require multiple bytes to represent a single character / code point; thus the length of this object in octets may be different from the number of characters encoded. Similarly, size constraints refer to the number of encoded octets, not the number of characters represented by an encoding.
Note that when this TC is used for an object that is used or envisioned to be used as an index, then a SIZE restriction MUST be specified so that the number of sub-identifiers for any object instance does not exceed the limit of 128, as defined by [RFC3416].
Note that the size of an SnmpAdminString object is measured in octets, not characters. SIZE (0..255) · OCTET STRING · hint 255t
The identity of the administrative entity that created this row of the table.
bldgHVACCfgTemplateStorage
1.3.6.1.3.122.1.3.1.6
StorageType1 = other2 = volatile3 = nonVolatile4 = permanent5 = readOnlyDescribes the memory realization of a conceptual row. A row which is volatile(2) is lost upon reboot. A row which is either nonVolatile(3), permanent(4) or readOnly(5), is backed up by stable storage. A row which is permanent(4) can be changed but not deleted. A row which is readOnly(5) cannot be changed nor deleted.
If the value of an object with this syntax is either permanent(4) or readOnly(5), it cannot be written. Conversely, if the value is either other(1), volatile(2) or nonVolatile(3), it cannot be modified to be permanent(4) or readOnly(5). (All illegal modifications result in a 'wrongValue' error.)
Every usage of this textual convention is required to specify the columnar objects which a permanent(4) row must at a minimum allow to be writable. · Integer32
The persistence of this row of the table across system resets. A columnar instance of this object with value 'permanent' need not allow write-access to any of the columnar object instances in the containing row.
bldgHVACCfgTemplateStatus
1.3.6.1.3.122.1.3.1.7
RowStatus1 = active2 = notInService3 = notReady4 = createAndGo5 = createAndWait6 = destroyThe RowStatus textual convention is used to manage the creation and deletion of conceptual rows, and is used as the value of the SYNTAX clause for the status column of a conceptual row (as described in Section 7.7.1 of [2].)
The status column has six defined values:
- `active', which indicates that the conceptual row is available for use by the managed device;
- `notInService', which indicates that the conceptual row exists in the agent, but is unavailable for use by the managed device (see NOTE below); 'notInService' has no implication regarding the internal consistency of the row, availability of resources, or consistency with the current state of the managed device;
- `notReady', which indicates that the conceptual row exists in the agent, but is missing information necessary in order to be available for use by the managed device (i.e., one or more required columns in the conceptual row have not been instanciated);
- `createAndGo', which is supplied by a management station wishing to create a new instance of a conceptual row and to have its status automatically set to active, making it available for use by the managed device;
- `createAndWait', which is supplied by a management station wishing to create a new instance of a conceptual row (but not make it available for use by the managed device); and, - `destroy', which is supplied by a management station wishing to delete all of the instances associated with an existing conceptual row.
Whereas five of the six values (all except `notReady') may be specified in a management protocol set operation, only three values will be returned in response to a management
protocol retrieval operation: `notReady', `notInService' or
`active'. That is, when queried, an existing conceptual row
has only three states: it is either available for use by
the managed device (the status column has value `active'); it is not available for use by the managed device, though the agent has sufficient information to attempt to make it so (the status column has value `notInService'); or, it is not available for use by the managed device, and an attempt to make it so would fail because the agent has insufficient information (the state column has value `notReady').
NOTE WELL
This textual convention may be used for a MIB table, irrespective of whether the values of that table's conceptual rows are able to be modified while it is active, or whether its conceptual rows must be taken out of service in order to be modified. That is, it is the responsibility of the DESCRIPTION clause of the status column to specify whether the status column must not be `active' in order for the value of some other column of the same conceptual row to be modified. If such a specification is made, affected columns may be changed by an SNMP set PDU if the RowStatus would not be equal to `active' either immediately before or after processing the PDU. In other words, if the PDU also contained a varbind that would change the RowStatus value, the column in question may be changed if the RowStatus was not equal to `active' as the PDU was received, or if the varbind sets the status to a value other than 'active'.
Also note that whenever any elements of a row exist, the RowStatus column must also exist.
