# Create Key

## Contents
Overview Configuration

## Overview
The Create Key filter is used to identify the part of the message that determines whether a message is unique. For example, you can use the request message body to determine uniqueness so that if two successive identical message bodies are received by the Enterprise Gateway, the response for the second request is taken from the cache. You can also use other parts of the request to determine uniqueness (for example, HTTP headers, client IP address, client SSL certificate, and so on). This means that you can use the Create Key filter to create keys for a range of different caching scenarios (for example, caching a user's role, or caching a session for a user). For more information on how to configure this filter in the context of a caching circuit, see the Global Caches tutorial. This shows the order in which caching filters such as the Create Key filter are placed in an example caching circuit.
## Configuration
Name: Enter a name for this filter here. Attribute Name: Enter the name of the Oracle message attribute to use to determine whether an incoming request is unique or not. For example, if http.request.clientcert (the client SSL certificate) is selected, the Enterprise Gateway takes a cached response for successive requests in which the client SSL certificate is the same.