Initializing help system before first use

# Requests

Requests can be made to your Xpress Insight endpoint via HTTP to elicit a response with a payload normally in JSON format (There are some exceptions, such as when dealing with file contents).

## Content Negotiation

To communicate with the REST API, clients must use content negotiation request headers which allow for the API version to be specified in the request and response. These headers take the following format:

     [mime type]/[API identifier].v[API major version]+[mime subtype]

For Xpress Insight, this is done using the `vnd.com.fico.xpress.insight` API identifier. Therefore a request for an application/json type response in API version 2.x must use the `application/vnd.com.fico.xpress.insight.v2+json` content negotiation header. All requests must send this versioned header as the value of the standard HTTP Accept header, and additionally as the standard HTTP Content-Type header for requests sending data, for example for a POST operation. The example will cause the server to respond with the latest available minor version of the 2.x API.

The following example shows the client requesting an application/json response from version 2.x of the REST API:

    POST /api/compute-jobs HTTP/1.1
     Host: <INSIGHTURL>
    Content-Type: application/vnd.com.fico.xpress.insight.v2+json
     Accept: application/vnd.com.fico.xpress.insight.v2+json
    {...}

Failure to supply valid content negotiation headers will result in one of the following responses;

`415 Unsupported Media Type (for Content-Type)` or `406 Not Acceptable (for Accept)`.

Tip: For information about calling the REST API using JavaScript, see Making REST Requests with the JavaScript API.
Parent Topic Accessing the Xpress Insight Server Using the REST API

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