Hi Christoph,
I am not sure if you are familiar with Firefox and Google chrome developer tools. This tools are particularly good for tracking the request communication and what is been sent back and forward. You can even edit the values and resend.
To show the metadata of your Odata model you just need to type service path in your internet browser and at the end you can type some of the below extensions.
<path>/<sevice name>.xsodata/$metadata
<path>/<sevice name>.xsodata/BusinessPartners/?$format=json
<path>/<sevice name>.xsodata/BusinessPartners/?$top=3
<path>/<sevice name>.xsodata/BusinessPartners/?$top=3&skip=1
This is how you would test the model before start building a user interface on it. That is what I have been doing at list.