Questão 1
Questão
What is a principal?
Questão 2
Questão 3
Questão
What annotations can be used to specify security privileges?
Questão 4
Questão
What is the difference between container-managed and application-managed security?
What are the pros and cons of each? When might you choose to use one in preference to the other?
Responda
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Pros and cons of application-managed security
Pro: complete control
Pro: can fine-tune for performance
Con: you might forget to put it in a method
Con: managing site-wide may be a problem
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Pros and cons of application-managed security
Questão 5
Questão
What is a native query?
Questão 6
Questão
Why is using a named query often more efficient than a JPQL query?
Responda
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Using named queries may improve code organisation by separating the JPQL query strings from the Java code. It also enforces the use of query parameters rather than embedding literals dynamically into the query string and results in more efficient queries.
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Using named queries may improve code organisation
Questão 7
Questão
Why is using a named query often more efficient than a JPQL query?
Questão 8
Questão
What is the JPA implementation that we use called? What other implementations are there?
Responda
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Hibernate,
Toplink, we use this for JPA implementation in our coursework
OpenJPA
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Toplink, we use this for JPA implementation in our coursework
Questão 9
Questão
What are the pros and cons of using JPQL queries and criteria queries?
Responda
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JPQL queries are defined as strings, similarly to SQL. JPA criteria queries, on the other hand, are defined by instantiation of Java objects that represent query elements.
Advantage of using the criteria API is that errors can be detected earlier, during compilation rather than at runtime. On the other hand, for many developers string based JPQL queries, which are very similar to SQL queries, are easier to use and understand.
For simple static queries - string based JPQL queries may be preferred.
For dynamic queries that are built at runtime - the criteria API may be preferred. It is cleaner when using the JPA criteria API, because it eliminates the need for building the query using many string concatenation operations.
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need for building the query using many string concatenation operations.
Questão 10
Questão
What is a native query?
Questão 11
Questão
What is the difference between optimistic and pessimistic transaction locking? Which do we normally use?
Questão 12
Questão
What is the relationship between a persistence unit and an entity manager?
Responda
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A persistence unit defines a set of all entity classes that are managed by EntityManager
While The EntityManager is the primary interface used by application developers to interact with the JPA runtime
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A persistence unit defines a set of all entity classes that are managed by EntityManager
Questão 13
Questão
What is a persistence unit and where are its details usually to be found?
Responda
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A persistence-unit provides a convenient way of specifying a set of metadata files, and classes, and jars that contain all classes to be persisted in a grouping.
To define a persistence-unit you first need to add a file persistence.xml to the META-INF/ directory of your application jar.
http://www.datanucleus.org/products/datanucleus/jpa/emf.html#persistenceunit
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A persistence-unit provides a convenient way of specifying a set of metadata files, and classes, and jars that contain all classes to be persisted in a grouping.
Questão 14
Questão
What is a data access object used for?
Questão 15
Questão
What is a named query and what is it useful for?
Questão 16
Questão
What major effort does JPQL save in comparison with SQL?
Responda
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The main difference between JPQL and SQL lies in that the former deals with JPA entities, while the latter deals directly with relational data. As a Java developer, you also maybe interested to learn that using JPQL, unlike SQL/JDBC, eliminates the need for you to use JDBC API from your Java code—the container does all this work for you behind the scenes.
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The main
Questão 17
Responda
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The Java Persistence Query Language (JPQL) is a platform-independent object-oriented query language defined as part of the Java Persistence API (JPA) specification. JPQL is used to make queries against entities stored in a relational database.
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The Java Persistence Query Language (
Questão 18
Questão
Why is JPQL useful?
Questão 19
Questão
What do we mean when we say that an entity is detached?
Responda
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A detached entity is an entity which state must not be reflected by the JPA provider.
In other words, if you change its state (i.e. through setters methods) these changes will not be saved to the underlying database, as the JPA provider doesn't have to "observe" such entities.
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A detached entity is an entity which state must not be reflected by the JPA provider.
