GeneXus Flow 16 is the most complete and robust version of GXflow that includes performance and scalability improvements and adds support for SAP Hana, among others.
Here follows a list of the most important improvements and a link to all the details too.
As you may know, GXflow is completely developed with GeneXus. So it also takes advantage of the latest GeneXus features that enable high scalability and performance.
To improve these aspects, all internal For Each commands have been improved with paging clauses so that the database queries now use databases' mechanisms for paging.
Also, different caching mechanisms are used (ref.: Caching in GeneXus applications) for caching data of tables, system parameters and sessions.
The scalability and stability improvements mentioned above, among others, helped that GXflow now can run on any Platform as a Service (PaaS) environment, like Amazon Beanstalk, Microsoft Azure, IBM Bluemix or SAP Cloud Platform.
GXflow 16 (Java) supports the SAP HANA Database, and it can now run on the SAP Cloud Platform as stated above.
More information: GeneXus for SAP Systems, GXflow Software Requirements
For those high scalability purposes and be able to run on PaaS, GeneXus Flow incorporates license types for different business purposes, and a new license protection method: Native, that stores license info in the database.
A license manager is now built-in to properly configure the GXflow's installation.
More Information: GXflow license scheme, HowTo: Work with GXflow license manager
There have been made changes to the database schema in Genexus 15 Upgrade 10, so if you are moving from GeneXus 15 Upgrade 9 or prior to GeneXus 16, some special steps may need to be followed.
More Information: HowTo: Deploying a Workflow-based Application
GXflow internally uses the Log external object to write low-level log information that facilitates troubleshooting. It does so if Log level property has been set to 'Debug' or 'All', and it writes the information under topics that start with 'GXFLOW.' to the output set by Log output property.
11:18:04,768  DEBUG GeneXus.Data.GxSqlCursorDataReader - Return LoadFirstBlock, Parameters: CursorHandle 180150009
11:18:04,768  DEBUG GXFLOW.STATE_MACHINE - Evaluate outgoing sequence flow
11:18:04,768  DEBUG GXFLOW.STATE_MACHINE - Task: 27
11:18:04,768  DEBUG GXFLOW.STATE_MACHINE - Flow Type: F
11:18:04,768  DEBUG GXFLOW.STATE_MACHINE - Create outgoing task : 27
11:18:04,772  DEBUG GXFLOW.STATE_MACHINE - Create Workitem
11:18:04,772  DEBUG GeneXus.Data.ADO.GxCommand - GxCommand.FetchSize: 1, handle '1'
Please check out the following link to read detailed information about the several improvements in GXflow 16 and also information about compatibility issues