To summarize the effect of having a conceptual row with a status column having a SYNTAX clause value of RowStatus, consider the following state diagram:
STATE +--------------+-----------+-------------+-------------
| A | B | C | D
| |status col.|status column|
|status column | is | is |status column
ACTION |does not exist| notReady | notInService| is active
--------------+--------------+-----------+-------------+-------------
set status |noError ->D|inconsist- |inconsistent-|inconsistent-
column to | or | entValue| Value| Value
createAndGo |inconsistent- | | |
| Value| | |
--------------+--------------+-----------+-------------+-------------
set status |noError see 1|inconsist- |inconsistent-|inconsistent-
column to | or | entValue| Value| Value
createAndWait |wrongValue | | |
--------------+--------------+-----------+-------------+-------------
set status |inconsistent- |inconsist- |noError |noError
column to | Value| entValue| |
active | | | |
| | or | |
| | | |
| |see 2 ->D|see 8 ->D| ->D
--------------+--------------+-----------+-------------+-------------
set status |inconsistent- |inconsist- |noError |noError ->C
column to | Value| entValue| |
notInService | | | |
| | or | | or
| | | |
| |see 3 ->C| ->C|see 6
--------------+--------------+-----------+-------------+-------------
set status |noError |noError |noError |noError ->A
column to | | | | or
destroy | ->A| ->A| ->A|see 7
--------------+--------------+-----------+-------------+-------------
set any other |see 4 |noError |noError |see 5
column to some| | | |
value | | see 1| ->C| ->D
--------------+--------------+-----------+-------------+-------------
(1) goto B or C, depending on information available to the agent.
(2) if other variable bindings included in the same PDU, provide values for all columns which are missing but required, and all columns have acceptable values, then return noError and goto D.
(3) if other variable bindings included in the same PDU, provide legal values for all columns which are missing but required, then return noError and goto C.
(4) at the discretion of the agent, the return value may be either:
inconsistentName: because the agent does not choose to
create such an instance when the corresponding RowStatus instance does not exist, or
inconsistentValue: if the supplied value is
inconsistent with the state of some other MIB object's value, or
noError: because the agent chooses to create the instance.
If noError is returned, then the instance of the status column must also be created, and the new state is B or C, depending on the information available to the agent. If inconsistentName or inconsistentValue is returned, the row remains in state A.
(5) depending on the MIB definition for the column/table, either noError or inconsistentValue may be returned.
(6) the return value can indicate one of the following errors:
wrongValue: because the agent does not support notInService (e.g., an agent which does not support createAndWait), or
inconsistentValue: because the agent is unable to take the row out of service at this time, perhaps because it is in use and cannot be de-activated.
(7) the return value can indicate the following error:
inconsistentValue: because the agent is unable to remove the row at this time, perhaps because it is in use and cannot be de-activated.
(8) the transition to D can fail, e.g., if the values of the conceptual row are inconsistent, then the error code would be inconsistentValue.
NOTE: Other processing of (this and other varbinds of) the set request may result in a response other than noError being returned, e.g., wrongValue, noCreation, etc.
Conceptual Row Creation
There are four potential interactions when creating a
conceptual row: selecting an instance-identifier which is
not in use; creating the conceptual row; initializing any objects for which the agent does not supply a default; and, making the conceptual row available for use by the managed device.
Interaction 1: Selecting an Instance-Identifier
The algorithm used to select an instance-identifier varies for each conceptual row. In some cases, the instance- identifier is semantically significant, e.g., the destination address of a route, and a management station selects the instance-identifier according to the semantics.
In other cases, the instance-identifier is used solely to distinguish conceptual rows, and a management station without specific knowledge of the conceptual row might examine the instances present in order to determine an unused instance-identifier. (This approach may be used, but it is often highly sub-optimal; however, it is also a questionable practice for a naive management station to attempt conceptual row creation.)
Alternately, the MIB module which defines the conceptual row might provide one or more objects which provide assistance in determining an unused instance-identifier. For example, if the conceptual row is indexed by an integer-value, then an object having an integer-valued SYNTAX clause might be defined for such a purpose, allowing a management station to issue a management protocol retrieval operation. In order to avoid unnecessary collisions between competing management stations, `adjacent' retrievals of this object should be different.