Questão 20
Questão
How do you obtain an entitymanager when operating in each environment
Responda
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A container-managed entity manager is obtained in an application through dependency injection or through JNDI lookup. A container-managed entity
manager requires the use of a JTA transaction. An Application managed entity manager is retrieved through the EntityManagerFactory API.
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A container-managed entity manager is obtained in an application through dependency injection or through JNDI lookup
Questão 21
Questão
What is an entity manager?
Questão 22
Questão
Which relationships are by default eager, and which are by default lazy?
Questão 23
Questão
What strategies are available for mapping inheritance relationships in JPA?we have
Questão 24
Questão
What do the terms eager and lazy mean in this context?
Responda
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It gives a hint to the persistence provider runtime that data should be fetched lazily (only when the application asks for the property) or eagerly (when the entity is initially loaded by the provider).
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the entity is initially loaded by the provider).
Questão 25
Questão
How do you tell JPA where to store the data that makes up a foreign key? [Be careful!]
Responda
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@OneToOne @JoinColumn(name="parent_id", referencedColumnName="ID") private Parent parent; }
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(name="parent_id", referencedColumnName="ID") private Parent parent; }
Questão 26
Questão
Explain what an HTTP request is
Questão 27
Questão
How does an HTTP request travel over a network?
Questão 28
Questão
Explain what an HTTP response is and its relationship to a request
Questão 29
Questão
Explain what HTTP status codes such as 200 and 404 mean
Responda
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404 code is the status code from the server to the client indicating the resource not found. 200 it is the code from server to client indicating that the request is received successful
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request is received successful
Questão 30
Questão
What is a mime type and what is its relationship to HTTP messages?
Responda
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Multipurpose Internet Mail Extension. The relation between the HTTP and MIME type is MIMIE type is part of HTTP header response
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The relation between the HTTP and MIME type is MIMIE type is part of HTTP header response
Questão 31
Questão
Why in the WWW might there be more HTTP requests than HTTP responses?
Questão 32
Questão
What is the difference between a static web page and a dynamic one?
Responda
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Developers generally create static pages with HTML, but use languages like PHP, Javascript, or Actionscript to create dynamic pages. They can also use frameworks like Ruby on Rails, Django, or Flex for dynamic pages. Dynamic languages and frameworks also have the technical capacity to create static Web page content. However, doing so creates source code that is unnecessarily complex for its purpose while being more difficult to maintain
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html
Questão 33
Questão
How does the content of a dynamic web page get created?
Questão 34
Questão
What are the four architectures for dynamic web applications?
Questão 35
Questão
Why is the architecture that Java uses the most scalable?
Questão 36
Questão
Why is the architecture that Java uses the most resilient?
Questão 37
Questão
How can you use Java's architecture to provide an enterprise web application on a global scale
Questão 38
Questão
What is a servlet?
Questão 39
Questão 40
Questão
What is the relationship between a JSP and a servlet?
Questão 41
Questão
What advantages does Java's servlet programming model have over (a) CGI? (b) PHP?
Responda
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threading and at each time CGI has to run a program which is not good practice for OS. The problem of php is in case the module is crashed than the web server is also down
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The problem of php is in case the module is crashed than the web server is also down
Questão 42
Questão
What is an exception and what is one used for?
Responda
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it is used to reporting the error.( exception is an event which occur during the execution of a program, that disrupts the normal flow of the program instructions.
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( exception is an event which occur during the execution of a program, that disrupts the normal flow of the program instructions.
Questão 43
Questão
Explain throwing and catching exceptions?
Questão 44
Questão
What do we mean when we say that one class inherits from another?
Questão 45
Questão
If an application had classes Person, StaffMember and Student, how might they be related?
Questão 46
Questão
java.util and jim.sums.entities are examples of what?
Questão 47
Questão
What is the difference between a field that is private, protected or public?
