Saturday, October 6, 2012

More on the semantic overloading of derived events

I am recently getting back to the time in which I have dealt with semantic data models, and now I am trying to view current event-driven applications in that way, thus the semantic overloading is one of the interesting first issues that emerge.  I'll write more about semantic modeling of event processing later, but right now I'll concentrate in the semantic overloading of derived events.   There are various definitions of the term "event", but in all of them event represents a VERB in the natural language.   Looking at what we defined as derived events, it seems that some of the derived events we are looking at can indeed be described by a verb in the natural language, while others are really described by nouns.    Thus my current thinking is to have the semantic notion of DERIVATION, but the derivation can yield different concepts:
Events - when indeed the derived conclusion is that something (virtually) happened.
Entity facts - when the derived conclusion is a value of some fact
Messages - when the derived conclusion is some observation that has to be notified to some actor. 

Examples from the Fast Flower Delivery use case that we used in the EPIA book.  

The automatic assignment creates a real event -- can be expressed by the verb ASSIGN
The timeout pattern "pickup alert" which means that a pickup was not done on time --- this is an observation that is notified to somebody.  It is therefore a message that can be expressed by NOTIFICATION
The driver-ranking calculated as a function of assignment count, is actually a fact related to driver, driver-ranking is a noun, thus it is a derived fact.

More - later. 

Tuesday, October 2, 2012

On family vacation in Malta

I have not disappeared, spent most of the previous week in a family vacation in Malta.   Malta is a small country consists of several islands in the  Mediterranean sea  The climate is similar to the one we have in Israel.  The local language is also a Semitic language like Hebrew, it is actually a descendant of the Arabic language mostly. Like any other Mediterranean people - they are nice, friendly, and take their time.  We lived 5 minutes walk from the capital city of Valletta, which is a small city surrounded by walls and looks somewhat similar to the old city of Jerusalem.  In the evening it looks like a deserted place, nobody is walking in the street, and besides a few restaurants it looks like a ghost town. 

Some highlights:
There is a prehistoric site which has limited visitation (10 per hours), we made reservation 2 months ahead to get inside. 
Malta is a catholic country, and have a lot of ancient churches, we have visited some of them. 
We decided to rely on public transportation, which is cheap but time consuming, some of the lines have low frequency --- not really a good choice.
We took a day trip to Gozo, the northern island which has nice beaches.  
The Maltese people like to celebrate - we have watched too separate celebrations, one of them in the honor of the national fish, called Lampuki,   the other in Valleta  is the Valleta white night.  I am not sure what the celebration is about, but it was crowded and noisy, which is a contrast to the regular silent in Valleta.
Hope that my daughters will post pictures on Facebook soon. 

In general:  nice place for vacation.
I'll continue with professional blogging, hopefully tomorrow.