WCF Interview Questions and Answers
Question - 91 : - What message encoding formats are available in WCF?
Answer - 91 : -
- Text – For interoperability
- MTOM (Transmission Optimization Mechanism) – For transferring large objects
- Binary – For speed
Question - 92 : - What are the 2 ways available for configuring bindings in WCF?
Answer - 92 : -
- Declaratively using a configuration file
- Programmatically in the code.
- Using a configuration file has several advantages.
Question - 93 : -
Answer - 93 : -
MTOM stands for Message Transmission Optimization Mechanism and is an Interoperable standard that reduces the overhead of large binary data transfer. Removes bloat and processing overhead of base64 encoded data. Improves overall message transfer performance.
What are the advantages of using Percall instancing mode in WCF?
Answer - 94 : -
In a Percall instance mode, a new service instance (object) is created for each call. The following are the advantages and Disadvantages of Percall instance mode.
Advantages:
- Less memory consumption
- Service instances are freed
- Concurrency is not an issue
- PerCall services increase overall throughput
Disadvantages:
- State not maintained between calls
Question - 95 : - What are the four-session types available in WCF?
Answer - 95 : -
- Transport session
- Reliable sessions
- Secure sessions
- Application sessions
Question - 96 : - What are the advantages and disadvantages of using Single, Instancing mode in WCF?
Answer - 96 : -
In a single instancing mode, a single service object is created for all calls from all clients and sessions this type of WCF service is also called a singleton service. The following are the advantages and Disadvantages of the Single instance mode.
Advantages:
- State maintained by the service instance
Disadvantages:
- Least throughput
- Potentially greater memory consumption
- Concurrency issues
Question - 97 : - What are the general guidelines for choosing an instancing mode?
Answer - 97 : -
In general, for scalability and throughput prefer to use PerCall services where ever possible. Use PerSession services only when necessary, but keep in mind the overhead of sessions and session timeouts. Try to avoid singletons almost always. Singleton services could be useful on client machines for shared functionality. These are only general guidelines, and your selection depends on what you are trying to achieve.
Question - 98 : - Are WCF services protected from concurrent access by default?
Answer - 98 : -
Yes, WCF services are protected from concurrent access by default, as the concurrency mode of a WCF service is set to Single by default.