Based on the paper

1
Web Services Myths Around it

• Based on the paper
• Myths around Web Services
• by Gustavo Alonso

Debashis Roy Deepa Saha
2
What is claimed?

• Web service is a natural evolution of
  conventional middleware necessary to meet the
  challenges of the Web and of B2B application
  integration.
• Author discusses the challenges and solutions
  that remain relevant regardless of how emerging
  standards and technologies evolve.

3
How the claim is proved?
M Y T H S

• Web services are an accepted dominant standard.
• Web services are the best way to implement
  conventional applications.
• Web services provide a direct link between
  middleware platforms of different corporations.
• Dynamic binding will be a common way of working
  with web services.
• All data will be in XML.

4
Outlook towards Web services

• A revolutionary technology
• radical change in middleware, application
  integration use of internet.
• An evolutionary step
• An additional layer on top of existing middleware
  and EAI platforms.

5
1-tier architecture
2-tier architecture
3-tier architecture
6
Web Services Myths Around it
From Middleware to Web Services
7
Middleware

• Basic infrastucture behind distributed
  information system
• Interaction between applications across
  heterogeneous platforms
• Solution to integrating set of servers and
  applications under a common service interface

8
Programming Languages
Databases
Middleware Systems
Operating Systems
Distributed Systems
Networking
9
Types of middleware

• RPC based systems
• Transforms procedure calls to remote procedure
  calls
• Foundation of web services middleware
• TP monitors
• RPC system with transactional capabilities
• Object brokers
• RPC system with object-oriented aspect
• Object monitor
• TP monitors with object-oriented aspect
• Message-Oriented Middleware (MOM)
• TP monitors with persistent message queuing
  feature
• Message brokers
• MOM with message filtering and transforming
  capability

10
Enterprise Application Integration (EAI)

• Extends middleware capabilities to cope with
  application integration
• Uses application logic layers of different
  middleware systems as building blocks
• Integrates applications and enterprise data
  sources so that they can easily share business
  processes and data

11
Middleware
Middleware
EAI
Middleware
Middleware
Middleware
Middleware
12
Web Technologies
.Intra-enterprise application integration
Web Technology
Inter-enterprise application integration
Web browsers HTML, Java
Web Server
Middleware Server
Databases
Legacy Systems
13
Web Services

• A way to expose the functionality of an
  information system and making it available
  through standard web technologies.

a software application identified by a URI,
whose interfaces and bindings are capable of
being defined, described, and discovered as XML
artifacts. A Web service supports direct
interactions with other software agents using
XML-based messages exchanged via Internet-based
protocols W3C
14
Web Services Myths Around it
Web Services Architecture
15
The two Facets of Web Services architecture

• Internal architecture
• Web services expose internal operations to be
  invoked through the web
• Receive requests through the web
• Pass the requests to the underlying IT system
• External architecture
• A middleware architecture which integrates
  different web services

16
Web service architecture comprises Internal and
external architecture
17
Clients from other companies
Conventional Middleware
Basic architecture of a Web service implemented
atop a tiered architecture
18
External architecture of Web services
19
Web Services Myths Around it
A Quick Overview of Web Services
20
Web Service Components

• Web service architecture has three components
• Service requester
• Service provider
• Service registry
• Basic infrastructure is implemented with
• UDDI
• A name and directory server
• WSDL
• A way to describe services
• SOAP
• A way to communicate

21
Universal Description, Discovery and Integration

• A specification that defines
• how to interact with a registry
• What the entries on the registry look like
• Interaction with UDDI
• Registration
• Adding new service descriptions to the registry
• Lookup
• Queries to search for right services
• Types of UDDI registry
• Public
• Open search-engines for web services
• Private
• Created by companies for their own use

22
Web Services Definition Language

• Defines the interface to a web service
• Types
• XML schema describing used data types
• Messages
• Necessary to invoke an operation of the service
• Operations
• Reference to input/output message
• Port type
• Set of operations that conform an instance of a
  service
• Binding
• Actual protocol to be used to invoke the
  operations
• Services and ports
• References to actual location of service

WSDL Specification
Abstract Part
Types
Message
Port Type
Operation
Operation
Concrete Part
Binding
Service
Port
23
Simple Object Access Protocol

• A specification of a protocol wrapper
• Interaction between requester, provider and
  registry happen through SOAP
• Provides a standardized way to
• Transform different protocols
• Interaction mechanisms into XML documents

24
Publish
Interaction among the Web service components
25
Web Services Myths Around it
The Myths Around Web Services
26
Web services and standards

• Assumption
• Most applications will speak and understand XML
• All systems will support SOAP
• Everybody will advertise their service in UDDI
  registries
• All services will be described in WSDL
• Reality
• Standards no longer means globally unique in the
  B2B world.
• Other competing B2B standards coexist
• In manufacturing Electronic Data Interchange
  (EDI)
• In financial world Society for World-wide
  Interbank Financial Telecommunication (SWIFT)

27
Web services and standards.(contd.)

• Fact
• Web services are biased towards the protocols,
  representation and standards of their underlying
  middleware.
• Web services add a new layer to the complex
  multi-tier architecture
• Translation to and from XML
• Tunneling of RPC through SOAP
• Clients embedded in web servers
• Alternative port types
• Problems
• Addition of a new layer on top of the complex
  multi-tier system
• Adds significant performance overhead
• Developing, tuning, maintaining and evolving of
  multi-tier systems becomes more complex.

28
Web Services in Conventional Applications

• Conventional applications using web services
• Flight reservations
• Car rental
• Hotel booking, etc.
• All of them are B2C but web services were created
  for B2B applications.
• There are some applications which can be
  implemented with web services but that might not
  be the best way
• Applications that sends periodic bug reports
• Applications that automatically download or
  install patches
• Systems that use remote service to provide a
  functionality

29
Web Services in Conventional Applications.
(contd.)

• Problems
• Web services are loosely coupled
• Not suitable for atomic transactions among
  financial institutions
• Trust
• Can applications trust external web services?
• Semantics
• Web services cannot ensure that the remote
  application receives understandable data.

30
Direct Connectivity Across Corporate Boundaries

• Claim
• Web services provide a direct link between
  middleware platforms of different corporations.
• Problem
• The complexities of application integration and
  software design increase.
• Claim
• Using RPC through SOAP is a gateway to
  interconnect the IT infrastructure of different
  companies.
• Reality
• RPC results in a tight integration among the
  components and make them dependent on each other.

31
UDDI and Dynamic Binding

• Functionality
• UDDI registries are web services catalogues for
  humans only.
• Semantic interpretation of parameters and
  operations
• Interaction between companies are regulated by
  contracts
• Software Engineering
• Dynamic binding does not make sense for web
  services.
• UDDI registry cannot do any load balancing nor
  any automatic redirection to a different URI in
  case of failure.

32
All Data will be in XML

• XML is a performance nightmare.
• Some data types does not get along well with it.
• In many cases application data need not to be in
  XML.
• XML can be used for linking heterogeneous
  systems.
• If data format is decided, then XML becomes the
  syntax of SOAP only.

33
Conclusion

• This paper intends to give a coherent picture of
• What web services are
• What they contribute
• Where they will be applied

Web services are, at the current stage, only a
natural evolutionary step from conventional
application integration platforms.
34
Web Services Myths Around it
Questions? and may be Answers