17 December 2024

#Circuit Breaker

-

30 May 2024

#CoreJava

#CoreJava

Key Concepts


Topic SubTopics (comma separated)
OOP Concepts Inheritance, Polymorphism, Abstraction, Encapsulation, Method Overriding
Classes & Objects Constructors, this keyword, super keyword, Overloading, Object Cloning
Access Modifiers public, private, protected, default, package-level access
Static & Final static variable, static method, static block, final class, final method
Data Types & Variables primitive types, type casting, var keyword, literals, reference variables
Strings immutability, StringBuilder, StringBuffer, String pool, equals vs ==
Arrays 1D array, 2D array, Arrays utility class, sorting, searching
Collections List, Set, Map, Iterator, HashMap
Generics bounded types, wildcards, generic methods, type erasure, raw types
Exception Handling try-catch, finally, throws, throw, custom exceptions
Java I/O InputStream, OutputStream, Reader, Writer, BufferedReader
NIO Path, Files, Channels, Buffers, Selectors
Multithreading Thread, Runnable, synchronization, sleep, join
Concurrency ExecutorService, Future, ConcurrentHashMap, Atomic classes, Locks
JVM Internals ClassLoader, Bytecode, Class loading, JIT, GC basics
Memory Model heap, stack, references, garbage collection, happens-before
Lambda & Functional Interfaces lambda syntax, Predicate, Function, Consumer, Method reference
Streams API map, filter, reduce, collect, flatMap
Annotations built-in annotations, custom annotation, Retention, Target, Marker annotations
Reflection Class object, getMethods, getFields, invoke, dynamic proxy
JDBC Connection, Statement, PreparedStatement, ResultSet, batch updates
Serialization Serializable, transient, serialVersionUID, writeObject, readObject
Date & Time API LocalDate, LocalTime, LocalDateTime, Instant, DateTimeFormatter
Modules (JPMS) module-info, requires, exports, opens, modular JARs
ClassLoader bootstrap loader, system loader, extension loader, delegation, custom loader
Garbage Collection G1 GC, CMS, GC roots, mark-sweep, pause time
JIT Compiler interpreter vs JIT, tiered compilation, inlining, escape analysis, optimization
Advanced Concurrency ForkJoinPool, CompletableFuture, parallel streams, RecursiveTask, locks
Bytecode & Instrumentation javap, Java Agent, ASM, bytecode inspection, class redefinition
Performance Tuning JFR, heap dump analysis, thread dump analysis, profiling, GC tuning

Interview question

Basic Level

  1. What is Java?
  2. What are the features of Java?
  3. What is JVM?
  4. What is JDK?
  5. What is JRE?
  6. What is bytecode?
  7. Why is Java platform independent?
  8. What are data types in Java?
  9. What is a variable?
  10. What are identifiers?
  11. What is type casting?
  12. What is implicit and explicit casting?
  13. What are access modifiers?
  14. Difference between local and instance variables?
  15. What is a class?
  16. What is an object?
  17. What is a constructor?
  18. Types of constructors?
  19. What is the main() method?
  20. Why is main() static?
  21. What is method overloading?
  22. What is method overriding?
  23. What is inheritance?
  24. Types of inheritance in Java?
  25. What is polymorphism?
  26. What is abstraction?
  27. What is encapsulation?
  28. What is the this keyword?
  29. What is the super keyword?
  30. Differences between == and equals()?
  31. What is an interface?
  32. What is an abstract class?
  33. Difference between abstract class and interface?
  34. What are packages?
  35. What is the final keyword?
  36. What is a static variable?
  37. What is a static method?
  38. What is a static block?
  39. Why is String immutable?
  40. Difference between String, StringBuilder, StringBuffer?
  41. What is an array?
  42. What is a 2D array?
  43. What is command-line argument?
  44. What is a wrapper class?
  45. What is autoboxing?
  46. What is unboxing?
  47. What is the default value of variables?
  48. What are escape sequences?
  49. What is the ternary operator?
  50. What is short-circuit operator?

Intermediate Level

  1. What is the Java Collections Framework?
  2. Difference between List, Set, and Map?
  3. Explain ArrayList vs LinkedList.
  4. Explain HashSet vs TreeSet.
  5. Explain HashMap vs Hashtable.
  6. What is LinkedHashMap?
  7. What is fail-fast and fail-safe?
  8. What is Iterator?
  9. What is ListIterator?
  10. What is Comparable?
  11. What is Comparator?
  12. Difference between compareTo() and compare()?
  13. What is generics?
  14. What are bounded type parameters?
  15. What are wildcards in generics?
  16. What is exception handling?
  17. What is try, catch, finally?
  18. What is checked exception?
  19. What is unchecked exception?
  20. What is throw keyword?
  21. What is throws keyword?
  22. What is custom exception?
  23. Difference between error and exception?
  24. What is Java I/O?
  25. What is InputStream and OutputStream?
  26. What is Reader and Writer?
  27. What is serialization?
  28. What is transient keyword?
  29. Explain Java Memory Model.
  30. Difference between stack and heap?
  31. What is garbage collection?
  32. What is finalize()?
  33. What is String pool?
  34. What is immutability in Java?
  35. What is a thread?
  36. How to create a thread?
  37. Difference between Thread and Runnable?
  38. What is synchronization?
  39. What is deadlock?
  40. What is race condition?
  41. What is thread safety?
  42. What is volatile keyword?
  43. What is daemon thread?
  44. What is thread lifecycle?
  45. What is JDBC?
  46. Difference between Statement and PreparedStatement?
  47. What is ResultSet?
  48. What is batch processing?
  49. What is metadata in JDBC?
  50. What is connection pooling?

