Welcome!

Java Authors: Lori MacVittie, JP Morgenthal, Ivan Antsipau, Esmeralda Swartz, Trevor Parsons

Related Topics: Java

Java: Article

Delivering JDBC-Based Applications

Delivering JDBC-Based Applications

Introduction
In this article, we take a look at using JDBC to build applications. Internet technology is changing so rapidly that some of the methods used today will become obsolete tomorrow. We are taking an approach that combines Java network programming and JDBC programming. Programming in JDBC is taking a step backward when you have mature 4GL tools like Sybase Powerbuilder. Programming in JDBC is similar to programming in any low level database library like ODBC or Sybase CT-LIB.

There is more than one way to deploy applications and applets using JDBC. The first approach is by using the JDBC-ODBC bridge that is part of JDK 1.1. You have to install ODBC Drivers and set the ODBC datasource in each client. If you are willing to do this existing client server tools will do a better job than Java. The second approach is to use a JDBC driver that is 100 Percent Java compliant. For writing Java applications, this method will work fine, but not for Java applets. Applets can not make arbitrary connection to other servers. You have to run your database server in the same machine where the Web server is running. This article will help you write Java applets or applications using JDBC without any of the above mentioned restrictions.

What are the Advantages?
This implementation follows a 3-tier client-server model. JDBC Client sends a request to JDBC server which processes the request, communicates to the database server and sends back the reply. Compatible with all Java enabled browsers. It's secure because the database server is not exposed. You can configure number of concurrent users allowed at any point of time. With little modification you can dynamically increase and decrease number of JDBC server listening for request or totally redirect the request to a different web server. You can also attach your own encryption and decryption routine before communicating with a remote client. JDBC server runs on the server side so you have total freedom to use any JDK, any ODBC driver and Java native methods. You can batch your request or can have real-time connection like any other client-server application.

There are some limitations in this implementation. If you want to have multiple connection you have to initialize multiple driver's in the client side. It will not handle blob or image data type even though it's very easy to implement one, by saving the image in the server and sending the filename back as URL. You can use the same method to transfer the whole ResultSet.

Architecture
There are three different functional pieces. Port allocator (PA) is a Java based server that listens on a predefined port. JDBC server listens for connection from client. JDBC client which makes the request. When client makes a request to Port Allocator it will send back a JDBC server port that is currently free. From that point onwards, JDBC client talks only to the JDBC server. Client sends a single byte command to server and waits for reply. The server sends back a status code and byte or string value. Commands can have arguments usually a byte or a string. While processing clients request, if server encounters an exception it converts the exception to a string and sends back an error code and the string to the client.

Let us look into the details. There are four client side classes RDriver, RConnection, Rstatement, RResultSet for connecting and fetching data. These are very similar to JDBC interfaces Driver, Connection, Statement, ResultSet. It does not implement these interfaces. JDBC client initializes the RDriver then creates a TCP socket to port allocator (PA) and gets a port to communicate to a JDBC server. It also sends command to initialize DriverManager in the server if everything is successful. This enables the client to connect directly to the JDBC server using RDriver.connect(username, password) and create a database connection. You only need username and password to create a database connection hiding all server details in the JDBC server code. You can call createStatement() method to create a RStatement() after successfully establishing a database connection. Send the SQL string to server using executeQuery function. It will create a ResultSet in the server and RResultSet in the client. Use executeUpdate() function for update and insert SQL statements. Access the ResultSet values using next() and getString() or getInt().

One of the advantages of this architecture is that all conversation between client and server happens as bytes and strings. If the client dies for some reason Driver.detach() will cleanup the connection, but if an exception occurs you have to take care of it. Rdriver has an overloaded finalize method which calls Driver.detach().

The example here shows how to connect to a Sybase SQL server using beta version of Jconnect. Before running the examples you may need to change hostname, port and any other parameters it may need in your environment.

Table 1 shows the commands, arguments and return code.

JDBC Protocol Implementation
JDBC Protocol is a layer above the Java socket layer. It hides the Java socket layer, but you have to still catch exceptions from this layer. Protocol structure follows the same structure as any other standard protocols (FTP, TELNET). JDBC protocol does session control by sending acknowledgment or negative acknowledgment after each request from client. Java takes care of presentation of data. This protocol fits in the top layers of OSI model. Like most other protocols this protocol has series of commands and expected return values. Most importantly these commands are not part of any standards. One other difference is it has only one path to the server, unlike FTP which uses a command port (21) and a data port (20).

