In order to extract the contextId from a specific embed code you have to use the findByProperties web service, which can be found within the contents package of xcontents. Information to be included within the body of the request are:

• clientId: it is the domain name used to access your THRON, usually your company name.
• xcontentId: it is the ID of the embedded content.

Within the response you will find th "embedCodes" section, illustrating all the embed codes generated for that specific content. For each one of them you will be able to read the contextId within the "useContextId" parameter.

You can try this procedure in our Developer Center, just paste the following JSON within the body of the request, filling required parameters.

{
    "client": {
        "clientId": ""
    },
    "criteria": {
        "contentIds": [
            ""
        ]
    }
}