Questão 48
Questão
What does static mean when associated with a class's fields or methods? it is a variable which is not changed wherever it called or used
Questão 49
Questão
Explain what the classes/interfaces Collection, Set, List, ArrayList and Vector represent and what are the distinctions between them?
Questão 50
Questão 51
Questão
What does the declaration Map<String, Person> represent?
Questão 52
Questão
What is a facelet?
Questão 53
Questão
What is a managed bean?
Questão 54
Questão
What is meant by the scope of a managed bean?
Questão 55
Questão
What are the available scopes to choose from?
Questão 56
Questão
Which scope is the default?
Questão 57
Questão
Give at least 10 examples of how different HTML controls can be represented using facelet tags
Responda
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h:inputText , h:inputHidden, h:inputSecret, h:inputTextarea, h:link, h:commandButton, h:button, h:form, h:panelGrid , h:dataTable
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h:inputText
Questão 58
Questão
What do the properties of a managed bean represent?
Questão 59
Questão
What notation is used in a facelet to associate a property or method with a control?
Questão 60
Questão
Why is JSF superior to JSP?
Questão 61
Questão
What are the 3 types of session bean?
Questão 62
Questão
In what circumstances would you use each of the 3 types?
Responda
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stateful: The bean needs to hold information about the client across method invocations.
stateless:- The bean’s state has no data for a specific client.
Singleton:-State needs to be shared across the application.
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Singleton:-State needs to be shared across the application.
Questão 63
Questão
Which of the 3 types is most commonly used?
Questão 64
Questão
What is the difference between a session bean and a message bean?
Questão 65
Questão
What is dependency injection?
Questão 66
Questão
Who or what does the injecting?
Questão 67
Questão
What annotation is normally used for dependency injection?
Questão 68
Questão
How would you specify the start and end of a transaction in a stateful EJB? BY using
Responda
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@REMOVE annotation
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@REMOVE annotationl
Questão 69
Questão
What annotations can be used to control what happens when an EJB is created or destroyed? @PreDestroy @PostConstruct
Questão 70
Questão
What is the timer service used for?
Responda
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Enables you to schedule timed notifications for all types of enterprise beans except for stateful session beans. You can schedule a timed notification to occur according to a calendar schedule, at a specific time, after a duration of time, or at timed. How to use it? intervals.timerService.createSingleActionTimer(duration, new TimerConfig());
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TimerConfig());
Questão 71
Questão
What is the difference between a local interface, a remote interface and a no-interface view?
Responda
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When EJB does not explicitly specify as interface type it is assume to be local otherwise it is remote. @localBean @remoteBean No -Interface :Is almost same as local client view, but there are differences. Your bean class is not required to implement client view interfaces in this case. All public methods of the bean class are automatically exposed to the caller. no-interface view always acquires an EJB reference
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l
Questão 72
Questão
What do we mean by pooling beans?
Questão 73
Questão
What is an entity bean?
Questão 74
Questão
How do you make a bean an entity bean?
Questão 75
Questão
What does the @Id annotation do?
Questão 76
Questão
What annotation is used to denote a composite primary key?
Questão 77
Questão
Under what particular circumstances would you have to use the @Column and/or @Table annotations?
Questão 78
Questão
Explain what is meant by a unidirectional relationship and a bidirectional relationship?
Responda
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In a unidirectional relationship, only one entity has a relationship field or property that refers to the other. For example, LineItem would have a relationship field that identifies Product, but Product would not have a relationship field or property for LineItem. In other words,LineItem knows about Product, but Product doesn’t know which LineItem instances refer to it.
while in a bidirectional relationship, each entity has a relationship field or property that refers to the other entity. Through the relationship field or property, an entity class’s code can access its related object. If an entity has a related field, the entity is said to “know” about its related object. For example, if Order knows what LineItem instances it has and if LineItem knows what Order it belongs to, they have a bidirectional relationship.
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relationship,
Questão 79
Questão
What are the annotations used to specify the chosen inheritance strategy? Where must those annotations be placed?
Questão 80
Questão
How do you get JPA to arrange your lists in the right order?