Advanced Level

  1. Explain class loading mechanism.
  2. What is ClassLoader?
  3. Types of classloaders?
  4. Explain double-checked locking.
  5. What is the Java Memory Model (JMM)?
  6. What is happens-before relationship?
  7. Explain ConcurrentHashMap internals.
  8. Difference between synchronizedMap and ConcurrentHashMap?
  9. What is CopyOnWriteArrayList?
  10. What are atomic variables?
  11. What is Executor framework?
  12. What is Callable vs Runnable?
  13. What is Future and FutureTask?
  14. What is ThreadPoolExecutor?
  15. What is ForkJoinPool?
  16. What is parallel stream?
  17. Explain lambda expressions.
  18. What are functional interfaces?
  19. What is the Predicate interface?
  20. What is Function interface?
  21. What is Supplier and Consumer?
  22. What is Optional class?
  23. Explain Stream API operations.
  24. Difference between intermediate and terminal operations?
  25. What is short-circuiting in streams?
  26. What is method reference?
  27. What is reflection in Java?
  28. What are annotations?
  29. What is custom annotation?
  30. What is retention policy?
  31. What is proxy in Java?
  32. What is dynamic proxy?
  33. What is bytecode instrumentation?
  34. What is class reloading?
  35. What is Java Agent?
  36. What is NIO?
  37. Difference between IO and NIO?
  38. What is a selector in NIO?
  39. What is buffer and channel?
  40. What is memory mapped file?
  41. What is weak reference?
  42. Types of references in Java? (Soft, Weak, Phantom)
  43. What is GC tuning?
  44. Explain G1 GC.
  45. Difference between CMS and G1?
  46. What is ZGC?
  47. What is JIT compiler?
  48. What is Java Flight Recorder?
  49. What is JMX?
  50. What is JPA (Java Persistence API)?

Expert Level

  1. Explain JVM architecture in detail.
  2. What is a class file structure?
  3. Explain bytecode verification.
  4. What is method area in JVM?
  5. Explain constant pool.
  6. What is escape analysis?
  7. What is lock coarsening?
  8. What is lock elision?
  9. Explain biased locking.
  10. Explain OSR (On Stack Replacement).
  11. What is tiered compilation?
  12. Explain GraalVM.
  13. What is AOT compilation?
  14. Explain metaspace.
  15. Explain GC phases.
  16. Difference between stop-the-world and concurrent GC?
  17. How does ConcurrentMarkSweep (CMS) work?
  18. How does Shenandoah GC work?
  19. Explain JVM diagnostic commands.
  20. What is JFR profiling?
  21. How does JVM handle thread scheduling?
  22. What is false sharing?
  23. What is memory barrier?
  24. What is instruction reordering?
  25. What is CAS (Compare And Swap)?
  26. What is ABA problem?
  27. Explain VarHandle.
  28. What is off-heap memory?
  29. What is direct byte buffer?
  30. Explain Java Module System (JPMS).
  31. What is reflection performance impact?
  32. How to avoid reflection overhead?
  33. Explain Java Security Manager.
  34. What is code signing in Java?
  35. What is a classpath vs modulepath?
  36. Explain custom classloader use cases.
  37. What is thread dump analysis?
  38. What is heap dump analysis?
  39. Explain race detection tools.
  40. What is Zero GC?
  41. What is ThreadLocal memory leak?
  42. Explain CompletableFuture in depth.
  43. What is reactive programming in Java?
  44. What is Project Loom?
  45. What are virtual threads?
  46. How does stack frame behave in virtual threads?
  47. Explain structured concurrency.
  48. Explain performance tuning for high-frequency trading systems.
  49. Explain memory model violations.
  50. Explain build-time bytecode generation techniques.

