Web Services choice With the hype surrounding .NET Web Services, and Sun bringing together an offering for Web Services, it's time we took a look at what's happening. In this article, we compare the two approaches to Web Services, along with examining why you might want to use one method or the other.

Web Services are currently concerned with four basic challenges:

1. Service Description
2. Service Implementation
3. Service Publishing, Discovery and Binding
4. Service Invocation and Execution

In the body of this article, we will take each of these challenges in turn and look briefly at how the two technologies handle them.

Service Description

In order for Web Services to proliferate it is important to be able to describe them in some structured way. The Web Services Description Language (WSDL) addresses this need by defining an XML grammar for describing Web Services as collections of message-enabled endpoints or ports.

In WSDL, the abstract definition of endpoints and messages is separated from their concrete deployment or bindings. The concrete protocol and data format specifications for a particular endpoint type constitute a binding. An endpoint is defined by associating a Web address with a binding, and a collection of endpoints defines a service.

J2EE

J2EE-enabled Web Services exchange information with interested parties using WSDL to come to an agreement on the proper format for each transferred XML document. Third parties who want to transact business with a J2EE-enabled Web Service company can look up information about the company's Web Services in a registry.

.NET

As with a J2EE Web Service, a .NET Web Service supports the WSDL 1.1 specification and uses a WSDL document to describe itself. In this case, however, an XML namespace is used within a WSDL document to uniquely identify the Web Service's endpoints.

.NET provides a client-side component that lets an application invoke Web Service operations described by a WSDL document and a server-side component that maps Web Service operations to COM-object method calls as described by a WSDL and a Web Services Meta Language (WSML) file. This file is needed for Microsoft's implementation of SOAP.

Service Implementation

Implementing Web Services currently means structuring data and operations inside of an XML document that complies with the SOAP specification. Once a Web Service component is implemented, a client sends a message to the component as an XML document and the component sends an XML document back to the client as the response.

J2EE

Existing Java classes and applications can be wrapped using the Java API for XML-based RPC (JAX-RPC) and exposed as Web Services. JAX-RPC uses XML to make remote procedure calls (RPC) and exposes an API for marshalling (packing parameters and return values to be distributed) and un-marshalling arguments and for transmitting and receiving procedure calls.

With J2EE, business services written as Enterprise JavaBeans are wrapped and exposed as Web Services. The resulting wrapper is a SOAP-enabled Web Service that conforms to a WSDL interface based on the original EJB's methods.

The J2EE Web Services architecture is a set of XML-based frameworks, providing infrastructures that allow companies to integrate business-service logic that was previously exposed as proprietary interfaces. Currently, J2EE supports Web Services via the Java API for XML Parsing (JAXP). This API allows developers to perform any Web Service operation by manually parsing XML documents.

.NET

.NET applications are no longer directly executed in native machine code. All programs are compiled to an intermediate binary code called the Microsoft Intermediate Language (MSIL). This portable, binary code is then compiled to native code using a Just In Time compiler (JIT) at run time and run in a virtual machine called the Common Language Runtime (CLR). This is similar to the way that Java works, except .NET encompasses several languages; each is translated to MSIL, which is executed in the CLR using the JIT – simple, really. With the .NET platform, Microsoft will provide several languages based on the Common Language Infrastructure (CLI), such as Managed C++, JScript, VB.NET and C#.

Service Publishing, Discovery, and Binding

Once a Web Service has been implemented, it must be published somewhere that allows interested parties to find it. Information about how a client would connect to a Web Service and interact with it must also be exposed somewhere accessible to them. This connection and interaction information is referred to as binding information.

Registries are currently the primary means to publish, discover, and bind Web Services. Registries contain the data structures and taxonomies used to describe Web Services and Web Service providers. A registry can either be hosted by private organizations or by neutral third parties.

IBM and Microsoft have recently announced the Web Services Inspection Language (WSIL) specification to allow applications to browse Web servers for XML Web Services. WSIL promises to complement UDDI by making it easier to discover available services on Web sites not listed in the UDDI registries.

J2EE

Sun Microsystems is positioning its Java API for XML Registries (JAXR) as a single general purpose API for interoperating with multiple registry types. JAXR allows its clients to access the Web Services provided by a Web Services implementer exposing Web Services built upon an implementation of the JAXR specification.

There are three types of JAXR providers:

* The JAXR Pluggable Provider, which implements features of the JAXR specification that are independent of any specific registry type.
* The Registry-specific JAXR Provider, which implements the JAXR specification in a registry-specific manner.
* The JAXR Bridge Provider, which is not specific to any particular registry. It serves as a bridge to a class of registries such as ebXML or UDDI.

.NET

At first, Microsoft had the discovery of Web Services with DISCO in the form of a discovery (DISCO) file. A published DISCO file is an XML document that contains links to other resources that describe the Web Service. Since the wide spread adoption of UDDI, however, Microsoft has supported it in order to maximize interoperability between solutions in what is, after all, a set of specifications for interoperability.

