Kimserey's blog

Moving from chaining to piping in rxjs 6.x Last month I updated all my NPM packages and realised that everything was broken! The reason why was that rxjs decided to move out of extensions on observable in favor of pipable functions from 5.x to 6.x. A major breaking change where majority if not all codebase built using rxjs needs to be changed. Today we will explore the reasoning behind this change. Reasons Example of migration Learnings 1. Reasons The reasons given on the official documentation are: Any library importing the patch operator augmenting the observable prototype would also augment it for all consumers. For example, when a library imports map extension from import 'rxjs/add/operators/map' , it makes map available for all code importing the library itself. This could bring confusion due to the inconsistent way of importing extensions. Some places would not need to important map (those were the library is used) while in other place of the code we would ...

Entity Framework Core Performance Optimization Last year I talked about Entity Framework Core . It is a easy and feature rich ORM which makes working with database in a .NET environment typesafe. But even though it makes things easy, there are ambiguous cases which can take us off guard. Today we will see four of this cases and how to deal with them. Client evaluation Iteration Include and ThenInclude NoTracking For the following examples, I will be using SQLite with Entity Framework Core. tl;dr Make sure that the query constructed in c# uses function that can be translated to SQL, Make sure that there isn’t an abnormal amount of queries created and that it does not iter item per item, Make sure to use Include and ThenInclude for object relation to include them after query execution, before query execution it is not needed, Use NoTracking for readonly queries to disable tracking on entity to yield better performance. 1. Client evaluation The following example illust...

Create a Navigation loading bar for Angular with PrimeNG In Angular, it is common practice to execute commands prior routing a page using guards and resolvers. Guards prevent the routing from occuring until the condition turns to true and resolvers prevent the routing from occuring until the data is returned. Those actions can take time to complete and during the time being, the component will not load leaving the user with an impression of unresponsiveness. Today we will see how we can implement a navigation loading bar for Angular using PrimeNG progress bar component in two parts: Setup an Angular project PrimeNG Progress bar If you are unfamiliar with the Angular router, you can have a look at my previous blog post explaining the feature of the router https://kimsereyblog.blogspot.com/2017/06/how-to-use-angular-router.html . 1. Setup an Angular project We start by creating a project and installing PrimeNG. npm install primeng --save npm install primeicons --save Next we a...

Monitor Upstream Response Time with Nginx and CloudWatch Last week we saw how we could Setup CloudWatch to push logs from our application to CloudWatch . Apart from the application logs, another type of logs that is worth looking into are the access logs from Nginx. Nginx being the entrypoint of the application, every traffic in and out goes through it and today we will see how we can leverage its access logs to monitor the response time of our application from CloudWatch in three parts: Setup Nginx to log upstream response time Setup logs to be pushed to CloudWatch Setup metrics filter on CloudWatch 1. Setup Nginx to log upstream response time By default Nginx does not log the upstream response time. In order to print it, we can create a new log format which includes it and configure logs to be written into a file using that format. We can add our log configuration in a file called log_format.conf which we can place under /etc/nginx/conf.d/ and nginx will include the configu...

Serilog with AWS Cloudwatch on Ubuntu Few weeks ago we saw How to configure Serilog to work with different environment . At the end of the post, we saw briefly how to get the structured logs synced to Cloudwatch. Today we will explore the configuration in more details. Unified Cloudwatch agent Literate and json logs with Serilog Debug the Cloudwatch agent 1. Unified Cloudwatch agent The Unified Cloudwatch agent can be installed by following the official documentation https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/UseCloudWatchUnifiedAgent.html . There is a previous version of the Cloudwatch agent, this new version, introduced in December 2017, unifies the collection of metrics and logs for Cloudwatch under the same configuration. To install the agent, execute the following commands: mkdir ~/tmp cd tmp wget https://s3.amazonaws.com/amazoncloudwatch-agent/linux/amd64/latest/AmazonCloudWatchAgent.zip unzip AmazonCloudWatchAgent.zip sudo install.sh This will install ...