EEM CLI Library XML-PI Support

XML Programmatic Interface (XML-PI) was introduced in Cisco IOS Release 12.4(22)T. XML-PI provides a programmable interface which encapsulates IOS command-line interface (CLI) show commands in XML format in a consistent way across different Cisco products. Customers using XML-PI will be able to parse IOS show command output from within Tcl scripts using well-known keywords instead of having to depend on the use of regular expression support to "screen-scrape" output.

The benefit of using the XML-PI command extensions is to facilitate the extraction of specific output information that is generated using a CLI show command. Most show commands return many fields within the output and currently a regular expression has to be used to extract specific information that may appear in the middle of a line. XML-PI support provides a set of Tcl library functions to facilitate the parsing of output from the IOS CLI format extension in the form of: 

show
 <
show-command
> | format
 {
spec-file
}

where a spec-file is a concatenation of all Spec File Entries (SFE) for each show command currently supported. As part of the XML-PI project a default spec-file will be included in the IOS Release 12.4(22)T images. The default spec-file will have a small set of commands and the SFE for the commands will have a subset of the possible tags. If no spec-file is provided with the format command, the default spec-file is used.

For more general details about XML-PI, see the "XML-PI" module.

xml_pi_exec

Writes the XML-PI command specified using the cmd argument to the channel whose handler is specified using the fd argument and the spec-file specified by the spec_file argument to execute the command. The raw XML output data of the command is then read from the channel and the XML output is returned.

Syntax

xml_pi_show fd cmd [spec_file]

Arguments

fd

(Mandatory) The CLI library file descriptor obtained from cli_open.

cmd

(Mandatory) IOS show command.

spec_file

(Optional) IOS CLI show command spec_file.

Result String

Result of IOS show command in XML format.

Set _cerrno

Possible error raised:

1. error reading the channel

xml_pi_parse

Processes the XML show command raw output passed into this function as xml_data and retrieve those fields that are specified by xml_tags_list. The following processing occurs:

Step 1: The XML tag list is validated as a Tcl list. An XML tag can be specified as the low order XML tag name or as a fully qualified XML tag name in case the low order name is ambiguous for a given command.

Example tags: <Interface> <ShowIpInterfaceBrief><IPInterfaces><entry><Interface>

Step 2: The xml_data is validated as valid XML and parsed into an XML parse tree.

Step 3: A walk is made through the XML parse tree and each tag is compared with entries in the XML tag list. When a match occurs it is determined if the tag name matches a Tcl procedure defined within the current Tcl scope. If so, that Tcl procedure will be called with the current result. If not, the tag name and the data associated with that tag name will be appended to the current result.

Syntax

xml_pi_parse fd xml_show_cmd_output xml_tags_list

Arguments

fd

(Mandatory) The CLI library file descriptor obtained from cli_open.

xml_show_cmd_output

(Mandatory) Output of xml_pi_show command extension in xml format.

xml_tags_list

(Mandatory) List of interesting tags.

Result String

Data in a Tcl array indexed by XML tag name.


Note

The current result is reset after Tcl procedure calls.

Set _cerrno

Possible errors raised:

1. error splitting the XML tags list 2. null XML tag list specified 3. XML tag tree exceeds 20 levels 4. called Tcl procedure returned an error 5. memory allocation failure 6. XML parse failure 7. failed to create XML domain

xml_pi_read

Reads the XML-PI command output (from the specified show command) from the CLI channel whose handler is given by the file descriptor until the pattern of the router prompt occurs in the contents that are read. Returns all the contents read up to the match in XML format.

Syntax

xml_pi_read fd

Arguments

fd

(Mandatory) The CLI library file descriptor obtained from cli_open.

Result String

All the contents that are read in XML format.

Set _cerrno

Possible errors raised:

1. cannot get router name 2. command error

xml_pi_write

Writes the XML-PI command specified using the cmd argument to the channel whose handler is given by the fd argument and the spec file specified by the spec_file argument.

Syntax

xml_pi_write fd cmd spec_file

Arguments

fd

(Mandatory) The CLI library file descriptor obtained from cli_open.

cmd

(Mandatory) IOS show command.

spec_file

(Optional) IOS CLI show command spec_file.