All commands are single byte followed by a byte or string. In special cases it is more than one string. For each command sent from client JDBC server replies with a return status of SUCCESS or FAIL. If the return status from the server is SUCCESS it returns either string, byte or no value depending on type of command. If an error occurs in the server the return status is FAIL server then sends a SQLExeption string to the client.

Table 2 explains the protocol implementation.

More Stories By Paul Ananth

Paul Ananth works with Barclays Global Investors, San Francisco, as a software engineer. He is a senior member in the client/server development team, specializing in building object-oriented software using C++, Java, PowerBuilder 5.0 and PFC.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
The Internet of Things will greatly expand the opportunities for data collection and new business models driven off of that data. In her session at Internet of @ThingsExpo, Esmeralda Swartz, CMO of MetraTech, will discuss how for this to be effective you not only need to have infrastructure and operational models capable of utilizing this new phenomenon, but increasingly service providers will need to convince a skeptical public to participate. Get ready to show them the money! Speaker Bio: Esmeralda Swartz, CMO of MetraTech, has spent 16 years as a marketing, product management, and busin...
Samsung VP Jacopo Lenzi, who headed the company's recent SmartThings acquisition under the auspices of Samsung's Open Innovaction Center (OIC), answered a few questions we had about the deal. This interview was in conjunction with our interview with SmartThings CEO Alex Hawkinson. IoT Journal: SmartThings was developed in an open, standards-agnostic platform, and will now be part of Samsung's Open Innovation Center. Can you elaborate on your commitment to keep the platform open? Jacopo Lenzi: Samsung recognizes that true, accelerated innovation cannot be driven from one source, but requires a...
SYS-CON Events announced today that Red Hat, the world's leading provider of open source solutions, will exhibit at Internet of @ThingsExpo, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Red Hat is the world's leading provider of open source software solutions, using a community-powered approach to reliable and high-performing cloud, Linux, middleware, storage and virtualization technologies. Red Hat also offers award-winning support, training, and consulting services. As the connective hub in a global network of enterprises, partners, a...
P2P RTC will impact the landscape of communications, shifting from traditional telephony style communications models to OTT (Over-The-Top) cloud assisted & PaaS (Platform as a Service) communication services. The P2P shift will impact many areas of our lives, from mobile communication, human interactive web services, RTC and telephony infrastructure, user federation, security and privacy implications, business costs, and scalability. In his session at Internet of @ThingsExpo, Robin Raymond, Chief Architect at Hookflash Inc., will walk through the shifting landscape of traditional telephone a...
SYS-CON Events announced today that Matrix.org has been named “Silver Sponsor” of Internet of @ThingsExpo, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Matrix is an ambitious new open standard for open, distributed, real-time communication over IP. It defines a new approach for interoperable Instant Messaging and VoIP based on pragmatic HTTP APIs and WebRTC, and provides open source reference implementations to showcase and bootstrap the new standard. Our focus is on simplicity, security, and supporting the fullest feature set.
BSQUARE is a global leader of embedded software solutions. We enable smart connected systems at the device level and beyond that millions use every day and provide actionable data solutions for the growing Internet of Things (IoT) market. We empower our world-class customers with our products, services and solutions to achieve innovation and success. For more information, visit www.bsquare.com.
How do APIs and IoT relate? The answer is not as simple as merely adding an API on top of a dumb device, but rather about understanding the architectural patterns for implementing an IoT fabric. There are typically two or three trends: Exposing the device to a management framework Exposing that management framework to a business centric logic • Exposing that business layer and data to end users. This last trend is the IoT stack, which involves a new shift in the separation of what stuff happens, where data lives and where the interface lies. For instance, it’s a mix of architectural style...
SYS-CON Events announced today that SOA Software, an API management leader, will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. SOA Software is a leading provider of API Management and SOA Governance products that equip business to deliver APIs and SOA together to drive their company to meet its business strategy quickly and effectively. SOA Software’s technology helps businesses to accelerate their digital channels with APIs, drive partner adoption, monetize their assets, and achieve a...
From a software development perspective IoT is about programming "things," about connecting them with each other or integrating them with existing applications. In his session at @ThingsExpo, Yakov Fain, co-founder of Farata Systems and SuranceBay, will show you how small IoT-enabled devices from multiple manufacturers can be integrated into the workflow of an enterprise application. This is a practical demo of building a framework and components in HTML/Java/Mobile technologies to serve as a platform that can integrate new devices as they become available on the market.
SYS-CON Events announced today that Utimaco will exhibit at SYS-CON's 15th International Cloud Expo®, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Utimaco is a leading manufacturer of hardware based security solutions that provide the root of trust to keep cryptographic keys safe, secure critical digital infrastructures and protect high value data assets. Only Utimaco delivers a general-purpose hardware security module (HSM) as a customizable platform to easily integrate into existing software solutions, embed business logic and build s...
Connected devices are changing the way we go about our everyday life, from wearables to driverless cars, to smart grids and entire industries revolutionizing business opportunities through smart objects, capable of two-way communication. But what happens when objects are given an IP-address, and we rely on that connection, sometimes with our lives? How do we secure those vast data infrastructures and safe-keep the privacy of sensitive information? This session will outline how each and every connected device can uphold a core root of trust via a unique cryptographic signature – a “bir...
Internet of @ThingsExpo Silicon Valley announced on Thursday its first 12 all-star speakers and sessions for its upcoming event, which will take place November 4-6, 2014, at the Santa Clara Convention Center in California. @ThingsExpo, the first and largest IoT event in the world, debuted at the Javits Center in New York City in June 10-12, 2014 with over 6,000 delegates attending the conference. Among the first 12 announced world class speakers, IBM will present two highly popular IoT sessions, which will take place November 4-6, 2014 at the Santa Clara Convention Center in Santa Clara, Calif...
Almost everyone sees the potential of Internet of Things but how can businesses truly unlock that potential. The key will be in the ability to discover business insight in the midst of an ocean of Big Data generated from billions of embedded devices via Systems of Discover. Businesses will also need to ensure that they can sustain that insight by leveraging the cloud for global reach, scale and elasticity.
WebRTC defines no default signaling protocol, causing fragmentation between WebRTC silos. SIP and XMPP provide possibilities, but come with considerable complexity and are not designed for use in a web environment. In his session at Internet of @ThingsExpo, Matthew Hodgson, technical co-founder of the Matrix.org, will discuss how Matrix is a new non-profit Open Source Project that defines both a new HTTP-based standard for VoIP & IM signaling and provides reference implementations.