In addition to providing a .NET UDDI server, the UDDI SDK provides support for Visual Studio .NET and depends on the .NET framework. Products such as Microsoft Office XP offer support for service discovery through UDDI.

Service Invocation and Execution

The Simple Object Access Protocol (SOAP) is a simple, lightweight XML-based protocol that defines a messaging framework for exchanging structured data and type information across the Web.

The SOAP specification consists of four main parts:

* A mandatory envelope for encapsulating data
* Optional data-encoding rules for representing application-defined data types, and a model for serializing non-syntactic data models
* A request/response message exchange pattern
* An optional binding between SOAP and HTTP

SOAP can be used in combination with any transport protocol or mechanism that is able to transport the SOAP envelope.

Web Service recipients operate as SOAP listeners and can notify interested parties (other Web Services, applications, etc.) when a Web Service request is received. The SOAP listener validates a SOAP message against corresponding XML schemas as defined in a WSDL file. The SOAP listener then un-marshals the SOAP message. Within the SOAP listener, message dispatchers can invoke the corresponding Web Service code implementation.

Finally, business logic is invoked to get the reply. The result of the business logic is transformed into a SOAP response and returned to the Web Service caller.

J2EE

J2EE uses the Java API for XML-based RPC (JAX-RPC) to send SOAP method calls to remote parties and receive the results. JAX-RPC enables Java developers to build Web Services incorporating XML based RPC functionality according to the SOAP 1.1 specification.

Once a JAX-RPC service has been defined and implemented, the service is deployed on a server-side JAX-RPC runtime system. The deployment step depends on the type of component that has been used to implement the JAX-RPC service. For example, an EJB based service is deployed in an EJB container.

During the deployment of a JAX-RPC service, the deployment tool configures one or more protocol bindings for this JAX-RPC service. A binding ties an abstract service definition to a specific XML based protocol and transport. An example of a binding is SOAP 1.1 over HTTP.

A Web Service client uses a JAX-RPC service by invoking remote methods on a service port described by a WSDL document.

.NET

In Microsoft's .NET framework, interested parties can gain access to a Web Service by implementing a Web Service listener. In order to implement this, a system needs to understand SOAP messages, generate SOAP responses, provide a WSDL contract for the Web Service, and advertise the Service via UDDI.

.NET Developers creating SOAP-based Web Service listeners and consumers currently have three choices:

1. Use the built in .NET SOAP message classes
2. Construct a Web Service listener manually, using MSXML, ASP, or ISAPI, etc.
3. Use the Microsoft Soap Toolkit version 2 to build a Web Service listener that connects to a business facade, implemented using COM.

The Microsoft SOAP Toolkit 2.0 offers a client-side component that lets an application invoke Web Service operations described by a WSDL document.

Time to Choose

Having looked at how J2EE and .NET handle Web Services, we are faced with a choice - which version do we implement? From a purely technical standpoint, each method has advantages and disadvantages.

The key advantage, perhaps, of using the .NET approach to Web Services is that it has been designed for that purpose, whereas J2EE is being retrofitted by the addition of further APIs.

One advantage of using J2EE as a base for your system is that you have a much wider choice of vendor for your pre-built software (application servers mostly), including numerous open source projects. In many ways, open source J2EE application servers are closer to the standard laid down by Sun, because they don't add proprietary extensions to overcome problems.

Ultimately, unless you are starting your system from the bottom up, your choice of Web Services implementation is more than likely going to be influenced by your present system. If you have a team of skilled programmers, with an existing business system, realistically you'll want to continue using that system, be it J2EE based or Microsoft based.

Summary

Web Services promise to revolutionize not only the way we develop software systems, but how we do business. Some aspects of Web Services development, such as security and transaction handling, are yet to be completely solved, but must be in order to make the Web Services dream a reality.

WDSL, SOAP, UDDI, XML, Microsoft's .NET and Sun's J2EE provide the technologies and tools needed to get Web Services off to a running start. Are these technologies and tools enough to make Web Services a reality and fulfill all of their promises? Time will tell.  ¶ 3:58:00 AM 1 comments

  Microsoft Vista: Delayed Again   ¶ 12:01:00 AM 0 comments

  UFO's Identified UFOs "Identified"

Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience... (Ephesians 2:2)

We want to take this opportunity to speak to the enormous fascination and confusion resulting from the ongoing craze about Unidentified Flying Objects or UFOs. Nearly every day we hear increasingly about supposed UFO activity, alien beings, and their alleged interaction with and even abduction of humans. Reports of visitors from other worlds now permeate our society. Once relegated to the pages of sensationalistic tabloids or fantasy novels, suspected UFO activities are now reported about during the world’s most respected newscasts. During recent times, nearly every newspaper and television magazine program has discussed UFOs and aliens. Radio personality Art Bell became one of the most listened to hosts in history by dedicating multiple hours each night to the discussion of UFOs and the paranormal. Mainstream wire services abound with articles on the subject, asking questions like, "If Aliens Visit Earth, Will They Be Friendly?" and "Speak up ET! Thanks to NASA, If You’re Out There, We’re Listening." The sheer numbers who now report sightings have become dramatically more frequent. Though credibility may be questionable in some cases, and regardless of NASA’s lack of official comment, more than one astronaut has acknowledged that they have actually seen alien craft while in space.

