Patterns: Implementing Self-Service in an SOA Environment

118 Patterns: Implementing Self-Service in an SOA Environment

򐂰 Message internationalization

򐂰 Hard coded JSP URIs

Struts is widely used, and supported by most J2EE IDE tools (including Rational

Software Architect and Rational Application Developer). However, JavaServer

Faces are likely to become the industry standard, because it has been adopted

as a J2EE standard. There are many similarities between the two frameworks,

and, in fact, many of the concepts originated in Struts were adopted in the JSF

specification.

6.3.5 Service Data Objects

Service Data Objects (SDO) is a data programming architecture and API for the

Java platform that unifies data programming across data source types, provides

support for common application patterns, and enables applications, tools, and

frameworks to more easily query, view, bind, update, and introspect data. SDO is

currently the subject of a Java specification request (JSR-235), but has not yet

been standardized under this process.

SDOs are designed to simplify and unify the way in which applications handle

data. Using SDO, application programmers can uniformly access and manipulate

data from heterogeneous data sources, including relational databases, XML data

sources, Web services, and enterprise information systems. The SDO

architecture consists of three major components:

򐂰 Data object

The data object is designed to be an easy way for a Java programmer to

access, traverse, and update structured data. Data objects have a rich variety

of strongly and loosely-typed interfaces for querying and updating properties.

This enables a simple programming model without sacrificing the dynamic

model required by tools and frameworks. A data object may also be a

composite of other data objects.

򐂰 Data graph

SDO is based on the concept of disconnected data graphs. A data graph is a

collection of tree-structured or graph-structured data objects. Under the

disconnected data graphs architecture, a client retrieves a data graph from a

data source, mutates the data graph, and can then apply the data graph

changes to the data source. The data graph also contains some metadata

about the data object including change summary and metadata information.

The metadata API allows applications, tools, and frameworks to introspect the

data model for a data graph, enabling applications to handle data from

heterogeneous data sources in a uniform way.

򐂰 Data mediator