Some advice is good even if it’s not necessarily precise. Just the common sense behind it is enough to be worthwhile. Here is one example: A while back, an article on email management stated that if you opened an email message and decided you could deal with it in two minutes or less, then do so immediately and get it out of your Inbox. I can’t remember where I got that from but I’ve been using it ever since and it’s helped me a great deal in managing the size of my Inbox.
What happens behind the scenes when you enter your credit card information online? Is it safe? For answers, I turned to the experts at Skipjack Financial Services, a Cincinnati-based company whose Canadian office is in Halifax. I know them well because my employees at Nicom IT Solutions often use Skipjack when they create web sites that have an online payment option.
The first thing the Skipjack folks pointed out is that online payment processing is not that much different from traditional credit and debit card processing. In fact, a large portion of the transactions that they process are from traditional devices, like point-of-sale terminals.
We now have this huge computer network called the Internet and we usually think of it in terms of Web pages, but it has potential for a lot more than just providing online marketing material for us to look at. Organizations with offices across multiple locations can make use of high-speed Internet connections and replicated databases to transfer data from one place to the other, and keep one another up-to-date on what’s going on.
Replicated databases, as the name implies, are sets of data that are kept in more than one place. Since it isn’t practical to simply copy entire databases, technologies exist to keep multiple databases in sync by copying only those parts of the database that have changed. As I’ve said in past articles, at NicomIT, we work mainly with Microsoft technologies, so this article deals primarily with Microsoft SQL Server databases, although similar types of technologies are used in other database systems. Oracle, for example, offers synchronization, and there is even the capability to send data from an Oracle database to a Microsoft SQL Server databases in a replicated fashion.
We usually use what’s known as a Virtual Private Network, or VPN, running over the Internet to transmit data in replicated scenarios. A VPN can be set up on any computer and offers a secure channel, via passwords and/or data encryption, for data to flow. So you get the ease and pervasiveness of the Internet with the security of the VPN. Replicated database applications can be scaled from very simple to very complex, depending on the size and frequency of data traffic.
There are basically three types of replication: snapshot, transactional, and merged. Snapshot replication consists of simply sending a read-only copy of a database from one place to another. This would be used where periodic updates are required (say once a day or once a week) and the destination is only interested in the resultant data, not the transactions that were processed.
Transactional Replication keeps replicated databases in sync by sending every transaction from one place to the other. These may be sent in batches on a periodic basis, or done immediately. This later scenario is the most common, and requires the different locations to be always connected together.
Merged Replication is also very common, and is used where there is a centralized server and decentralized clients that are not always connected. This type of technology is similar to what you use if you have a Palm Pilot or other such PDA (personal digital assistant) that
you occasionally have to synchronize with your office computer. On occasion the clients have to be synchronized with the server, and changes made at either end are brought across to the other end. There must be rules put in place to deal with conflicts which occur when changes are made to the same record by different people.
We’re finding Merged Replication to be the most common in our client base, where multiple sites and/or agents in the field keep track of data that must be brought back to the central office, and vice-versa. One of our clients, for example, moves inventory in vans and we are setting them up so that their inventory application is available to the people in the vans, yet head office is kept up-to-date via their centralized system. Other uses we have found for replicated databases are creating subsets of data for reporting and business intelligence purposes, and for doing real-time instantaneous backups of databases in offsite locations, so that no data is lost in the case of a fire or some other disaster.
I should also note that a computer application does not have to be built with replication in mind. Replication can be retrofitted to existing applications if the need arises.
The bottom line: Replicating databases is a secure way of keeping data synchronized across multiple locations, and the network you need to send the data from one place to the other is the ubiquitous Internet.
So am I. I decided to at a look at some well known software development publishers to see what they have available for Silverlight books.
Apress has five titles listed for Silverlight, but as of this blog posting, all are “NOT YET PUBLISHED”. It doesn’t look like they are offering a Silverlight 1.0 book as most titles reference specifically Silverlight 1.1. I like Apress books and I highly recommend their “Pro” series. I am a little disappointed in their lack of a decent Silverlight 1.0 book.
O’Reilly has three titles that are currently in print, all three at an introductory (or essentials) level. Their “Getting Started with Silverlight” began shipping back in April 2007. There are not many reviews listed with this title, but the average rating is five stars out of six.
AJAX is still a large buzz in the industry. For some that are just beginning to use this technology, it can be confusing to know where to start. There are dozens of choices of technologies that will allow you to create AJAX enabled systems, but which do you choose? Which is the “right” one?
This post will explore some the options we’ve tried as well as the pros and cons of each.
Our experiences in developing web-based applications have not been limited to developing only ASP.NET applications. We have run the gamut of development technologies though we have standardized on two technologies in particular in the recent number of years; ASP.NET and PHP.
Nicom IT Solutions Inc. is a full service IT professional services firm providing Software Development, IT Consulting, E-commerce Solutions, Technical Support, and Web Design & Development in addition to Staffing Services.
Pat d'Entremont
Mike Hatfield
Barry Milne
Ryan GrantThe opinions expressed herein are the authors' own personal opinions and do not represent their employer's view in any way.
© Copyright 2008 Nicom IT Solutions, Inc. and the authors 
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