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Thundering Herd Problem - ASP Core Solution Architect

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  What is the Thundering herd problem? Lets describe it using a realistic problem to get better understanding. Suppose an exposed Weather-API that returns current temperature degree, called by web/mobile apps, and optimized for performance so, for simplicity it utilize caching capabilities so, when it is called, checks for caching and if there is "cache miss", proceed and call a third-party API and cache for later use. The problem happens when there are a multiple calls to Weather-API at the same time and there is a "cache miss" (e.g. data not found in cache) so, each request go and call third-party API and then if succeed, it will cache data.   The 3-party API is slow and not well-designed for this huge number of requests so, it will be down and typically Weather-API  goes down or out of functionality (e.g. due to coupling with third-party API and not a proper handling for exceptions). It is a real complicated problem especially when there are a multiple running ...
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Fluent Notification Sender .Net Package

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  Most modern software projects have need to an essential feature of sending notifications to clients (e.g., user registration & confirmation, automated request process follow up, topic & news subscription and alerting system…).   Notifications can be in many flavors (Email, SMS, Realtime, and mobile push notification) beside send by multiple methods according to system or client preferences (e.g., sending both Email and SMS notification for specific events occurs in system). Each software project has a different requirement so, it can use a different provider vendor (e.g., send email by SMTP protocol or by SendGrid API, …etc.) to fulfil it. Sending notifications is expensive I/O operation and can affect application performance if it not coded will. Some project's requirements need to log or retry failed notifications .   So , Notification project as a component designed to deal with the above concerns. Design Specifications: Support multiple notifications metho...
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Distributed Synchronized Background Jobs ASP Core

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Problem:- In the age of containerized apps, running multiple instances, and Kubernetes, sometimes you face a situation where you want to run a background jobs in the ASP Core, but you have multiple instances of application running on Kubernetes for example, so you will end up with duplicated running background jobs equal to the number of running application instances (e.g. same background job runs for each application instance) Solution :- Easy and straight forward : separate the background jobs into a new solution and deploy one instance of it (100% confidence of running one instance) Do a synchronization mechanism to allow only one instance runs jobs ( not 100% confidence of running one instance)  We will talk about second solution:- We need to start jobs at different times, not at the same time, so, we can synchronize work (e.g. one job-instance start with the smallest time and the others in a different times). We need a "centralized store" to store the ...
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Async/Await - OS Concept

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 There are many question about Async/Await in "dot net"? what really are? what is the issues it handle? is there any dedicated thread/mechanism monitor when a task completes, so notify thread pool to choose thread and continue execution? when to use it? to answer this question let us deep dive a little in some Operating System (OS) concepts and mechanism to handle I/O. What is I/O?:-  I/O (input/output), pronounced "eye-oh," describes any operation, program, or device that transfers data to or from a computer. Typical I/O devices are printers, network card, hard disks, keyboards, and mouses. In fact, some devices are basically input-only devices (keyboards and mouses); others are primarily output-only devices (printers); and others provide both input and output of data (hard disks, diskettes, writable CD-ROMs). Programing examples require I/O operations:- - when application query database it get data from hard disk(I/O) - when call api, it call network card(I/O) - w...
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