The benefits of location transparency in an SOA
By Jeff Hanson and Ryan Ireland, Builder.com
Monday, March 17, 2003 12:01 PM
One of the major benefits provided by a service oriented architecture (SOA) is
the decoupling of the client requesting the service and the service itself.
Through a registration and discovery mechanism, the SOA provides location
transparency, which allows clients to not know (or care) about where a component
or service is actually located. Let's take a look at some of the advantages and
disadvantages of location transparency.Monday, March 17, 2003 12:01 PM
Find out more about decoupling
To find out more about the benefits of decoupled systems, check out “Take advantage of the benefits of loosely coupled Web services.”
Location transparency means virtual platforms
A service is generally registered with a public or private registry, such as a database, a directory service, a UDDI registry, or an XML file. Once a service is registered, components that want to call the service may use the registry to locate and then call the service. The registration and discovery of the service are enabled through the SOA platform in a manner that releases the service from needing to know where or how it has been deployed.
This registration and discovery mechanism allows the location of a component or service to be unknown (or transparent) to the developer. In this way, a virtual platform in which all components or services seem to reside within the same machine or programming space is created, as illustrated in Figure A.
| Figure A |
 |
| Location transparency creates a virtual computing platform. |
The virtual platform illusion allows you to access both local and remote services using identical calls, an ability known as transparent access. To do this, references to services should be made abstractly, such as by using SOAP/HTTP. For example, the following SOAP envelope is passed as the reference information, providing the service name, operation name, and parameters for a stock quote service:
<?xml version="1.0"?>
<soap:Envelope
xmlns:soap=http://www.w3.org/2001/12/soap-envelope
soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
<soap:Body xmlns:m="http://www.stocksrus.com/stockquote">
<m:GetStockQuote>
<m:Symbol>MSFT</m:Symbol>
</m:GetStockQuote >
</soap:Body>
</soap:Envelope>
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