Object livetimes and Data consistency between app and DB layer?

[plautzer]

Hi,

 

I am writing a paper on the effects of external data manipulation in database layer to the application layer. Or in other words  does a direct change in the database effect the (object) data consistency in the application and if so how?

 

A possible scenario which I can think of is, if an object is stored in the heap for a longer time and another application changes the persistent data of the object in the database than the data in the heap would be inconsistent to the data in database… which means the application working with the object works with the wrong data.

 

I am trying to understand how the memory management / allocation and the (general) lifetime

of objects / data in the heap/cache is working within PHP amongst other languages… in order to find an answer to the question above.

 

Since I am new to this topic I want to ask if you can give me a hint where to look / or what might be interesting to look at in order to get an answer?

 

Additionally I have following questions:

 

1. How long is a lifetime of object/application? For PHP is it the lifetime of the script or the time an application is available online?

2. How long does the object/ variable live? To the end of the script / end of application

3. If the object live longer than a script... can it be adresse by other another script? (I know some things about PHP and IMHO an object is created for the  time of a script, to get the data from and to the database... am I right?)

 

I am grateful for any advice for that matter...

Plautzer