What are redundant Connections
Since v3.1.0, Alpana implements a redundancy mechanism on Connections that allows to store multiple connection configurations inside a single Connection.
Each connection configuration is defined by a set of parameters (database name, user name, etc…), called a Parameter Set.
This can be used in basically 3 types of scenarios :
- Using different databases for design time and run time
- Implementing a fail-over mechanism to keep Dashboards working even when the primary database is down
- a combination of scenario 1 and 2
Scenario 1 : Design Time / Run Time
You can select a different Parameter Set for Alpana Designer and Alpana Server.
This is useful for example if the developer doesn’t have access to the production database from the development machine, maybe because they are on a different network.
In this case, you can configure 2 different Parameter Sets :
- one to work in the Designer by pointing on the local development database
- one for the published Dashboards by pointing to the production database
Scenario 2 : Database1 / Database2
The Primary Parameter Set is where Alpana will try to connect first.
If the connection fails, Alpana will use the Secondary Parameter Set.
This is useful for example to ensure that Dashboards can always get data, even when the main database is unavailable.
In this case, you can configure 2 different Parameter Sets :
- one pointing to the main database
- one pointing to the backup database
Scenario 3 : combine
You can create 3 parameter sets for handling both scenarios above :
- Parameter Set 1 : primary development
- Parameter Set 2 : primary production
- Parameter Set 3 : backup production
Fallback Logic
When a primary connection fails, Alpana will check the next one in order until it succeeds, or until all fail.
As a mitigation, all widgets that use the same connection will inherit the fallback.
This means that during a single page load, the timeout will happen only once per Connection.
Alpana Designer
In Alpana Designer, the order is :
- try to connect to the Primary parameters at design time
- if it fails, try to connect to the Primary parameters after publication
- if it fails, try to connect to other parameters
Alpana Server
In Alpana Server, the order is :
- try to connect to the Primary parameters after publication
- if it fails, try to connect to the Primary parameters at design time
- if it fails, try to connect to other parameters
Connection Types
Redundant connections are supported by the following Connection types :
- SQL
- Historian
- Web
Managing Parameter Sets
A Parameter Set is the set of all the parameters required to connect to the data.
Default behavior
By default, only one Parameter Set is created for the current connection, and is used for both Designer and Server.
Renaming Parameter Sets
You can rename each Parameter Set :
Creating Parameter Sets
Click the + icon to create a new Parameter Set :
Editing other Parameter Sets
To edit a Parameter Set, click on the corresponding tab :
Deleting Parameter Sets
Click on the red cross to delete the corresponding Parameter Set :
Designer ⇔ Server switching
To choose which Parameter Set to use for Designer or Server, select the desired Parameter Set in each list :
- Primary parameters at design time : primary connection to use while in Alpana Designer
- Primary parameters after publication : primary connection to use while published in Alpana Server
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