Node names types and keys

The majority of nodes created by patterns are Software Instances and Business Application Instances. Both node kinds have attributes name and type, and, in common with all nodes maintained by patterns, must have a key. This appendix discusses how to set those attributes in a number of scenarios. In the following scenarios, the node kind is consistently referred to as a Software Instance (SI), but equivalent suggestions apply to Business Application Instances (BAIs).

The name attribute is intended to be a human-readable summary of the identity of the node - it need not be globally unique, but it should give the reader a good idea about which instance it is.

SI on single host, uniquely identified and versioned

Scenario 1 — The SI is running on a single host. The pattern can determine a unique identity, and determine the version for each SI:

Type

The name of the product, for example, "Oracle Database" or "Apache Web Server"

instance

The unique instance name of the SI, for example, "TRADING_DB" or "www.example.com".

name

A string of the form "%type% version %version% called %instance% running on %host.name%", for example, "Oracle Database version 10g called TRADING_DB running on londb01".
As appropriate, the word "called" should be replaced with similar words such as "identified by" or "using".
The version number used should either be the product version or the full version, whichever is most appropriate for the product.

key

A string of the form "%instance%/%type%/%host.key%"


SI on single host, uniquely identified but not versioned

Scenario 2 — The SI is running on a single host. The pattern can determine a unique identity, but cannot determine the version for each SI:

Type

The name of the product, for example, "Oracle Database" or "Apache Web Server"

instance

The unique instance name of the SI, for example, "TRADING_DB" or "counterexamples".

name

A string of the form "%type% called %instance% running on %host.name%", for example, "Oracle Database version 10g called TRADING_DB running on londb01".
As appropriate, the word "called" should be replaced with similar words such as "identified by" or "using".

key

A string of the form "%instance%/%type%/%host.key%"


SI versioned but not uniquely identified

Scenario 3 — Cannot determine a unique name for each SI, but can find version

Type

The name of the product, for example, "Oracle Database" or "Apache Web Server"

name

A string of the form "%type% version %version% running on %host.name%".

key

Not set.

key_group

Not set, or set to the empty string. The system creates a suitable key embedding the type and the host's key.


SI not versioned or uniquely identified

Scenario 4 — No unique name or version available

Type

The name of the product, for example, "Oracle Database" or "Apache Web Server"

name

A string of the form "%type% running on %host.name%".

key

Not set.

key_group

Not set, or set to the empty string. The system will create a suitable key embedding the type and the host's key


Product with only one instance on a host

Scenario 5 — A product that can fundamentally only have one instance running on a host

Type

The name of the product, for example, "Oracle Database" or "Apache Web Server"

name

A string of the form "%type% running on %host.name%".

key

A string of the form "%type%/%host.key%".


An SI or BAI spanning multiple hosts

Scenario 6 — A Software Instance or Business Application Instance spanning multiple hosts:

Type

The name of the product, for example, "Oracle Database" or "Apache Web Server"

instance

In this case, the SI / BAI is composed of other SIs / BAIs. To group them together, there must be some identifying characteristic for the group. In cases where there is one global instance of the application, the instance would not be set.

name

A string of the form "%type% version %version% called %instance%".
As appropriate, the word "called" should be replaced with similar words such as "identified by" or "using". If there is one global instance, the instance information should be left out.
The version number used should either be the product version or the full version, whichever is most appropriate for the product, or absent altogether if no version information is available.

key

A string of the form "%instance%/%type%"


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