XBird/D introduces a distributed query extention to XQuery called XBird Distributed Query, BDQ for short.

Syntax

   BDQExpr ::= "execute at" [ VarRef "in" ] Expr "{" Expr "}"

Usage

Configuring a service

The distiributed query processor, XBird/D in short, is configurable through xbird.properties.

# The port number used by XBird/D.
# This effects host:port as appears in the later.
xbird.rmi.registry.local.port=1099

# The identifying name of the services: name(,name)*
# caution: name should not start with slash.
xbird.rmi.engine.name=xbird/srv-01

Note: You can override the settings by putting xbird.properties on the directory where System.getProperty("user.dir") specifies.

Starting a service

Just run a server as in this document where the remote query executed.

We assume here that the serive xbird/srv-01 is run at port 1099 on the host knuth.naist.jp.

Example Query

declare variable $remote-endpoint := "//knuth.naist.jp:1099/xbird/srv-01";
declare function local:remote-eval($colname) 
{
  execute at $remote-endpoint {
	for $a in fn:collection($colname)/site/closed_auctions/closed_auction
	where $a/price/text() >= 40
	return $a
  }/price
};
local:remote-eval("/repos/xmark1.xml")

Nesting distributed queries as in mapreduce1.xq can also be accepted.

Reference

• Makoto Yui, Jun Miyazaki, Shunsuke Uemura and Hirokazu Kato. ``XBird/D: Distributed and Parallel XQuery Processing using Remote Proxy'', In Proc. ACM SAC (DTTA track), pp. 1003-1007, 2008.