Actions encapsulate the possible interactions with Amazon EC2. These can be viewed as remote procedure calls and consist of a request and response message pair. Requests must be signed, allowing Amazon EC2 to Request Authentication. For clarity, the sample requests and responses illustrating each of the operations described in this reference are not signed.

The current version of the Amazon EC2 WSDL is available at: http://ec2.amazonaws.com/doc/2009-03-01/AmazonEC2.wsdl. Some libraries can generate code directly from the WSDL. Other libraries require a little more work on your part.

Values provided as parameters to the various operations must be of the indicated type. Standard XSD types (like string, boolean, int) are prefixed with xsd:. Complex types defined by the Amazon EC2 WSDL are prefixed with ec2:.

Parameters that consist of lists of information are defined within our WSDL to require <info> tags around each member. Throughout the API, type references for parameters that accept such a list of values are specified using the notation type[] The type referred to in these instances is the type nested within the <info> tag (for Amazon EC2 types this is defined in the WSDL).

For example, the <imagesSet> element in the following XML snippet is of type xsd:string[].

<imagesSet>
  <item>
    <imageId>ami-61a54008</imageId>
  </item>
  <item>
    <imageId>ami-61b54608</imageId>
  </item>
</imagesSet>

The <instancesSet> element in the following XML snippet is of type xsd:string[].

<instancesSet>
    <item>
        <imageId>ami-60a54009</imageId>
        <minCount>10</minCount>
        <maxCount>30</maxCount>
    </item>
    <item>
        <imageId>ami-60b54209</imageId>
        <minCount>5</minCount>
        <maxCount>20</maxCount>
    </item>
</instancesSet>