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Building Java™ Enterprise Applications Volume I: Architecture 182 standard programming techniques using documented APIs are in play. Again, some rather simple (and logical) decisions early on can greatly increase the flexibility of your applications in the long run. 10.2 Decision Point I don't want to leave you completely on your own in terms of what to program next. Obviously, you need some sort of user interface on top of the infrastructure put together so far, and of course it needs to fit in with the architecture described up to this point. The two most common application front-end paradigms, as of this writing, are the standard web application (servlets, JSP) and the web services framework (SOAP, UDDI, WSDL). I'll briefly touch on each. This will also give you some insight as to what the next volumes will cover. 10.2.1 Web Applications A web application, in the context of this book, is meant to refer to a J2EE-centric application programming model. This means that servlets are used for application logic, and either provide presentation on their own or defer to some other presentation technology. Popular options in this area are JavaServer Pages (JSP), frameworks like Apache Turbine (http://jakarta.apache.org/turbine), and Apache Cocoon (http://xml.apache.org/cocoon). While these are just a few of many examples for handling content and presentation, they all build on the J2EE core APIs (usually servlets), and well-understood Java and XML APIs like SAX, DOM, and JDOM. If you don't know what type of front-end you want to provide to the end user, this is almost certainly the best choice. It is the most common, and as a result you can easily find resources on the relevant technologies. Books like Java Servlet Programming and JavaServer Pages (both from O'Reilly) provide good introductions to these APIs, and will get you quickly up and running. Additionally, building web services and other front-ends can most easily be done upon an existing web application. And, obviously, a web application provides access through any standard web browser, as well as providing easy inroads into web-enabled phones, PDAs, and other mobile devices. If you do decide to move into the web application world, you should employ the same principles endorsed in this book. Start with a layer for application logic, using servlets. Ensure that any content is handled independently of presentation details, so the same data can be shown to an HTML browser, an XML viewer, or a WML phone; this is in the same vein as the clean separation of data and business logic detailed in this book. From there, move into presentation technologies, and try not to code in such a way that only specifically formatted content is accepted. In other words, developing an engine for converting data into presentation is a better idea than simply taking very specific data and creating a very specific screen for viewing. I will focus on these very ideas in Volume II of this series, Web Applications. 10.2.2 Web Services Coming in a close second to the traditional web application is the web services paradigm. I should start by saying that web services are still young enough that any predictions here or anywhere else are just that: predictions. Don't depend on them, as things could easily change a year, a month, or even a week from now. That said, it does appear that web services are going Building Java™ Enterprise Applications Volume I: Architecture 183 to play an important part in the next generation of web-enabled applications. The emergence of semi-standards like WSDL and full-blown standards like UDDI and SOAP offer a lot of promise to a higher degree of application interoperation than what is currently available. If you do want to web-service-enable your application, you should probably start by adding some application logic on top of what was discussed in this book. Remember, the more context you can add to your data, the more useful it becomes to other companies. A book is more useful than a collection of titles