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
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
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
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 [...]
November 18, 2008
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 [...]
October 9, 2008
The Design Decomposition Blog is written by Doug Barry.
Most commonly, data that's already stored in the database is allowed to remain in the
relational database and it is accessed as it is needed. This allows relational data and object data to exist together in the same system without converting the relational data.
The class hierarchy you create for the existing data allows you to access the non-object data in an object manner. In this example, the views used to create the classes at the various levels would be used at run-time to imitate the object structure. For instance, the Employee View would imitate querying the object structure at the Employee Class level.
See Employee View (new
window) and Employee
View equivalent from the class hierarchy (new
window).
The upside of this approach is that you can leave all your existing data in place and yet have an object schema of the data that can be used by object applications. This is one of the excellent uses of object-relational
mapping products (new window).
The downside of this approach is that you generally will not get higher performance from your data in the object application. You may if you can take advantage of caching the data in the client application, thereby minimizing access to the
relational database. See caching (new window).
It is the access to the relational database that is not faster.
In fact it may be slower because of the additional layer of software to convert relational tuples to object instances. Also, accessing classes using underlying relational views that use joins could still be quite slow, depending how slow the joining operations are in the
Relational DBMS. In the example of the Workstudy Class, it requires the use of joins.
See WorkStudy View (new
window).
If the application cannot take advantage of caching the results of these joins, there is a potential performance problem. Finally, traversals of references
between objects (new window) still will use index searches and, in some cases, intersection entities and joins, when the relational data accessed by the objects first comes from the
Relational DBMS.
There are nearly 400 pages of articles on this site with over 50 pages on object-relational mapping.
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Click on the topics below to browse the articles on this site. You can see more detail by clicking on the arrows. This highlights the location of the current
article: Leaving the data in the relational database.
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