#Circuit Breaker

#CoreJava

Last updated    - V7 (19-Dec-2025)

Key Concepts

S.No	Topic	Sub-Topics
1	Setup & Basics	JDK Install, PATH Setup, IDE Setup, Hello Java, javac/java
2	Java Fundamentals	Data Types, Variables, Operators, Comments, Naming Rules
3	Control Flow	if/else, switch, loops, break/continue, nested loops
4	Methods	Method syntax, parameters, return types, overloading, static
5	OOP Basics	Class, Object, Constructor, this keyword, instance vs static
6	Encapsulation	private, getter/setter, access modifiers, immutability, POJO
7	Inheritance	extends, super, overriding, runtime polymorphism, final keyword
8	Abstraction	abstract class, interfaces, default methods, multiple inheritance, design purpose
9	Polymorphism	method overriding, overloading, dynamic binding, instanceof, casting
10	Packages & Imports	package keyword, import, naming conventions, JAR basics, folder structure
11	Exceptions Basics	try/catch, finally, throw/throws, checked vs unchecked, stacktrace
12	Custom Exceptions	create exception, exception hierarchy, multiple catch, global handling, best practices
13	Strings	String pool, immutability, common methods, compareTo, StringBuilder/Buffer
14	Arrays	declaration, initialization, iteration, multidimensional, Arrays utility
15	Collections Overview	Collection interfaces, List/Set/Map, ArrayList, LinkedList, HashMap
16	Generics	type parameters, wildcards, bounded types, generic methods, raw types
17	Streams API	stream(), filter(), map(), reduce(), collectors
18	Functional Interfaces	Predicate, Function, Supplier, Consumer, method references
19	Lambda Expressions	syntax, lambda as variable, target types, closures, best practices
20	Concurrency Basics	Thread class, Runnable, thread states, start vs run(), sleep
21	Synchronization	synchronized, volatile, race condition, deadlock, lock ordering
22	Executor Framework	ExecutorService, Future, Callable, Thread pool, submit/invoke
23	File I/O Basics	File class, InputStream, OutputStream, Reader, Writer
24	NIO & Path API	Path, Files utility, Channels, Buffers, Directory walking
25	JVM Architecture	Classloader, memory structure, bytecode, JIT, Heap & Stack
26	Garbage Collection	GC algorithms, references, finalize(), tuning, memory leaks
27	Reflection	Class object, getMethods(), newInstance(), annotations, metadata
28	JDBC Basics	DriverManager, Connection, PreparedStatement, ResultSet, commit/rollback
29	Design Patterns	Singleton, Factory, Strategy, Builder, DAO
30	Testing & Build Tools	JUnit basics, assertions, Maven, Gradle, logging

Interview question

Basic

1. What is Java and why is it platform independent?
2. Explain JVM, JRE, and JDK.
3. What are primitive data types in Java?
4. Difference between == and equals()?
5. What is class and object?
6. Explain method overloading.
7. Explain method overriding.
8. What is inheritance?
9. What is polymorphism?
10. What is abstraction?
11. Difference between abstract class and interface?
12. What are access modifiers?
13. What is a constructor?
14. What is the use of static keyword?
15. What is final keyword?
16. What is package in Java?
17. What is exception?
18. Difference between checked and unchecked exceptions?
19. What is try-catch block?
20. What is String immutability?
21. Difference between String, StringBuilder, StringBuffer?
22. What is array?
23. What is wrapper class?
24. What is autoboxing and unboxing?
25. What is garbage collection?

Intermediate

26. Explain Java memory areas.
27. Difference between Stack and Heap?
28. What is Java Collections Framework?
29. Difference between List, Set, and Map?
30. Difference between ArrayList and LinkedList?
31. Difference between HashSet and TreeSet?
32. Difference between HashMap and Hashtable?
33. What is Iterator?
34. Difference between Iterator and ListIterator?
35. What is fail-fast and fail-safe?
36. What are generics?
37. What is type erasure?
38. Explain Comparable and Comparator.
39. What is Java I/O?
40. Difference between byte stream and character stream?
41. What is serialization?
42. What is transient keyword?
43. Difference between File and Path?
44. What is multithreading?
45. Difference between Thread and Runnable?
46. What is thread lifecycle?
47. What is synchronization?
48. What is deadlock?
49. What is volatile keyword?
50. What are daemon threads?

