|By Paul Ananth||
|May 1, 1997 12:00 AM EDT||
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.
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.
Pulzze Systems was happy to participate in such a premier event and thankful to be receiving the winning investment and global network support from G-Startup Worldwide. It is an exciting time for Pulzze to showcase the effectiveness of innovative technologies and enable them to make the world smarter and better. The reputable contest is held to identify promising startups around the globe that are assured to change the world through their innovative products and disruptive technologies. There w...
Aug. 26, 2016 11:30 AM EDT Reads: 543
Internet of @ThingsExpo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devices - comp...
Aug. 26, 2016 10:15 AM EDT Reads: 3,566
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at Cloud Expo, Ed Featherston, a director and senior enterprise architect at Collaborative Consulting, will discuss the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
Aug. 26, 2016 09:45 AM EDT Reads: 1,816
There is growing need for data-driven applications and the need for digital platforms to build these apps. In his session at 19th Cloud Expo, Muddu Sudhakar, VP and GM of Security & IoT at Splunk, will cover different PaaS solutions and Big Data platforms that are available to build applications. In addition, AI and machine learning are creating new requirements that developers need in the building of next-gen apps. The next-generation digital platforms have some of the past platform needs a...
Aug. 26, 2016 09:45 AM EDT Reads: 309
The 19th International Cloud Expo has announced that its Call for Papers is open. Cloud Expo, to be held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, brings together Cloud Computing, Big Data, Internet of Things, DevOps, Digital Transformation, Microservices and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding business opportuni...
Aug. 26, 2016 07:00 AM EDT Reads: 3,907
19th Cloud Expo, taking place November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy. Meanwhile, 94% of enterpri...
Aug. 26, 2016 05:00 AM EDT Reads: 3,026
Personalization has long been the holy grail of marketing. Simply stated, communicate the most relevant offer to the right person and you will increase sales. To achieve this, you must understand the individual. Consequently, digital marketers developed many ways to gather and leverage customer information to deliver targeted experiences. In his session at @ThingsExpo, Lou Casal, Founder and Principal Consultant at Practicala, discussed how the Internet of Things (IoT) has accelerated our abil...
Aug. 26, 2016 02:15 AM EDT Reads: 1,951
With so much going on in this space you could be forgiven for thinking you were always working with yesterday’s technologies. So much change, so quickly. What do you do if you have to build a solution from the ground up that is expected to live in the field for at least 5-10 years? This is the challenge we faced when we looked to refresh our existing 10-year-old custom hardware stack to measure the fullness of trash cans and compactors.
Aug. 26, 2016 01:30 AM EDT Reads: 1,672
The emerging Internet of Everything creates tremendous new opportunities for customer engagement and business model innovation. However, enterprises must overcome a number of critical challenges to bring these new solutions to market. In his session at @ThingsExpo, Michael Martin, CTO/CIO at nfrastructure, outlined these key challenges and recommended approaches for overcoming them to achieve speed and agility in the design, development and implementation of Internet of Everything solutions wi...
Aug. 26, 2016 01:00 AM EDT Reads: 1,964
DevOps at Cloud Expo, taking place Nov 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 19th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait for long dev...
Aug. 26, 2016 12:45 AM EDT Reads: 2,276
Cloud computing is being adopted in one form or another by 94% of enterprises today. Tens of billions of new devices are being connected to The Internet of Things. And Big Data is driving this bus. An exponential increase is expected in the amount of information being processed, managed, analyzed, and acted upon by enterprise IT. This amazing is not part of some distant future - it is happening today. One report shows a 650% increase in enterprise data by 2020. Other estimates are even higher....
Aug. 26, 2016 12:30 AM EDT Reads: 2,908
I wanted to gather all of my Internet of Things (IOT) blogs into a single blog (that I could later use with my University of San Francisco (USF) Big Data “MBA” course). However as I started to pull these blogs together, I realized that my IOT discussion lacked a vision; it lacked an end point towards which an organization could drive their IOT envisioning, proof of value, app dev, data engineering and data science efforts. And I think that the IOT end point is really quite simple…
Aug. 25, 2016 11:45 PM EDT Reads: 2,292
Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more business becomes digital the more stakeholders are interested in this data including how it relates to business. Some of these people have never used a monitoring tool before. They have a question on their mind like “How is my application doing” but no id...
Aug. 25, 2016 10:15 PM EDT Reads: 1,724
Identity is in everything and customers are looking to their providers to ensure the security of their identities, transactions and data. With the increased reliance on cloud-based services, service providers must build security and trust into their offerings, adding value to customers and improving the user experience. Making identity, security and privacy easy for customers provides a unique advantage over the competition.
Aug. 25, 2016 09:15 PM EDT Reads: 2,214
Is the ongoing quest for agility in the data center forcing you to evaluate how to be a part of infrastructure automation efforts? As organizations evolve toward bimodal IT operations, they are embracing new service delivery models and leveraging virtualization to increase infrastructure agility. Therefore, the network must evolve in parallel to become equally agile. Read this essential piece of Gartner research for recommendations on achieving greater agility.
Aug. 25, 2016 05:15 PM EDT Reads: 718
Smart Cities are here to stay, but for their promise to be delivered, the data they produce must not be put in new siloes. In his session at @ThingsExpo, Mathias Herberts, Co-founder and CTO of Cityzen Data, will deep dive into best practices that will ensure a successful smart city journey.
Aug. 25, 2016 03:30 PM EDT Reads: 1,505
SYS-CON Events announced today that Venafi, the Immune System for the Internet™ and the leading provider of Next Generation Trust Protection, will exhibit at @DevOpsSummit at 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Venafi is the Immune System for the Internet™ that protects the foundation of all cybersecurity – cryptographic keys and digital certificates – so they can’t be misused by bad guys in attacks...
Aug. 25, 2016 01:00 PM EDT Reads: 2,605
SYS-CON Events announced today Telecom Reseller has been named “Media Sponsor” of SYS-CON's 19th International Cloud Expo, which will take place on November 1–3, 2016, at the Santa Clara Convention Center in Santa Clara, CA. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.
Aug. 25, 2016 09:00 AM EDT Reads: 596
For basic one-to-one voice or video calling solutions, WebRTC has proven to be a very powerful technology. Although WebRTC’s core functionality is to provide secure, real-time p2p media streaming, leveraging native platform features and server-side components brings up new communication capabilities for web and native mobile applications, allowing for advanced multi-user use cases such as video broadcasting, conferencing, and media recording.
Aug. 25, 2016 08:45 AM EDT Reads: 2,137
Akana has announced the availability of version 8 of its API Management solution. The Akana Platform provides an end-to-end API Management solution for designing, implementing, securing, managing, monitoring, and publishing APIs. It is available as a SaaS platform, on-premises, and as a hybrid deployment. Version 8 introduces a lot of new functionality, all aimed at offering customers the richest API Management capabilities in a way that is easier than ever for API and app developers to use.
Aug. 25, 2016 06:00 AM EDT Reads: 1,457