Tuesday, September 20, 2005

Web Service Protocol Stack in a Nutshell

The Web service protocol stack is the collection of computer networking protocols that are used to define, locate, implement, and make Web services interact with each other.

The Web service protocol stack is mainly comprised of four areas:
  1. Service Transport: It is responsible for transporting messages between network applications and includes protocols such as HTTP, SMTP, FTP, as well as the more recent Blocks Extensible Exchange Protocol (BEEP).
  2. XML Messaging: It is responsible for encoding messages in a common XML format so that messages can be understood at either end of the network connection. Currently, this area includes such protocols as XML-RPC and SOAP.
  3. Service Description: It is used for describing the public interface to a specific web service. The WSDL protocol is typically used for this purpose.
  4. Service Discovery: It centralizes services into a common registry such that network web services can publish their location and description, and makes it easy to discover what services are available on the network. At present, the UDDI protocol is normally used for service discovery.
Using XML as Part of Web Services:

XML: All data to be exchanged is formatted with XML tags. This encoding can be performed by SOAP or XML-RPC (note: industry standards for security, interoperability, etc. are based on SOAP).

Common protocols: XML data can be transported between applications using common protocols such as HTTP, FTP, SMTP and XMPP.

WSDL: The public interface to the web service is described by Web Services Description Language, or WSDL. This is an XML-based service description on how to communicate using the web service.

Monday, September 19, 2005

Elements of the Java Platform: An Outline

Here are the key elements that make up Java. as a platform:

Virtual Machine – (JVM)
Java API – ready made software components; grouped into libraries (packages):
  • Objects, strings, threads, I/O
  • Applets
  • Networking (TCP, UDP)
  • Internationalisation
  • Security
  • Software like Javabeans
  • Object Serialisation (RMI)
  • JDBC
Java Program
Java API
Java Virtual Machine
Hardware-Based Platform

Seven Stages of Soft Systems Methodology

In a nutshell, here are the seven stages of SSM:

1. Unstructured Problem Situation -find as much info as possible, accept many different views
2. Expressed Problem Situation – drawing rich pictures, show problem and relationships
3. Root Definitions - Tighten the constructed description of human activity system, Use the CATWOE technique
4. Build Conceptual Models - Logical model of key activities and processes to satisfy root definition
5. Compare conceptual models with reality - Different alternative models can be compared to reality
6. Accessing feasible and desirable change - An analysis of the proposed changes can be made, feasible and desirable?
7. Action to improve the problem situation - Application of the model. SSM does not describe methods for implementing solutions! Only provides a framework through which problem situations can be understood.