Responses

By default, the JSON data is provided directly as root object. Please see this example code of a menu root object.

{
    "headline": "My Menu",
    "menu": [{
            "label": "My Menu Item"
        }]
}

This data structure is very suitable if the HTTP server hosts static JSON files. However, if the HTTP server uses a database or an external API to dynamically create JSON files, an extended data structure is useful. Therefore, it is possible to wrap any JSON data in a response object to have an unified root object and to provide advanced error handling. Please see this example code of a wrapped menu root object.

{
    "response": {
        "status": 200,
        "text": "OK",
        "message": null,
        "data": {
            "headline": "My Menu",
            "menu": [{
                    "label": "My Menu Item"
                }]
        }
    }
}

The next example code shows how an error response can look like.

{
    "response": {
        "status": 404,
        "text": "Not Found",
        "message": "Menu for database ID 'xyz' not found.",
        "data": null
    }
}

If you execute actions on server side, the server action response must always be wrapped in a response object. Please see the next example code of how a server action response can look like.

{
    "response": {
        "status": 200,
        "text": "OK",
        "message": null,
        "data": {
            "action": "menu:data",
            "data": {
                "headline": "My Menu",
                "menu": [{
                        "label": "My Menu Item"
                    }]
            }
        }
    }
}

Please see Actions#Server Actions for more information.

Property syntax of response object

Property	Type	Default Value	Mandatory	Since Version	Description
status	number	0	Yes	0.1.0	HTTP-compliant status code. This property must be set to 200 for success responses. Note: Error responses must also be sent as successful HTTP (2xx) responses. The actual error status code is provided in this property.
text	string	null	No	0.1.0	HTTP-compliant status text.
message	string	null	No	0.1.0	This property is only used in error responses and can be used to provide a detailed error description.
data	object	null	No	0.1.0	This property is only used in success responses and contains the actual JSON data.

Note: MSX is a pure client-side framework. There is no server component included — you provide the JSON endpoints on any HTTP server of your choice. MSX fetches these URLs, parses the responses, and renders the UI or executes the action. Please note that every HTTP request made by MSX has a timeout of 30 seconds. If no response is received within this time, MSX discards the request and throws an internal error. Design your endpoints to respond well within this limit.

Error Handling

There are three distinct error scenarios.

Scenario	Cause	Behavior
HTTP error	The server returns a non-2xx HTTP status (e.g. 404, 500).	Platform-dependent. Most TV platforms cannot display error details in this case — the error message may appear or a generic one is shown. Avoid relying on this for user-facing error details.
Response error	The server returns HTTP 200 but the response.status is not 200.	MSX displays the message property to the user. This is the recommended approach for surfacing errors, because it works reliably across all TV platforms.
Request timeout	No response received within 30 seconds.	MSX discards the request and throws an internal error.

The response wrapper was introduced specifically to work around the limitation that many TV platforms cannot reliably display non-200 HTTP errors. By always returning HTTP 200 and encoding the error state inside the response object, errors are guaranteed to reach the user.