Related Topics


   CoreJava_08   
   CoreJava_17   
   OOP Concepts   
   String Handling   
   Arrays   
   Exception_Handling   
   Collections   
   MultiThread   
   Generics   
   JDBC   
   Java_IO   
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25 May 2024

#SQL_Server

#SQL_Server

Key Concepts


Topic SubTopics Basic Intermediate Advanced Expert
Introduction & Basics Overview, Editions, Versions, Features ✅
Installation & Configuration System Requirements, Installation, Configuration, Services ✅ ✅
Databases Creating Databases, Database Properties, Collation, Filegroups ✅ ✅
Tables & Schemas Creating Tables, Data Types, Constraints, Schemas ✅ ✅
Data Types Numeric, String, DateTime, Binary, XML, JSON ✅ ✅
Primary & Foreign Keys PK, FK, Relationships, Referential Integrity ✅ ✅
Indexes Clustered, Non-Clustered, Columnstore, Filtered Indexes ✅ ✅
Views Simple Views, Indexed Views, Partitioned Views, Security ✅ ✅ ✅
Stored Procedures Creating, Executing, Parameters, Error Handling ✅ ✅ ✅
Functions Scalar, Table-Valued, Inline, User-Defined ✅ ✅ ✅
Triggers DML Triggers, DDL Triggers, INSTEAD OF, AFTER ✅ ✅
Transactions ACID, BEGIN/COMMIT/ROLLBACK, Isolation Levels ✅ ✅ ✅
Locks & Deadlocks Lock Types, Blocking, Deadlock Detection ✅ ✅
Constraints CHECK, DEFAULT, UNIQUE, NOT NULL ✅ ✅
Normalization & Design 1NF, 2NF, 3NF, Denormalization, ERD ✅ ✅
Querying SELECT, JOINs, WHERE, GROUP BY, HAVING, ORDER BY ✅ ✅ ✅
Advanced Queries CTE, Window Functions, Ranking, Pivot/Unpivot ✅ ✅
Performance Tuning Index Tuning, Execution Plans, Query Optimization ✅ ✅
Transactions & Concurrency Isolation Levels, Locks, Deadlocks, Snapshot Isolation ✅ ✅
Backup & Restore Full, Differential, Log Backup, Restore Scenarios ✅ ✅ ✅
Security Authentication, Authorization, Roles, Permissions, Encryption ✅ ✅ ✅ ✅
Replication & Mirroring Snapshot, Transactional, Merge, Database Mirroring ✅ ✅ ✅
High Availability Always On, Failover Cluster Instances, Log Shipping ✅ ✅ ✅
Monitoring & Maintenance Performance Monitoring, SQL Agent Jobs, Maintenance Plans ✅ ✅ ✅
Advanced Topics Partitioning, Service Broker, Query Store, PolyBase ✅ ✅
Cloud & Hybrid Azure SQL, Managed Instance, Synapse Analytics, Migrations ✅ ✅

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.

Related Topics


   Complex_Query   
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04 May 2024

#SOAP

#SOAP

Key Concepts


Topic SubTopics Basic Intermediate Advanced Expert
SOAP Fundamentals Definition, Purpose, Characteristics ✅
SOAP Message Structure Envelope, Header, Body, Fault ✅ ✅
SOAP Protocols HTTP, SMTP, JMS, TCP ✅ ✅
SOAP vs REST Differences, Advantages, Disadvantages ✅ ✅
SOAP Elements Envelope, Namespace, Encoding ✅ ✅
WSDL Definition, Structure, Operations, Bindings ✅ ✅
UDDI Service Registry, Lookup, Discovery ✅ ✅
SOAP Binding Styles Document Style, RPC Style, Encoded, Literal ✅ ✅
SOAP Fault Handling Fault Code, Fault String, Detail ✅ ✅ ✅
SOAP Headers Authentication, Transaction, Routing ✅ ✅ ✅
SOAP Attachments SwA, DIME, MTOM ✅ ✅ ✅
SOAP Security Basics SSL, Basic Auth, Token-based ✅ ✅
WS-Security Encryption, Signatures, UsernameToken ✅ ✅
WS-Addressing Endpoint References, Message Routing ✅ ✅
WS-ReliableMessaging Message Ordering, Delivery Assurance ✅ ✅
WS-Policy Policy Assertion, Policy Attachment ✅ ✅
WS-AtomicTransaction Commit, Rollback, Coordination ✅ ✅
WS-Federation Identity Federation, Trust Relationships ✅ ✅
SOAP Interoperability Namespaces, Encoding Rules, Standards ✅ ✅ ✅
SOAP Handlers Request/Response Processing, Logging ✅ ✅ ✅
Development Approaches Contract-first, Code-first ✅ ✅ ✅
SOAP Tools SoapUI, Postman, Apache CXF, Axis2 ✅ ✅ ✅ ✅
SOAP in Java JAX-WS, Spring-WS, CXF ✅ ✅ ✅
SOAP in .NET WCF, ASMX, Visual Studio ✅ ✅ ✅
SOAP Performance Optimization, Compression, Scalability ✅ ✅
SOAP Security Advanced Replay Attack Prevention, SAML Tokens ✅ ✅
Monitoring & Debugging Logging, Tracing, Message Inspection ✅ ✅ ✅
Testing SOAP Unit Tests, Integration Tests, Load Tests ✅ ✅ ✅ ✅
SOAP in ESB Service Orchestration, Mediation, Routing ✅ ✅
SOAP in Microservices Integration, Migration to REST ✅ ✅

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


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