Result String

None

Set _cerrno

None

Sample Usage of the XML-PI feature

The following EEM policy (sample.tcl) presents one example that illustrates five different implementations of the new EEM XML-PI functionality. The odm spec-file (required for Example 2) follows this policy. 

::cisco::eem::event_register_none maxrun 60
namespace import ::cisco::eem::*
namespace import ::cisco::lib::*
# open the cli_lib.tcl channel
if [catch {cli_open} result] {
error $result $errorInfo
} else {
array set cli1 $result
}
# enter "enable" privilege mode
if [catch {cli_exec $cli1(fd) "en"} result] {
error $result $errorInfo
}
# Example 1:
#
# Detect if XML-PI is present in this image
# Invoke xml_pi_exec with the default spec file for the "show inventory"
# command. After the command executes $result contains the raw XML data if
# the command is successful.
if [catch {xml_pi_exec $cli1(fd) "show inventory" ""} result] {
puts "Example 1: XML-PI support is not present in this image - exiting"
exit
} else {
puts "Example 1: XML-PI support is present in this image"
}
# Example 2:
#
# In the next example we demonstrate how to extract two data elements
# from the "show version" command using the specified XML-PI spec file.
# The raw output from this command is as follows:
#
# Device#show version | format disk2:speceemtest.odm
# <?xml version="1.0" encoding="UTF-8"?>
# <ShowVersion>
# <Version>12.4(20071029:194217)</Version>
# <Compiled>Thu 08-Nov-07 11:28</Compiled>
# <ROM>System Bootstrap, Version 12.2(20030826:190624) [BLD-npeg1_rommon_r11 102], DEVELOPMENT</ROM>
# <uptime>17 minutes</uptime>
# <processor>NPE-G1</processor>
# <bytesofmemory>983040K/65536K</bytesofmemory>
# <CPU>700MHz</CPU>
# <L2Cache>0.2</L2Cache>
# <GigabitEthernetinterfaces>3</GigabitEthernetinterfaces>
# <bytesofNVRAM>509K</bytesofNVRAM>
# <bytesofATAPCMCIAcard>125952K</bytesofATAPCMCIAcard>
# <Sectorsize>512 bytes</Sectorsize>
# <bytesofFlashinternalSIMM>16384K</bytesofFlashinternalSIMM>
# <Configurationregister>0x2100</Configurationregister>
# </ShowVersion>
#
# Invoke xml_pi_exec with the spec file "disk2:speceemtest.odm" for the
# "show version" command. After the command executes $result contains
# the raw XML data. 
if [catch {xml_pi_exec $cli1(fd) "show version" "disk2:speceemtest.odm"} result] {
error $result $errorInfo
} else {
# Pass the raw XML data to the xml_pi_parse routine to extract fields
# of interest:
# we ask that only the <processor> and <CPU> fields be returned.
array set xml_result [xml_pi_parse $cli1(fd) $result "<processor> <CPU>"]
puts "Example 2: Processor is $xml_result(<processor>) CPU is $xml_result(<CPU>)"
}
# Example 3:
#
# In the next example we demonstrate how to extract two data elements
# from the multi-record "show inventory" command using the default built-in
# XML-PI spec file. Sample raw output from this command is as follows:
#
# Device#show inventory | format
# <?xml version="1.0" encoding="UTF-8"?>
# <ShowInventory>
# <SpecVersion>built-in</SpecVersion>
# <InventoryEntry>
# <ChassisName>&quot;Chassis&quot;</ChassisName>
# <Description>&quot;Cisco 7206VXR, 6-slot chassis&quot;</Description>
# <PID>CISCO7206VXR</PID>
# <VID>
# </VID>
# <SN>31413378 </SN>
# </InventoryEntry>
# <InventoryEntry>
# <ChassisName>&quot;NPE-G1 0&quot;</ChassisName>
# <Description>&quot;Cisco 7200 Series Network Processing Engine
NPE-G1&quot;</Description>
# <PID>NPE-G1</PID>
# <VID>
# </VID>
# <SN>31493825 </SN>
# </InventoryEntry>
# <InventoryEntry>
# <ChassisName>&quot;disk2&quot;</ChassisName>
# <Description>&quot;128MB Compact Flash Disk for NPE-G1&quot;</Description>
# <PID>MEM-NPE-G1-FLD128</PID>
# <VID>
# </VID>
# <SN>NAME: &quot;module 1&quot;</SN>
# </InventoryEntry>
# <InventoryEntry>
# <ChassisName>&quot;module 1&quot;</ChassisName>
# <Description>&quot;Dual Port FastEthernet (RJ45)&quot;</Description>
# <PID>PA-2FE-TX</PID>
# <VID>
# </VID>
# <SN>JAE0827NGKX</SN>
# </InventoryEntry>
# <InventoryEntry>
# <ChassisName>&quot;Power Supply 2&quot;</ChassisName>
# <Description>&quot;Cisco 7200 AC Power Supply&quot;</Description>
# <PID>PWR-7200-AC</PID>
# <VID>
# </VID>
# </InventoryEntry>
# </ShowInventory>
#
# Define a procedure to be called every time the <InventoryEntry> tag
# is processed. Since this tag precedes each new output record, the data 
# that is passed into this procedure contains the fields that have been 
# requested via xml_pi_parse since the previous time this procedure was
# called. 
proc <InventoryEntry> {xml_line} {
