From the frontend through the kernel to the backend processWhen we send a request to a backend most of us focus on the processing aspect of the request which is really just the last step. There is so much more happening before a request is ready to be processed, most of this step happens in the Kernel. I break this into 6 steps, each step can theoretically be executed by a dedicated thread or process. Pretty much all backends, web servers, proxies, frameworks and even databases have to do all these steps and they all do choose to do it differently.  Grab my backend performance course https://performance.husseinnasser.com  0:00 Intro 3:50 What is a Request? 10:14 Step 1 - Accept  21:30 Step 2 - Read 29:30 Step 3 - Decrypt 34:00 Step 4 - Parse 40:36 Step 5 - Decode 43:14 Step 6 - Process   Medium article https://medium.com/@hnasr/the-journey-of-a-request-to-the-backend-c3de704de223

From the frontend through the kernel to the backend process When we send a request to a backend most of us focus on the processing aspect of the request which is really just the last step. There is so much more happening before a request is ready to be processed, most of this step happens in the Kernel. I break this into 6 steps, each step can theoretically be executed by a dedicated thread or process. Pretty much all backends, web servers, proxies, frameworks and even databases have to do all these steps and they all do choose to do it differently. Grab my backend performance course <a href="https://performance.husseinnasser.com" rel="nofollow" target="_blank">https://performance.husseinnasser.com</a> 0:00 Intro 3:50 What is a Request? 10:14 Step 1 - Accept  21:30 Step 2 - Read 29:30 Step 3 - Decrypt 34:00 Step 4 - Parse 40:36 Step 5 - Decode 43:14 Step 6 - Process Medium article <a href="https://medium.com/@hnasr/the-journey-of-a-request-to-the-backend-c3de704de223" rel="nofollow" target="_blank">https://medium.com/@hnasr/the-journey-of-a-request-to-the-backend-c3de704de223</a>

The Journey of a Request to the Backend

In a wonderful blog, Kyle explores the pains he faced managing a Postgres instance for a startup he works for and how enabling partitioning sigintfically created wait events causing the backend and subsequently NGINX to through 500 errors.We discuss this in this video/podcasthttps://www.kylehailey.com/post/postgres-partition-pains-lockmanager-waits

In a wonderful blog, Kyle explores the pains he faced managing a Postgres instance for a startup he works for and how enabling partitioning sigintfically created wait events causing the backend and subsequently NGINX to through 500 errors. We discuss this in this video/podcast <a href="https://www.kylehailey.com/post/postgres-partition-pains-lockmanager-waits" rel="nofollow" target="_blank">https://www.kylehailey.com/post/postgres-partition-pains-lockmanager-waits</a>

They Enabled Postgres Partitioning and their Backend fell apart

WebTransport is a cutting-edge protocol framework designed to support multiplexed and secure transport over HTTP/2 and HTTP/3. It brings together the best of web and transport technologies, providing an all-in-one solution for real-time, bidirectional communication on the web.  Watch full episode (subscribers only) https://spotifyanchor-web.app.link/e/cTSGkq5XuAb

WebTransport is a cutting-edge protocol framework designed to support multiplexed and secure transport over HTTP/2 and HTTP/3. It brings together the best of web and transport technologies, providing an all-in-one solution for real-time, bidirectional communication on the web. Watch full episode (subscribers only) https://spotifyanchor-web.app.link/e/cTSGkq5XuAb

WebTransport - A Backend Game Changer

fsync is a linux system call that flushes all pages and metadata for a given file to the disk. It is indeed an expensive operation but required for durability especially for database systems. Regular writes that make it to the disk controller are often placed in the SSD local cache to accumulate more writes before getting flushed to the NAND cells.  However when the disk controller receives this flush command it is required to immediately persist all of the data to the NAND cells.   Some SSDs however don't do that because they don't trust the host and no-op the fsync. In this video I explain this in details and go through details on how postgres provide so many options to fine tune fsync   0:00 Intro 1:00 A Write doesn’t write 2:00 File System Page Cache 6:00 Fsync 7:30 SSD Cache 9:20 SSD ignores the flush 9:30 15 Year old Firefox fsync bug 12:30 What happens if SSD loses power 15:00 What options does Postgres exposes? 15:30 open_sync (O_SYNC) 16:15 open_datasync (O_DSYNC) 17:10 O_DIRECT 19:00 fsync 20:50 fdatasync  21:13 fsync = off 23:30 Don’t make your API simple 26:00 Database on metal? 

