this is example API for pulling data from google places, and saving them to local database with feature to add it as favorite place in database, where in any time I can pull all my favorite stored places.
I built this app by following next documentation: Documentation
- Visual studio - IDE
- Postman - For testing my endpoints
- Json formatter - For creating my c# models from google documentation.
- Microsoft SQL Server Managment Studio - for database managment
- .NET 8 - for my API and SignalR
- MediatR - for CQRS
- EF CORE - for ORM
- MSSQL - for my database
- JWT - For my authentication and authorization
- Serilog - For some basic logging
- AutoMapper - For mapping my DTOs
- Onion architecture - (Not tecnology) Architecture of my app
- Asp.Versioning.Mvc - Library for versioning our API endpoints
- Fluent validator - For validating my user inputs, but I gave up on that. No special need for that.
This is how I organized my application. Like I mentioned already I used Onion Architecture because I found it easy and comfortable to use. Also to upgrade it in any time without some common problems. Green arrows are showing flow of project references. Gray boxes indicate layers of onion architecture. In my application every project have suffix with e.g. ' .Domain '. That suffix indicates in which layer given project is placed.
All my logic is located in MediatR handlers and some basic services. I found out that MediatR library and CQRS pattern will help me a lot with some features, so I implemented almost all logic inside handlers and behaviors.
For example lets take SignalR feature. If my given request is type of: SearchPlacesForLocationCommand, my behavior will send to all subscribed clients, message via SignalR about searched place. Let check the diagram how this actually work.
We can see how our request travels inside MediatR > Thru pipeline where SignalR will send message if condition is valid > Some handler which will inject needed services.
WARNING In some behaviors and handlers I sent user claims from command to handler, but later I created service called IUserAccessor from which I could get my current user easier.
In this way all others MediatR behaviors works... And they are:
- CachingBehavior
- LockingRequestMechanismBehavior
- RequestExceptionHandler
- SaveToDatabaseBehavior
Where RequestExceptionHandler is not classic behavior, but IRequestExceptionHandler but for sake of simplicity I will put him just as behavior.
With handlers and behaviors, I have put some of my logic inside services. There is next services in my app:
- AuthenticationService
- RepositoryManager
- RequestLocker
- ServiceManager
- UserAccessor
I will not go to any details about app services, because I want to mention one thing. And that is ServiceManager.
I have created this manager class for all my services, but for some reason, manager is empty? Its empty because at beginning of project I was not expecting to use so much MediatR, but to use it only for behaviors... And for all logic e.g. mapping, to place it inside services. This is why you can find only Lazy class of IAuthenticationService which was first created service in my project.
All my logic for ORM and database is placed inside Repository.Infrastructure layer, because in future it is much easier to switch technologies if needed. For every repository I used specific interface to follow SOLID principle. Specific Interface Segregation Pattern.
For configure all my data I used EF CORE Fluent API where I really lost a lot of time, can say like 3 days, just because I am used to configuring that inside database. But in this application it was much much better to go with fluent API, which I didnt know very well, so I spent great amount of time on research some basic features, until I got valid migration and database update.
This part was most interesting part, yet so simple to implement with MediatR. As I mentioned earlier I have behavior called LockingRequestMechanismBehavior which is paired with singleton service RequestLocker. To avoid some complicated explanation how I created this, lets look at flow diagram:
This may look complicated, but important part of this story is that, request after locking behavior does not jump automatically on other behavior or to return response, instead it will be catched inside semaphore and there request will wait until semaphore will be free again.
After I created this solution, I was curious if this actually work... So I created one simple test with Postman. I used something called Postman runner in which I send 10 same requests almost in same time (0ms delay). To check how semaphore behaive I added some basic logging, which will be printed in .txt file. So lets check it...
- Lets do login do get new JWT token.
- Lets create new request tab for all locations in which we insert new JWT
- Open up Runner and insert our newly created request tab.
- Run benchmark.
Lets check log.txt file:
2024-10-30 13:39:44.431 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 91 ||
2024-10-30 13:39:50.440 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:39:50.443 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 91 || is finished. Next may enter...
2024-10-30 13:40:56.067 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 60 ||
2024-10-30 13:40:56.069 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.070 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 60 || is finished. Next may enter...
2024-10-30 13:40:56.117 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 80 ||
2024-10-30 13:40:56.118 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.120 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 80 || is finished. Next may enter...
2024-10-30 13:40:56.192 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 34 ||
2024-10-30 13:40:56.194 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.195 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 34 || is finished. Next may enter...
2024-10-30 13:40:56.289 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 45 ||
2024-10-30 13:40:56.290 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.291 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 45 || is finished. Next may enter...
2024-10-30 13:40:56.349 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 97 ||
2024-10-30 13:40:56.351 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.352 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 97 || is finished. Next may enter...
2024-10-30 13:40:56.437 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 35 ||
2024-10-30 13:40:56.438 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.439 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 35 || is finished. Next may enter...
2024-10-30 13:40:56.517 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 25 ||
2024-10-30 13:40:56.518 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.518 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 25 || is finished. Next may enter...
2024-10-30 13:40:56.612 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 69 ||
2024-10-30 13:40:56.613 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.614 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 69 || is finished. Next may enter...
2024-10-30 13:40:56.705 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 60 ||
2024-10-30 13:40:56.706 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.707 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 60 || is finished. Next may enter...
2024-10-30 13:40:56.798 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb assigned new semphore for his/her task. Action ID is: || 39 ||
2024-10-30 13:40:56.799 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb Finished activated task, semaphore release must be triggered.
2024-10-30 13:40:56.800 +01:00 [DBG] User: 518c34ff-b7a3-4fc3-9067-e86e8431cddb disposed semphore, Action with ID || 39 || is finished. Next may enter...
For every request I just gave some random number inserted in || number || double apsolute symbols.
By checking given log we can se that after user sent request,and we market it by 91, all others requests waited for semaphore to release it. And also we can se when task is done, how
our logger say: Action with ID || 91 || is finished. Next may enter...
this information is credible for our basic testing, so we can say this solution should work. (at least in developing env.)