Exposing a web service

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Mendix supports many ways to expose functionality or data of your application to others. The easiest way is to use web services. A web service can contain multiple operations.

After completing this how-to you will know:

  • How to create a web service.
  • How to publish a microflow as web service operation.

1. Preparation

Before you can start with this how-to, make sure you have completed the following prerequisites.

  • Download the Mendix Modeler.

SoftwareVersion used in this how-to
Mendix Modeler5.20.0

2. Data structure and GUI

  1. Create the following entity Customer in your domain model. If you don’t know how to create an entity, take a look at this how-to.
  2. Create overview and detail pages to manage objects of type Customer. If you don’t know how to create overview and detail pages, take a look at this how-to.
  3. Create a menu item to access the customer overview page. If you don’t know how to create menu items, take a look at this how-to.
  4. Run the application and add some data to expose in the web service.

3. Create a published web service

  1. Right click the module you want to store the published web service in.
  2. Select Add > Published services > Published web service from the menu.
  3. Name the web service CustomerWebservice and click OK. You should now see the published web service properties.
  4. At the General tab you can change the name.
  5. At the Operations tab you can see the available operations of the web service. Currently this list is empty. We’ll add an operation in the following steps.
  6. At the Settings tab you can configure the other settings. For now leave the settings as they are, here you can read more about these settings.
  7. At the Documentation tab you can change the documentation.
  8. Click OK.

4. Create functionality to expose

  1. Create a Microflow that retrieves and returns a list of customers from the database. If you don’t know how to create a Microflow, take a look at this how-to.
  2. To make the Microflow a little more exciting, you could add 2 input parameters to dynamically set the range settings of the retrieve action. Configure the range options of the retrieve action as shown below:

5. Publish a Microflow

  1. Right click somewhere in the background of the Microflow and select Publish as Web service operation….

  2. Locate the web service created in step 2 of this how-to and click Select.

    You should now see the operation properties editor. At the General tab you can change the name and documentation.

    At the Parameters tab you can mark the input parameters as Optional and Nillable.

    At the Return type tab you can configure the return type.

  3. Click Select… to select which attributes and associations of the return object Customer you want to expose.

  4. Select the members you want to expose and click OK. Only the selected ones will be returned by the web service.

  5. Click OK to save the operation.


You need a WSDL to allow others to interact with the web service you just created. The WSDL describes how to call the operations in the web service.

  1. Run the application locally or in a sandbox.
  2. View the application in your browser. If you run the application locally, the application url should look like this: http://localhost:8080/index.html. If you run the application in a sandbox, the application url should look like this: https://myfirstapp.mendixcloud.com/index.html.
  3. In both cases you can replace /index.html with /ws-doc/ to open the web service documentation page. You should see the name of your web service in the list.
  4. Click the upper URL to open the WSDL. This WSDL can be given to others so that they interact with your web service.

7. Authentication and Users

  1. Double click the published web service in the project explorer to open it.
  2. Open the Settings tab. Currently users of the web service don’t need to authenticate.
  3. Switch Authentication to Username and password.  
  4. Click OK and re-run the application. Users now need to authenticate before they can use the web service.

Mendix allows you to create your own user management functionality as long as your own user object inherits from ‘System.User’. The ‘User’ entity in the ‘System’ module contains a boolean attribute ‘WebServiceUser’. This attribute determines if an user is able to interact with web services. If you want a certain user to be able to interact with web services, the value of this attribute must be ‘true’.

8. Considerations