Extended query protocol violation?

While playing with Java application using JDBC driver, I noticed
an interesting fact:

When autocommit is off, JDBC driver issues following messages:

20:10:54.731 (2) FE=> Parse(stmt=S_1,query="BEGIN",oids={})
20:10:54.731 (2) FE=> Bind(stmt=S_1,portal=null)
20:10:54.731 (2) FE=> Execute(portal=null,limit=0)
20:10:54.732 (2) FE=> Parse(stmt=null,query="SELECT ...
20:10:54.733 (2) FE=> Bind(stmt=null,portal=null)
20:10:54.733 (2) FE=> Describe(portal=null)
20:10:54.733 (2) FE=> Execute(portal=null,limit=0)
20:10:54.733 (2) FE=> Sync
20:10:54.734 (2) <=BE ParseComplete [S_1]
20:10:54.734 (2) <=BE BindComplete [null]
20:10:54.734 (2) <=BE CommandStatus(BEGIN)
20:10:54.735 (2) <=BE ParseComplete [null]
20:10:54.735 (2) <=BE BindComplete [null]
20:10:54.735 (2) <=BE RowDescription(15)

Notice that JDBC driver sends Parse, Bind and Execute without Sync
followed then immediately sends another Parse message. I wonder if
this violates our extended query protocol. From the manual:

"At completion of each series of extended-query messages, the frontend
should issue a Sync message."

"each series of extended-query messages" is a little vague here but it
seems it referes to a sequence of message starting with parse and
ending with execute message to me. If so, I think above example of
message sequence violates the protocol.

The application produces the packet sequence is essentially like this:

connection.setAutoCommit(false);
stmt = connection.createStatement();
rs = stmt.executeQuery(sql);

Comments?
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp