What is ID - is it an auto-incremented unique ID? Hypertable does not have auto-increments, but uses random GUIDs for unique IDs if you don't want to provide your own ID. Here's a link with more information:
http://hypertable.com/documentation/developer_guide/#unique-cells
I would maybe combine Host and Port into a single column ("hypertable.com:8080"), but that's my personal preference.
Everything else looks fine. You can simply translate this to a CREATE TABLE statement in HQL:
CREATE TABLE ExceptionLog (ID, ExceptionClass, ExceptionMessage, Host, Port, HttpHeader, HttpPostBody, HttpMethod);
You might also want to have secondary indices, i.e. on ExceptionClass, if you have frequent queries like
SELECT ExceptionClass FROM ExceptionLog WHERE ExceptionClass = "Segfault";
Secondary indices are documented here: http://hypertable.com/documentation/developer_guide/#secondary-indices
Here's a sample which shows how to use the Java client. It's fairly simple: https://github.com/cruppstahl/hypertable/blob/v0.9.6/src/java/ThriftClient/org/hypertable/thrift/BasicClientTest.java