fsync is a linux system call that flushes all pages and metadata for a given file to the disk. It is indeed an expensive operation but required for durability especially for database systems. Regular writes that make it to the disk controller are often placed in the SSD local cache to accumulate more writes before getting flushed to the NAND cells. However when the disk controller receives this flush command it is required to immediately persist all of the data to the NAND cells. Some SSDs however don't do that because they don't trust the host and no-op the fsync. In this video I explain this in details and go through details on how postgres provide so many options to fine tune fsync 0:00 Intro 1:00 A Write doesn’t write 2:00 File System Page Cache 6:00 Fsync 7:30 SSD Cache 9:20 SSD ignores the flush 9:30 15 Year old Firefox fsync bug 12:30 What happens if SSD loses power 15:00 What options does Postgres exposes? 15:30 open_sync (O_SYNC) 16:15 open_datasync (O_DSYNC) 17:10 O_DIRECT 19:00 fsync 20:50 fdatasync 21:13 fsync = off 23:30 Don’t make your API simple 26:00 Database on metal?

Your SSD lies but that's ok | Postgres fsync

ego is the main problem to a defective software product. the ego of the engineer or the tech lead seeps into the quality of the product. Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon)https://backend.husseinnasser.com

ego is the main problem to a defective software product. the ego of the engineer or the tech lead seeps into the quality of the product. Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon) <a href="https://backend.husseinnasser.com" rel="nofollow" target="_blank">https://backend.husseinnasser.com</a>

The problem with software engineering

 Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon) https://database.husseinnasser.com  In version 5.3, MongoDB introduced a feature called clustered collection which stores documents in the _id index as oppose to the hidden wiredTiger hidden index. This eliminates an entire b+tree seek for reads using the _id index and also removes the additional write to the hidden index speeding both reads and writes.   However like we know in software engineering, everything has a cost. This feature does come with a few that one must be aware of before using it. In this video I discuss the following    How Original MongoDB Collections Work How Clustered Collections Work Benefits of Clustered Collections Limitations of Clustered Collections 

Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon) <a href="https://database.husseinnasser.com" rel="nofollow" target="_blank">https://database.husseinnasser.com</a> In version 5.3, MongoDB introduced a feature called clustered collection which stores documents in the _id index as oppose to the hidden wiredTiger hidden index. This eliminates an entire b+tree seek for reads using the _id index and also removes the additional write to the hidden index speeding both reads and writes.  However like we know in software engineering, everything has a cost. This feature does come with a few that one must be aware of before using it. In this video I discuss the following  <ul> <li>How Original MongoDB Collections Work</li> <li>How Clustered Collections Work</li> <li>Benefits of Clustered Collections</li> <li>Limitations of Clustered Collections</li> </ul>

2x Faster Reads and Writes with this MongoDB feature | Clustered Collections

Prime video engineering team has posted a blog detailing how they moved their live stream monitoring service from microservices to a monolith reducing their cost by 90%, let us discuss this0:00 Intro2:00 Overview10:35 Distributed System Overhead21:30 From Microservices to Monolith 29:00 Scaling the Monolith32:30 Takeawayshttps://www.primevideotech.com/video-streaming/scaling-up-the-prime-video-audio-video-monitoring-service-and-reducing-costs-by-90Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon)https://backend.husseinnasser.com

