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• XML/Java databinding frameworks
  • SDO
  • JAXB
  • XMLBeans
  • Castor
  • AxiomAXIOM
  • JavaBeansFastInfoset
• XML Parsing Technologies
  • SAX (InputSource, ContentHandler)
  • DOM (Node)
  • StAX (XMLStreamReader/XMLStreamWriter/XMLEventReader/XMLEventWriter)
• I/O
  • InputStream/OutputStream
  • Reader/Writer
  • byte[] or String
• Other
  • JavaBeans
  • Simple Java Types
  • JSON

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interfaces for services and references are the contracts for SCA assembly.

1. Incoming data for component implementation

2. Interace mapping

• interface.java <--> interface.java
• interface.wsdl <--> interface.java
• interface.wsdl <--> interface.wsdl
• interface.* <--> other

Mapping from interface.wsdl to interface.java

JaxbAddress getAddress(JaxbCustomer customer)

SdoAddress getAddress(SdoCustomer customer)

Data Transformations

How to transform data across databindings

Data Transformations

How to transform data across databindings

• A databinding is a terminal for the data transformation
• Three types of databindings depending on how the data is represented by the databinding
  • Some databindings can feed the data for consumption
  • Some databindings serve a sink to receive data
  • Some databindings
• A databinding is a terminal for the data transformation
• Three types of databindings depending on how the data is represented by the databinding
  • Some databindings can feed the data for consumption
  • Some databindings serve a sink to receive data
  • Some databindings can bridge the sink so that data coming into the sink can be consumed by others
    Scenario 1: Source --> Source
    Scenario 2: Source --> Sink
    Scenario 3: Sink --> Source (Pipe)

How to use databindings?
Declare the data binding for the interfaces

• Data Binding requirement can be expressed as:
  • SCDL extension

<interface.wsdl ...>
<db:databinding xmlns:db="http://tuscany.apache.org/xmlns/sca/databinding/1.0" name="commonj.sdo.DataObject">
</interface.wsdl>

Java annotations for a remotable interface

• @DataType can be applied to remotable interfaces at type and method level

@Remotable
@DataType(name="org.w3c.dom.Node")
public interface Interface2

the data binding for the interfaces

• Data Binding requirement can be expressed as:
  • SCDL extension

@Remotable
public interface MyInterface {
   

{ Node call(Node msg); @DataType(name="javax.xml.stream.XMLStreamReader") 
    XMLStreamReader call1(XMLStreamReader msg); 
}

Fine-grained databinding control

Java annotations for a remotable interface

What's behind the magic?

Load and build the data binding metadata

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• The transformers are registered and selected using the following algorithm.
  • The data transformation capabilities for various databindings can be nicely modeled as a weighted, directed graph with the following rules. (Illustrated in the attached diagram).
  • Each databinding is mapped to a vertex.
  • If databinding A can be transformed to databinding B, then an edge will be added from vertex A to vertex B.
  • The weight of the edge is the cost of the transformation from the source to the sink.
• In the data interceptor on the wire, if we find out that the data needs to be transformed from databinding A to databinding E. Then we can apply Dijkstra's Shortest Path Algorithm to the graph and figure the most performed path. It can be A->E, or A>C->E depending on the weights. If no path can be found, then the data cannot be mediated.
  Transform data
• Direct transformation

• Multi-hop transformation

Deal with different IDLs
Dealing with WSDL/XSD based IDLs

• SCA allows the interfaces to be defined using various IDLs, for example, java interface or WSDL portType
• IDLs may have different ways to represent the input/output/fault data
• The databinding framework is designed to support the transformation across IDLs
• Some special databindings are internally used for this purpose:
  • idl:input
  • idl:ouput
    Dealing with WSDL/XSD based IDLs
• WrapperHandler
  • Provide WrapperStyle WSDL wrapping/unwrapping support

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