During the last twenty-five years, UFOs have allegedly been sighted over nearly every major city worldwide, as well as over military bases and nuclear sites. From the rural backwoods to the main streets of our cities, sightings of unexplained phenomenon in the skies continue to mount. Entire city populations have witnessed UFO events that local governments could not explain, most notably a saucer-shaped UFO which hovered over downtown Mexico City in broad daylight, producing thousands of eyewitnesses in July of 1997. Pictures and video of that sighting were broadcast around the world. To this date, the much-reported event remains unexplained. It is no wonder that recent polls indicate that a majority of Americans believe that extraterrestrials most likely do exist. The study of UFOs or ufology has now become an obsession for multiple thousands, perhaps millions of people. All of this has contributed to the U.S. government spending millions of tax dollars trying to contact aliens.

Until 1954, only ten thousand people claimed that they had seen a UFO. However, it was around this time that the number of sightings skyrocketed. On November 29, 1973, a Gallup poll reported that fifteen million Americans had personally seen UFOs. Senator Barry Goldwater believed he saw a UFO. Boxer Muhammed Ali and Prince Charles both say they saw UFOs. Actor William Shatner claims that his motorcycle stopped in the desert and UFOs led him to safety. Even former president Jimmy Carter claims to have seen a UFO. Christopher Columbus reportedly saw UFOs four hours before he discovered America in 1492. And then there was the highly publicized sighting that guitarist Jimi Hendrix believed he had at the Woodstock Pop Festival in 1968. However, we surmise in Hendrix’s case that what he thought he saw was probably induced by the LSD he had taken! But what about the millions of others?

Perhaps for us the most impressive barometer of just how expansive the study and discussion of UFOs has become happened during the writing of this book. While researching, we went to the World Wide Web and entered the term "UFO" into the powerful Inktomi search engine, which gleans prospective web sites across the Internet according to any desired search term. The results were staggering. As of mid-July 2000, the Inktomi search engine, which supplies Yahoo, AOL, MSN, Canada.com, and other search engines and directories with data, recorded a whopping 428,405 Internet web sites with information on UFOs! And that is just a partial figure, for the technology used in search engines normally picks up only the sites where embedded keywords actually reflect the exact term being searched for, such as "UFO"! Truly, the phenomenal interest surrounding UFOs has reached uncanny proportions today.

Alien Public Relations

Perhaps Hollywood’s spotlight on the topic has done more to further the UFO craze than any other single thing. Obviously, there has been a constant stream of motion picture and television programming built around outer space, beings from other worlds, and space travel. Leading the way were movies like Close Encounters, Alien, and Star Wars, as well as the extremely popular television and movie series’ "Star Trek" and "The X Files." And of course the blockbuster, ET: The Extra Terrestrial.

Over the years, the improvement in the quality of Hollywood’s presentations has truly been staggering. Great advancements have been made since the early days of Buck Rogers and Flash Gordon. Now, the electronic age has brought with it the capacity to blend ultra-surrealism with near absolute believability in recent box office hits such as, Armageddon and Independence Day. Coupled with the state-of-the-art theaters of today, filmmakers have been able to employ ingenious electronic special effects, making powerful presentations that have deeply impacted viewers. While the special effects may be phenomenal, Hollywood’s "magic" has left an unmistakable effect of a different sort on the lives of many people. The line between fantasy and reality has become more blurred with each passing year. The realism and tremendous effects leave the impression that there is at least a possibility that what one is viewing could be reality. Adding to this is the volume of actual real-life news reports concerning the very things that are now also supernatural subject matter for the big screen. Through news coverage, in books, and in particular, Hollywood’s capitalization on the subject, there is no doubt that a psychological conditioning of the culture concerning the possible existence of UFOs and alien beings has taken place. However, the question remains: What would we do if and when a UFO should land on the White House lawn? What reaction would Americans have to such an event, let alone a hostile attack such as depicted in Orson Well’s classic radio play and subsequent motion picture War of the Worlds?

