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iPhone calendar synchronization: iOS settings for Baïkal (CalDAV), certificates

2019-09-23T11:49:10Z

Somewhere at the end of 2018, the Baïkal calendar synchronization on my iPhone started to show some problems. Continuous synchronization in the background did not seem to work.

By changing some of the Baïkal account settings on the iPhone, the synchronization could be made to work again. Intentionally, I create invalid settings, let the validation pass and save the settings. Then, I restore the original, correct settings again. As a result, the iPhone starts a full synchronization, which takes a few minutes in my case.

Further analysis showed that probably iOS does not like to synchronize using a self-signed certificate on the Baïkal-server. There is no error reported. Other users with comparable issues have reported this in discussion groups.

Some research led me to trying LetsEncrypt. For my server setup, there is a script available for using Certbot, a tool that automates issuing and installation of LetsEncrypt-certificates. Worked like a charm. The Baïkal-server now uses a real certificate and iOS synchronization works again.

SQL - Calculation of the date of the first day of the week (ISO 8601)

2017-10-17T14:37:01Z

Calculations involving dates in database selections can cause headaches. For aggregation into “week buckets”, we were looking for a way to calculate the date of the first day of the week, given an arbitrary date and using the ISO 8601 definiton of a week.

iPhone calendar synchronization: iOS settings for Baïkal (CalDAV)

2017-07-04T12:49:51Z

For synchronization of contacts and calendar on iOS using a Baïkal-server running on Nginx:

The redirect rules (for iOS) must be correctly applied in Nginx, so in its base configuration.
The url’s that must be entered into iOS for connecting with Baïkal are different from what other Baïkal-clients use.

New: iPhone

2017-07-04T10:07:38Z

Since a few weeks, I am using an iPhone as business smartphone.

This has a long history. For quite some time, I have been using Nokia smartphones with Symbian. First, the N95, and later some of its successors. Their specifications were never best in class, and configuring them required quite a lot of work. But, they generally met my requirements for a business smartphone. Then came a robust Samsung Galaxy S4 Active and later an S6. Many of their functions work perfectly, as long as you want to use the Google prepared solutions. Until recently, I have been using a Jolla, using SailfishOS, which can be considered a descendant of Symbian. Its specifications were mediocre. Still, email and the calendar used to work fine. Later, the device was showing a number of issues, which were difficult to grasp, but recurring. This became so elaborate that I decided to look for another smartphone.

For business use, my requirements are modest. Email, calendar and contacts need to be available. The smartphone is only one of the devices, so everything must be kept synchronized, using various accounts. The most important central functions (email, synchronization) is hosted on my own servers.

Additionally, it would be convenient to have some other functions available when on the road: taking pictures, social media, etc. For this, I considered two alternatives: a separate tablet next to the (simple) smartphone. Or, a single smartphone that can do all. I decided for a large iPhone 7 Plus, which can do it all. Android is not my preferred smartphone operating system. Windows smartphones provide value for money, but Windows appears to become marginal. A smartphone running something different from Android, Windows or Apple’s iOS is not available, currently.

So, what is the verdict after a few weeks of using? The device is easy to use. It is surprising how quick and easy configuration is done. Having a powerful smartphone with a nice display and a good camera is of course very nice. After a few weeks, the last issue regarding the business functions has been resolved: calendar synchronization.

The SAP HANA delta-stores

2017-01-21T20:46:55Z

In order to avoid impacting the run time of data changing operations too much, SAP HANA does not immediately update the row and column versions of a columnar tabular upon posting the changes. Every change to the table’s content is initially saved to a delta-store for that table, to be processed at a later moment. A consequence is that, for simple operations on the data, different administrations have to be read.