In this follow-up to the article titled “’Haunted Apps’ – How to Avoid Ghost (Unresponsive) Windows”, you’ll learn about the multi-threading capabilities available to PowerBuilder applications and how multi-threading can be used to perform tasks that typically freeze the application’s Graphical User Interface (GUI). Multi-threading can be utilized for many purposes, but this discussion will focus primarily on the use case of long-running data retrieval requests.

This article covers what you need to know in order to get started using multi-threading in PowerBuilder. A new example application that can be easily customized to test multi-threaded data retrieval in your development environment(s) is now available in the PowerBuilder section of CodeXchange. An expanded, but slightly earlier version of this article is included in the example application’s download package that explains the objects and code in detail.

PowerBuilder can create an entire application from the object source files stored in a source code control system without relying on existing PBLs. This has been public knowledge for years, but since I cannot find the article anymore where I read about this for the first time, and since I still see people saying the opposite, I decided to put together this short how-to guide hoping that this information will become searchable.

If someone knows the link to the original article, I will be happy to include it here or even replace this article with the link.

12/26/2021 Update:  A PowerBuilder 2021 sample app that includes all of the following code is available in CodeXchange at: https://community.appeon.com/index.php/codeexchange/powerbuilder/306-reading-a-smard-card-from-powerbuilder

We’re going to look at using the Smart Card SDK provided in more recent versions of Windows (XP and later).  Earlier versions of Windows had an ActiveX installed called CAPICOM which could be accessed from PowerBuilder through OLE Automation, but that control was removed as of Windows Vista because of security issues.

We’re going to look at a number of operations:

·         Communication with the card

·         Validating the user’s PIN

·         Reading the certificate Subject Name

·         Reading other certificate data

 
Note:  This post was updated on December 8th, 2021 to support 64 bit compilation.  Thanks to Jason Schultz for pointing out the problem and to John Fauss and others for pointing out the necessary changes.

Communicating with the card

The first step is establish a context for the API calls.  To do that, we need to declare the following local external function for SCardEstablishContext:

And call it as follows:

Note:  This blog entry is basically the written version of a video I did for the SAP Database and Technology Academy.  You can either watch the video or read the blog entry, or both if you're so inclined.

One PDF capability that still hasn't been introduced as a native feature in PowerBuilder is the ability to merge PDF files. We're going to look at how we can easily add that capability using the open source (LGPL) PoDoFo library.

FYI -

Summary:
   You can create multiple databases from a single PostgreSQL driver.

Details:
PowerBuilder R2019R3
PostgreSQL 12
Windows 10

These instructions assume that at least one PostgreSQL driver has been successfully installed onto the Windows 10 platform.