Transcript Added Value to XForms by Web Services Supporting XML

Added Value to XForms by Web Services
Supporting XML Protocols
Elina Vartiainen
Timo-Pekka Viljamaa
T-111.590 Research Seminar on Digital Media
Autumn 2004: Web Service Technologies
9.12.2004
Agenda
• Introduction
• Background
• XML, XForms, Web services, JMS
• Objective and motivation
• Use cases
• Results
• Implementation and demo
• Comparison to HTTP and possible other implementations
• Conclusions
Introduction
• XForms is developed by W3C to overcome the limitations of
HTML forms and is based on XML
• Web services are a technology that provides interoperability
between different platforms
• XForms can be configured to submit any XML data
• XForms can be connected to Web services by defining the
submission data to be a SOAP message
Introduction (cont.)
• Today, the main transfer protocol of XForms and Web services
is HTTP.
• Both are designed to allow other future transmission
methods, for example, non-HTTP transfer protocols
• The goal of the paper is to examine, if Web services could
bring added value to the XForms
Background
XML:
• Flexible markup language derived to describe the structure of
documents
• No predefined tag set
• All semantics are defined either by the processing applications
or style sheets
Background (cont.)
XForms:
• XML application that represents the next generation of forms
for the World Wide Web
• Separates the purpose from the presentation
• Enables the developer to design different user interfaces,
without having to change the actual data
• May be integrated into any suitable markup language
Background (cont.)
Web services:
• Software systems designed to support interoperable machineto-machine interaction over a network
• XML, WSDL, SOAP and UDDI as key standards for Web
services
• Web services describe themselves with WSDL
• SOAP defines a common format for XML messages
• UDDI is the group of registries that expose information about a
business and its technical interfaces
Background (cont.)
Java Messaging Service (JMS):
• Allows applications to create, send, receive, and read
messages
• Loosely coupled messaging
• Also provides asynchrony and reliability
Objective and motivation
• Limitations of HTTP:
• No support for asynchrony
• No selectable routing
• No sufficient reliability or security
• Statelessness
• Objective:
• If the limitations of HTTP are solvable
• If potential new features and functionalities exist
• Motivation:
• Explore relatively familiar technology: XForms
• Connect it to Web services and XML protocols
Use cases
• Finding and using a Web service
• Giving an order
• Multi-phased ordering
• Payment of an order
• Administration of distributed systems
• Cache
• Chat application
Results
• Implementation of use case, in which a customer locates the
web service (calculator) from an UDDI repository
• Java and Apache SOAP running on Apache Jakarta Tomcat
application server
• UDDI repository used was provided by IBM
Results (cont.)
Results (cont.)
Comparison to HTTP
• Preceding kind of functionality is
not standardized
• could be implemented with a
database and a dynamic web
page
• Inefficiency of SOAP
• multiple system calls to send
one logical message
• XML parsing and formatting
time
• Delay in the request caused by the
interaction between the Nagle
algorithm and TCP delayed ACK
algorithm
Results (cont.)
• Implementation of use case for asynchronous messaging was
specified using XForms, Java Messaging System (JMS), and
Apache Axis
Results (cont.)
Comparison to HTTP and other possible implementations
• Asynchronous messaging using only HTTP creates a lot of
overhead (288kB/24h with 1kb/10min) in the network
• Messaging is client initiatiated
• Specification is done using current technologies
• Not the most optimal one in the future
• SOAP 1.2 specification allows to replace HTTP with any
protocol, also with asynchronous messaging protocols, as
long as the protocol binding conforms to SOAP’s binding
framework
Conclusions
• XForms and Web services can overcome the limitations of
HTTP
• Exists many use cases for the integration of XForms and Web
services that bring added value to the user
• Integration is implementable and useful in practice
• Proved by our implementation