iNTERFACEWARE™ Inc.

From Database

In order to configure the From Database source component described in the Channel Source Components section of the manual, you must specify the properties described in the table below:

Ordering For Multiple Outbound Messages

You can easily order for multiple outbound messages in Iguana. This feature in Iguana does not affect existing VMDs or the user's existing database schema.

The Order Messages By Column can be configured to globally order messages across the entire set of tables in your database. All of the outbound tables must have:

• MESSAGE_ID to get the data.
• Data type for Order Messages By Column must be a type that can easily be sorted (e.g. string or number). An error will be logged if the type is a binary, boolean, etc.).
• Column type with the same name must exist in all message root tables.
• Column type with the same name must be used for ordering the messages.

	In cases where the MESSAGE_ID/Order Messages By Column values are the same, the outbound messages will be sent in the order that they are first processed (i.e. first come, first served basis).

Separate SELECT Queries on All Message Tables

Every time Iguana polls for a message from the database, it will execute a select query on each message that was defined in the vmd file. The select query will utilize the MIN() or MAX() function (for ascending or descending, respectively) to retrieve just one row from each table (no limits required).

When Iguana iterates through all the retrieved values, it will know which message has the global minimum/maximum MESSAGE_ID (or other order by column).

For example:

• SELECT MIN(MESSAGE_ID) FROM MESSAGEA; => GlobalMin = MessageA[2]
• SELECT MIN(MESSAGE_ID) FROM MESSAGEB; => GlobalMin = MessageB[1]
• SELECT MIN(MESSAGE_ID) FROM MESSAGEC; => GlobalMin still MessageB[1]

Therefore, Iguana sends MessageB[1]. After sending, Iguana re-executes the queries and sends MessageA[2].

Re-executing the queries will handle situations where you decide to rearrange the order of messages of, say, MessageA[2] and MessageC[3] before MessageB[1] is finished.

If all tables are empty, Iguana will wait for the poll time (as it does now) before re-executing the queries.

Updating the Data Tables

If you change the table definitions in the mapping VMD file, or you add a new message definition to the VMD file, you must update the source data tables in the database that you have specified for this channel. There are two ways to update these data tables:

• Re-export the Source Data Tables: This will drop the existing data tables and replace them with new ones. Any data in the existing tables is lost, which may lead to undesirable results. (See Exporting Tables for more details on re-exporting the source data tables.)

• Modify the existing databases manually: Any columns that you add to a table definition in the VMD file must be manually added to its corresponding database table. You must also create a new status table for each new message definition you have added to the VMD file; to get an idea of what this table should look like, examine one of the existing status tables.