Cost-Based Optimization of Integration Flows - Datenbanken ...

2 Preliminaries and Existing Techniques
integration flow. Second, the flow meta model describes the operational aspects in terms
of the control flow and the data flow.
Message Meta Model
Assume a sequence 2 of incoming messages M = {m 1 , m 2 , . . . , m n } that is processed by an
integration flow. We model each message m i as a (t i , d i , a i )-tuple, where t i ∈ Z + denotes
the incoming timestamp of the message, d i denotes a semi-structured (self-describing) tree
of name-value data elements that represents the payload of the message, and a i denotes a
list of additional, atomic name-value attributes, which is used for meta data and message
protocol information.
Example 2.3 (Order Message). We assume a simple order message that has been received
from a Web shop in the form of a proprietary binary message. This message has been
transformed into an internal XML representation by an inbound adapter:
ti = 61238178981000 //Fr Jun 25 7:16:21 2010
di = "
7000000
1001
2010-06-25
398.80
109 4.0
49.95 1
Color: blue
57 1.0
199.00 1
"
ai = msgtype,
"web_order";
RcvPort, "5010"’;
RcvAdapter, "WSO";
We received this message at timestamp t 1 = 61238178981000 (Fr Jun 25 7:16:21 2010).
The content of the message is represented by the semi-structured tree of data elements d i ,
which includes the general order information as well as two detailed orderlines. Finally,
the list a i of key/value pairs is used to hold meta data such as the message type that has
been annotated by the configured inbound adapter instance.
Using the tree of name-value data elements d i , we can represent heterogeneous data
formats and all operators can be realized according to this internal representation.
2 We use the term sequence for finite and infinite sequences (or synonymously streams) of incoming
messages. In case of infinite sequences, we have n = ∞.
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