Have there been government cover-ups intended to shield us from knowing the truth? Are there really alien beings being held by our military deep in the Nevada desert at the secretive base know only as "Area 51" or elsewhere? Was there really a UFO crash and subsequent news blackout at Roswell, New Mexico, in July 1947? If so, who piloted the ill-fated craft and where are the remains of the occupants today? Are we really being visited by beings from outer space? Or are we experiencing an elaborate, well-orchestrated brainwashing in an attempt to make us believe we have otherworldly visitors among us? If so, why and by who?

What Do You Believe?

Here are four scenarios that cover the UFO question.

1. UFOs are a hoax and do not exist. There has undoubtedly been some hoaxing through the years, but the overwhelming weight of evidence suggests that there are indeed vehicles or craft in our physical reality that are unexplained, thus Unidentified Flying Objects.

2. If UFOs exist, they are man-made and merely a part of secret military operations, testing and refining secret technologies around the world. This possibility exists also and certainly could be the case in some instances. But again, the evidence seems to suggest that nothing mankind has invented could be responsible for the majority of the sightings to date.

3. UFOs exist and are piloted by beings from outer space. Questions abound if this is the case. Are they here just observing us? Are they friendly? Or will they eventually become hostile? Are all of the UFOs sighted from the same planet or galaxy, or do we have multiple civilizations visiting us simultaneously?

One would think that if aliens actually desired to make contact that we would have at least one rock-solid, irrefutable close encounter of the third kind, complete with credible eyewitnesses and proof to substantiate it beyond question, before the military could seal off the area and deny everything. If they actually wanted to make contact with us and really are of superior intelligence, wouldn’t you think that by now they would have figured out that the best way to do so is to actually appear and land in a populated area—not Roswell, New Mexico, or Sedona, Arizona? This rather diminishes the argument that New Agers have advanced, which states that aliens are here to teach us and help us stave off elimination as a race. As a New Age author or leader, wouldn’t it do wonders for your ego (and probably your checkbook as well), to believe that otherworldly beings have picked you out of the over five billion inhabitants of earth to communicate their still–secretive agenda to?

We can deduce as well that if alien beings were casing earth for a possible takeover, they would have likely made their move by now. If they can come from other worlds, it stands to reason that their technology, and presumably their intelligence, could overpower us quicker than you can say, "Take me to your leader." No, it appears that so far UFOs have purposely eluded mankind for the most part, being revealed only enough to let the mystique and speculation build to unprecedented heights. We believe this is no accident.

Note that evolutionists and atheists could theoretically line up with any of the three possibilities above, but could never agree with our last scenario, which is the one these authors believe.

4. UFOs are not from another galaxy. It is our personal belief that the UFO/alien phenomenon is one hundred percent inspired and engineered by Satan. They are actually demonic materializations in a very well orchestrated plan to deceive mankind and condition him to accept the supernatural in the end days. Thus, any alien beings that have been sighted or communicated with are demonic in nature. In fact, we believe in the very real possibility that aliens/UFOs could play a defining role in either events surrounding the explanation of the Rapture of the church and/or the subsequent rise to power of the Antichrist. We are not alone in this belief. Some of the greatest Christian minds of this century, including Dr. Walter Martin, thought the same.

The Identity of Aliens

In examining the UFO and alien phenomenon from both a biblical and New Age point of view, there are striking parallels. Though New Agers do not regard alien beings as demons, the information that some New Agers claim to have received from them certainly substantiates our belief that the Bible identifies these previously Unidentified Flying Objects and their occupants.

First, if you wish to study UFOs, you need to visit the occult section of your local library to find information. This in itself should be a tip-off. There you will find books with such titles as, Science and the Paranormal: Probing the Existence of the Supernatural, Creatures from UFOs, and The Supernatural From ESP to UFOs. A perusal of the Internet shows the same mixture of UFO and occult information on many of the same web sites as well. In fact, the array of web pages that correlate New Age beliefs, the occult, and UFOs is blatant and staggering. For example, one web site advertised itself as follows:

"This site contains a huge amount of New Age and Spiritual information including Astrology, Wicca and Pagan, UFOs & ETs, Ascension, Earth Changes, Channellings (sic) Crystals, Dreams, Divination, Angels, Magick, Karma, Meditation and Healing."

Another said: "Channeling, Reiki, new-age, metaphysics, Feng Shui, angels, chakras, spirit, Bortner, masters, healing."

Still another ad said: "New Age Web Works Supports and informs the New Age, UFO, Pagan, Occult and Alternative Spirituality communities."

If aliens really are coming from other planets, why are they so closely linked with the occult? Why would occultists and New Agers have a corner on the market in communicating with aliens, if indeed they were actually from another world? The answer is simple but often ignored. The occult is about one thing—power from or communication with the spirit realm. Though most New Agers believe that aliens have chosen them to communicate with due to their spiritual "enlightenment," that’s not really the case. What has actually attracted these beings who claim to be aliens is the proclivity New Agers have for spiritualism and other occult practices. Occultists and New Agers are versed in communicating with the spirit world—exactly where these "aliens" originate. So associating UFOs, aliens, and the occult together is for us a no-brainer. The outgrowth of the UFO phenomenon is doctrinally rotten. It lines up again and again with the world of the occult—not with God’s Word. If for no other reason, this is why we believe these "aliens" to be nothing but masquerading demonic intruders, who are weaving a deceitful web in order to further trap millions today.