Prime video engineering team has posted a blog detailing how they moved their live stream monitoring service from microservices to a monolith reducing their cost by 90%, let us discuss this 0:00 Intro 2:00 Overview 10:35 Distributed System Overhead 21:30 From Microservices to Monolith 29:00 Scaling the Monolith 32:30 Takeaways <a href="https://www.primevideotech.com/video-streaming/scaling-up-the-prime-video-audio-video-monitoring-service-and-reducing-costs-by-90" rel="nofollow" target="_blank">https://www.primevideotech.com/video-streaming/scaling-up-the-prime-video-audio-video-monitoring-service-and-reducing-costs-by-90</a> Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon) <a href="https://backend.husseinnasser.com" rel="nofollow" target="_blank">https://backend.husseinnasser.com</a>

Prime Video Swaps Microservices for Monolith: 90% Cost Reduction

Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon) https://database.husseinnasser.com  In a row-store database engine, rows are stored in units called pages. Each page has a fixed header and contains multiple rows, with each row having a record header followed by its respective columns. When the database fetches a page and places it in the shared buffer pool, we gain access to all rows and columns within that page. So, the question arises: if we have all the columns readily available in memory, why would SELECT * be slow and costly? Is it really as slow as people claim it to be? And if so why is it so? In this post, we will explore these questions and more.  0:00 Intro 1:49 Database Page Layout 5:00 How SELECT Works 10:49 No Index-Only Scans 18:00 Deserialization Cost 21:00 Not All Columns are Inline 28:00 Network Cost 36:00 Client Deserialization  https://medium.com/@hnasr/how-slow-is-select-8d4308ca1f0c

Fundamentals of Database Engineering udemy course (link redirects to udemy with coupon) <a href="https://database.husseinnasser.com" rel="nofollow" target="_blank">https://database.husseinnasser.com</a> In a row-store database engine, rows are stored in units called pages. Each page has a fixed header and contains multiple rows, with each row having a record header followed by its respective columns. When the database fetches a page and places it in the shared buffer pool, we gain access to all rows and columns within that page. So, the question arises: if we have all the columns readily available in memory, why would SELECT * be slow and costly? Is it really as slow as people claim it to be? And if so why is it so? In this post, we will explore these questions and more. 0:00 Intro 1:49 Database Page Layout 5:00 How SELECT Works 10:49 No Index-Only Scans 18:00 Deserialization Cost 21:00 Not All Columns are Inline 28:00 Network Cost 36:00 Client Deserialization <a href="https://medium.com/@hnasr/how-slow-is-select-8d4308ca1f0c" rel="nofollow" target="_blank">https://medium.com/@hnasr/how-slow-is-select-8d4308ca1f0c</a>

A Deep Dive in How Slow SELECT * is

Lambda now supports Response payload streaming, now you can flush changes to the network socket as soon as it is available and it will be written to the client socket. I think this is a game changing feature    0:00 Intro 1:00 Traditional Lambda 3:00 Server Sent Events &amp; Chunk-Encoding 5:00 What happens to clients? 6:00 Supported Regions 7:00 My thoughts  Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon) https://backend.husseinnasser.com

Lambda now supports Response payload streaming, now you can flush changes to the network socket as soon as it is available and it will be written to the client socket. I think this is a game changing feature 0:00 Intro 1:00 Traditional Lambda 3:00 Server Sent Events &amp; Chunk-Encoding 5:00 What happens to clients? 6:00 Supported Regions 7:00 My thoughts Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon) <a href="https://backend.husseinnasser.com" rel="nofollow" target="_blank">https://backend.husseinnasser.com</a>

AWS Serverless Lambda Supports Response Streaming

Cloudflare released a blog detailing a vulnerability that has been in their system for nearly two years. it is related to mTLS or mutual TLS and specifically client certificate revocation. I explore this in details 0:00 Intro3:00 The Vulnerability7:00 What happened?8:50 Certificate Revocation12:30 Rejecting certain endpoints 17:00 Certificate Authentication20:30 Certificate serial number24:00 Session Resumption (PSK)35:00 The bug37:00 How they addressed the problemFundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon)https://backend.husseinnasser.com