global num
# The first time that this function is called there is no data and
# xml_line will be null.
if [string length $xml_line] {
array set xml_result $xml_line
incr num
set output [format "Example 3: Item %2d %-18s %s" \
$num $xml_result(<PID>) $xml_result(<Description>)]
puts $output
}
}
set num 0
# Invoke xml_pi_exec with the default built-in spec file for the
# "show inventory" command. After the command executes $result contains
# the raw XML data. 
if [catch {xml_pi_exec $cli1(fd) "show inventory"} result] {
error $result $errorInfo
} else {
# Pass the raw XML data to the xml_pi_parse routine to extract fields
# of interest:
# we ask that only the <PID> and <Description> fields be returned.
# If an XML tag name is requested and a Tcl proc exists with that name,
# the Tcl proc will be called every time that tag is encountered in the
# output data. Specify the <InventoryEntry> tag and define the proc
# before executing the xml_pi_parse statement.
array set xml_result [xml_pi_parse $cli1(fd) $result \
"<InventoryEntry> <PID> <Description>"]
# Display the data from the last record.
incr num
set output [format "Example 3: Item %2d %-18s %s" \
$num $xml_result(<PID>) $xml_result(<Description>)]
puts $output
}
# Example 4:
#
# In the next example we demonstrate how to extract two data elements
# from the multi-record "show ip interface brief" command using the default
# built-in XML-PI spec file. Sample raw output from this command is as 
# follows:
#
# Device#show ip interface brief | format
# <?xml version="1.0" encoding="UTF-8"?>
# <ShowIpInterfaceBrief>
# <SpecVersion>built-in</SpecVersion>
# <IPInterfaces>
# <entry>
# <Interface>GigabitEthernet0/1</Interface>
# <IP-Address>172.19.209.34</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>up</Status>
# <Protocol>up</Protocol>
# </entry>
# <entry>
# <Interface>GigabitEthernet0/2</Interface>
# <IP-Address>unassigned</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>administratively down</Status>
# <Protocol>down</Protocol>
# </entry>
# <entry>
# <Interface>GigabitEthernet0/3</Interface>
# <IP-Address>unassigned</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>administratively down</Status>
# <Protocol>down</Protocol>
# </entry>
# <entry>
# <Interface>FastEthernet1/0</Interface>
# <IP-Address>unassigned</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>administratively down</Status>
# <Protocol>down</Protocol>
# </entry>
# <entry>
# <Interface>FastEthernet1/1</Interface>
# <IP-Address>unassigned</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>administratively down</Status>
# <Protocol>down</Protocol>
# </entry>
# </IPInterfaces>
# </ShowIpInterfaceBrief>
#
# Define a procedure to be called every time the fully qualified name
# <ShowIpInterfaceBrief><IPInterfaces><entry> tag is processed. Since 
# this tag precedes each new output record, the data that is passed into 
# this procedure contains the fields that have been requested via 
# xml_pi_parse since the previous time this procedure was called. 
proc <ShowIpInterfaceBrief><IPInterfaces><entry> {xml_line} {
global num
# The first time that this function is called there is no data and
# xml_line will be null.
if [string length $xml_line] {
array set xml_result $xml_line
incr num
set output [format "Example 4: Interface %2d %-30s %s" \
$num $xml_result(<Interface>) $xml_result(<Status>)]
puts $output
} else {
puts "Example 4: Display All Interfaces"
}
}
set num 0
# Invoke xml_pi_exec with the default built-in spec file for the
# "show ip interface brief" command. After the command executes $result 
# contains the raw XML data. 
if [catch {xml_pi_exec $cli1(fd) "show ip interface brief"} result] {
error $result $errorInfo
} else {