Even without integrating biblical understanding we see that both New Agers and UFO researchers concur, that there is indeed reason to believe that UFOs actually originate from another dimension and not from other planets or galaxies. Jay Allen Hynek, probably the world’s foremost expert on ufology, said: "I do not believe they are coming from another planet. I believe they are coming from a parallel reality." We believe the parallel reality he is referring to would be the non-three dimensional supernatural realm described in the Bible. Entertaining this idea should be no quantum leap for the Christian. After all, Scripture reminds us that the Devil IS the "prince of the power of the air" (Ephesians 2:2) and the "god of this world" (2 Corinthians 4:4). Plus, we have instances throughout Scripture where angels appeared and operated in the natural physical realm in which we live. Let us remind skeptics for example that angels came to Abraham to announce Sarah’s pending pregnancy (Genesis 18). They also came to Sodom and led Lot to safety (Genesis 19). And an angel appeared at the tomb of Christ announcing that He was risen to the two Mary’s (Matthew 29). In the first two instances, the angels were presumably dressed in the garb of the time and ate human food. They all communicated in the earthly languages of those they met as well. This harmonizes perfectly with the warning we are given in Hebrews 13:2 to be careful to entertain strangers for they could be angels. All of this biblical evidence certainly gives good explanation as to how UFOs and their occupants could indeed maintain prolonged physical materialization. To magnify his plan for this age, Satan could, will, and does use many means to deceive his prey. He is the father of lies and illusion and his leash seems to get a bit longer with each passing day as we race toward the climax of the church age and the Tribulation to follow. That plan includes UFOs.

In her 1979 best-seller, Aliens Among Us, Ruth Montgomery broke new ground within the New Age community by laying out a case for the idea that some "humans" had evolved beyond the point of being born or going through childbearing. She believes that these beings who have come from "beyond the veil" are actually living as humans here on earth. She deemed these ETs "walk-ins." Millions say they’ve had past life experiences, which seems to verify the concept of reincarnation, so why not the belief that you were previously an alien life form? Sound far out? Well, there are a number of Internet web sites, some very intellectual, some very weird, that advertise themselves as touch points for these "walk-ins" to meet and share ideas and experiences. The first line on the back of Montgomery’s book reads: "Prepare to meet our wondrous gods from beyond the earth." In researching "walk-ins" we found it interesting that the common denominators appear to be a belief in angels, UFOs, and the occult. To us, this is just one more confirmation that aliens and demons are one in the same.

  ¶ 6:57:00 AM 0 comments

  How to be Crash Free

Having bugs in your code may be unavoidable, but crashing *is* avoidable. Barring cosmic rays playing yahtzee with your memory there is no reason why your program should ever crash. Crashing is totally avoidable!

What do I mean by crashing? A program has crashed when the operating system has to close your application or one of the threads of your application for you. Usually this is accompanied by a user-unfriendly dialog box popping up with messages like, "An access violation has occurred in your application. Press OK to debug or Cancel to close." Sometimes it makes a nice blue screen, and sometimes you manage to confuse the OS so much that it ceases to function altogether. Crashes in your code should always fall into the "nasty dialog box" category unless you are writing device drivers or other kernel level stuff, or operating in less safe OSes such as Windows 95, Windows 3.1, and the like.

When a problem arises you want the worst case scenario to be a managed shutdown of your application. You want to be able to control the closing of your threads and applications; you do not want the OS to have to kill them. If you have control you can close handles, let remote services know you are going down, free up resources, etc. The biggest advantage of managing the shutdown yourself is that you can tell the user what happened in the correct context and in a user friendly way. You can put up a dialog box saying something like, "A fatal error was encountered while trying to connect to resolve the server xxx.yyy.com, please run the error reporting utility to forward your error logs to technical support." A user or a programmer is much more likely to be able to figure out what went wrong with a nice informative error message like that than with the nebulous "access violation" we saw in the crash scenario.

In code you write, there are only two things that will crash your program, accessing or deleting memory you do not own and failing to catch an exception at the top of a thread. Lets break these down.