Advanced

51. Explain Java memory model.
52. What are soft, weak, and phantom references?
53. How garbage collection works internally?
54. What are different GC algorithms?
55. What is ConcurrentHashMap?
56. Difference between synchronized and Lock?
57. What is ExecutorService?
58. Difference between Callable and Runnable?
59. What is Future?
60. What is CompletableFuture?
61. Explain Java NIO.
62. Difference between IO and NIO?
63. What is immutability?
64. How to create immutable class?
65. What are functional interfaces?
66. What are lambda expressions?
67. What is Stream API?
68. Difference between map() and flatMap()?
69. Difference between intermediate and terminal operations?
70. What is Optional?
71. What is method reference?
72. What are default methods in interface?
73. What is parallel stream?
74. What are spliterators?
75. What is memory leak in Java?

Expert

76. Explain class loading mechanism.
77. What are different class loaders?
78. How JVM handles exceptions internally?
79. What is escape analysis?
80. What is JIT compiler?
81. Difference between deep copy and shallow copy?
82. How does HashMap work internally?
83. Why HashMap allows one null key?
84. What is resizing in HashMap?
85. How ConcurrentHashMap avoids locking?
86. Explain happens-before relationship.
87. What is ForkJoin framework?
88. What is reactive programming in Java?
89. Explain Java module system.
90. What is metaspace?
91. Difference between PermGen and Metaspace?
92. How to tune JVM performance?
93. What are JVM options?
94. How to analyze memory leaks?
95. Explain Java design patterns usage.
96. How Streams improve performance?
97. What is backpressure?
98. Explain non-blocking concurrency.
99. What is GraalVM?
100. How Java supports high scalability systems?

Related Topics

CoreJava_17

Java Fundamentals

Collections

MultiThread

#SQL_Server

Last updated    - V7 (19-Dec-2025)

Key Concepts

S.No	Topic	Sub-Topics
1	Introduction to Databases	What is a database?, DBMS vs RDBMS, Types of databases, Use cases, Advantages
2	Database Architecture	Three-tier architecture, Client-server model, Relational model, NoSQL model, Distributed databases
3	SQL Basics	Data types, SELECT queries, WHERE clause, ORDER BY, GROUP BY
4	Data Definition Language (DDL)	CREATE, ALTER, DROP, TRUNCATE, Constraints
5	Data Manipulation Language (DML)	INSERT, UPDATE, DELETE, MERGE, Transactions
6	Data Control Language (DCL)	GRANT, REVOKE, Privileges, Roles, Security
7	Transaction Management	ACID properties, Commit, Rollback, Savepoints, Isolation levels
8	Indexes	Primary index, Unique index, Composite index, Full-text index, Indexing strategies
9	Joins	INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL OUTER JOIN, Self join
10	Subqueries	Single-row subqueries, Multi-row subqueries, Correlated subqueries, EXISTS, IN
11	Views	Creating views, Updating views, Materialized views, Security, Use cases
12	Stored Procedures	Creating procedures, Parameters, Control statements, Error handling, Best practices
13	Functions	Scalar functions, Aggregate functions, User-defined functions, System functions, Usage examples
14	Triggers	BEFORE triggers, AFTER triggers, INSTEAD OF triggers, Event types, Use cases
15	Normalization	1NF, 2NF, 3NF, BCNF, Denormalization
16	Database Design	ER diagrams, Tables and relationships, Keys, Constraints, Schema design best practices
17	Backup & Recovery	Full backup, Incremental backup, Point-in-time recovery, Recovery strategies, Tools
18	Performance Tuning	Query optimization, Index tuning, Execution plans, Caching, Monitoring tools
19	Replication	Master-slave replication, Multi-master replication, Synchronous vs asynchronous, Failover, Use cases
20	Sharding & Partitioning	Horizontal partitioning, Vertical partitioning, Range-based sharding, Hash-based sharding, Load balancing
21	NoSQL Databases	Document store, Key-value store, Column-family store, Graph database, Use cases
22	MongoDB Basics	Documents, Collections, CRUD operations, Indexing, Aggregation framework
23	Redis Basics	Key-value data, Data types, Persistence, Pub/Sub, Use cases
24	Database Security	Authentication, Authorization, Roles, Encryption, Auditing
25	Concurrency Control	Locks, Deadlocks, Optimistic concurrency, Pessimistic concurrency, Isolation levels
26	Data Warehousing	OLAP vs OLTP, Star schema, Snowflake schema, ETL process, Tools
27	Big Data Integration	Hadoop, Spark, Hive, Data lakes, ETL pipelines
28	Database Testing	Unit testing, Integration testing, Performance testing, Security testing, Automation tools
29	Cloud Databases	AWS RDS, Azure SQL Database, Google Cloud SQL, MongoDB Atlas, Benefits
30	Database Projects & Labs	ER modeling project, CRUD project, Aggregation project, Replication/sharding lab, Cloud deployment lab

