Hotel Reservation System Flashcards
Interview
What are the functional requirements ?
- Show the hotel-related page.
- Show the hotel room-related detail page.
- Reserve a room.
- Admin panel to add/remove/update hotel or room info.
- Support the overbooking feature.
- Prices change dynamically depending how full they will be in one day.
What are the non-functional requirements ?
Support high concurrency. During peak season or big events, some popular hotels may have a lot of customers trying to book the same room.
Moderate latency. It’s ideal to have a fast response time when a user makes the reservation, but it’s acceptable if the system takes a few seconds to process a reservation request.
What is gPRC ?
In gRPC, a client application can directly call a method on a server application on a different machine as if it were a local object, making it easier for you to create distributed applications and services. As in many RPC systems, gRPC is based around the idea of defining a service, specifying the methods that can be called remotely with their parameters and return types. On the server side, the server implements this interface and runs a gRPC server to handle client calls. On the client side, the client has a stub (referred to as just a client in some languages) that provides the same methods as the server.
What is an Idempotent API?
Idempotency essentially means that the effect of a successfully performed request on a server resource is independent of the number of times it is executed.
We have to make our APIs fault-tolerant so that duplicate requests do not leave the system unstable.
What is Pessimistic locking ?
Pessimistic locking , also called pessimistic concurrency control, prevents simultaneous updates by placing a lock on a record as soon as one user starts to update it. Other users who attempt to update the record have to wait until the first user has released the lock (committed the changes).
“SELECT … FOR UPDATE’’
What is Optimistic locking ?
Optimistic locking, also referred to as optimistic concurrency control, allows multiple concurrent users to attempt to update the same resource.
There are two common ways to implement optimistic locking: version number and timestamp. Version number is generally considered to be a better option because the server clock can be inaccurate over time. We explain how optimistic locking works with version number.
What is Database constraints locking ?
Constraints are placed on database fields.
What is Debezium ?
Debezium is an open source distributed platform for change data capture. Start it up, point it at your databases, and your apps can start responding to all of the inserts, updates, and deletes that other apps commit to your databases.
What is Two Phase Commit (2PC) ?
Two-phase commit (2PC). 2PC is a database protocol used to guarantee atomic transaction commit across multiple nodes, i.e., either all nodes succeeded or all nodes failed. Because 2PC is a blocking protocol, a single node failure blocks the progress until the node has recovered. It’s not performant.
What is Saga ?
A saga is a sequence of local transactions. Each transaction updates and publishes a message to trigger the next transaction step. If a step fails, the saga executes compensating transactions to undo the changes that were made by preceding transactions. 2PC works as a single commit to perform ACID transactions while Saga consists of multiple steps and relies on eventual consistency.