and ISBN numbers, and a "library" (in some object form) is generally more useful than just a book. Although it is certainly possible to expose EJBs directly as web services, it is generally a better idea to add some layer of functionality on top of these beans. You should also begin to dig into the various web services specifications, like SOAP and UDDI. You may also want to check out related books, like Programming Web Services with SOAP (O'Reilly), a language-independent look at web applications, and Java & XML (O'Reilly), which covers SOAP, WSDL, and UDDI for Java specifically. You can also find example code online at locations like http://xml.apache.org/soap. Many application server vendors, like BEA Weblogic and Lutris Enhydra, also offer web services "packs" or add-ons to their server products, which provide tools to aid in conversion from beans and Java classes to web services. I won't cover web services in detail until Volume III of this series, in order to let some of the glitter shake off the paradigm in favor of stability and proven techniques. 10.3 What's Next? Despite all of the information covered, it can still be confusing to decide what to do next. With over a thousand lines of code in this book, you still do not have a complete application. And while I hope you pick up Volume II of this series when it becomes available, I certainly wouldn't advise you not to press on in the interim. So, in closing, I want to provide some suggestions on how to proceed in your enterprise application programming. First, take some time to understand the supplemental code in Appendix E. While I didn't cover all of this in detail in the various chapters, there is quite a bit of information stuffed in between curly braces and brackets. The code (particularly when downloaded from http://www.newinstance.com/) is loaded with comments and Javadoc, and illustrates some concepts in addition to those explicitly covered in the text of the book. You can also gain a good bit of insight about container-managed persistence in EJB 2.0, the nuts and bolts of the Java Message Service and message-driven beans, and more. I've included all of this code in printed form in Appendix E, so take advantage of the listings. Next, try to find something at your job to apply these concepts to. Your own assignments in the enterprise application space should allow you a test bed for the concepts mentioned here and for techniques of your own. My ideas all stem from actual problems I've had to solve; you should assemble your own toolkit of similar ideas and programming idioms. In other words, practice makes perfect, and you need to do more than simply read through this book to master application programming in Java. Finally, don't wait on a book to start building out your application. Develop a servlet front- end, code up some JSPs, or delve into web services, using either the Forethought backbone or an application of your own. This will put you ahead of those who won't venture into new territory without a roadmap, and you may find yourself teaching them before long. Future Building Java™ Enterprise Applications Volume I: Architecture 184 volumes of this series, or other books, may cause you to make changes down the line; however, you will have a sound understanding of what led you to these changes, and that experience is invaluable. Most of all, enjoy yourself, and I'll see you online. Building Java™ Enterprise Applications Volume I: Architecture 185 Appendix A. SQL Scripts This appendix contains the SQL scripts that are specific to a variety of different databases. In addition to adding enhancements that will improve performance on a specific database, these scripts omit any constructs that are not supported by a specific database (for example, the InstantDB script does not employ foreign keys, a feature still under development). If you are having trouble with the standard SQL scripts provided in Chapter 3 or Chapter 5, check to see if a script for your specific database is included here. [A] All of the scripts shown here are available