Mule Dev Tricks: Using xpath3

Introduction

Even though today most web services using RESTful architecture, there are still a lot of legacy systems using SOAP. Handling xml file is challenging, if not difficult. Fortunately, Mule Application platform provide several utilities to alleviate the pain. The most powerful component is Dataweave, which is very handle to build SOAP request and handle responses. However, some cases, xpath3 is an easier solution. Sometimes it may be the best solution, for instance, if we want to split the xml payload based on certain node.

In this short article, I will introduce two use cases:

1. Extract values from xml payload
2. Split the payload

Use Case One: Extract Value Of An Element

Input Example

Here is the input:

    
        31bf3ce3d6bb1025d71346c6ec276bd6
    
    
        31bf3ce3d6bb1025d71348e2f1c26bdc
        35119960
    

I want to extract the value of Position_ID in the line of:

    35119960

Solution

There are two solutions in this case. The first is:

    #[xpath3('/*:Create_Position_Response/*:Position_Reference/*:ID[2]')]

The above MEL will assign position_id to 35119960. Note: XML node count starting from 1 not from 0 as in Java array.

The other better solution is the following:

#[xpath3('/*:Create_Position_Response/*:Position_Reference/*:ID[@*:type=\'Position_ID\']')]

Here is the trick is \/*:ID[@*:type=\'Position_ID\'].

1. Refer element attribute using [@*:type]
2. Escape the single quote with backslash \'

Use Case Two: Use xpath3 To Split Payload

Example Input

In this use case, I would like to extract the node of StockMovementData, so that I can process the data.

    

        Warehouse
        Location
        idm1468201212
        2016-04-13T11:55:30.263+10:00
    
    
        YES
        2016-04-13T11:55:30.263+10:00
        30-80
        client
        7CAGL3G00
        700030011
        100
    
    
        YES
        2016-04-13T11:55:30.263+10:00
        30-80
        client
        7CAGL3G00
        700029911
        100
    

Here is the mule flow:

Solution

The above flow, split the xml payload using the following xpath3 expression:

Complete Mule Flow Configuration