Request Operational Information Using the Junos XML Protocol

Within a Junos XML protocol session, a client application can request information about the current status of a Junos device. To request operational information, a client application emits the specific request tag element from the Junos XML API that returns the desired information.

Table 1 provides examples of request tags, which request the same information as the equivalent CLI command..

You can determine the appropriate Junos XML request tag using multiple methods, including:

• Appending | display xml rpc to an operational command in the CLI.

• Using the Junos XML API Explorer - Operational Tags application to search for a command or request tag in a given release.

For example, the following command displays the request tag corresponding to the show interfaces command:

user@router> show interfaces | display xml rpc
<rpc-reply xmlns:junos="http://xml.juniper.net/junos/23.4R1.9/junos">
    <rpc>
        <get-interface-information>
        </get-interface-information>
    </rpc>
</rpc-reply>

To execute an RPC, the client application encloses a request tag in an <rpc> element. The syntax depends on whether the corresponding CLI command has any options included.

<rpc>
    <!-- If the command does not have options -->
    <operational-request/>
     

    <!-- If the command has options -->
    <operational-request>
        <!-- tag elements representing the options -->
    </operational-request>
</rpc>

The client application can specify the format of the information returned by the Junos XML protocol server. By setting the optional format attribute in the opening operational request tag, a client application can specify the format of the response as XML-tagged format, which is the default, formatted ASCII text, or JavaScript Object Notation (JSON). For more information about specifying the format, see Specify the Output Format for Operational Information Requests in a Junos XML Protocol Session.

If the client application requests XML output, the Junos XML protocol server encloses its response in the specific response tag element that corresponds to the request tag element, which is then enclosed in an <rpc-reply> tag element.

<rpc-reply xmlns:junos="URL">
    <operational-response xmlns="URL-for-DTD">
        <!-- Junos XML tag elements for the requested information -->
    </operational-response>
</rpc-reply>

For example, if the client application sends the <get-interface-information> RPC, the server returns the <interface-information> response tag.

<rpc-reply xmlns:junos="http://xml.juniper.net/junos/23.4R1.9/junos">
<interface-information xmlns="http://xml.juniper.net/junos/23.4R1.9/junos-interface" junos:style="normal">
<physical-interface>
<name>ge-0/0/0</name>
<admin-status junos:format="Enabled">up</admin-status>
<oper-status>up</oper-status>
...

For XML format, the opening tag for each operational response includes the xmlns attribute. The attribute defines the XML namespace for the enclosed tag elements that do not have a namespace prefix (such as junos:). The namespace indicates which Junos XML document type definition (DTD) defines the set of tag elements in the response.

The Junos XML API defines separate DTDs for operational responses from different software modules. For instance, the DTD for interface information is called junos-interface.dtd and the DTD for chassis information is called junos-chassis.dtd. The division into separate DTDs and XML namespaces means that a tag element with the same name can have distinct functions depending on which DTD it is defined in.

The namespace is a URL of the following form:

http://xml.juniper.net/junos/release-code/junos-category 

where:

• release-code is the standard string that represents the Junos OS release that is running on the Junos XML protocol server device.

• category specifies the DTD.

If the client application requests the output in formatted ASCII text, the Junos XML protocol server encloses its response in an <output> tag, which is enclosed in an <rpc-reply> tag.

<rpc-reply xmlns:junos="URL">
    <output>
        operational-response
    </output>
</rpc-reply>

If the client application requests the output in JSON format, the Junos XML protocol server encloses the JSON data in the <rpc-reply> tag element.

<rpc-reply xmlns="URN" xmlns:junos="URL">
    operational-response
</rpc-reply>