Java Reference
In-Depth Information
items described in XML, including prices. The procurement system could simply
display the results in a browser or store the results in a database for later access.
The Web services standard encapsulates these advantages. Web services are es-
sentially XML documents embedded in HTTP requests and responses. Web ser-
vices combine the expressiveness and flexibility of XML with the omnipresence of
the HTTP transport mechanism to create a powerful, adaptable, and standard in-
tersystem communication technology.
XML
AND
OAG
The Open Application Group (OAG) is an organization whose mission is to sim-
plify integration processes between business systems. OAG frequently addresses
integration issues as they apply to enterprise resource planning (ERP), accounting,
and human resource packaged application systems.
OAG has defined a set of XML DTDs and is promoting these document defin-
itions as standards for business documents, such as purchase orders and invoices.
They have also defined intersystem document types, such as journal transactions to
a general ledger system. Business applications that support these document defini-
tions can reliably integrate with other systems, even when the two systems come
from distinct vendors.
For example, an accounts payable system from one vendor can generate an
XML document that conforms to OAG's DTD specification for journals. An OAG-
compliant general ledger from another system can accept that document as input
and post the transactions in an appropriate manner.
The following is a sample journal DTD from OAG. It has been simplified
slightly from its complete representation. The complete OAG DTD specification is
included on the CD-ROM.
The sample begins with a pair of base DTDs named domains.dtd and fields.dtd.
These define the basic data type entity (STRDOM) and the field-level entity names
that will be used in the OAG documents.
ON THE DVD
<!-- String Data: Generic Data Domains -->
<!ENTITY % STRDOM "(#PCDATA)">
<!ELEMENT ACCTPERIOD %STRDOM;>
<!ELEMENT ACCTTYPE %STRDOM;>
<!ELEMENT ACCTYEAR %STRDOM;>
<!ELEMENT BUSNAREA %STRDOM;>
<!ELEMENT COSTCENTER %STRDOM;>
<!ELEMENT CURRENCY %STRDOM;>
<!ELEMENT DRCR %STRDOM;>