# Pass the raw XML data to the xml_pi_parse routine to extract fields
# of interest:
# we ask that only the <Interface> and <Status> fields be returned.
# If an XML tag name is requested and a Tcl proc exists with that name,
# the Tcl proc will be called every time that tag is encountered in the
# output data. Specify the <entry> tag and define the proc
# before executing the xml_pi_parse statement.
array set xml_result [xml_pi_parse $cli1(fd) $result \
"<ShowIpInterfaceBrief><IPInterfaces><entry> <Interface> <Status>"]
# Display the data from the last record.
incr num
set output [format "Example 4: Interface %2d %-30s %s" \
$num $xml_result(<Interface>) $xml_result(<Status>)]
puts $output
}
# Example 5:
#
# In the next example we demonstrate how to extract two data elements
# from the multi-record "show ip interface brief" command using the default
# built-in XML-PI spec file. Sample raw output from this command is as 
# follows:
#
# Device#show ip interface brief | format
# <?xml version="1.0" encoding="UTF-8"?>
# <ShowIpInterfaceBrief>
# <SpecVersion>built-in</SpecVersion>
# <IPInterfaces>
# <entry>
# <Interface>GigabitEthernet0/1</Interface>
# <IP-Address>172.19.209.34</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>up</Status>
# <Protocol>up</Protocol>
# </entry>
# <entry>
# <Interface>GigabitEthernet0/2</Interface>
# <IP-Address>unassigned</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>administratively down</Status>
# <Protocol>down</Protocol>
# </entry>
# <entry>
# <Interface>GigabitEthernet0/3</Interface>
# <IP-Address>unassigned</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>administratively down</Status>
# <Protocol>down</Protocol>
# </entry>
# <entry>
# <Interface>FastEthernet1/0</Interface>
# <IP-Address>unassigned</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>administratively down</Status>
# <Protocol>down</Protocol>
# </entry>
# <entry>
# <Interface>FastEthernet1/1</Interface>
# <IP-Address>unassigned</IP-Address>
# <OK>YES</OK>
# <Method>NVRAM</Method>
# <Status>administratively down</Status>
# <Protocol>down</Protocol>
# </entry>
# </IPInterfaces>
# </ShowIpInterfaceBrief>
#
# Note: This example is the same as Example 4 with the exception that
# the new record procedure is called by the un-qualified tag name. The
# ability to specify the un-qualified tag names is simplier but only works
# if the un-qualified name is used once per Tcl program. In this example
# the unqualified new record tag name is "<entry>" which is a very
# common name in the Cisco spec file.
# Define a procedure to be called every time the <entry> tag
# is processed. Since this tag precedes each new output record, the data 
# that is passed into this procedure contains the fields that have been 
# requested via xml_pi_parse since the previous time this procedure was
# called. 
proc <entry> {xml_line} {
global num
# The first time that this function is called there is no data and
# xml_line will be null.
if [string length $xml_line] {
array set xml_result $xml_line
incr num
if ([string equal $xml_result(<Status>) "up"]) {
set output [format "Example 5: Interface %2d %-30s %s" \
$num $xml_result(<Interface>) $xml_result(<Status>)]
puts $output
}
} else {
puts "Example 5: Display All Interfaces That Are Up"
}
}
set num 0
# Invoke xml_pi_exec with the default built-in spec file for the
# "show ip interface brief" command. After the command executes $result 
# contains the raw XML data. 
if [catch {xml_pi_exec $cli1(fd) "show ip interface brief"} result] {
error $result $errorInfo
} else {
# Pass the raw XML data to the xml_pi_parse routine to extract fields
# of interest:
# we ask that only the <Interface> and <Status> fields be returned.
# If an XML tag name is requested and a Tcl proc exists with that name,
# the Tcl proc will be called every time that tag is encountered in the
# output data. Specify the <entry> tag and define the proc
# before executing the xml_pi_parse statement.
array set xml_result [xml_pi_parse $cli1(fd) $result \
"<entry> <Interface> <Status>"]
# Display the data from the last record.
incr num
if ([string equal $xml_result(<Status>) "up"]) {
set output [format "Example 5: Interface %2d %-30s %s" \
$num $xml_result(<Interface>) $xml_result(<Status>)]
puts $output
}
}