Cloudflare released a blog detailing a vulnerability that has been in their system for nearly two years. it is related to mTLS or mutual TLS and specifically client certificate revocation. I explore this in details 0:00 Intro 3:00 The Vulnerability 7:00 What happened? 8:50 Certificate Revocation 12:30 Rejecting certain endpoints 17:00 Certificate Authentication 20:30 Certificate serial number 24:00 Session Resumption (PSK) 35:00 The bug 37:00 How they addressed the problem Fundamentals of Backend Engineering Design patterns udemy course (link redirects to udemy with coupon) <a href="https://backend.husseinnasser.com" rel="nofollow" target="_blank">https://backend.husseinnasser.com</a>

The Cloudflare mTLS vulnerability - A Deep Dive Analysis

Welcome to the Backend Engineering Show podcast with your host Hussein Nasser. If you like software engineering you’ve come to the right place. I discuss all sorts of software engineering technologies and news with specific focus on the backend. All opinions are my own. Most of my content in the podcast is an audio version of videos I post on my youtube channel here http://www.youtube.com/c/HusseinNasser-software-engineering Buy me a coffee https://www.buymeacoffee.com/hnasr🧑‍🏫 Courses I Teachhttps://husseinnasser.com/courses

I absolutely love this podcast. As a GIS person, l’m trying to learn as much about software engineering as I can, especially application development. Hussein delivers, both as an educator and entertaining podcast host. He covers super relevant topics that are useful in the industry. Keep up the great work!

My favorite GIS podcast

I listen to this podcast on my way into work or while exercising. It gives me food for thought and a lead in discussion at work for knowing what topics to continue researching or learn about. I especially love how Hussein breaks down the complicated topics and to piecemeal bits for every day discussion. Thank you for all your hard work Hussein!

Staying on the leading edge in the cross section of GIS and software engineer in

Welcome to the Backend Engineering Show podcast with your host Hussein Nasser. If you like software engineering you’ve come to the right place. I discuss all sorts of software engineering technologies and news with specific focus on the backend. All opinions are my own. Most of my content in the podcast is an audio version of videos I post on my youtube channel here <a href="http://www.youtube.com/c/HusseinNasser-software-engineering" rel="nofollow" target="_blank">http://www.youtube.com/c/HusseinNasser-software-engineering</a> Buy me a coffee <a href="https://www.buymeacoffee.com/hnasr" rel="nofollow" target="_blank">https://www.buymeacoffee.com/hnasr</a> 🧑‍🏫 Courses I Teach <a href="https://husseinnasser.com/courses" rel="nofollow" target="_blank">https://husseinnasser.com/courses</a>

The Backend Engineering Show with Hussein Nasser

In this episode of software engineering by example we discuss how software engineers should be empathetic and never underestimate and brush a problem as simple. We have to give it some thoughts and think it all the way through.

Episode 43 - Never underestimate a coding task

 TCP and UDP are communication protocols that allows us to send and receive data in a network. We have both for a reason since each has its advantages and disadvantages. In this video we will talk about two protocols, pros and cons of each one and will write tcp and udp server with nodejs showing you these in ACTION. coming up Code!  https://github.com/hnasr/javascript_playground/tree/master/tcp Jump Codes 🏷  tcp pros cons(4:12) Tcp demo (19:00) Udp pros cons (24:25) Udp demo (31:25) Summary (35:40) Explain TCP  Pros:  acknolwedgment,  garenteed delivery,  connection based congestion control ordered packets  Cons Larger packets More bandwidth since more headers.  Slower (because of retransmission)  stateful once connection is lost its lost, cannot resume it.   TCP Example (Code) telnet 127.0.0.1 8080 Explain UDP Pros Statless,  Less bandwidth  smaller packets Faster to transmit  Cons no ack,  no garenteed delivery,  no congestion control no ordered packets  UDP client echo "foo" | nc -w1 -u 127.0.0.1 41234 2:24 osi model tag  14:20 stateful. S stateless video 

