XML Interface for Network Services
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XML Interface for Network Services (XINS) is an open source technology for definition and implementation of internet applications, which enforces a specification-oriented approach.
The specification-oriented approach is at the heart of XINS:
- first specifications need to be written;
- then documentation and code is generated from these specifications;
- then both testing and implementation can start.
From specifications, XINS is able to generate:
- HTML documentation
- test forms
- SOAP-compliant WSDL
- a basic Java web application
- unit test code (in Java)
- stubs (in Java)
- client-side code (in Java)
Components of the XINS technology
Technically, XINS is composed of the following:
- An XML-based specification format for projects, APIs, functions, types and error codes
- A POX-style RPC protocol (called the XINS Standard Calling Convention), compatible with web browsers (HTTP parameters in, XML out).
- A tool for generating human-readable documentation, from the specifications.
- A tool for generating WSDL, from the specifications.
- A Log4J-based technology for logging (called Logdoc), offering a specification format, internationalization of log messages, generation of HTML documentation and generation of code.
- A Java library for calling XINS functions, the XINS/Java Client Framework; in xins-client.jar.
- A server-side container for Java-based XINS API implementations, the XINS/Java Server Framework; in xins-server.jar. This is like a servlet container for XINS APIs.
- A Java library with some common functionality, used by both the XINS/Java Client Framework and the XINS/Java Server Framework: the XINS/Java Common Library, in xins-common.jar.
An introductory tutorial called the XINS Primer takes the reader by the hand with easy-to-follow steps to perform, with screenshots.
Since version 1.3.0, the XINS/Java Server Framework supports not only POX-style calls, but also SOAP and XML-RPC. And it supports conversion using XSLT. As of version 2.0, it also supports JSON and JSON-RPC.
XINS is open-source and is distributed under the liberal BSD license.
All XINS specification files are Plain Old XML. Compared to SOAP/WSDL/UDDI/etc. the format is extremely simple. There are specifications for projects, environment lists, APIs, functions, types and error codes.
Below is an example of a XINS project definition.
<project name="MyProject" domain="com.mycompany"> <api name="MyAPI"> <impl/> <environments/> </api> </project>
Here is an example of a specification of an environment list:
<environments> <environment id="netarray" url="http://xins.users.mcs2.netarray.com/myproject/xins/"/> </environments>
An example of an API specification file:
<api name="MyAPI"> <description>My first XINS API</description> <function name="Hello"/> </api>
An example of a function definition:
<function name="Hello"> <description>Greets the indicated person.</description> <input> <param name="name" required="true"> <description>The name of the person to be greeted.</description> </param> </input> <output> <param name="greeting" required="true"> <description>The constructed greeting.</description> </param> </output> </function>
The XINS Standard Calling Convention is a simple HTTP-based RPC protocol. Input consists of HTTP parameters, while output is an XML document. This approach makes it compatible with plain Web browsers.
Example of a request:
Example of a successful response:
<result> <param name="greeting">Hello John Doe!</param> </result>
There are no known products that provide an integrated approach to specification-oriented development, similar to XINS. However, there are several frameworks and libraries that provide functionality similar to individual parts of XINS, including:
- JWSDP: Collection of various XML and SOAP technologies for the Java programming language.
- Apache Axis: Java-based framework for SOAP implementations.
- Codehaus XFire: Idem.
- Hessian Web Service Protocol: Binary alternative to the XINS Standard Calling Convention.