xml (Source Mapper)

This mapper converts XML input to Stream App event. Transports which accepts XML messages can utilize this extension to convert the incoming XML message to Stream App event. Users can either send a pre-defined XML format where event conversion will happen without any configs or can use xpath to map from a custom XML message.

Syntax

CREATE SOURCE <NAME> WITH (map.type="xml", map.namespaces="<STRING>", map.enclosing.element="<STRING>", map.fail.on.missing.attribute="<BOOL>")

Query Parameters

Name	Description	Default Value	Possible Data Types	Optional	Dynamic
namespaces	Used to provide namespaces used in the incoming XML message beforehand to configure xpath expressions. User can provide a comma separated list. If these are not provided xpath evaluations will fail	None	STRING	Yes	No
enclosing.element	Used to specify the enclosing element in case of sending multiple events in same XML message. gdn DAS will treat the child element of given enclosing element as events and execute xpath expressions on child elements. If enclosing.element is not provided multiple event scenario is disregarded and xpaths will be evaluated with respect to root element.	Root element	STRING	Yes	No
fail.on.missing.attribute	This can either have value true or false. By default it will be true. This attribute allows user to handle unknown attributes. By default if an xpath execution fails or returns null DAS will drop that message. However setting this property to false will prompt DAS to send and event with null value to Stream App where user can handle it accordingly(ie. Assign a default value)	True	BOOL	Yes	No

Example 1

CREATE SOURCE FooStream WITH (type='inMemory', topic='stock', map.type='xml') (symbol string, price float, volume long);

Above configuration will do a default XML input mapping. Expected input will look like below:

<events>     
    <event>
        <symbol>gdn</symbol>         
        <price>55.6</price>
        <volume>100</volume>    
    </event> 
</events>

Example 2

CREATE SOURCE FooStream WITH (type='inMemory', topic='stock', map.type='xml', map.namespaces = "dt=urn:schemas-microsoft-com:datatypes", map.enclosing.element="//portfolio", map.attributes="symbol = 'company/symbol', price = 'price', volume = 'volume'") (symbol string, price float, volume long);

Above configuration will perform a custom XML mapping. In the custom mapping user can add xpath expressions representing each event attribute using @attribute annotation. Expected input will look like below.

<portfolio xmlns:dt="urn:schemas-microsoft-com:datatypes">
    <stock exchange="nasdaq">         
    <volume>100</volume>
    <company><symbol>gdn</symbol></company>         
    <price dt:type="number">55.6</price>
    </stock> 
</portfolio>