for download online by visiting http://www.newinstance.com/. Additionally, many of these scripts contain information that is not SQL, but instead is an instruction set for the database. For example, the Cloudscape database needs connection information specified at the head of any SQL script run against it, and InstantDB needs information about the JDBC driver to use. For each of the databases covered here, specific deployment details are covered in Appendix B. Any additional information specified in the examples in this appendix is also used in Appendix B as part of deployment. Finally, the scripts used to create the accounts storage assume that the scripts to create the user store have already been run. In other words, if you are using Cloudscape, you must execute the script in Example A-1 before executing the one in Example A-6. This is because the foreign key constraint on the USER_ID in the ACCOUNTS table references a column that must already exist from the USERS table. Errors will result if the user store has not already been created. Again, following the steps outlined in Appendix B will ensure these problems do not arise. A If your database is not covered here, please feel free to send a working SQL script (for both the users and accounts storage) to me directly at brett@newInstance.com. If I can ensure that it works, I will be happy to include it online and in updated versions of this book. I welcome people helping me to support a large number of databases. Building Java™ Enterprise Applications Volume I: Architecture 186 A.1 The User Store The SQL scripts in this section duplicate the functionality of the script shown in Example 3-1, and create the storage for user information. A.1.1 Cloudscape Example A-1 is a version of the SQL script that works on the Cloudscape Java database. Example A-1. SQL Script for Creating the User Store on Cloudscape Databases USER_TYPES table CREATE TABLE USER_TYPES ( USER_TYPE_ID INT PRIMARY KEY NOT NULL, USER_TYPE VARCHAR(20) NOT NULL ); OFFICES table CREATE TABLE OFFICES ( OFFICE_ID INT PRIMARY KEY NOT NULL, CITY VARCHAR(20) NOT NULL, STATE CHAR(2) NOT NULL ); USERS table CREATE TABLE USERS ( USER_ID INT PRIMARY KEY NOT NULL, OFFICE_ID INT NOT NULL, USER_DN VARCHAR(100) NOT NULL, USER_TYPE_ID INT NOT NULL, FIRST_NAME VARCHAR(20) NOT NULL, LAST_NAME VARCHAR(30) NOT NULL, CONSTRAINT OFFICE_ID_FK FOREIGN KEY (OFFICE_ID) REFERENCES OFFICES (OFFICE_ID), CONSTRAINT USER_TYPE_ID_FK FOREIGN KEY (USER_TYPE_ID) REFERENCES USER_TYPES (USER_TYPE_ID) ); Building Java™ Enterprise Applications Volume I: Architecture 187 A.1.2 InstantDB Example A-2 is a version of the SQL script that creates the user store for an InstantDB database, and in particular work on the version of InstantDB that ships with Lutris EAS, Version 4.1. Example A-2. SQL Script for Creating the User Store on InstantDB Databases ; Load InstantDB JDBC drivers d org.enhydra.instantdb.jdbc.idbDriver; o jdbc:idb=forethought.prp; ; USER_TYPES table e CREATE TABLE USER_TYPES ( USER_TYPE_ID INT PRIMARY KEY NOT NULL, USER_TYPE VARCHAR(20) NOT NULL ); ; OFFICES table e CREATE TABLE OFFICES ( OFFICE_ID INT PRIMARY KEY NOT NULL, CITY VARCHAR(20) NOT NULL, STATE CHAR(2) NOT NULL ); ; USERS table e CREATE TABLE USERS ( USER_ID INT PRIMARY KEY NOT NULL, OFFICE_ID INT NOT NULL, USER_DN VARCHAR(100) NOT NULL, USER_TYPE_ID INT NOT NULL, FIRST_NAME VARCHAR(20) NOT NULL, LAST_NAME VARCHAR(30) NOT NULL ); ; Close up c close; Building Java™ Enterprise Applications Volume I: Architecture 188 A.1.3 MySQL Example A-3 is a version of the SQL script that creates the user store on a MySQL database. Example A-3. SQL Script for Creating the User Store on MySQL Databases USER_TYPES table CREATE TABLE USER_TYPES ( USER_TYPE_ID INT PRIMARY KEY NOT NULL, USER_TYPE VARCHAR(20) NOT NULL ); OFFICES table CREATE TABLE OFFICES ( OFFICE_ID INT PRIMARY KEY NOT NULL, CITY VARCHAR(20) NOT NULL, STATE CHAR(2) NOT NULL ); USERS table CREATE TABLE USERS ( USER_ID INT PRIMARY KEY NOT NULL, OFFICE_ID INT NOT NULL, USER_DN VARCHAR(100) NOT NULL, USER_TYPE_ID