Published Web Services

Last modified: August 20, 2024

Introduction

This document describes published web services. If you’re looking for specific information on the published web services screen, see the Published web service documentation.

You can publish your own web services in a Mendix application. Published web services are based on SOAP 1.1. These web services are made up of operations. Other applications can then call operations of this web service and returns a result. This result is based on a microflow that is executed when the web service is called.

To enable usage of a microflow as a web service, right-click anywhere in the white space of the microflow and select Publish as web service operation….

Runtime Documentation

When running, Studio Pro projects publish web services documentation. The address is (if running locally) http://localhost:8080/ws-doc/. This documentation explains how the service can be used in two ways.

WSDL

This is an XML document that is computer-readable. Studio Pro can read this document and automatically figure out how to interact with the web service.

Example Request/Response XML Messages

On the Published web services page (http://localhost:8080/ws-doc/), you will find a list of all operations per published web service. These link to pages which describe sample messages. Note that you do not need these examples when building a Mendix-to-Mendix interaction; they are there solely to help users who want to create their own clients.

How Does a Published Web Service Call Work?

A microflow that has been published can be called by systems from the outside. This section describes how this process works.

Call Is Initiated

A web service call is simply a HTTP call that the Runtime receives and recognizes as a web service call. An XML message is received and parsed to a format that the Runtime understands.

Authentication

Every web service call requires authentication. Specifically, the SOAP envelope header should contain an Authentication element, which contains a user name and password:

<soap:Header>
  <tns:authentication>
    <username>john</username>
    <password>john'ssecretpassword</password>
  </tns:authentication>
</soap:Header>

These details must match an existing web service user in the Runtime. These users can be created by signing in as an Administrator and clicking Create web service user in the Users data grid in the system module. Normal (non-web service) users cannot be used to call web services and web service users cannot sign in via the standard login page.

Otherwise, there is no difference between how normal users and web service users call microflows.

Parameter Handling

Depending on which types of parameters are inputs to the published microflow, two things can happen:

  1. If an input is a domain entity, the XML is translated to the entity using an XML-to-Domain mapping. Note that these mappings create actual domain objects, depending on the mapping.
  2. Normal parameters (integer, string, etc.) aren’t converted in any way and are used as inputs directly.

Microflow Is Executed

Once the parameters have been parsed from the XML, the microflow call proceeds as normal.

Result Is Converted Back to XML

If the microflow has a return value, it will be returned as a result of the web service call. As with the parameters, basic types will be returned directly, and domain entities require a mapping to be converted to XML. Number formatting is consistent between consumed and published web services. Trailing zeroes are removed from numbers and scientific notation is not used.

Response Statuses

The default HTTP status code in the response is 200 (OK). When the client sends a malformed request, or when an internal server error occurs, the Runtime responds with a SOAP fault. The HTTP header will contain status 500 in these cases.

Note that the status code is sent before the actual response. If during the response, a sending an error occurs, the response status cannot be changed. This means the receiving side may receive a status code 200, even though the service failed after, during the serialization of the response. This happens because to optimize memory usage, Studio Pro does not create the entire response in memory. Instead, during serialization, the response is immediately sent to the client to free up memory. This means you need to have the data needed to create a valid response before finishing the web service.