Accessing or deleting memory you do not own

1. Dereferencing a NULL pointer
1. *(NULL)
2. NULL->member
3. NULL[1]
4. NULL->function()
5. strcpy( NULL, "hello" )
6. *(NULL)(params);
7. this == NULL during an implicit (*this).
2. Dereferencing an uninitialized pointer
1. blah* pPointer; *pPointer
2. All same cases as (1)
3. Dereferencing a deleted pointer
1. delete pPointer; *pPointer
2. All same cases as (1)
4. Deleting an uninitialized pointer
1. blah* pPointer; delete pPointer;
5. Deleting a pointer twice
1. delete pPointer; delete pPointer;
6. Deleting non-dynamic memory
1. int x; int* p = &x; delete p;
7. Writing beyond the bounds of an array
1. int x[10]; x[-1] = 1;
2. int x[10]; x[10] = 1;
3. (a) and (b) but hidden in loops

Uncaught exceptions

1. Divide by zero
1. int x = 0; 2/x
2. double x = 0.0; 2.0/x
3. int x = 0; 2%x
4. You will also see overflow and underflow occasionally
2. Stack overflow
1. Infinitely recursive function

   void InfiniteRecurse( int x )
   {
    if ( false )
    {
        // terminating condition which is never met
        return;
    }
    else
    {
        // recurse condition which is always met
        InifiniteRecurse(x+1);
    }
   }

2. Infinitely recursive set of functions
   Same as (a) but a set of functions are mutually recursive, so the call stack looks like a -> b -> c -> a -> b -> c -> a -> b -> c -> a -> b -> c -> ...
3. Valid recursive function but each call using too much stack space

   void BigRecurse( unsigned int x )
   {
    int aBigArray[1000];
   
    if( x >= 1000 )
    {
        return;
    }
    else
    {
        aBigArray[x] = x;
        BigRecurse(x+1);
    }
   }

3. Out of memory; this may show up as an exception on some systems, others will just return NULL from the new or malloc (Visual C++'s C library returns NULL and does not throw an exception).
1. int* p = new int;
4. User or library code generated exceptions that failed to get wrapped in a try/catch. Third party code may throw exceptions under some circumstances. Your code might intentionally throw exceptions. If these miss getting caught then the exceptions will make it all the way to the top of the thread.
1. ret = ThisFunctionThrowsAnException();

How to prevent memory violations

If we prevent the two cases above from occurring then code you write will not crash. Third party code that you call can still crash, but we will get to how to minimize that shortly.

First, we want to prevent access to memory we do not own. Let me lay out some rules to follow:

1. Pointers must be initialized when they are created, either to NULL or to valid memory.
2. Deleted pointers must always be set to NULL or to valid memory on the very next line after the delete.
3. Before dereferencing a pointer, you must check that it is not NULL. You can only skip this check if you checked the pointer before in the same function, and you did not call ANY function or execute any code that could access that pointer between then and now.
4. Only one pointer can own a given block of memory. This means that for any block of memory there can be only one definitive pointer and all other pointers to that block of memory must be temporary and be set back to NULL as soon as possible. You cannot trust any temporary pointer to be valid between function calls or be valid once you called code in another object.
5. Bounds must be checked before using an index to dereference an array pointer.

Look at these rules and apply them to the seven causes of memory violations.

• Dereferencing a NULL is prevented by rule 3.
• Dereferencing an uninitialized pointer is prevented by rule 1.
• Dereferencing a deleted pointer is prevented by the combination of rule 2 and 3 in most cases and by rule 4 in rare cases.
• Deleting an uninitialized pointer is prevented by rule 1.
• Deleting a pointer twice is prevented by rule 4 and rule 2 in different cases.
• Deleting non-dynamic memory is prevented by rule 4 (and common sense).
• Writing beyond the bounds of an array is prevented by rule 5.

That takes care of your code causing memory violations, but third party code that your code calls might still blow up. The vast majority of such blowups are caused by your code passing in a NULL when this third party code did not expect it. If this code followed rule 3 there would not be a problem, but since it doesn't you will have to do the NULL check yourself. You must not pass NULL to any function that does not specifically allow for it in its documentation. Other violations that can result in exceptions being thrown are covered in the next section.

How to prevent unhandled exception violations

We also have to stop exceptions from forcing the OS to kill our threads or our application. The final line of defense here is to put an all-encompassing try/catch block in each thread start function and the main. The thread start functions are the first function called when starting a new thread; when this function exits the thread will terminate. A thread start function is often referred to as a ThreadProc. This catch all will stop all exceptions from killing your threads or application, but this is not the preferred place to catch any exception. You cannot tell anything about this exception from a "catch(...)". All you can say is, "some unknown error occurred!" This is not acceptable in a professional application. Instead, you should catch all exceptions as soon as they happen; this will give you the most context so you can report exactly what did cause this exception.

Third party code libraries you use *should* only throw documented exceptions. If you catch all the exceptions that they document you would think you would be safe, but of course you know that things do not always work as advertised. To catch these unexpected problems as soon as possible, follow these exception rules:

1. Code that accesses hardware fairly directly is always highly suspect. Due to this, any function which accesses an external subsystem like network, hard drive, etc. must be wrapped in try/catch blocks to catch any and all potential unexpected exceptions.
2. Any function of a complexity for which you cannot test every case must be wrapped with try/catch blocks.
3. Any function you suspect has the potential to change outside of your control must be wrapped with try/catch blocks.

