asp.net ean 13

asp.net ean 13

asp.net ean 13

asp.net ean 13

asp.net ean 13

asp.net ean 13,

asp.net ean 13,
asp.net ean 13,

asp.net ean 13,

asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,

asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,

asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,
asp.net ean 13,

When developing UIs, verifying constraints on the data entered by the users is a recurring issue. For example, all data entered to create a new client should be verified and checked for accuracy. The program should test that the e-mail, ZIP code, and so forth are correctly formatted. The program can also force the user to enter additional information. It is important to clearly modularize this concern for three main reasons: First, it is a concern that crosscuts all the functions related to data input and validation. Second, in general, it is a concern that evolves and is refined over time, sometimes independent of other concerns. Third, for the security of the application, the entered data should be controlled on the server side. For client latency reasons, it is also preferable to implement some control on the client. Aspect-oriented modularization makes it easier to maintain consistency between the client and server sides.

public void createAccount() { try { Statement statement = connection.createStatement(); statement.execute( "INSERT INTO BIDDERS(" + "username, " + ... "first_name, " + ... "credit_card_type, " + ... ") VALUES (" + " " + loginInfo.getUsername() + " , " + ... " " + biographicalInfo.getFirstName() + " , " + ... " " + billingInfo.getCreditCardType() + " , " + ... ")"); statement.close(); } catch (SQLException sqle) { sqle.printStackTrace(); } } } ... @Remote public interface BidderAccountCreator implements Remote { void addLoginInfo(LoginInfo loginInfo); void addBiographicalInfo(BiographicalInfo biographicalInfo); void addBillingInfo(BillingInfo billingInfo); void cancelAccountCreation(); void createAccount(); }

SystemException Thrown if an unexpected error occurs while the transac-

As we mentioned earlier, it should not surprise you that the code has a lot in common with the stateless session bean code in listing 3.1.

As before, we are using JDBC for simplicity in this example because we want you to focus on the session bean code right now and not JPA. We ll cover JPA in the part 3 of this book. An interesting exercise for you is to refactor this code using JPA and notice the radical improvement over JDBC!

To clarify the second point, we can compare the aspect-oriented development of the constraint verification to a use case based development methodology. In a use case based methodology, we find primary use cases, which correspond to the normal behavior of the application (here, the entering of the data by the user), and secondary use cases, which correspond to the abnormal behavior of the application (here, errors and input error handling). Among secondary cases, a use case guided analysis generally assigns priorities to the use cases. Some of them are not critical and do not need to be implemented during the first iterations (for instance, checking that the entered name starts with an uppercase letter). Similarly, when developing UI and data verification, we start with primary cases (verifications) and critical secondary cases. Only after the development of these cases is completed can we implement the noncritical cases (verifications). If the verification concern is not correctly modularized, testing a new case will be difficult because its code will be tangled up with the code of the preexisting cases. Thus, the use of AOP helps to handle the growing complexity of the verification concern. In particular, the use of well-chosen pre-/postcondition aspects (such as the ones explained in s 9 and 11) allow the modularized implementation of the verification concern.

We are using the @Stateful annotation to mark the BidderAccountCreatorBean POJO b. Other than the annotation name, this annotation behaves exactly like the @Stateless annotation, so we won t mention it any further. The bean implements the BidderAccountCreator remote business interface. As per stateful bean programming rules, the BidderAccountCreatorBean has a no-argument constructor. Just like in listing 3.1, a JDBC data source is injected using the @Resource annotation. Both the PostConstruct D and PostPassivate E callbacks prepare the bean for use by opening a database connection from the injected data source. On the other hand, both the PrePassivate F and PreDestroy G callbacks close the cached connection. The loginInfo, biographicalInfo, and billingInfo instance variables are used to store client conversational state across business method calls C. Each of the business methods models a step in the account creation workflow and incrementally populates the state instance variables. The workflow is terminated when the client invokes either of the @Remove annotated methods H. There is no point to repeating our discussion of the features that are identical to the ones for stateless session beans, so we ll avoid doing so. However, let s explore the features unique to stateful session beans next, starting with the stateful bean business interfaces.