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Required IIS Configuration

This section describes some important configuration changes that need to be applied when using Internet Information Services (IIS) as the front-end web server for the Open Data API.

Supporting + in Schema Endpoint URLs

Where there are spaces in the ID of an element within the data catalogue, the Open Data API /schema  endpoint represents the space using a +  character.

For example, the following excerpt from a dataset schema response shows a field group with a space in the name, and the corresponding endpoint URL for querying that group has + in place of the spaces:

    "id": "str:group:UKRoadSafetyData:X_Vehicle+Make+and+Model",
    "label": "Vehicle Make and Model",
    "location": "",
    "type": "GROUP"

IIS versions 7 and onwards do not automatically convert the + back to a space by default. This means that if a user or application attempts to query the location  endpoint it received from the API, IIS will return a 404 (Not Found) HTTP response.

One way to resolve this is to set allowDoubleEscaping to true in the IIS application web.config file.

Supporting : in Schema Endpoint URLs

The Open Data API uses the :  character as a separator when representing items in the schema. For example, datasets are represented using an ID in the format:


Where <dataset_id>  is replaced by the ID configured for that dataset in SuperADMIN. For example:

    "id": "str:database:bank",
    "label": "Retail Banking (Sample)",
    "location": "",
    "type": "DATABASE",
    "lastModified": 1629864501084,
    "recordViewEnabled": true

API users need to be able to query these lower-level endpoints containing the :  character (such as in this example). However, IIS does not support the :  character in URLs by default, and queries to these endpoints will return a 400 (Bad Request) HTTP response.

You can resolve this by adding a rule similar to the following to the IIS application web.config file:

    <httpRuntime requestValidationMode="2.0" requestPathInvalidCharacters="<,>,*,%,&,\,?" />

Hostname in Schema Responses

To ensure that the Open Data API reports the correct hostname in responses to requests to the /schema  endpoint, you must ensure that preserveHostHeader  is set to true  in the IIS Application Request Routing module for the reverse proxy to Tomcat.

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