Creates a service on a service node. You must have OPER privilege
to use this command.
Format
CREATE SERVICE [service-name]
1 – Parameter
service-name
Specifies a LAT service name. By default, a service name is the
name of the local node you defined with the SET NODE command.
The service name can be from 1 to 16 ASCII characters in length.
The characters allowed are as follows:
o Alphanumeric characters: A-Z, a-z, 0-9
o A subset of the international character set: ASCII codes 192-
253
o Punctuation characters: dollar sign ($), hyphen (-), period
(.), and underscore (_)
2 – Qualifiers
2.1 /APPLICATION
Specifies that the created service is an application service. An
application service offers a specific application on the service
node rather than a general interactive service. You can define a
dedicated port for the service by using the CREATE PORT and SET
PORT commands.
2.2 /IDENTIFICATION
/IDENTIFICATION[="identification-string"]
Describes and identifies a service. Service nodes include the
identification string in service announcements. A service node
announces its services at regular intervals established with the
SET NODE command. Entering the LATCP SHOW NODE command or the
DECserver SHOW NODE command generates a display that includes
this identification string. By default, the identification string
is a translation of SYS$ANNOUNCE.
You cannot specify more than 64 ASCII characters in an
identification string (a SYS$ANNOUNCE longer than that will be
truncated to the first 64 characters). Enclose the string in
quotation marks (").
2.3 /LIMITED
Specifies that the service is a limited service, using devices
assigned the limited characteristic and associated with (mapped
to) this limited service. This qualifier is used in conjunction
with the SET PORT /LIMITED command (see example).
2.4 /LOG
/LOG
/NOLOG
Specifies whether LATCP displays a message confirming that the
service was created. If you do not specify the /LOG or /NOLOG
qualifier, the default is that no message will be displayed.
2.5 /STATIC_RATING
/STATIC_RATING=rating
/NOSTATIC_RATING
Enables or disables dynamic service ratings. A dynamic service
rating means that a LAT algorithm calculates the availability
of a service dynamically, based on the overall level of activity
of the node that offers the service and the amount of memory.
When a terminal server or node requests a connection to a service
that is offered on two or more service nodes, the requesting
node selects the service node with the highest (most favorable)
service rating. This selection process is called load balancing.
The dynamic service rating, which is the default, is usually
adequate for efficient load balancing on the LAT network.
However, when necessary, you can use the /STATIC_RATING qualifier
to disable dynamic service ratings so that you can specify a
static (fixed) rating. That static rating value does not change
until the dynamic service rating is reenabled.
Use the static rating to direct users away from or toward your
node temporarily. Static ratings range from 0 to 255. Specify a
low value to make the local service node less likely to be used;
specify a high value to make the local service node more likely
to be used.
If you do not specify either the /STATIC_RATING or /NOSTATIC_
RATING qualifier, the default is that the LAT software uses the
dynamic service rating.
Limited and application services do not rely exclusively on
the dynamically calculated service rating. Instead, they use
a portion of the dynamic rating based on how many ports are
available for the service. For example, if a limited service has
50% of its ports available, the dynamic service rating will be
scaled, halved, and then added to 105. When ports are available,
the rating will always be above the value 105.
When all ports for a limited or application service are in use,
the rating will be based on the scaled dynamic rating and the
number of free queue slots on the local node. The rating will
always be less then 90.
This rating procedure for limited and application services
follows the terminal server rating algorithm for services and
available ports that the service offers, while at the same time
taking into account the availability of the node (which is the
factor used to calculate the dynamic rating).
If your system is licensed for a specific number of units (where
only a fixed number of users can log in to the system regardless
of how the login limit is set), then all dynamic ratings become 0
when all OpenVMS license units have been consumed. (This forces
all node service ratings to the lowest possible value when logins
are not possible because all OpenVMS license units have been
consumed.)
Note as well that the LAT software transmits a service
announcement message when a user logs in to or out of the system.
This allows the system to more quickly provide information
about service rating changes that result from a login or logout
operation.
3 – Examples
1.LATCP> CREATE SERVICE/STATIC_RATING=195 SALES
The CREATE SERVICE command in this example creates the service
SALES on a service node. This command assigns a static rating
of 195 so terminal servers (and nodes that support outgoing
connections) can assess the availability of services on the
node.
2.LATCP> CREATE SERVICE/APPLICATION GRAPHICS
This command creates the service GRAPHICS on the local node.
Use the CREATE PORT/DEDICATED and SET PORT/SERVICE=GRAPHICS
commands to create a port that is dedicated to this service.
3.$ LCP :== $LATCP
$ LCP CREATE SERVICE/LIMITED ONLY_ONE
$ LCP CREATE PORT/LIMITED LTA1234:
$ LCP SET PORT LTA1234: /SERVICE=ONLY_ONE
This series of commands creates a limited service that allows
only one user to log in to the system through that service.
When a user connects to service ONLY_ONE by responding to the
terminal server prompt (Local>), the user is assigned port
LTA1234 and then prompted for the user name. Any user who
attempts to connect to the same service while LTA1234 has a
user logged in receives the "service in use" message.