Interview Questions on SOA and OSB

1) BPEL/OSB – File Adapter – Polling in Cluster – Need to conf in order to read only one file at a time (create only one instance in SOA)

https://forums.oracle.com/forums/thread.jspa?messageID=10181951

we need to singleton property!

Singleton Services : are services which must run only on one server at given time. In OSB cluster most of services run on all servers which are part of cluster however some services must run on only one server at a time . Singleton Services for OSB include
a) File, FTP and E-Mail Pollers for Proxy Services
b) SLA Manager
c) JMS Server
d) ALSB domain Singleton Marker Application

2) Schema – Difference between Include and Import in XSD

The fundamental difference between include and import is that you must use import to refer to declarations or definitions that are in a different target namespace and you must use include to refer to declarations or definitions that are (or will be) in the same target namespace.

3) BPEL – Correlation Set – can have different data types for each correlation elements?

Elements can be different names and in different structures in the two messages, but they must contain the same value if correlation is to work.

https://blogs.oracle.com/reynolds/entry/bpel_correlation
4) OSB- How to make the business service to propagate the error to proxy service

When the value of the qualityOfService element is best-effort for a publish action, all errors are ignored. However, when the value of the qualityOfService element is best-effort for a route node action or a Service callout action, any error will raise an exception.

http://docs.oracle.com/cd/E17904_01/doc.1111/e15867/modelingmessageflow.htm#i1134374

Exactly once reliability means that messages are delivered from inbound to outbound exactly once, assuming a terminating error does not occur before the outbound message send is initiated. Exactly once means reliability is optimized.

Best effort means that there is no reliable messaging and there is no elimination of duplicate messages—however, performance is optimized.

• Service callout action — always best-effort, but can be changed if required.
• Publish action — defaults to best-effort, modifiable
• Route node is best-effort for the following inbound transports:
  • HTTP
  • JMS/nonXA
  • Non-Transactional Tuxedo
• Route node is exactly-once for the following inbound transports:e-mail
  • FTP
  • File
  • JMS/XA
  • SFTP
  • Transactional Tuxedo

5) WebLogic- Connection pooling means what. Why we need it?

WebLogic communicates with the database through a connection pool. The connection pool enables WebLogic to use a fixed number of connections to databases rather than incur the overhead of constantly creating and disposing of connections. Because of this, you must establish a data connection pool that accesses your database.

In Oracle words… A connection pool contains a group of JDBC connections that are created when the connection pool is registered, usually when starting up WebLogic Server. Your application borrows a connection from the connection pool, uses it, then returns it to the connection pool by closing it.

6) WebService – Difference btw SOAP and Rest?
7) OSB/BPEL – How to make HTTP call? Not SOAP over HTTP
8) General / BPEL – Diff btw Synch and Asynch invocation?
9) BPEL – Non-blocking Invoke means what?

Flow in BPEL (or at least Oracle BPEL PM) allows for parallel branches of activities. When executed, the branches in the Flow get their turn to execute the next step. Steps are not truly executed at the same time – which may be a blessing in disguise in situations where activities in various branches access the same variables. Even synchronous calls with nonBlockingInvoke set to true block other activities from being processed.

10) Transaction handling in OSB

http://atheek.wordpress.com/2011/04/21/transaction-handling-within-osb/