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Our Uptime is "3 nines"

Don't take our word for it, we happily provide links to third-party independent uptime monitoring services.

  1. webhostingstuff.com - webhostingstuff.com has been monitoring us since 2008!
  2. montools.com - no outages detected in the last year.

At 99.98% overall uptime, 2020Media's uptime is considered excellent.

But don't all hosts have downtime?

Yes it's true, all hosts have times when they need to take a system offline for scheduled maintenance. If our scheduled maintenance periods were excluded from the testing our public results would show even better performance. For example webhostingstuff.com noted 259 mins downtime in August 2013. This outage of our primary website www.2020media.com was actually a period of planned maintenance for a complete physical move of servers from one datacentre to another.

But we believe third party data is the only data that 100% trustworthy so we're happy to link to their data to all prospective and existing customers.

In actual fact, since we joined {tip What is RIPE::The Réseaux IP Européens Network Coordination Centre is the Regional Internet Registry for Europe, the Middle East and parts of Central Asia. It oversees the alllocation of IP Addresses to it's members}RIPE{/tip} in 2002, our network has never been down - that's thanks to our system of multi-homing of network and redundant routing. That's over 12 years network uptime at 100%.

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Introduction to EJB

Notice

This is a personal view of EJB and the Java Enterprise Platform (J2EE). I expect that is does not nearly cover the scope of these technologies or bring out the many applications in which they could be used. However I have found it difficult to find concise descriptions of the beneifts of EJB and J2EE and I hope this brief introduction may at least spark some ideas and further Interest.

General

Most business systems (and many others) can be viewed as a number of transactions between different components of the business. For example buying a ticket involves a transaction from the request to the seller, which then could cause multiple transations to stock control, accounts etc. Each of these transactions and the items that they work on can be represented by Enterprise JavaBeans, and the environment in which they work is J2EE.

Enterprise Beans

Enterprise beans come in two flavours: entity beans and session beans. Typically entity beans represent ideas that can be expressed as nouns - a customer, an item, a place, or any other 'real-world' object. On the other hand session beans tend to manage 'transactions' - the process of buying a ticket,

Enterprise Platform

The environment in which these beans exist provides much of the power of the whole concept. Entity beans (which represent real-world objects) are 'persistant' - they need to maintain state - and the platform provides a variety of mechanisms for easily storing this state. Session beans doesn't retain state, but needs to manage transations - this involves the ability to recover from particular functions that might not suceed. For example, two ticking buying processes might be competing for the last seat - one of these processes will need to abort the transaction and recover any state changes back to their origional states. The platform also provides mechanisms for this.

The Big Winner

All the above things can be implemented reasonably well in other systems - where J2EE wins is in the scaleability of the system. Object pooling, location independence and flexibility mean that systems can be build that will handle huge number of transactions reliably. Objects can be seamless distributed between multiple servers.

Finding Out More

Books

Enterprise JavaBeans by Richard Monson-Haefel Published by O'Reilly & Associates 1999 ISBN 1-56592-605-6
Java 2 Platform, Enterprise Edition by Bill Shannon et al. Published by Addison-Wesley 2000 ISBN 0-201-70456-0

Web Sites

http://www.java.sun.com/products/ejb/index.html

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JDBC Case Sensitivity Issues


There are a number of issues surrounding getting JDBC to work with different databases.

The following is extracted from

"JDBC Database Access with Java" by Graham Hamilton & others from Sun
(Addison-Wesley ISDN 0-201-30995-5

"The standard in SQL is that keywords are not case sensitive, so, for example, the following SELECT statement can be written in various ways."
.... 
"Quoted material, however, is case sensitive: ".

"Requirements can vary from one DBMS to another when it comes to identifier names.  For example, some DBMSs require that column and table names be given exactly as they were created in the CREATE TABLE statement, while others do not."
.....
"The only sure way to make patterns database-independent is to discover the way identifiers are stored, (with DatabaseMetaData methods), and then use the appropiate case in identifier name patterns. DatabaseMetaData has several methods for determining whether identifier names are stored in the database as lowercase, mixed case or uppercase

  •  storesLowerCaseIdentifiers
  • storesLowerCaseQuotedIdentifiers
  • storesMixedCaseIdentifiers
  • storedMixedCaseQuotedIdentifiers
  • storesUpperCaseIdentifiers
  • storesUpperCaseQuotedIdentifiers
  • supportsMixedCaseIdentifiers
  • supportsMixedCaseQuotedIdentifiers

If the methods with QuotedIndentifiers in their names return true, they allow nonalphanumeric characters if those characters are enclosed in quotation marks."

I guess what this means is that to ensure compatibility across JDBC drivers the way to do it is to ensure that identifiers are all stored the same way (either upper or lower case, but not a mixture and not quoted) and then use functions to convert appropiately in the code.

 

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