Instance Directory Overview

The Instance Directory serves as an index of available Case Manager databases. Client applications make use of this centralized information to connect to the appropriate database - thereby giving you centralized control of the database all applications connect to.

Definitions

Instance

An instance is a representation of the database, thus, the instance contains the name of the database and its location (where the database is currently stored).

Instance Directory

The Instance Directory is a network-wide database directory that keeps track of all Case Manager instances. Anyone can access an Instance Directory over the network.

Default Instance

The Default Instance is a reference, stored per workstation (per user), to the instance the applications on that workstation should connect to by default. Only the applications that make use of policies dependent on the default instance will be affected by changes to the workstation's default instance value.

Multiple Instance Directory

A Multiple Instance Directory error occurs when one network has more than one Instance Directory running to which people can connect. This, however, is not advised and the Case Manager team recommends that only one Instance Directory be implemented at a site.

Instance Directory Windows Service

The Instance Directory operates via a Windows Service (typically installed on the server) which publishes the necessary Web Service and maintains the instance information.

Local Instance Directory

A Local Instance Directory is stored and maintained in the Windows Registry on the workstation per user. The Local Instance Directory is updated to contain the same information as the Instance Directory (on the server).

Instance Directory Utility

The Instance Directory Utility provides management of the Instance Directory and all the instance information. It also provides processes such as Backup and Restore capabilities, Database user verification, and Case Manager version upgrades.

Policy

A policy, in terms of the Instance Directory, defines how the application interacts with the Instance Directory - specifically in getting the updated instance information, selecting the appropriate instance from available instances, and behavior upon failure of initialisation.

Command-line Argument

A command-line argument is a parameter that can be specified when the application is started. It is defined, in a console environment, by trailing the application execution command with the argument values.

How does it work?

The Instance Directory is installed as a Windows Service on the server, and publishes a web service making the information available client applications. This web service makes use of WS-Discovery technology, which makes it detectable on a local network. The Instance Directory does not connect to a database itself; instead it stores database connection information locally. When client applications initialize, the following process executes to establish a connection with the database:

1. During Start-up, the application policies are determined to initialize the database connection.
2. The Update process maintains a local copy of the instance directory information (stored in the Windows Registry). Unless bypassed by command-line arguments, or a set-up alternative, the application will detect where the Instance Directory Service is running on the network. Once the Instance Directory is located the latest information is requested and the local copy is updated.
3. The Selection policy determines how the correct database (or instance) is selected from the local copy of the directory. This is usually determined by the application itself, but can be overwritten by command-line arguments. For example
   • The Configuration Tools will present you with a selection screen, to select the correct instance.
   • The main Case Manager application will try to connect to the last instance it connected to (default instance).
   • The schedulable console applications (e.g. DailyMaintenanceRunner) will attempt to connect to the instance as specified in the command-line argument, and otherwise it will fail.
4. The Database Initialization sets the connection details to be used throughout the application.
5. Lastly, control is given the application itself.

Guides

We take a deeper look into the the follow aspects of the Instance Directory in the following documents of this guide:

• Instance Directory Service covers the installation and setup of the Instance Directory service running on the server.
• Instance Directory Utility explains how to make use of the utility to set up and maintain instances in your environment.
• Application Connections elaborates on how Case Manager applications connect to the correct instance by making use of the Instance Directory. We also look at the options you have in configuring this behavior in console applications.