Finally, the management station could select a pseudo-random number to use as the index. In the event that this index
was already in use and an inconsistentValue was returned in response to the management protocol set operation, the management station should simply select a new pseudo-random number and retry the operation.
A MIB designer should choose between the two latter algorithms based on the size of the table (and therefore the efficiency of each algorithm). For tables in which a large number of entries are expected, it is recommended that a MIB object be defined that returns an acceptable index for creation. For tables with small numbers of entries, it is recommended that the latter pseudo-random index mechanism be used.
Interaction 2: Creating the Conceptual Row
Once an unused instance-identifier has been selected, the management station determines if it wishes to create and activate the conceptual row in one transaction or in a negotiated set of interactions.
Interaction 2a: Creating and Activating the Conceptual Row
The management station must first determine the column requirements, i.e., it must determine those columns for which it must or must not provide values. Depending on the complexity of the table and the management station's knowledge of the agent's capabilities, this determination can be made locally by the management station. Alternately, the management station issues a management protocol get operation to examine all columns in the conceptual row that it wishes to create. In response, for each column, there are three possible outcomes:
- a value is returned, indicating that some other management station has already created this conceptual row. We return to interaction 1.
- the exception `noSuchInstance' is returned, indicating that the agent implements the object-type associated with this column, and that this column in at least one conceptual row would be accessible in the MIB view used by the retrieval were it to exist. For those columns to which the agent provides read-create access, the `noSuchInstance' exception tells the management station that it should supply a value for this column when the conceptual row is to be created.
- the exception `noSuchObject' is returned, indicating that the agent does not implement the object-type associated with this column or that there is no conceptual row for which this column would be accessible in the MIB view used by the retrieval. As such, the management station can not issue any management protocol set operations to create an instance of this column.
Once the column requirements have been determined, a management protocol set operation is accordingly issued. This operation also sets the new instance of the status column to `createAndGo'.
When the agent processes the set operation, it verifies that it has sufficient information to make the conceptual row available for use by the managed device. The information
available to the agent is provided by two sources: the
management protocol set operation which creates the conceptual row, and, implementation-specific defaults supplied by the agent (note that an agent must provide implementation-specific defaults for at least those objects which it implements as read-only). If there is sufficient information available, then the conceptual row is created, a `noError' response is returned, the status column is set to `active', and no further interactions are necessary (i.e., interactions 3 and 4 are skipped). If there is insufficient information, then the conceptual row is not created, and the set operation fails with an error of `inconsistentValue'. On this error, the management station can issue a management protocol retrieval operation to determine if this was because it failed to specify a value for a required column, or, because the selected instance of the status column already existed. In the latter case, we return to interaction 1. In the former case, the management station can re-issue the set operation with the additional information, or begin interaction 2 again using `createAndWait' in order to negotiate creation of the conceptual row.
NOTE WELL
Regardless of the method used to determine the column requirements, it is possible that the management station might deem a column necessary when, in fact, the agent will not allow that particular columnar instance to be created or written. In this case, the management protocol set operation will fail with an error such as `noCreation' or `notWritable'. In this case, the management station decides whether it needs to be able to set a value for that particular columnar instance. If not, the management station re-issues the management protocol set operation, but without setting a value for that particular columnar instance; otherwise, the management station aborts the row creation algorithm.
Interaction 2b: Negotiating the Creation of the Conceptual Row
The management station issues a management protocol set operation which sets the desired instance of the status column to `createAndWait'. If the agent is unwilling to process a request of this sort, the set operation fails with an error of `wrongValue'. (As a consequence, such an agent must be prepared to accept a single management protocol set operation, i.e., interaction 2a above, containing all of the
columns indicated by its column requirements.) Otherwise,
the conceptual row is created, a `noError' response is returned, and the status column is immediately set to either `notInService' or `notReady', depending on whether it has sufficient information to (attempt to) make the conceptual row available for use by the managed device. If there is sufficient information available, then the status column is set to `notInService'; otherwise, if there is insufficient information, then the status column is set to `notReady'. Regardless, we proceed to interaction 3.
