Question AR007 What are the most notable weaknesses of one-tier architectures? (A) Scalability (B) Manageability (C) Security (D) Performance Ian, one of the answers you have is (D) Performance. That is not a weakness. You can even debate that you have faster performance when everything is local to one machine. I have yet to see any 3-tier or 2-tier Oracle application outperform a query from Foxpro running locally on one machine.
Q1) ID - EL001 How are entity beans persisted? (A) Entity beans are stored in memory by the Application server. (B) Entity beans aren't persisted (C) They are serialized and stored on a database. (D) They are NOT serialized and are kept on a database. Answer C, but when I think of serialized I think of an object being serialized, either to a file or passed through RMI to a client. However, not to a database. In BEA Weblogic you map the instance variables to fields, it does not store the object in the database, unless you are using a object database. Mark [ April 15, 2002: Message edited by: Mark Spritzler ]
Hello Mark, OK hands up guiltily as charged! I need to rephrase or edit the answers for question AR007, I will do this when I get in tonight. The second ones more interesting though… OK Entity, Session beans extend from the EnterpriseBean interface, which in turn inherits from the Serializable interface. This to me suggested this was how they would be stored. In the guidebook they have a similar question (in chapter 2 question 10) where the answer is containers can use any serialization technique to passivate a bean instance as long as it follows the Java rules. But on the other hand when I read in the Monson-Haefel book (pg 66) it does say that when using OO databases it is better to use the serialized mapping because “Serializable objects can be preserved without the mismatch associated with object-to-relational persistence”. But of course when mapping to a relational database you just map the individual fields. OK I feel a re-wording on the question may be needed! I will do this later as well. Hey if all my questions were worded correctly and all answers were correct without any debate what kind of preparation would that be for the real exam! Ian
Then again when you talk about Entity Beans then you need to specify CMP or BMP. In BMP the programmer can choose any method they wish to persist the Entity, it is entirely up to the Developer. In CMP, Entities are typically persisted to a relational database through some type of O-R Mapping or to an Object Database but this is really up the the individual App Server. No Application Server I know of will serialize the Entity to persist it, the performance would be horrible. A simple search would require unserializing each and every Entity.