Hristo Atanasov, Author at ELIS Co Blog

April 1, 2025April 1, 2025

Extracting String Items from JSON Arrays in Snowflake

Introduction

Have you ever struggled with handling JSON data in SQL queries? If so, you’re not alone. In this post, we’ll explore a real-world scenario where we tackled this challenge in Snowflake, transforming complex JSON structures into structured, queryable data.

Understanding the Challenge

In one of our ETL projects, we process raw data ingested from a third-party REST API into a Snowflake database. Some parent-child relationships within this data are stored as JSON strings inside VARCHAR columns.

Here is a simplified example for the purposes of this article:

March 31, 2025March 31, 2025

Boosting DAX Performance: Practical Optimizations for Faster Queries

We are excited to share a few key tips for optimizing DAX queries that significantly improved the efficiency of our Azure Analysis Services (AAS) Tabular Model project.

Our project involves various financial measures that calculate key metrics such as LTM Sales, LTM EBITDA, and Net Debt. Each of these measures incorporates logic for FX conversions and period filtering. While individual measures performed well, combining many measures in a single dashboard negatively impacted performance. After analyzing our DAX expressions, we identified two major factors affecting execution time. Below, we outline how we optimized performance in each case.

February 19, 2025March 28, 2025

Use DAX to Manipulate Relationships in Tabular Model Projects (Analysis Services)

Welcome to the next piece of our series of articles describing the challenges we handled while working on the “Snowflake Warehouse and AAS Tabular Model” project.

We are happy to share our recent findings that helped us implement specific requirements in the tabular model project on which we have been working for a while.

March 27, 2024March 28, 2025

Mastering OLAP Cube Reporting: Solving Grand Total Calculations in Snowflake Warehouse and AAS Cube Projects

Welcome to the first installment of our promised series of articles detailing the challenges we encountered and conquered during our work on the “Snowflake Warehouse and AAS Cube” project.

Today, we’re excited to share how we tackled a particularly thorny issue while developing an AAS Cube project for one of our valued clients. Our task involved creating measures to extract financial data such as Sales and EBITDA. Given that reports are generated in specific currencies (e.g., USD), we needed to incorporate currency (FX) conversions within these measures. The parameters for these calculations varied depending on the particular company, with each company having its base currency code.

April 24, 2019March 28, 2025

Automatically set unique permissions in SharePoint with Microsoft Flow

We have a customer who is using SharePoint Online and they recently asked us to find a solution for the following situation in the Documents library.

December 9, 2015March 28, 2025

Mobile App with Corporate Authentication (Ionic + ASP.NET Web API + OAuth 2.0 tokens + Okta)

Recently we had to build a mobile application and one of the requirements was to implement a corporate authentication for managing the user accounts. We think the approach that we used could be interesting and helpful in similar scenarios that is why we would like the share our experience.

December 20, 2014March 27, 2025

TinyMCE in ASP.NET UpdatePanel

TinyMCE is a great HTML editor and it is pretty easy to install and configure the editor on a web page. You should just call the init() function while loading the web page at the client’s browser and the target text-area will be transformed into a nice looking HTML editor.

However, we run into some troubles when we tried to use the TinyMCE editor on an ASP.NET page containing server inputs that are handled by the Microsoft’s UpdatePanel control.

December 11, 2014March 27, 2025

Online Technical Documentation based on WordPress

Recently, we were asked to implement an online technical documentation solution by one of clients. We had to move the existing offline documents (mainly MS Word and PDF files) to an online accessible format that would also allow the users to modify the documents by themselves. We thought about the following options for implementing this:

Implement a custom web based ASP.NET solution, starting from scratch
Use Wiki engine
Use CMS (e.g. WordPress)

We did not choose the custom implementation because it was the most time consuming option. We also did not choose the Wiki software because we found it a bit outdated and too restrictive and finally we focused on the CMS solution.

December 8, 2014March 27, 2025

WIF SSO and Forms Authentication in ASP.NET

One of the projects on which we are working is a long-lived ASP.NET Web Forms system that is customized for a specific client. It is hosted by another company on a server which is external to the client’s environment and it does not have an access to the client’s internal network. The system is built by using the Form Authentication mechanism to authenticate and authorize the users. The list of users and their hashed passwords is stored into the database and the login functionality works in a classic manner – the credentials provided by the user on the login page are validated against the list of users in the database. If the provided credentials are valid then a new Forms Authentication session is established by calling the standard method FormsAuthentication.SetAuthCookie().

Recently, we had to extend that authentication mechanism by adding a single sign-on (SSO) capability which allows the client to integrate the ASP.NET web application with their internal Active Directory (AD) infrastructure. The requirement was to allow some internal employees to access the ASP.NET web application through SSO, but also keep the exiting database login functionality for the rest of the users who are external and they do not have internal AD accounts.

The ASP.NET web application is hosted on an external server and it does not have a direct access to the secured AD infrastructure. After doing some research, we found that in order to connect the external ASP.NET web application to the internal AD environment we can use a middle service called Security Token Service (STS).

December 19, 2013March 27, 2025

HTML 5 – The Offline Challenge

HTML 5 – The Offline Challenge

I. Introduction

Some time ago our team had to add a new feature to one of our web projects. There was a request to add a capability to allow the users to use the application in “offline” mode. It was a great opportunity to dive into HTML 5 and more specifically the “offline” part of it. The new features of HTML5 are pretty interesting, but also “tricky” and this is why I would like to share some of the challenges we met.

First, I would like to say a few words about the technology on which the project is build. That is ASP.NET application which is storing data in SQL Server database. This is not a public application and only authorized users can access it. The system allows the users to go through their business process by entering the information in some structured web forms and at the end it allows them to generate a Word document, which is their final product. The web application is completely client-orientated and there is a huge usage of jQuery and AJAX. The AJAX calls are handled by WCF services. Frankly, this architecture made the implementation of the “offline mode” pretty straightforward.