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Petri Nets & Randezvous Concurrency, an Idiom.


... just had an insight about Petri Nets for Concurrency & Tasks' Randezvous combined together.

... this is a simple musing & experimenting with ideas, but probably will stay in one form or another.

Tasks with Objects.

we wish to model Interleaving Tasks as Actions with Object(s).

one Object can be aggregate, contain many objects - thus a Task might have many objects that are involved in that a Task.

Tokens as Preconditions.

Token accumulation might be a seen as precondition(s) accumulation for a Task to go past a certain 'wait' stage(s), a signal that something occured.

When a Token is in queue it signifies that a certain precondition associated with that queue is met.

When enough of tokens/preconditions are ready to be consumed, event is fired & a Task can proceed to next Wait Stage or a Randezvous Point.

How to ensure that there can be one token in a queue at most? By adding another queue back to originator object - only one token can be in either go forward queue or in return queue.


i think that there might be a nice syntax in 'Ola AH' Programming Language for defining:
- Tasks' 'Wait Stages' with 'Token Queues',
- 'Randezvous Points' with 'Token Queues' & 'Task(s) to meet'.


we have Fighter Jet software, with Task 1 & Task 2 among other parts.

Task 1: Loading Ammunition ... it's a complex process that lasts continuously & has a 'Randezvous Point' where it has to wait for barrel to be ready for load.
Task 2: Shooting ... it's again a complex process with a Randezvous Point where it waits for ammo to be loaded.

when the Tasks meet, Task 1 can transfer data objects to Task 2 & both can proceed after a Randezvous.

what's the difference between 'Wait Stage' & 'Randezvous Point' ? with 'Randezvous Point' data is transferred between Tasks, with 'Wait Stages' we only note that certain precondition(s) is/are met.

see also, if You wish or need, ... : 'Ola AH' Programming Language Randezvous System, Petri Nets.


Single Sign On Protection.

(article in development, perhaps will change or be elaborated in future).

How to protect company's network infrastructure?

there are many ways to be used together, one of them is using the Single Sign On server, for example: compatible with the Kerberos Service.

Single Sign On service is protecting other services, to access other services users must go through Single Sign On authentication first.

this can be compared to setting up a check point with security personnel that checks anyone wishing to go into company & gives them signed set of keys, according to privilege needs.

only way to go into company is either stealing key-set from someone, or cheating the security guard.

no key-borrowing as well.

Why Kerberos?

Kerberos is stable & mature solution, many of security experts maitain it for long time.

Drawbacks, Costs & Advantages.

while Single Sign On service is extra cost - there must be the extra computer system dedicated to authentication that requires maintenance, hardware costs, software costs, electricity costs - overall security of company is better, less of work as well.

there's need for network as well, but this is just a part of the system anyway.

for large applications, distributed for example, overall cost is lower with Single Sign On service.

Single Sign On is also a convenience for users as well, no need to login many times into every software's part.

Weak Points.

if i wished to hack Single Sign On protected system, i could go following routes:
- checking for misconfiguration in the secure system,
- stealing tickets (keys) from users who are often not the security experts by themselves.

other drawbacks:
- if the Single Sign On server fails, access to secured system is paralyzed, but perhaps better that way.

What to do when protected system is compromised?

i'd check the log files in Single Sign On authentication server & in compromised service(s) then decide.

probably would employ security talks with compromised personnel as well.