Interview question

Basic Level

1. What is SQL Server and how does it differ from other RDBMS?
2. What are the main editions of SQL Server?
3. How do you install SQL Server?
4. What is SQL Server Management Studio (SSMS)?
5. What are databases, tables, and schemas in SQL Server?
6. How do you create a database in SQL Server?
7. How do you create a table in SQL Server?
8. What are the different data types in SQL Server?
9. What is a primary key? How do you define it in SQL Server?
10. What is a foreign key? How do you define it in SQL Server?
11. What is the difference between CHAR, VARCHAR, and NVARCHAR?
12. How do you insert data into a table?
13. How do you update and delete records in SQL Server?
14. What is the difference between DELETE, TRUNCATE, and DROP?
15. What are constraints in SQL Server? Name a few types.
16. How do you create indexes in SQL Server?
17. What is a clustered index? How does it differ from a non-clustered index?
18. How do you check the structure of a table in SQL Server?
19. How do you retrieve all databases on a SQL Server instance?
20. What is the difference between UNION and UNION ALL?
21. How do you filter data using the WHERE clause?
22. Explain the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.
23. What is the purpose of the TOP keyword in SQL Server?
24. What is IDENTITY in SQL Server? How is it used?
25. How do you back up and restore a SQL Server database?

---

Intermediate Level

1. What are SQL Server system databases?
2. Explain the purpose of master, msdb, model, and tempdb.
3. What is tempdb used for?
4. Explain the difference between a view and a materialized view.
5. What are stored procedures in SQL Server?
6. How do you create and execute a stored procedure?
7. What are triggers in SQL Server?
8. Explain the difference between AFTER and INSTEAD OF triggers.
9. What are functions in SQL Server? Differentiate between scalar and table-valued functions.
10. What is a common table expression (CTE)?
11. How do you implement recursive queries in SQL Server?
12. What are transactions in SQL Server?
13. Explain ACID properties in SQL Server.
14. What is the difference between COMMIT and ROLLBACK?
15. How does SQL Server handle concurrency?
16. What are isolation levels in SQL Server? List them.
17. What is the difference between optimistic and pessimistic concurrency control?
18. How do you use the EXCEPT and INTERSECT operators?
19. What are SQL Server Operators like LIKE, BETWEEN, IN, and EXISTS?
20. What is the CASE statement in SQL Server?
21. How do you handle NULL values in SQL Server?
22. What is the difference between ISNULL() and COALESCE()?
23. How do you grant and revoke permissions in SQL Server?
24. What are SQL Server logins and users? How do they differ?
25. What is the SQL Server Agent? What is it used for?

---

Advanced Level

1. What is indexing strategy in SQL Server?
2. What are included columns in a non-clustered index?
3. What is a filtered index in SQL Server?
4. What are indexed views in SQL Server?
5. What are statistics in SQL Server? Why are they important?
6. How does SQL Server query optimizer work?
7. What is the execution plan in SQL Server? How do you read it?
8. What is parameter sniffing in SQL Server?
9. How do you avoid parameter sniffing issues?
10. What is a deadlock in SQL Server? How do you resolve it?
11. How do you detect blocking in SQL Server?
12. Explain difference between NOLOCK and other table hints.
13. What is sp_who2 used for?
14. How do you find the longest-running queries in SQL Server?
15. What are Dynamic Management Views (DMVs)?
16. How do you monitor performance using DMVs?
17. What is partitioning in SQL Server?
18. What are partitioned tables and partitioned indexes?
19. What is replication in SQL Server? Types?
20. What is the difference between snapshot, transactional, and merge replication?
21. What is log shipping in SQL Server?
22. What is database mirroring in SQL Server?
23. What is AlwaysOn Availability Groups in SQL Server?
24. How do you configure failover clustering in SQL Server?
25. What is database sharding? Is it supported in SQL Server?

