AdWords API How do you make multiple requests in one pass?

Here's a snippet that does getAllKeywords for a single adgroup.
Instead of cycling through http requests - one for each ad group - can
you make one single big request?

Today we do:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
xmlns="https://adwords.google.com/api/adwords/v2">
<soap:Header>
<email>xxxxxx@yyyyy.com</email>
<password>pwpwpwpwpw</password>
<useragent>abcdef</useragent>
<token>***************</token>
</soap:Header>
<soap:Body>
<getAllKeywords>
<adgroupID>1234567890</adgroupID>
</getAllKeywords>
</soap:Body>
</soap:Envelope>

And, for 100 ad groups we make 100 requests.

Is there a syntax to do something like (and we've tried but failed):
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
xmlns="https://adwords.google.com/api/adwords/v2">
<soap:Header>
<email>xxxxxx@yyyyy.com</email>
<password>pwpwpwpwpw</password>
<useragent>abcdef</useragent>
<token>***************</token>
</soap:Header>
<soap:Body>
<getAllKeywords>
<adgroupID>10001</adgroupID>
<adgroupID>10002</adgroupID>
<adgroupID>10003</adgroupID>
....
<adgroupID>10100</adgroupID>
</getAllKeywords>
</soap:Body>
</soap:Envelope>

Thanks