INT NOT NULL, FIRST_NAME VARCHAR(20) NOT NULL, LAST_NAME VARCHAR(30) NOT NULL, CONSTRAINT OFFICE_ID_FK FOREIGN KEY (OFFICE_ID) REFERENCES OFFICES (OFFICE_ID), CONSTRAINT USER_TYPE_ID_FK FOREIGN KEY (USER_TYPE_ID) REFERENCES USER_TYPES (USER_TYPE_ID) ); Building Java™ Enterprise Applications Volume I: Architecture 189 A.1.4 Oracle The SQL script shown in Example A-4 creates the user store on Oracle databases, and in particular Version 8.x of the database. Example A-4. SQL Script for Creating the User Store on Oracle Databases USER_TYPES table CREATE TABLE USER_TYPES ( USER_TYPE_ID INTEGER PRIMARY KEY NOT NULL, USER_TYPE VARCHAR2(20) NOT NULL ); OFFICES table CREATE TABLE OFFICES ( OFFICE_ID INTEGER PRIMARY KEY NOT NULL, CITY VARCHAR2(20) NOT NULL, STATE CHAR(2) NOT NULL ); USERS table CREATE TABLE USERS ( USER_ID INTEGER PRIMARY KEY NOT NULL, OFFICE_ID INTEGER NOT NULL, USER_DN VARCHAR2(100) NOT NULL, USER_TYPE_ID INTEGER NOT NULL, FIRST_NAME VARCHAR2(20) NOT NULL, LAST_NAME VARCHAR2(30) NOT NULL, CONSTRAINT OFFICE_ID_FK FOREIGN KEY (OFFICE_ID) REFERENCES OFFICES (OFFICE_ID), CONSTRAINT USER_TYPE_ID_FK FOREIGN KEY (USER_TYPE_ID) REFERENCES USER_TYPES (USER_TYPE_ID) ); Building Java™ Enterprise Applications Volume I: Architecture 190 A.1.5 PostgreSQL Example A-5 is an SQL script that creates the user store on PostgreSQL databases. Example A-5. SQL Script for Creating the User Store on PostgreSQL Databases USER_TYPES table CREATE TABLE USER_TYPES ( USER_TYPE_ID INT PRIMARY KEY NOT NULL, USER_TYPE VARCHAR(20) NOT NULL ); OFFICES table CREATE TABLE OFFICES ( OFFICE_ID INT PRIMARY KEY NOT NULL, CITY VARCHAR(20) NOT NULL, STATE CHAR(2) NOT NULL ); USERS table CREATE TABLE USERS ( USER_ID INT PRIMARY KEY NOT NULL, OFFICE_ID INT NOT NULL, USER_DN VARCHAR(100) NOT NULL, USER_TYPE_ID INT NOT NULL, FIRST_NAME VARCHAR(20) NOT NULL, LAST_NAME VARCHAR(30) NOT NULL, CONSTRAINT OFFICE_ID_FK FOREIGN KEY (OFFICE_ID) REFERENCES OFFICES (OFFICE_ID), CONSTRAINT USER_TYPE_ID_FK FOREIGN KEY (USER_TYPE_ID) REFERENCES USER_TYPES (USER_TYPE_ID) ); Building Java™ Enterprise Applications Volume I: Architecture 191 A.2 The Accounts Store The SQL scripts in this section handle the creation of the accounts store under different databases, and are equivalent to the script shown in Example 3-3 of the text. A.2.1 Cloudscape The SQL script shown in Example A-6 creates the accounts store and constraints on Cloudscape databases. Example A-6. SQL Script for Creating the Accounts Store on Cloudscape Databases ACCOUNT_TYPES table CREATE TABLE ACCOUNT_TYPES ( ACCOUNT_TYPE_ID INT PRIMARY KEY NOT NULL, ACCOUNT_TYPE VARCHAR(20) NOT NULL ); ACCOUNTS table CREATE TABLE ACCOUNTS ( ACCOUNT_ID INT PRIMARY KEY NOT NULL, USER_ID INT NOT NULL, ACCOUNT_TYPE_ID INT NOT NULL, BALANCE FLOAT NOT NULL, CONSTRAINT USER_ID_FK FOREIGN KEY (USER_ID) REFERENCES USERS (USER_ID), CONSTRAINT ACCOUNT_TYPE_ID_FK FOREIGN KEY (ACCOUNT_TYPE_ID) REFERENCES ACCOUNT_TYPES (ACCOUNT_TYPE_ID) ); TRANSACTIONS table CREATE TABLE TRANSACTIONS ( TRANSACTION_ID INT PRIMARY KEY NOT NULL, ACCOUNT_ID INT NOT NULL, AMOUNT FLOAT NOT NULL, DATE_TIME DATE NOT NULL, CONSTRAINT ACCOUNT_ID_FK FOREIGN KEY (ACCOUNT_ID) REFERENCES ACCOUNTS (ACCOUNT_ID) ); FUNDS table CREATE TABLE FUNDS ( FUND_ID INT PRIMARY KEY NOT NULL, NAME VARCHAR(20) NOT NULL, DESCRIPTION VARCHAR(200) ); INVESTMENTS table CREATE TABLE INVESTMENTS ( INVESTMENT_ID INT PRIMARY KEY NOT NULL, FUND_ID INT NOT NULL, ACCOUNT_ID INT NOT NULL, INITIAL_AMOUNT FLOAT NOT NULL, YIELD FLOAT, CONSTRAINT FUND_ID_FK FOREIGN KEY (FUND_ID) REFERENCES FUNDS (FUND_ID), CONSTRAINT ACCOUNT_ID_FK2 FOREIGN KEY (ACCOUNT_ID) REFERENCES ACCOUNTS (ACCOUNT_ID) ); [...]