---

Expert Level

1. Explain SQL Server architecture (SQL OS, storage engine, relational engine).
2. What is the difference between SQL Server on-premises and Azure SQL Database?
3. What are extended events in SQL Server?
4. What is SQL Profiler? Why is it deprecated?
5. How do you capture deadlock graphs in SQL Server?
6. Explain tempdb contention and how to resolve it.
7. How do you tune queries in SQL Server?
8. What is Query Store in SQL Server?
9. How do you use Query Store for performance troubleshooting?
10. What are columnstore indexes? When should you use them?
11. What is in-memory OLTP in SQL Server?
12. How does SQL Server handle encryption (TDE, Always Encrypted)?
13. What is row-level security (RLS) in SQL Server?
14. What are dynamic data masking techniques in SQL Server?
15. Explain PolyBase in SQL Server.
16. How do you connect SQL Server to external data sources (linked servers)?
17. What is Service Broker in SQL Server?
18. What is Change Data Capture (CDC)?
19. What is Change Tracking in SQL Server?
20. What is the difference between CDC and Change Tracking?
21. How do you implement auditing in SQL Server?
22. What are best practices for SQL Server index maintenance?
23. How do you configure high availability and disaster recovery (HADR)?
24. What is the difference between synchronous and asynchronous replication in SQL Server?
25. Compare SQL Server with PostgreSQL and Oracle in terms of scalability, features, and use cases.

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Related Topics

Index

Views

Stored Procedures

#SOAP

Last updated    - V7 (19-Dec-2025)

Key Concepts

S.No	Topic	Sub-Topics
1	Introduction to SOAP	What is SOAP?, History of SOAP, SOAP vs REST, Use cases, Advantages and limitations
2	SOAP Architecture	SOAP message structure, Envelope, Header, Body, Fault element
3	XML Basics for SOAP	XML syntax, Elements and attributes, Namespaces, Schema definitions (XSD), Validation
4	WSDL Overview	What is WSDL?, Structure of WSDL, Types, Messages, Port and binding
5	SOAP Message Exchange	Request-response pattern, RPC style, Document style, Message flow, Example SOAP message
6	SOAP Fault Handling	Fault structure, Faultcode, Faultstring, Faultactor, Detail element
7	SOAP Headers	Purpose of headers, Adding headers, Role of headers, Security headers, Processing headers
8	SOAP Bindings	HTTP binding, SMTP binding, JMS binding, RPC vs Document binding, Encoding styles
9	SOAP with Java	JAX-WS overview, Creating web service, Endpoint interface, Implementation class, Deployment
10	SOAP with Spring	Spring-WS introduction, Configuration, Endpoint mapping, Message handling, Security integration
11	Creating SOAP Clients	Using wsimport, Dynamic client, Stubs and proxies, Consuming services, Handling responses
12	SOAP Message Structure Deep Dive	Envelope details, Header examples, Body examples, Namespaces usage, Complex types
13	Data Types in SOAP	Primitive types, Complex types, Arrays, Custom objects, XSD mapping
14	SOAP Security	WS-Security overview, UsernameToken, Signature, Encryption, Security policies
15	Transport Protocols	HTTP/HTTPS, SMTP, JMS, TCP, Reliability considerations
16	SOAP Attachments	MTOM overview, SwA, Sending binary data, Receiving attachments, Use cases
17	SOAP Fault Handling in Java	SOAPFaultException, Throwing faults, Custom fault details, Handling in clients, Best practices
18	Versioning in SOAP	SOAP 1.1 vs 1.2, Message compatibility, WSDL versioning, Deprecation strategy, Backward compatibility
19	Testing SOAP Services	SOAP UI, Postman, Unit testing with JUnit, Mock services, Integration testing
20	Error Handling Best Practices	SOAP faults, Logging errors, Retry mechanisms, Exception mapping, Client notification
21	Advanced WSDL Concepts	Importing WSDLs, Types section, PortType details, Binding options, Service definitions
22	SOAP Interoperability	Cross-platform communication, Java & .NET interoperability, Version handling, Data type mapping, Testing
23	SOAP and REST Comparison	Differences, Use cases, Performance considerations, Security differences, Choosing between SOAP and REST
24	Logging and Monitoring	SOAP message logging, Auditing, Monitoring tools, Error tracking, Analytics
25	SOAP in Enterprise Applications	Integration patterns, ESB usage, Legacy system integration, Transaction handling, Security considerations
26	SOAP Best Practices	Design guidelines, Reusable WSDLs, Versioning, Error handling, Security
27	SOAP Performance Optimization	Message size reduction, MTOM usage, Connection pooling, Caching, Load balancing
28	SOAP with Legacy Systems	Integration challenges, Wrapping legacy APIs, Adapter design, Testing legacy services, Security considerations
29	SOAP Projects & Labs	Hands-on exercises, Creating services, Consuming services, Security implementation, Testing scenarios
30	SOAP Certification & Career Path	Industry relevance, Certifications, Advanced topics, Real-time project examples, Learning resources