SUNNYVALE, Calif., Oct. 20, 2014 /PRNewswire/ -- Spansion Inc. (NYSE: CODE), a global leader in embedded systems, today added 96 new products to the Spansion® FM4 Family of flexible microcontrollers (MCUs). Based on the ARM® Cortex®-M4F core, the new MCUs boast a 200 MHz operating frequency and support a diverse set of on-chip peripherals for enhanced human machine interfaces (HMIs) and machine-to-machine (M2M) communications. The rich set of periphera...

SYS-CON Events announced today that Aria Systems, the recurring revenue expert, has been named "Bronze Sponsor" of SYS-CON's 15th International Cloud Expo®, which will take place on November 4-6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Aria Systems helps leading businesses connect their customers with the products and services they love. Industry leaders like Pitney Bowes, Experian, AAA NCNU, VMware, HootSuite and many others choose Aria to power their recurring revenue business and deliver exceptional experiences to their customers.
The Internet of Things (IoT) is going to require a new way of thinking and of developing software for speed, security and innovation. This requires IT leaders to balance business as usual while anticipating for the next market and technology trends. Cloud provides the right IT asset portfolio to help today’s IT leaders manage the old and prepare for the new. Today the cloud conversation is evolving from private and public to hybrid. This session will provide use cases and insights to reinforce the value of the network in helping organizations to maximize their company’s cloud experience.
The Internet of Things (IoT) is making everything it touches smarter – smart devices, smart cars and smart cities. And lucky us, we’re just beginning to reap the benefits as we work toward a networked society. However, this technology-driven innovation is impacting more than just individuals. The IoT has an environmental impact as well, which brings us to the theme of this month’s #IoTuesday Twitter chat. The ability to remove inefficiencies through connected objects is driving change throughout every sector, including waste management. BigBelly Solar, located just outside of Boston, is trans...
SYS-CON Events announced today that Matrix.org has been named “Silver Sponsor” of Internet of @ThingsExpo, which will take place on November 4–6, 2014, at the Santa Clara Convention Center in Santa Clara, CA. Matrix is an ambitious new open standard for open, distributed, real-time communication over IP. It defines a new approach for interoperable Instant Messaging and VoIP based on pragmatic HTTP APIs and WebRTC, and provides open source reference implementations to showcase and bootstrap the new standard. Our focus is on simplicity, security, and supporting the fullest feature set.
Predicted by Gartner to add $1.9 trillion to the global economy by 2020, the Internet of Everything (IoE) is based on the idea that devices, systems and services will connect in simple, transparent ways, enabling seamless interactions among devices across brands and sectors. As this vision unfolds, it is clear that no single company can accomplish the level of interoperability required to support the horizontal aspects of the IoE. The AllSeen Alliance, announced in December 2013, was formed with the goal to advance IoE adoption and innovation in the connected home, healthcare, education, aut...