The document discusses the key concepts and components of an enterprise service bus (ESB). An ESB acts as a centralized routing and mediation layer between services, facilitating loose coupling, policy enforcement, and management. Key components include proxy services that expose endpoints and routes, sequences to mediate and transform messages, and transports to connect various protocols. The ESB virtualizes endpoints, enables versioning and updates without disruption, and brings more order and consistency to service integration compared to direct connections.

1. UltraESB
Introduction in Depth

2. SOA
● Is about building an architecture as a set of
reusable software modules exposed as
“Services” with well defined interfaces
● The services facilitate loose coupling and
abstracts its implementation details from the
clients
● Stateless is the most optimal

3. SOA itself could end-up messy
If each component called on services directly

4. Some Common Issues
● How do you find which services are used, which are rarely used,
which can/should be retired etc?
● How do you find if any clients are using a particular service?
● How do you roll out updates to a service or expose new versions
to existing services without disruption?
● How do you support backwards compatibility for older clients
invoking older service interfaces
● How do you perform logging, auditing, security enforcement etc
across all services for internal / external traffic?

5. But with an ESB..
Always expose service endpoints on the ESB
- i.e. prevent direct service invocations

6. The ESB..
● Brings in more order
● Can strictly enforce corporate policies
● Where direct access (unless from the ESB) is prevented
● Security, throttling, auditing etc applied consistently
● Virtualizes service endpoints
● Facilitate versioning, flexible updates, HA by load balancing etc.
● Can perform routing, mediation, transformation, etc

7. ESB within an Organization

8. ESB as a Gateway
HTTP/S
AS2
S/FTP
Email

9. The view to a client of the ESB
* TransportListeners accept
messages from these
clients and injects to the
ESB for processing

10. The view to a Service or Partner
* TransportSenders sends
messages over the specific
transports to the external
services

11. Key Transports
● HTTP/S, TCP/S, Custom (e.g. LogB)
● JMS, AMQP
● Email
● S/FTP, FTPS, File (local / shared)
● Timed / Quartz Services
● Can be made to poll Databases for rows etc

12. Transports
● Are configured in the conf/ultra-root.xml
● Required transports needs to be enabled by including the
entries
● Any changes requires a cold restart
– unlike for services
● To receive HTTP
● To send HTTP

13. In Software Development
● Do not re-invent the wheel
● Use the best of breed components
● For some use cases maybe Oracle DB is great
● For some, MySQL maybe much better / cheaper

14. What the ESB is not..
● Relational database
● JMS Provider or AMQP Server
● SFTP server
● Email server
● Work flow engine etc
But each of these may be integrated with the ESB and into its flows
●
UltraESB does not ship any of these by default, the user is free to pick and
chose what they are used to, and what works best for the use case

15. Proxy Services – whats inside?
(uses
Transport
Senders)
(uses
Transport
Receivers)

16. Sequences
● Where user specifies the actions ESB should take on the
messages passing through
● InSequence – on “incoming” messages
● OutSequence – on “outgoing” messages
● e.g.
● Save a message or some of it into a database
● Parse a message and make a decision on where to send it onwards
● Log into a file or write an audit entry to a database
● Transform the messages to another format

17. Endpoints
● Specifies to the ESB where to send a message and how to send it
● Specified as one or more (LB/FO) “addresses”
● Address → a URL address
– Absolute URL (SOAP, SFTP etc) or a prefix (REST)
● Special address of type “response”
– Send a response over the incoming message channel (e.g. HTTP)
● In Destination and outDestination
● Specify default endpoints for incoming and outgoing messages
● A sequence can override and send to a selected Endpoint
● instead of the default if specified

18. A Proxy Service configuration

19. Sequences, Interceptors & Mediation
msg
mediation
logger
Fragment, Class, Spring bean..
Native byte code execution
Use try-catch-finally
Javadoc for API

20. Endpoints

21. Some possible combinations