Transcript UDDI, Discovery and Web Services Registries

UDDI, Discovery and Web
Services Registries
Introduction
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To facilitate e-commerce, companies needed
a way to locate one another and exchange
information electronically
Organizations responded by creating their
own methods of publishing business-related
data on the Web and offering third parties
access to the data.
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inefficient, difficult and time-consuming
Introduction
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IBM, Microsoft and Ariba developed Universal
Description, Discovery and Integration (UDDI) to
address the problem
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A specification that defines registries in which
businesses can publish information about themselves
and the services they provide.
Service consumers can use UDDI registries to
locate general and technical information about
various service providers.
Consumers can initiate business transactions,
form partnerships and purchase services
Web Services Registries
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Web services registries
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Repositories containing documents that describe
business data
Provide features such as search capabilities and
programmatic access to remote applications
E.g.,
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Find the best Web service for credit card payments
Discovery
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The process of locating Web services
through registries
Two categories
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Direct discovery
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The process of obtaining data from a registry maintained
by the service provider
Improves the likelihood that data is accurate
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The organization providing the information also operates
the Web service
Discovery
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Indirect discovery
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Obtains data through a third-party registry
Data might not be as accurate
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because service providers might not update information in
thirdparty registries as frequently
When performing indirect discovery,
organizations must pose the question: How
often do third-party registries interact with
service providers to ensure that the data is
still accurate?
SOAP, UDDI and WSDL
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Technologies enable communication among
applications in a manner that is independent
of specific programming languages,
operating systems and hardware platforms
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SOAP provides a communication mechanism
between Web services and other applications
WSDL offers a uniform method of describing Web
services to other programs
UDDI enables the creation of searchable Web
services registries
Web Services Architecture
Universal Description, Discovery and
Integration (UDDI)
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In September 2000, the UDDI project - led by IBM,
Microsoft and Ariba - released Version 1.0 of the UDDI
specification
Defines a framework for centralized registries that
facilitate the storage, discovery and exchange of
information about businesses and their Web services
In June 2001, the UDDI project released a beta
specification of UDDI Version 2.0
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Offers advanced searching capabilities
Increases the global scope of UDDI registries
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E.g., provide company and product descriptions in various
languages
Operator Nodes and Registrars
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Operator node - an organization that hosts an
implementation of the UDDI Business Registry
(UBR)
Four operator nodes - Hewlett-Packard, IBM,
Microsoft and SAP - host beta implementations
of the UBR that adhere to the UDDI Version 2.0
Two operator nodes - IBM and Microsoft - host
implementations of the UBR that adhere to the
UDDI Version 1.0.
Operator Nodes and Registrars
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Replication
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the process of updating records so that all instances of
those records are identical
operator nodes synchronize their data at least every 12
hours
“Register once, publish everywhere" principle
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A company needs to register with only one operator node
to be listed in the UBR
Information contained in one registry is replicated in the
other registries
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when a company registers with one operator node (known as
a custodian), the company's data appears in the other three
registries, as well
Operator Nodes and Registrars
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A company can update its information only
through its custodian
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Because the UDDI Version 2.0 API Specification
does not provide a protocol for reconciling
disparate or duplicate data
Advantages of Registering
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Registering in the UBR offers advantages to both
service providers and service consumers
For service providers,
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the UBR is an effective method of advertising Web services
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Global visibility
Helps service providers expand their markets
For service consumers,
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the UBR saves time and simplifies the process of using
Web services
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Integrate applications with remote services more quickly and
efficiently
Do not have to spend time locating service-related information
Advantages of Registering
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The UBR also can reduce costs for service
providers and service consumers
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Service providers can advertise their businesses
and services for free
Service consumers can locate compatible Web
services for free
Role of UDDI in Web Services
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Vendors often compare the UBR' s structure
to that of a phone book
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The components of the UBR's phone-book
structure - white pages, yellow pages and green
pages.
White pages
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Contain general information about a company
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Such as its name, address, contact information and
identifiers.
Role of UDDI in Web Services
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Yellow pages
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divide companies into various categories on the
basis of their products or services
E.g., a software company might be categorized
under computer software or software engineering
Allow registry users to search for companies or
services that fit a particular category (such as
sales, travel or books)
Role of UDDI in Web Services
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Green pages
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Contain technical information about a company's
products, services and Web services
This data allows a service client to bind (i.e.,
establish a communication channel) to a Web
service, because the information defines how to
invoke the service.
UDDI Registries
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UDDI can be supported on both public and
private registries
Public registry
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E.g., the UDDI Business Registry (UBR)
Can be accessed by individuals or businesses
Private registries
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Restrict access to services
Impose additional security measures to safeguard
against unauthorized access
UDDI Business Registry
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Contains information about companies and
their technical capabilities
Allows service providers to organize and
describe Web services in a central location
Service consumers can browse this registry
to find information about businesses and
Web services
To post information in the UBR, businesses
need to register with the UDDI project
UDDI Business Registry
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The UBR usually is referred to as a Public Cloud
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The "UDDI Business Registry" consists of several
registries owned and maintained by public operator nodes
Data entered in one registry is replicated in the other
registries.
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The replication of data is guaranteed,
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Because the operator nodes are governed by the Operator's
Council
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A committee that consists of the current operator nodes
Governs the UDDI specifications and quality-of-service (QoS)
issues
Private Registries
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Limit access to Web services.
Restricting access to services can reduce
concerns regarding service-level agreements
and security
Implemented by organizations that are
uncomfortable exposing services in a public
forum
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Access to which is restricted to certain parties
E.g., the employees, partners and affiliates of a
particular company
Private Registries
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Companies are adopting private registries
more quickly than public registries
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Partly because most organizations want to
experiment with Web services by deploying them
internally before offering publicly accessible Web
services.
Organizations can use private registries to locate
services offered by their own departments or by
their partners
Limitations of UDDI
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Although UODI facilitates the discovery of Web
services, there are certain limitations to UODI
and UDDI registries.
The most significant limitation of UDDI is the
immaturity of the UDDI specification
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No "official" organization is controlling its development
The specification may change significantly in future
versions
Data reliability
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E.g., UBR does not indicate when data was last updated
or checked for accuracy
Limitations of UDDI
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UDDI registries describe Web services, but
do not evaluate them
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QoS?
E.g.,
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Service consumers might want to know the following:
How often can I access a certain Web service?
Will the Web service "crash" if numerous companies use
it simultaneously?
Does the service provider offer technical support? If so,
what is the turnaround time for resolving issues?