Interaction 3: Initializing non-defaulted Objects
The management station must now determine the column requirements. It issues a management protocol get operation to examine all columns in the created conceptual row. In the response, for each column, there are three possible outcomes:
- a value is returned, indicating that the agent implements the object-type associated with this column and had sufficient information to provide a value. For those columns to which the agent provides read-create access (and for which the agent allows their values to be changed after their creation), a value return tells the management station that it may issue additional management protocol set operations, if it desires, in order to change the value associated with this column.
- the exception `noSuchInstance' is returned, indicating that the agent implements the object-type associated with this column, and that this column in at least one conceptual row would be accessible in the MIB view used by the retrieval were it to exist. However, the agent does not have sufficient information to provide a value, and until a value is provided, the conceptual row may not be made available for use by the managed device. For those columns to which the agent provides read-create access, the `noSuchInstance' exception tells the management station that it must issue additional management protocol set operations, in order to provide a value associated with this column.
- the exception `noSuchObject' is returned, indicating that the agent does not implement the object-type associated with this column or that there is no conceptual row for which this column would be accessible in the MIB view used by the retrieval. As such, the management station can not issue any management protocol set operations to create an instance of this column.
If the value associated with the status column is `notReady', then the management station must first deal with all `noSuchInstance' columns, if any. Having done so, the value of the status column becomes `notInService', and we proceed to interaction 4.
Interaction 4: Making the Conceptual Row Available
Once the management station is satisfied with the values associated with the columns of the conceptual row, it issues a management protocol set operation to set the status column to `active'. If the agent has sufficient information to make the conceptual row available for use by the managed device, the management protocol set operation succeeds (a `noError' response is returned). Otherwise, the management protocol set operation fails with an error of `inconsistentValue'.
NOTE WELL
A conceptual row having a status column with value `notInService' or `notReady' is unavailable to the managed device. As such, it is possible for the managed device to create its own instances during the time between the management protocol set operation which sets the status column to `createAndWait' and the management protocol set operation which sets the status column to `active'. In this case, when the management protocol set operation is issued to set the status column to `active', the values held in the agent supersede those used by the managed device.
If the management station is prevented from setting the status column to `active' (e.g., due to management station or network failure) the conceptual row will be left in the `notInService' or `notReady' state, consuming resources indefinitely. The agent must detect conceptual rows that have been in either state for an abnormally long period of time and remove them. It is the responsibility of the DESCRIPTION clause of the status column to indicate what an abnormally long period of time would be. This period of time should be long enough to allow for human response time (including `think time') between the creation of the conceptual row and the setting of the status to `active'. In the absence of such information in the DESCRIPTION clause, it is suggested that this period be approximately 5 minutes in length. This removal action applies not only to newly-created rows, but also to previously active rows which are set to, and left in, the notInService state for a prolonged period exceeding that which is considered normal for such a conceptual row.
Conceptual Row Suspension
When a conceptual row is `active', the management station may issue a management protocol set operation which sets the instance of the status column to `notInService'. If the agent is unwilling to do so, the set operation fails with an error of `wrongValue' or `inconsistentValue'. Otherwise, the conceptual row is taken out of service, and a `noError' response is returned. It is the responsibility of the DESCRIPTION clause of the status column to indicate under what circumstances the status column should be taken out of service (e.g., in order for the value of some other column of the same conceptual row to be modified).
Conceptual Row Deletion
For deletion of conceptual rows, a management protocol set operation is issued which sets the instance of the status column to `destroy'. This request may be made regardless of the current value of the status column (e.g., it is possible to delete conceptual rows which are either `notReady',
`notInService' or `active'.) If the operation succeeds,
then all instances associated with the conceptual row are immediately removed. · Integer32
The activation status of this row of the table.
No attempt to modify a row columnar object instance value in the bldgHVACCfgTemplateTable should be issued while the value of bldgHVACCfgTemplateStatus is active(1). Should an agent receive a SET PDU attempting such a modification in this state, an inconsistentValue error should be returned as a result of the SET attempt.