Short Guide to the Ideas of QNAP2  Nov 7 99

1. Data Structures and Objects

(a) variables of types {integer | real | boolean | string} may be scalar
or arrays. Array dimensions may be parameters read in at run-time.

(b) model objects of types {queue | customer | class | flag} may be
scalar or arrays themselves, and may have attributes which are scalar or
array variables, or pointers, or objects.

Some of these attributes are automatic, and others may be added by
DECLARE statements. For example:

/DECLARE/ QUEUE REAL t....... adds an attribute t to every QUEUE
object in the model, which can be accessed as "queuename.t".

2. Service stations are instances of queues and servers. They have a
lot of automatic parameters. Each 
service station is defined in a section headed /STATION/ and includes:

NAME = a queue name;
SCHED = {FIFO | LIFO | PS PRIOR};
SERVICE = EXP(mean); or = some other canned procedure, or a
   BEGIN...END block in the QNAP2 algorithmic language (see the refernce
   manual) that calculates a value of the service time.
TRANSIT = {station, value of probability} repeated;
   or = {(list of stations),(list of values of probability)};
   or = other forms including classes of customers.
TYPE = {SINGLE_SERVER | INFINITE | MULTIPLE(n) | RESOURCE | SOURCE};
INIT = no. of tokens at the station

The queue name in NAME may be an array, in which case the range of
indices for the instances is given as "NAME = name(i STEP 1 UNTIL j)"

There is a default station OUT to give an exit, which does not have to
be defined. 

A SOURCE type station generates arrivals at intervals defined by the
SERVICE statement, with a class set on leaving (in the TRANSIT statement)

3. Classes are treated as objects like queues, and can have a lot of
parameters attached to them (example p 29):

-- the service times at stations
-- the class size
-- their transition probabilities on leaving each station

ALL CLASS is a list of all classes.

4. Program layout

/DECLARE/  is just one block with all the object classes and variable
types, and global variable instances
/STATION/  is a block for each station declaring instances
/CONTROL/  describes the initialization and termination
	--- an initial printout in a statement ENTRY = procedure
	--- the ending and reporting 
in a EXIT = begin.... end procedure
(IMPORTANT for multiclass systems, it you want the automatic output to
give details by class, is to include a statement in CONTROL:
	/control/ class = all queue)
See example p 50.
There is an automatic output which is recommended. For custom output
to supplement it, printing uses a statement print("string" [,list of
expressions]); and the expressions may use the following reserved
variables which contain results:
mthruput(station [,class])
mbusypct(...)
mresponse (...) (wait plus service)
mcust_nb (...)
mservice (...)
mblocked(....) (wait only)

/EXEC/  gives the detailed control of the flow of the solution,
including initialization and solution and reporting.

	It may consist of just the one statement SOLVE, or it can
include a loop iterating over sets of parameter values. There can be
several EXEC blocks.
If the program cannot find a suitable solver it will simulate the
system; beware of this as it can take a long time. Analytic solution
takes seconds, simulation can take hours. As well as SOLVE, which
invokes a range of analytic methods, there are commands SIMUL and MARKOV.

There is a default output summary with results for each station, which
will be printed unless it is suppressed by the command in the
/control/ block of "option = nresult;", after which it could be
reinstated by /exec/ output;


5. Notes on syntax for TRANSIT in QNAP2

The syntax (p 3.20 in the Reference manual) is 

TRANSIT [(class list)] = transition list

transition list = {queue sublist [,class sublist], real sublist} one
or more times.

You can have a s many of these statements as you like so the simple
way is to put in one for each class

The brackets do not appear; [..] means optional

The sublists must be of the same length; if of length one the
statement can have the forms:

TRANSIT (all_class) = queue
TRANSIT (class0) = queue1,class1,prob1, queue2,class2,prob2, etc

TRANSIT (class0) = queue1,prob1, queue2,class2,prob2, etc

6. Programming

Use lower case for all characters.

No tabs if you use emacs as an editor

Invoke as qnap2 <inputfile >outputfile

There are facilities for taking parameters from a file, or from the
keyboard, but they are really hard to use with unix Fortran.

There is a User Guide, full of examples, and a Reference Manual which
describes the syntax of all statements.