Request Change Indicators for Configuration Elements Using the Junos XML Protocol
In a Junos XML protocol session with a device running
Junos OS, to request that the server indicate which configuration
elements have changed since the last commit, a client application
includes the changed="changed" attribute
in the <get-configuration/> request
tag. It encloses the request in an <rpc> tag element:
<rpc>
<get-configuration changed="changed"/>
<!-- OR -->
<get-configuration changed="changed">
<!-- tag elements for the configuration elements to return -->
</get-configuration>
</rpc>For information about the tag elements to enclose in the <get-configuration> tag element, see Specifying the Scope of Configuration Data to Return
in a Junos XML Protocol Session.
The configuration source determines which elements are marked
as changed. When the database="candidate" attribute is included in the <get-configuration/> tag or when the database attribute is
omitted, the candidate configuration is compared to the active configuration.
Elements added to the candidate configuration after the last commit
operation are marked with the junos:changed="changed" attribute. When the database="committed" attribute is included in the <get-configuration/> tag, the active configuration is compared to the first rollback
configuration. Elements added to the active configuration by the most
recent commit are marked with the junos:changed="changed" attribute.
The Junos XML protocol server indicates which elements have
changed by including the junos:changed="changed" attribute in the opening tag of every parent tag element in the
path to the changed configuration element. If the changed configuration
element is represented by a single (empty) tag, the junos:changed="changed" attribute appears in the tag. If the changed element is represented
by a container tag element, the junos:changed="changed" attribute appears in the opening container tag and also in the opening
tag for each child tag element enclosed in the container tag element.
The Junos XML protocol server encloses its response in <rpc-reply> and <configuration> tag elements. For information about the standard attributes
in the opening <configuration> tag,
see Specifying the Source for Configuration
Information Requests in a Junos XML Protocol Session.
<rpc-reply xmlns:junos="URL">
<configuration standard-attributes junos:changed="changed">
<!-- opening-tag-for-each-parent-level junos:changed="changed" -->
<!-- For each changed element, EITHER -->
<element junos:changed="changed"/>
<!-- OR -->
<element junos:changed="changed">
<first-child-of-element junos:changed="changed">
<second-child-of-element junos:changed="changed">
<!-- additional children of element -->
</element>
<!-- closing-tag-for-each-parent-level -->
</configuration>
</rpc-reply>If the requested output format is JSON, the Junos XML protocol
server includes the "junos:changed" : "changed" attribute in the attribute lists for the same elements as described
previously and encloses the response in <configuration-json> and <rpc-reply> tag elements.
Starting in Junos OS Release 16.1, devices running Junos OS emit JSON-formatted configuration data using a new default implementation for serialization. The new default uses the "@" symbol instead of the field name "attribute" to indicate an attribute.
When a commit operation succeeds, the Junos XML protocol
server removes the junos:changed="changed" attribute from all tag elements. However, if warnings are generated
during the commit, the attribute is not removed. In this case, the junos:changed="changed" attribute appears on tag elements
that changed before the commit as well as those that changed after
the commit.
An example of a commit-time warning is the message explaining
that a configuration element will not actually apply until the device
is rebooted. The warning appears in the tag string that the Junos
XML protocol server returns to confirm the success of the commit,
enclosed in an <xnm:warning> tag element.
To remove the junos:changed="changed" attribute from elements that changed before the commit, the client
application must take any action necessary to eliminate the cause
of the warning, and commit the configuration again.
The changed attribute can
be combined with one or more of the following other attributes in
the <get-configuration/> tag or opening <get-configuration> tag:
database, which is described in Specifying the Source for Configuration Information Requests in a Junos XML Protocol Session. Request change indicators in either the candidate or active configuration.inheritand optionallygroupsandinterface-ranges, which are described in Specifying the Output Format for Configuration Groups and Interface Ranges Using the Junos XML Protocol.junos:key, which is described in Requesting Identifier Indicators for Configuration Elements Using the Junos XML Protocol.
It does not make sense to combine the changed attribute with the format="text" attribute
or with the compare attribute, which produces
only text output. The junos:changed="changed" attribute appears only in Junos XML-tagged output, which is
the default output format, and in JSON output. When the commit-scripts="view" attribute is included in the <get-configuration> tag, the junos:changed="changed" attribute is automatically included in the output, and you do not
need to explicitly include this attribute in the <get-configuration> request.
The application can also include the changed attribute after requesting an indicator for identifiers (as described
in Requesting Identifier Indicators for
Configuration Elements Using the Junos XML Protocol).
The following example shows how to request change indicators
for configuration elements at the [edit system syslog] hierarchy level in the candidate configuration. The output indicates
that a log file called interactive-commands has been configured since the last commit.
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