Ibm Websphere Esb Placement Papers - Ibm Websphere Esb Interview Questions and Answers updated on 16.Aug.2022

SDO: Service Data Object is the representation of the variable or Object.

SMO: The SMO model is a pattern for using SDO Data Objects to represent messages

By using Fan-in and Fan-out primitive.

The SMO model is a pattern for using SDO Data Objects to represent messages.

The SMO contains a representation of the following groups of data:

  1. The business payload of the message. The payload is the application data exchanged between service endpoints.
  2. Header information associated with the message. For example, Java Message Service (JMS) headers if a message have been conveyed using the JMS API.
  3. Context information (data other than the message payload).

Data Source need to be created and need to configure with DB. If we have security, then need to created security authentication.

Stop: Stops a particular path in the flow, without generating an exception.

Fail: Generates a failure in the flow.

We have different types of primitives in mediation.

Message Filter

  1. Type Filter
  2. Endpoint Lookup
  3. Service Invoke
  4. Fan-out
  5. Fan-in
  6. XSLT
  7. BO Map
  8. Message Element Setter
  9. DB lookup
  10. Data Handler
  11. Custom Mediation
  12. Header Setters
  13. Message Logger
  14. Even Emitter
  15. Stop
  16. Fail
  17. Sub Flow

Fan-out:We can use the Fan Out primitive to fire the output terminal once (with the  input message) or to fire the output terminal multiple times. You can use Fan Out in isolation or as part of a Fan Out and Fan In combination.

Fan-In: Fan In is always partnered with a Fan Out in the same flow and acts   as a decision point for when to continue flow execution. It receives a number of messages until a decision point is reached, at which point the last message to be received is propagated to the output terminal. The Fan In primitive may only be used in combination with Fan Out. 

We have future called Promotable properties in ESB. We can configure this future while development. Then we can make it changed at runtime without restarting  the server it can be published.

@Shared Context: Context is a temporary area which is created along with   Service Message Object (SMO) in the Mediation Flows. Shared Context is a type of context which is present in the SMO. Shared Context is mainly used   when we are using Aggregation process where we need to Iterate the BO for Certain times. Shared Context maintains Aggregation data between Aggregation (FanOut and FanIn) primitives. The Content (data) which is present in the shared context BO does not persist across Request and Response flows i.e The Data in the Shared Context which is used in Request flow can not be used again in Response flow.

@Trient Context: Used for passing values between Mediation primitives within the current flow — either the request flow or the responses flow. The trient context cannot link requests and responses and hence cannot be used across.

Used when you want to save an input message before a service invokes call(within a request or response flow). After the services invoke call, the next primitive can create another message by combining the service invoke response and the original message stored in the trient context.

@Correlation Context: Used when Mediation primitives want to pass values from the request flow to the response flow. Used to pass values from the request message onto the response.

An enterprise service bus (ESB) is software architecture for middleware that provides fundamental services for more complex architectures. For example, an ESB incorporates the features required to implement a service-oriented architecture (SOA). In a general sense, an ESB can be thought of as a mechanism that manages access to applications and services (especially legacy versions) to present a single, simple, and consistent interface to end-users via Web- or forms-based client-side front ends.

Service Invoke: The Service Invoke primitive is used to make a service request in either a request or response mediation flow. The service may be Request/Response or One-Way. Multiple instances of the Service Invoke primitive are permitted in a flow, allowing a series of service invocations to be performed. 

Callout: The Callout receives the message and calls the requested service and operation. There is a Callout node for each connected target operation in the mediation flow.

  1. If the call is successful, the Callout Response node in the response flow receives the response message.
  2. If the call is unsuccessful, the Callout can be set to retry service invocations depending on the type of fault received.