Sample XML-PI spec eemtest.odm ODM File:

###
show version
<?xml version='1.0' encoding='utf-8'?>
<ODMSpec>
<Command>
<Name>show version</Name>
</Command>
<OS>ios</OS>
<DataModel>
<Container name="ShowVersion">
<Property name="Version" distance = "1.0" length = "1" type = "IpAddress"/>
<Property name="Technical Support" distance = "1.0" length = "1" type = "IpAddress"/>
<Property name="Compiled" distance = "1.0" length = "3" type = "String"/>
<Property name="ROM" distance = "1.0" length = "7" type = "IpAddress"/>
<Property name="uptime" distance = "2" length = "8" type = "String"/>
<Property name="image" distance = "4" length = "1" type = "IpAddress"/>
<Property name="processor" distance = "-1" length = "1" type = "String"/>
<Property name="bytes of memory" distance = "-1" length = "1" type = "Port"/>
<Property name="CPU" distance = "2" length = "1" end-delimiter = "," type = "String"/>
<Property name="L2 Cache" distance = "-2" length = "1" end-delimiter = "," type = "String"/>
<Property name="Gigabit Ethernet interfaces" distance = "-1" length = "1" type = "Integer"/>
<Property name="bytes of NVRAM" distance = "-1" length = "1" type = "String"/>
<Property name="bytes of ATA PCMCIA card" distance = "-1" length = "1" type = "String"/>
<Property name="Sector size" distance = "1.0" length = "2" end-delimiter = ")" type = "String"/>
<Property name="bytes of Flash internal SIMM" distance = "-1" length = "1" type = "String"/>
<Property name="Configuration register" distance = "2" length = "1" type = "String"/>
</Container>
</DataModel>
</ODMSpec>

Example sample.tcl Run:

Device#config t
Enter configuration commands, one per line. End with CNTL/Z.
Device(config)#event manager policy sample.tcl 
Device(config)#end
Device#
Oct 10 20:21:26: %SYS-5-CONFIG_I: Configured from console by console 
Device#event manager run sample.tcl
Example 1: XML-PI support is present in this image
Example 2: Processor is NPE-G1 CPU is 700MHz
Example 3: Item 1 CISCO7206VXR "Cisco 7206VXR, 6-slot chassis"
Example 3: Item 2 NPE-G1 "Cisco 7200 Series Network Processing Engine NPE-G1"
Example 3: Item 3 MEM-NPE-G1-FLD128 "128MB Compact Flash Disk for NPE-G1"
Example 3: Item 4 PA-2FE-TX "Dual Port FastEthernet (RJ45)"
Example 3: Item 5 PWR-7200-AC "Cisco 7200 AC Power Supply"
Example 4: Display All Interfaces
Example 4: Interface 1 GigabitEthernet0/1 up
Example 4: Interface 2 GigabitEthernet0/2 administratively down
Example 4: Interface 3 GigabitEthernet0/3 administratively down
Example 4: Interface 4 FastEthernet1/0 administratively down
Example 4: Interface 5 FastEthernet1/1 administratively down
Example 4: Interface 6 SSLVPN-VIF0 up
Example 5: Display All Interfaces That Are Up
Example 5: Interface 1 GigabitEthernet0/1 up
Example 5: Interface 6 SSLVPN-VIF0 up