xml - OSB replace node -

i've been trying replace node action "replace" don't understand, hope me.

i've errorhandler, inside stage , inside; assign > replace > reply.

in assign; expression: $body variable: faultstring  in replace; xpath: . in variable: faultstring expression: $body replace node contents  in reply; failure 

so here i'm getting echo, this;

<soapenv:envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:cli="http://www.xxxx.com.mx/xxxx/xxxxxxx">        <soapenv:header xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"></soapenv:header>        <soapenv:body>           <cli:getxxxxxxxxxxxxxxx>              <json>{"principal":"principal","secundario":"secundario"}</json>           </cli:getxxxxxxxxxxxxxxx>        </soapenv:body> </soapenv:envelope> 

i want replace node

<json>{"principal":"principal","secundario":"secundario"}</json> 

with;

<json>{"otracosa":"otro","final":"final"}</json> 

by way i'm getting echo when osb don't reach endpoint , want replace said.

many in advance.

in order replace want use configuration:

xpath: ./*:getxxxxxxxxxxxxxxx/json in variable: $body expression: <json>{"otracosa":"otro","final":"final"}</json> replace entire node 

another option:

xpath: ./*:getxxxxxxxxxxxxxxx/json in variable: $body expression: xs:string('{"otracosa":"otro","final":"final"}') replace node contents 

some explanation: (with words)

variable: payload want replace. root variable.

xpath: xpath node want replace in variable. in example "." root bariable, "" can namespace. (you can use "cli" instead "" if define namespace in ide)

expression: data want put.

replace entire node/replace node content: if want replace content including tag xpath or content inside tags. put 2 examples same.

about echo, maybe have no route node, or maybe not reaching endpoint. response pipeline run in separate thread, if have no route node, echo created response pipeline.