When we think about the work of an organization that involves data processing it can be convenient to separate it out so that we can focus on one aspect at a time. Of course we are doing processing of data, but where does the data come from and where does it go, and how do we process it?
Surely we intend to have customers? They have to be handled carefully, openly, and appropriately. There will be all sorts of ways to communicate with them: at least
– in person
– through the web
– through email
We are certainly going to sell something? and buy something? Suppliers have their own methods and forms, and while we don’t necessarily have to humor them we dp have to honor them, and observe whatever formalities they require or desire.
– through their supply-chain
– over the web
– through email
I think businesses tend to have licenses? And pay taxes? And deal with building inspectors? If we do not handle these matters very precisely following exactimg time constraints we are doomed.
– our tax people
– keeping up with regulations
– through email
This is getting complicated! Also in dealing with customers especially we need to be outward-facing, on the other hand our records should probably not be exposed at all to the outside, except through properly and carefully prepared reports that we may issue, and those are not issued to the public, but specifically only to certain outsiders.
Separation of concerns to the rescue!
Triple-P: from now on just PPP.
– Presentation: our front
– Processing: our back
– Persistence: our vault
The three-tier PPP structure
diagram gives us the general flow.
We not only handle programming differently for various concerns the whole organization changes for each one. The dots show where the action is, the whole thing just outlines the communication.
The entire exterior appearance of an organization is shown here, and its communication with its public. This is the front office.
– We are listening at the front, waiting to receive a communication from a customer.
– When a communication arrives we write to the back office.
– These writes may set various retrievals into action.
– As we retrieve materials from Processing , we may also send messages or materials to the customer. Presentation has often keyed this to the original receipt, so the sends are done in an appropriate manner to an appropriate place.
– As Processing sends reponses to us for our writes, we send responses to the customer, often keyed to the way the original request was received.
The entire way an organization deals with its customers is encompassed here. It is the business office or the back room, and what goes on here is of necessity not exosed to the public. From here we may communicate with suppliers and authorities, and not expose those communications to the public.
– When a write from Presentation has been pushed in, we negin processing, which will usually involve several stores to Persistence. Some of them are for record. often most set in motion activities with various supply chains.
– As we receive material from the vault, or learn about changes in status (maybe the customer has paid in advance so an order can be released) we may send back to the customer.
– our datbasehas its own rules and language
– we may use remote storage for some records
What is in this tier is the entire legal record of the organization. The content is not only to be protcted from disclosure, but especially from modification, and this protection from modifiction may need to extend even to members of the staff. It is the vault.
Many businesses realize in a very real sense this “is” the business. If we lose records of our customers we do not last long; if we lose records for the authorities we may be in jail!
Dealing with customers is often informal in part
Dealing with suppliers is more formal, but depends on them to a degree
Dealing with our datbase is totally formal
– it must be journaled
– it involves formal permissions
– it cannot typically be redone
– The operation of Persistence involves out database system, supply chains, accounting, all the aspects of the work that must be done in a formal manner following strict rules. They all are done in a strict send-receive discipline, without the internal dialogue that goes on in Processing.
A major objective is to see that Persistence is buried deep within the organizational structure, and its only contact with Presentation is through Processing.
The diagram PPP isolation makes this structure more clear.