... classpath is shown as follows: /java/ instantdb (bmclaugh)> echo $CLASSPATH /java/ instantdb/classes/idb.jar: /java/ instantdb/classes/idbf.jar: /java/ instantdb/classes/idbf.jar: /java/ instantdb/classes/jta-spec1_0_1.jar: /java/ instantdb/classes/jdbc2_0-stdext.jar 2 08 Building Java Enterprise Applications Volume I: Architecture The Java class used to execute SQL scripts is org.enhydra.instantdb.ScriptTool... VALUES VALUES VALUES (1, (2, (3, (4, (5, 'Everyday'); 'Investment'); 'Investment Plus'); 'Money Market'); 'Savings'); 204 Building Java Enterprise Applications Volume I: Architecture A.6.3 MySQL Example A- 28 is an SQL script that creates type data on MySQL databases Example A- 28 SQL Script for Creating Type Data on MySQL Databases Create User Types INSERT INTO USER_TYPES VALUES (1, 'Client'); INSERT... NULL, VARCHAR(200) INT PRIMARY KEY NOT NULL, INT NOT NULL, INT NOT NULL, FLOAT NOT NULL, FLOAT ; Close up c close; 192 Building Java Enterprise Applications Volume I: Architecture A.2.3 MySQL Example A -8 is an SQL script that creates the accounts store on MySQL databases Example A -8 SQL Script for Creating the Accounts Store on MySQL Databases ACCOUNT_TYPES table CREATE TABLE ACCOUNT_TYPES ( ACCOUNT_TYPE_ID... DROP TABLE INVESTMENTS; DROP TABLE FUNDS; DROP TABLE TRANSACTIONS; DROP TABLE ACCOUNTS; DROP TABLE ACCOUNT_TYPES; DROP TABLE USERS; DROP TABLE USER_TYPES; DROP TABLE OFFICES; 1 98 Building Java Enterprise Applications Volume I: Architecture A.4.2 InstantDB Example A-17 is an SQL script that deletes the user and accounts storage on InstantDB databases Example A-17 SQL Script for Deleting All Tables on... YIELD FLOAT, CONSTRAINT FUND_ID_FK FOREIGN KEY (FUND_ID) REFERENCES FUNDS (FUND_ID), CONSTRAINT ACCOUNT_ID_FK2 FOREIGN KEY (ACCOUNT_ID) REFERENCES ACCOUNTS (ACCOUNT_ID) ); 195 Building Java Enterprise Applications Volume I: Architecture A.3 Events and Scheduling With the user and accounts stores in place, all that's left to add to the core database schema is the storage for events This includes the... CONSTRAINT AT_USER_ID_FK FOREIGN KEY (USER_ID) REFERENCES USERS (USER_ID), CONSTRAINT EVENT_ID_FK FOREIGN KEY (EVENT_ID) REFERENCES EVENTS (EVENT_ID) ); ; Close up c close; 196 Building Java Enterprise Applications Volume I: Architecture A.3.3 MySQL Example A-13 is an SQL script that creates the events storage on MySQL databases Example A-13 SQL Script for Creating the Events Store on MySQL Databases... EVENT_ID INTEGER NOT NULL, CONSTRAINT AT_USER_ID_FK FOREIGN KEY (USER_ID) REFERENCES USERS (USER_ID), CONSTRAINT EVENT_ID_FK FOREIGN KEY (EVENT_ID) REFERENCES EVENTS (EVENT_ID) ); 197 Building Java Enterprise Applications Volume I: Architecture A.3.5 PostgreSQL The SQL script for PostgreSQL databases is shown in Example A-15 Example A-15 SQL Script for Creating the Events Store on PostgreSQL Databases EVENTS.. .Building Java Enterprise Applications Volume I: Architecture A.2.2 InstantDB Example A-7 is an SQL script that creates the accounts store for InstantDB databases Example A-7 SQL Script for Creating the Accounts Store on InstantDB... DROP TABLE INVESTMENTS; DROP TABLE FUNDS; DROP TABLE TRANSACTIONS; DROP TABLE ACCOUNTS; DROP TABLE ACCOUNT_TYPES; DROP TABLE USERS; DROP TABLE USER_TYPES; DROP TABLE OFFICES; 199 Building Java Enterprise Applications Volume I: Architecture A.4.5 PostgreSQL Example A-20 is the SQL script used to delete the Forethought data store on PostgreSQL databases Example A-20 SQL Script for Deleting All Tables on... DROP TABLE INVESTMENTS; DROP TABLE FUNDS; DROP TABLE TRANSACTIONS; DROP TABLE ACCOUNTS; DROP TABLE ACCOUNT_TYPES; DROP TABLE USERS; DROP TABLE USER_TYPES; DROP TABLE OFFICES; 200 Building Java Enterprise Applications Volume I: Architecture A.5 Primary Keys The storage described in Chapter 5 for primary key generation requires an additional table in the database schema The scripts in this section are . that web services are going Building Java Enterprise Applications Volume I: Architecture 183 to play an important part in the next generation of web-enabled applications. The emergence of. and you may find yourself teaching them before long. Future Building Java Enterprise Applications Volume I: Architecture 184 volumes of this series, or other books, may cause you to make. LAST_NAME VARCHAR(30) NOT NULL ); ; Close up c close; Building Java Enterprise Applications Volume I: Architecture 188 A.1.3 MySQL Example A-3 is a version of the SQL script that