TCP and UDP are communication protocols that allows us to send and receive data in a network. We have both for a reason since each has its advantages and disadvantages. In this video we will talk about two protocols, pros and cons of each one and will write tcp and udp server with nodejs showing you these in ACTION. coming up Code!  <a href="https://github.com/hnasr/javascript_playground/tree/master/tcp" rel="nofollow" target="_blank">https://github.com/hnasr/javascript_playground/tree/master/tcp</a> Jump Codes 🏷  tcp pros cons(4:12) Tcp demo (19:00) Udp pros cons (24:25) Udp demo (31:25) Summary (35:40) Explain TCP  Pros:  acknolwedgment,  garenteed delivery,  connection based congestion control ordered packets  Cons Larger packets More bandwidth since more headers.  Slower (because of retransmission)  stateful once connection is lost its lost, cannot resume it.   TCP Example (Code) telnet 127.0.0.1 8080 Explain UDP Pros Statless,  Less bandwidth  smaller packets Faster to transmit  Cons no ack,  no garenteed delivery,  no congestion control no ordered packets  UDP client echo "foo" | nc -w1 -u 127.0.0.1 41234 2:24 osi model tag  14:20 stateful. S stateless video

Episode 95 - TCP vs UDP

We explain how the asynchronous geoprocessing service works in ArcGIS. We also briefly explain the difference between synchronous vs asynchronous request. Enjoy !

Episode 48 - ArcGIS Server - Asynchronous Geoprocessing Service

In this episode of ArcGIS Server Talk we discuss logging.

Episode 52 - ArcGIS Server Talk - Logging

In this episode of #softwaretalk we discuss the art of software troubleshooting. We can become better software engineers by aiming to excel at our craft. Not just find a bug, but track its cause. Not just find a bad performing workflow in the app but find out what causes the performance bottleneck. Do the due diligence. Enjoy this episode guyswww.husseinnasser.com

In this episode of #softwaretalk we discuss the art of software troubleshooting. We can become better software engineers by aiming to excel at our craft. Not just find a bug, but track its cause. Not just find a bad performing workflow in the app but find out what causes the performance bottleneck. Do the due diligence. Enjoy this episode guys <a href="http://www.husseinnasser.com" rel="nofollow" target="_blank">www.husseinnasser.com</a>

Episode 58 - The Art of Software Troubleshooting

Discussing Connection Pooling in ArcGIS Server

Episode 35 - ArcGIS Server Talk - Pooling

We discuss memory leaks. What are they? How they happen? How dangerous can they be?

Episode 18 - Memory Leaks

Episode 34 - ArcGIS Server Talk - Process isolation

Episode 45 - Geodatabase Talk - Domains

We discuss software scaling in three tiers. The front end, the backend and the middle. We take instagram as an example for all three tiers.

Episode 10 - Scalable Software

This podcast is for software engineers that just started their career and facing pressure from outside world to divert their path. Keep doing what you love.

Episode 09 - Advice to new Software Engineers

Does the user experience derive the software architecture or vise versa? Can user experience help determine what backend database you end up using? We discuss both styles of engineering and talk about pros and cons. Enjoy

Episode 08 - UX and Software Architecture

In this video I talk about RabbitMQ Channels compared to HTTP/2 Streams and how QUIC helps mitigate some of the major limitations in Channels and Streams. Chapters 0:00 Intro 0:10 RabbitMQ Channels 3:10 HTTP/2 Streams 6:00 How QUIC Helps

In this video I talk about RabbitMQ Channels compared to HTTP/2 Streams and how QUIC helps mitigate some of the major limitations in Channels and Streams. Chapters 0:00 Intro 0:10 RabbitMQ Channels 3:10 HTTP/2 Streams 6:00 How QUIC Helps

RabbitMQ Channels, HTTP/2 Streams and How QUIC can fix the limitation Message Queues

In this episode we discuss how using the new ArcGIS Server version management service we can undo edits even after the service goes down!