Interview question

Basic

1. What is SOAP?
2. What does SOAP stand for?
3. What is the main purpose of SOAP in web services?
4. Explain the SOAP message structure.
5. What are the main parts of a SOAP message?
6. What is the SOAP Envelope element?
7. What is the SOAP Header used for?
8. What is the SOAP Body used for?
9. What is the SOAP Fault element?
10. What transport protocols can SOAP use?
11. What is the difference between SOAP and REST?
12. What is XML in the context of SOAP?
13. Is SOAP platform independent? Explain.
14. What is WSDL in SOAP web services?
15. What are SOAP bindings?
16. What is the role of UDDI in SOAP?
17. What are the advantages of SOAP over REST?
18. What are the disadvantages of SOAP?
19. What is the SOAP action in HTTP headers?
20. What data format does SOAP use?
21. Can SOAP work without WSDL?
22. What is a SOAP client?
23. What is a SOAP server?
24. What is the default port for SOAP web services?
25. Explain the difference between SOAP request and SOAP response.

---

Intermediate

1. Explain the role of namespaces in SOAP.
2. What are the different encoding styles in SOAP?
3. What is document-style SOAP?
4. What is RPC-style SOAP?
5. Compare RPC and document-style SOAP.
6. What is a SOAP Fault code?
7. Explain the SOAP Fault string.
8. What is the role of SOAP intermediaries?
9. What are SOAP modules?
10. What is the difference between SOAP encoding and literal?
11. How does SOAP handle stateful operations?
12. What is the difference between SOAP and JSON-RPC?
13. Explain the difference between SOAP and XML-RPC.
14. What is the SOAP processing model?
15. Explain message-level security in SOAP.
16. What are SOAP headers used for in authentication?
17. How do you define operations in WSDL for SOAP?
18. What is the difference between SOAP 1.1 and SOAP 1.2?
19. What are SOAP faults in SOAP 1.2?
20. What is the SOAP Message Transmission Optimization Mechanism (MTOM)?
21. How does SOAP handle attachments?
22. What is the difference between DIME and MTOM?
23. How is error handling done in SOAP?
24. How does SOAP handle multiple operations in a single service?
25. What are the different WSDL binding styles for SOAP?

---

Advanced

1. Explain the security challenges in SOAP.
2. What is WS-Security in SOAP?
3. What are WS-* standards?
4. Explain WS-Addressing in SOAP.
5. What is WS-ReliableMessaging?
6. What is WS-Policy?
7. Explain WS-AtomicTransaction.
8. What is WS-Federation?
9. How does WS-Security implement encryption in SOAP?
10. How does WS-Security implement digital signatures?
11. Explain UsernameToken in WS-Security.
12. What is the difference between message-level and transport-level security in SOAP?
13. What is the role of SAML tokens in SOAP web services?
14. How do SOAP services handle large messages?
15. What are best practices for SOAP fault handling?
16. What are SOAP handlers?
17. What is the difference between a handler and an interceptor in SOAP?
18. How does SOAP ensure interoperability?
19. Explain contract-first vs code-first SOAP service development.
20. How do you generate SOAP client stubs from WSDL?
21. What are the advantages of WSDL over manual SOAP XML creation?
22. What is the difference between synchronous and asynchronous SOAP calls?
23. How do you monitor SOAP web services?
24. What is the impact of namespaces on SOAP interoperability?
25. Explain SOAP over JMS (Java Messaging Service).

---

Expert

1. How do you design scalable SOAP web services?
2. How does SOAP integrate with Enterprise Service Bus (ESB)?
3. How do you optimize SOAP performance?
4. Explain SOAP message compression techniques.
5. How do you debug SOAP messages?
6. How do you log SOAP requests and responses securely?
7. What are common SOAP security vulnerabilities?
8. How do you mitigate XML External Entity (XXE) attacks in SOAP?
9. How do you secure SOAP against replay attacks?
10. How do you implement SSL/TLS with SOAP?
11. How do you load test SOAP services?
12. What are some SOAP testing tools?
13. Explain how SOAP integrates with Spring Web Services.
14. How do you expose SOAP web services in Java (JAX-WS)?
15. How do you consume SOAP services in Java?
16. How do you consume SOAP services in .NET?
17. How does SOAP integrate with Apache CXF?
18. Explain the role of Axis2 in SOAP web services.
19. How do you migrate SOAP to REST?
20. What are common real-world use cases for SOAP?
21. How do you design fault-tolerant SOAP web services?
22. How do you implement versioning in SOAP services?
23. Explain SOAP in the context of microservices.
24. What is the future of SOAP in modern architectures?
25. Compare SOAP, REST, GraphQL, and gRPC in enterprise applications.

Related Topics