Common Query Parameters

All Query operations share a set of common parameters that must be present in each call:

Parameter NameDescriptionExample Value
Action Indicates the action to perform. RunInstances
Version The API version to use, as specified in the WSDL. 2007-03-01
AWSAccessKeyId The Access Key ID for the request sender. This identifies the account which will be charged for usage of the service. The account with which the Access Key ID is associated must be signed up for EC2, or requests will not be accepted. 10QMXFEV71ZS32XQFTR2
Timestamp The date and time at which the request is signed, in the format YYYY-MM-DDThh:mm:ssZ, as specified in the ISO 8601 standard. 2006-07-07T15:04:56Z
Expires The date and time at which the signature included in the request expires, in the format YYYY-MM-DDThh:mm:ssZ, as specified in the ISO 8601 standard. 2006-07-07T15:04:56Z
Signature A request signature is calculated as explained in Request Authentication. Qnpl4Qk/7tINHzfXCiT7VbBatDA=
SignatureVersion A value of 0 or 1 indicates the method chosen to construct the string to be signed. Currently, only a value of 1 is valid. 1
[Note]Note

The Timestamp parameter can be used instead of Expires. Requests must include either Timestamp or Expires, but cannot contain both.

Parameter values must be URL-encoded. This is true for any Query parameter passed to EC2 and is typically necessary in the Signature parameter. Some clients do this automatically, but this is not the norm.