Episode 56 - Geodatabase Talk - Undo edits through services

In this video I want to go through what really happens under the hood when you type google.com and you hit enter in a browser. This is inspired by alex’s github page below, it is a great detailed description of what happens. I did however add more details to certain areas and I removed some stuff like keyboard events and low level operating system like that. So if you are interested stay tuned! https://github.com/alex/what-happens-when  5:30 HSTS https://youtu.be/kYhMnw4aJTw 19:30 tcp vs udp https://youtu.be/qqRYkcta6IE 24:42 tls https://youtu.be/AlE5X1NlHgg 40:56 mimesniffing https://youtu.be/eq6R6dxRuiU Initial typing - lookup for most visited sites or an actual search Google.com Enter - parse is it a url or search term? If search do a search if url visit website Which protocol? which port ? HSTS? HTTPS or HTTP? DNS cached? Hosts? DoH? Lookup ? TCP ip / port ? arp? NAT? proxy? HTTP 1.1 ? More than one connection TLS version? ciphers? Alpn? SNI ? H2 ? H3? Quic? GET / - ? Headers compress cookies? binary stream? HTML? H2 push? HTML Parse? Make multiple requests css? JS? Multiple streams? If H1 then pipeline?

In this video I want to go through what really happens under the hood when you type <a href="http://google.com/" rel="nofollow" target="_blank">google.com</a> and you hit enter in a browser. This is inspired by alex’s github page below, it is a great detailed description of what happens. I did however add more details to certain areas and I removed some stuff like keyboard events and low level operating system like that. So if you are interested stay tuned! <a href="https://github.com/alex/what-happens-when" rel="nofollow" target="_blank">https://github.com/alex/what-happens-when</a> 5:30 HSTS <a href="https://youtu.be/kYhMnw4aJTw" rel="nofollow" target="_blank">https://youtu.be/kYhMnw4aJTw</a> 19:30 tcp vs udp <a href="https://youtu.be/qqRYkcta6IE" rel="nofollow" target="_blank">https://youtu.be/qqRYkcta6IE</a> 24:42 tls <a href="https://youtu.be/AlE5X1NlHgg" rel="nofollow" target="_blank">https://youtu.be/AlE5X1NlHgg</a> 40:56 mimesniffing <a href="https://youtu.be/eq6R6dxRuiU" rel="nofollow" target="_blank">https://youtu.be/eq6R6dxRuiU</a> Initial typing - lookup for most visited sites or an actual search <a href="http://Google.com" rel="nofollow" target="_blank">Google.com</a> Enter - parse is it a url or search term? If search do a search if url visit website Which protocol? which port ? HSTS? HTTPS or HTTP? DNS cached? Hosts? DoH? Lookup ? TCP ip / port ? arp? NAT? proxy? HTTP 1.1 ? More than one connection TLS version? ciphers? Alpn? SNI ? H2 ? H3? Quic? GET / - ? Headers compress cookies? binary stream? HTML? H2 push? HTML Parse? Make multiple requests css? JS? Multiple streams? If H1 then pipeline?

Episode 121 - What happens when you type google.com into your browser address box and hit enter?

The communication between the client and the enterprise geodatabase is done through the spatial database engine. We explain that layer in this episode.

Episode 50 - Geodatabase Talk - SDE

I discovered git submodules today. I talk about how I found them and how they helped my code reusability.

Episode 20 - Cool feature in git

In software development, introducing a new feature or functionality always introduces bugs specially in a large software. In this episode we discuss should we fix all the bugs that get introduced from a new feature or install the feature and worry about the bugs later? #agile

Episode 55 - When to Fix the bugs?

We answer the question can Python runs on the backend and serve REST end points

Episode 19 - Python as a Web Server

In this episode we explain the difference between ddl and dml, with respect to the geodatabase

Episode 51 - Geodatabase Talk - DDL vs DML

The best podcast episodes on romantic relationships. Episodes talk about the 5 love languages, intimacy, and the taboo topics of sexual desires and infidelity. This topic is a deep dive into the science and complexities that face us in our relationships with others. Add episodes you're interested into your queue below!

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The best podcast episodes on parenting. Interviewing experts and talking through common issues surrounding parenting. This topic is filled with important lessons and insights for anyone listening. Add episodes you're interested into your queue below!