Preventing silent problems

You follow all the rules above, and put catch all statements at the top of threads. Now your code only crashes in the places you forgot to follow the rules. This no crashing is nice, but your code still does not actually do what it is supposed to do all the time. Before, you at least saw the explosion when something went wrong, and using that you could sort of tell what might have happened. Now it just silently does not work. Well, that is because you have to actually handle and report all the errors! Ignoring errors will not make them go away! You will often see (wrong) code like this:

        try
       {
           DoSomeFunction();
           // ignoring return code
       }
       catch(...)
       {
           // ignoring exception
       }

When these errors are ignored then you of course get silent failures. Here are some basic error handling rules:

1. You must handle every error condition; ignoring a problem will not make it go away.
2. Every non-trivial function must return an error object.
3. The error object shall be filled in with detailed error information when an error occurs. Suggested information:
1. Error level
2. Error code
3. User displayed or internal flag
4. Error description string or string ID for user-displayed errors
5. Call stack if possible or whatever information you know about line/module/class/function instead
6. Thread ID
7. Timestamp
4. The error object should normally be handled before it gets back to the event loop.
5. If an error makes it up to the event loop it must be logged and action appropriate to the error level must be taken.
6. Errors shall have a level above which they are always logged; if they are not logged before their destructor is called, they must log themselves.
7. Non-logged errors should only be used for expected failures.
8. Exceptions should always create a logged error; if an exception is expected, it is not an exception (some of the external libraries you use may violate this beyond your control).
9. Do not pass on an error that you can handle appropriately.

  ¶ 1:57:00 AM 4 comments

  Don't Man-Handle a Laptop: Please Be Gentle Try to guess which piece of hardware is most often replaced on laptop computers. LCD Monitor? Cold. Keyboard? Getting warmer. Mouse pad? Getting hot. Actually the most frequently replaced piece of hardware on laptop computers is the handrest. The piece that surrounds the mouse pad, just below the keyboard. It's where, you guessed it, you rest your hands.

You can tell when the IT budget is managed by the company and when individual units pay for service levels. When it's a service level system in which each unit has its own budget, people are more careful or else they get their bosses giving them crap for spilling coffee on the laptop for the third time in a year.

What is worrisome is the amount of abuse people can dish out to laptops. Let's get real here folks; these puppies are not made of titanium. They are plastic. And yet they are still very expensive. Here's a list of DON'Ts for handling your laptop. And this is important since 98% of users store all their work on the local hard-drive and never back them up on the network shares, of which back-ups are made every single day.

DON'T:

• ...keep your coffee-mug warmer near the laptop; you're just asking for trouble. I once replaced a client's laptop three times because on all three occasions he spilled his coffee cup (on the warmer) into the keyboard. Laptop go bye-bye in a blaze of sparks.
• ...use the laptop as a leaning point when pushing the chair away from the desk or getting up. You will end up crushing the handrest and whatever hardware is under it. Most often what happens is the mouse becomes damaged and is soon followed by the keyboard.
• ...carry the laptop around like it's this morning's paper. It's an electronic device, not a book, not a package. Carrying it by the corner (handrest) with the LCD flipped open is just asking for a swift kick in the ass.
• ...use the laptop as a carry-all. I'm serious. I see you freaks all the time loading the keyboard with paperwork, peripherals and pens and then shutting the lid (LCD Monitor) on top of it and carrying it to your precious meeting. This will likely damage the keyboard and most probably will scratch the LCD. The out of warranty LCD is sometimes as expensive as a new laptop.
• ...bring the laptop outside in the sun. To begin with, the hotter electronics get, the slower they become, the faster they overheat the faster they... wait for it... melt. Yes they melt. I know it's cool to say to your friends that you are working from the park while your kids play, but get real. Same goes for leaving it in car in the sun.
• ...keep it on while carrying it around; don't even put it in hibernation. If you just drop it while it's on you will kill your hard-drive and since most of you clowns can't do your backups, you will lose all your precious files, for good. Just turn it off and save me the crying game I have to go through at least twice a month because you lost two years of work one day before the deadline, or lost your master's thesis — need those files right away it's an emergency. Some of my clients have lost their jobs because of these events. At the very least do your backups. It's a simple rule, it's not if the hard drive will fail, it's more about when it will fail.
• ...undock the laptop without doing the undocking procedure. It's just a few clicks. How urgent is that meeting that you can't do a few clicks?
• ...poke the LCD screen. It will not recognise your finger as a pointing device. Plug and Play just hasn't evolved to this point yet. What will happen though is it will damage the LCD and the display will end up looking like a rainbow acid trip.
• ...stack stuff on top of a closed laptop. It's not made to support books and paper work. Just touch the back of the LCD screen and press on it and see how easily it bends. If the back of the monitor doesn't get damaged, you'll get a keyboard imprint into the screen. IT'S PLASTIC not IRON.
• ...stuff it in a school bag or purse; your employer can provide you with a nice carrying bag with padding made especially for that very model of laptop. They sometimes even come with wheels and support so you can wheel it around if the bag is too heavy.
• ...jackhammer the keyboard. See how thin and delicate it is? Hey you wanted the thin client, now deal with it. Think of a laptop as a high-maintenance girlfriend. There's no need to pound the living shit out of the keys. It'll just break it and whether no one has told you or not, it annoys the hell out of your cubicle buddies.
• ...whack in the CD/DVD drawer like it's your sock drawer. These babies are so small and delicate, the breeze could break them.
• ...for god's sake, bring it to a beach. If you're on the beach ogle the honeys and forget the laptop at the hotel. Like trekkies at a convention, get a life. Enjoy the view of beautiful women in spank-worthy bikinis. That way the techies won't have to vacuum 3 tea-spoons of sand out of your dead laptop (true story) and you'll still have a working laptop.
• ...leave your laptop un-padlocked on the desk. It's a sure way to bring out the kleptos. From one walk from the elevator to my office, I once grabbed seven laptops. Everyone came back from lunch. Panic was soon established. They came running to my office looking for new laptops. I told them to pick the one with their name on it from the pile.

