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Design Decomposition Blog
Iridium Satellite Collision in Space
You might have seen the recent news reports about the collision between U.S. and Russian communication satellites. The U.S. satellite was one of the Iridium satellites. What wasn’t reported and you probably don’t know is that an object database management system (ODBMS) is an important part of the Iridium system. Even though ODBMSs are a [...]
February 13, 2009
(The Acronym) SOA is (Perhaps) Dead (at Some Companies); Long Live Services
I am now also posting on the Cutter Blog. My initial posting is (The Acronym) SOA is (Perhaps) Dead (at Some Companies); Long Live Services. It is a response to Anne Thomas Manes’ SOA is Dead; Long Live Services on her blog at the Burton Group.
January 9, 2009
Atomicity
The typical definition of an atomic task or process is one that cannot be decomposed further. This is vague and subject to interpretation. The Decomposition Matrix on this site uses a specific definition: A task (for business process diagrams) or a process (for data flow diagrams) is atomic if every input relates to every output [...]
December 3, 2008
Well-Formed Business Process Diagrams
My last posting referenced the criteria for a well-formed business process diagram mentioned in Business Process Driven SOA using BPMN and BPEL by Matjaz B. Juric and Kapil Pant. I am going to expand on their criteria to create a more comprehensive definition of a well-formed business process diagram. To start, here are three criteria from [...]
November 18, 2008
Recent Business Process Modeling Books
I recently received two new books on business process modeling. Both books looked interesting because they had great titles. As it turns out, one book is great and the other not so good. The not so good book is Business Process Driven SOA using BPMN and BPEL by Matjaz B. Juric and Kapil Pant. There are [...]
October 9, 2008
The Design Decomposition Blog
is written by Doug Barry.

Concurrency control and locking is the mechanism used by DBMSs for the sharing of data. Atomicity, consistency, and isolation are achieved through concurrency control and locking. See ACID properties (new window).

When many people may be reading the same data item at the same time, it is usually necessary to ensure that only one application at a time can change a data item. Locking is a way to do this. Because of locking, all changes to a particular data item will be made in the correct order in a transaction. See isolation (new window)

The amount of data that can be locked with the single instance or groups of instances defines the granularity of the lock. The types of granularity are illustrated here are:

Additional information on this subject along with examples of multi-user considerations can be found in the Object Database Handbook (new window).

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