112 Patterns: Extended Enterprise SOA and Web Services
encapsulated reusable business function and explicit implementation- indepen-
dent interfaces within the enterprise.
Service Consumers and Service Providers replace the Application Server and
Services from the generic profile.
6.4 Exposed Broker runtime pattern
The Exposed Broker runtime pattern applies to solutions where the source
application starts an interaction that is distributed to multiple target applications
across organizational boundaries. It allows a single interaction from a partner’s
source application to be distributed to multiple target partner applications
concurrently. It separates the application logic from the distribution logic based
on broker rules from the Rules Directory.
The Exposed Broker pattern reuses the Exposed Direct Connection pattern to
provide connectivity between the tiers. The Broker Rules tier can support
Message variation or Call variation (or both variations) of the Exposed Direct
Connection pattern.
6.4.1 Generic profile
The Broker Rules tier of the application pattern is implemented in this Runtime
pattern with an Exposed Broker node as shown in Figure 6-4 on page 113. The
Exposed Broker node is responsible for the routing and distribution of incoming
or outgoing messages to the target applications. It has the ability to decompose
and recompose messages. It also includes functionality to include external
partners by exposing their processes to internal processes.
Chapter 6. Extended Enterprise runtime patterns 113
Figure 6-4 Exposed Broker runtime pattern: generic profile
The Directory and Security Services supplies authentication and authorization
services. It also holds the user ID and password and related privileges. This node
typically leverages LDAP-based directories. It also contains configuration
information needed to support secure access between the enterprise and
partner services.
The Application Server and Services nodes execute the logic of the target and
source applications.
6.4.2 SOA profile
In the SOA profile for the Exposed Broker runtime pattern, the Exposed Broker,
Rules Directory and Partner Infrastructure are specialized as shown in Figure 6-5
on page 114 to instead become:
an Exposed ESB Gateway
an ESB
Service Consumers and Providers
Inter-enterprise
Zone
Enterprise
Demilitarized Zone Enterprise Secure ZonePartner Zone
App Server/
Services
App Server/
Services
Network
Infrastructure
Domain FirewallDomain Firewall
Exposed
Broker
Protocol FirewallProtocol Firewall
Connector
App Server/
Services
App Server/
Services
App Server/
Services
Rules
Directory
Directory
& Security
Services
Broker
Rules
Source
Application
Exposed Broker
Target
Application
Partner A
Target
Application
Partner B
Target
Application
Partner C
WIP
Broker Rules &
WIP Results
114 Patterns: Extended Enterprise SOA and Web Services
Figure 6-5 Exposed Broker runtime pattern: SOA profile
The Exposed ESB Gateway provides support for the exposed requirement of the
Extended Enterprise pattern. It provides a single point of access between:
External Service Consumers and Service Providers in the Enterprise Secure
Zone
Service Consumers in the Enterprise Secure Zone and external Service
Providers
The Exposed ESB Gateway secures the connection between enterprises and
provides namespace mapping.
The ESB meets the broker and rules directory requirement of the Runtime
pattern generic profile, but also gives support for the SOA infrastructure by
providing for service location transparency and interoperability, encapsulated
reusable business function and explicit implementation-independent interfaces
within the enterprise.
Service Consumers and Service Providers replace the Application
Server/Services in the generic profile.
Inter-enterprise
Zone
Enterprise
Demilitarized Zone Enterprise Secure ZonePartner Zone
App Server/
Services
App Server/
Services
Network
Infrastructure
ESBESBESB
Domain FirewallDomain Firewall
Exposed
ESB
Gateway
Protocol FirewallProtocol Firewall
Connector
App Server/
Services
App Server/
Services
<Service Consumer>
App Server/
Services
<Service Provider>
Directory
& Security
Services
Broker
Rules
Source
Application
Exposed Broker
Target
Application
Partner A
Target
Application
Partner B
Target
Application
Partner C
WIP
Broker Rules &
WIP Results
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