These are just a few things you can do to keep your laptop working and your data safe. I can't emphasize it enough though, BACK THAT DATA UP. It could save your career. And also, keep in mind that Big Brother truly is watching. If you are networked I can read everything on your laptop and at any time I can read your e-mail. So keep the porn on the home computer, especially the one with your girlfriend or wife. You could ruin HER life and career by doing this. Only a few techies are ethical.

Laptops aren't like condiments; they aren't free. Just keep in mind TCO. That stands for Total Cost of Ownership. Where I work, a single call to the helpdesk ends up costing hundreds of dollars — sometimes over a thousand dollars — to the company you work for. IT is the least profitable division of any company because it costs a lot of money. The more money gets poured into IT, the less is left for your bonus, pay raise and the little goodies that are afforded to you free of charge.

  ¶ 1:23:00 AM 2 comments

  Using RSS Feeds to improve browsing speed

Chances are, you're not entirely sure what the point of RSS is. I saw that little orange icon in Firefox, I've also seen their "live bookmarks" feature, which just looks cumbersome, and just never thought it could be helpful to me. Now, I wouldn't live without it. Here's why.

If you're like me, you have a ton of sites bookmarked or on your favorites list, depending on your browser of choice. That browser should be Firefox, by the way, but that's beside the point. You may have evolved and developed a list of maybe five, ten, fifteen sites you check every day to "stay in touch." RSS is a way you can be MORE in touch — with a higher number of sites — while doing less work.

Here's what you do. Get an RSS reader; I'm using Sage for Firefox right now. There's a search button in the Sage sidebar that searches for feeds of the site you're currently reading (feeds are XML documents that provide updated content from a particular website).

Let's say you're reading a blog and you enjoy the writing, so you want to check in on it regularly to read new posts. Great, it turns out this blog has a feed to enable this, as do many ordinary websites and online publications.

If you click on the feed URL (in the case of a Blogger blog, it's the URL with "atom.xml" after it) you will see a messy document you can't read, but your RSS reader can. That document is updated each time a new post is saved to this blog. Your RSS reader pulls down that document and shows you each post's title — and "marks as unread" any new ones you haven't seen yet.

In fact, the RSS reader pulls all your feeds when you click "Refresh" and highlights the ones with new content. In one button-click and about 30 seconds of refreshing, I can tell that (as an example) there is new content on two of my friends' blogs but not four others, new articles on four online magazines I read but not six others, etc. Just in that example, there are ten websites I no longer have to open!

For the ones with new content, I click the feed name and get a list of all the articles, with unread ones highlighted. I can read any of the unread content I wish by clicking on the article title, and the article pulls up in the main browser pane on the right. Once done, I click "mark all as read" and move on to the next feed. If you select your feeds well — specifically, blogs that focus on topics you are interested in, where the blog author frequently links to news articles about the topic, as it is his or her passionate area of interest — you can have a handful of blog publishers doing a lot of your research for you.

As an example, I keep up with several of my favorite musical artists this way. I subscribe to active blogs about them, which link to as many band-related news articles as they can find. This is, literally, the best thing since sliced bread. And heaven knows I love sliced bread, so that's saying a lot.

So now you know what RSS is, and how to use it. Be off, get yourself an RSS reader, and stop visiting any blog when there's nothing new to read.

But do visit this blog.....to read some nice stuff....  ¶ 12:31:00 AM 0 comments