Now let's take a look at how those events would be handled in Visual Basic .NET. Now you'll notice a couple of differences here, and I'll switch back and forth and I'll show you the main differences. First of all we can use classes inside other code structures, inside our modules and so forth. And so this public class actually could have been inside here; but we won't get into that right now. But notice if you go back to VB6, we had a class module and you had put your code in there and save that module, and compile it. And in VB .NET you just simply declare it as a class and everything in between there becomes a member of that class. So in our class definition, one of the first things we do here is say - Public Event Test - and notice I don't have all of the code in here. This is just to help you understand the skeletal aspects of events. I declare the event by saying public event test. And this is the name of our event: test. We will be passing this event ByVal s As string; then in our class, this is just the first thing we have to do for an event is to first of all declare it inside our class. And then we have to raise it from inside our class. And so here is a raise event test; now it is inside a sub and every time this sub is called on the object that is created off of this class, this event will fire. OK, and this event will raise this event test, and kick it up here and event test will begin to broadcast out that it needs to be handled, it needs to be listened to, and so what's going to happen then, is because of the handles keyword right here. And notice - handles X.test - that when this event goes, it will go automatically go down here and be handled right here. So let's look at our code in our form one VB. Notice, we create a new instance of our class the event right here. We create this new instance as X, and so X now exists as an instantiated object of that class, and so, what we are going to do is, when anybody clicks on the button OK on our form, the click event for the button OK will fire or will call the fire event right here, which will in turn raise the event test. And when that happens the test event will fire, it will be handled right here and whatever code we put here will take place. Now a couple of things I want you to notice, in VB6 all of our events were handled based on the object name, and underline and then the event. If you'll notice right here, this was tied to handling test in VB6 by the virtue of the fact that it used this name right here. And so, if you ever changed this name, it created a problem for our code. Well in .NET the magic now is this handles keyword, because now this really don't matter. I could change this name all I want to, but the fact of the matter is that the public event test is going to be handled right here every time because it says handles X.test. The handles keyword is what ties this particular sub to this particular event; this is what makes it the handler of that event. Now let's go look at this in code, and I want to show you exactly of what's happening here. So, let me start off down here at the bottom, this is a windows application, let me show you the form. There is just a simple button in the middle of the form and when we click it that click event is going to kick all this off. So the first thing I did here was created a class called the event class and I declared my event - Public Event SendMessage - and it takes an argument of a string. And then second thing I did was, have to raise that event, had to do something to cause this event to be fired off. And so, I executed - RaiseEvent SendMessage - and passed it some text, whenever somebody calls the trigger event method, or the trigger event method that is going to be in this object that comes from this class. And so at this point we are basically through with the class. We would probably have other functionality in our class, but for now we are just going to have this event in here. Now in my code, in my client side code if you want to call it that, first thing I want to do is instantiate my object, and I am going to instantiate it with - Private WithEvents - and we are going to call this object ec, and it's a new instantiation of the event class. Then when somebody clicks on button one on our form, notice this particular Sub - Handles Button1.Click. Ok, now it's just kind of interesting and I'll show in the next video, if there was a button two, I could put, you know - Handles Button2.Click - but I don't have one out there. I'll show you later. But it is real easy to have events handled in .NET as compared to six. So when they click the button, we are going to call our ec trigger event which is going to raise that test; then notice what is going to happen. We are then going to tell it that when the event send message happens, that this particular sub right here is going to handle it. And so message sent (MsgSent) is going to handle ec SendMessage. So whenever the SendMessage event gets fired off of that object, then there you go. Its going to happen right here. And you'll see a message box; so let's run this and take a look at it and see what happens. Now the form will pop up here, and when I click on it, all it's going to do is call that method off of that object that raises the event, then it comes out and gets handler and simply says the button has been clicked. And if you'll remember, back over here that's exactly what we passed- "the button has been clicked". So this is what we passed out when we set this event out, it says hey somebody handle this thing, and right here handles ec SendMessage says I'll handle anything that comes from ec's SendMessage event. And sure enough it dropped our text, the button has been clicked into the message box. And it put "message sent from the event class" as the title of that message box.
TERMS & CONDITIONS OF USE
BY SUBSCRIBING TO THIS SERVICE, YOU ARE CONSENTING TO BE BOUND BY AND ARE BECOMING A PARTY TO THIS AGREEMENT, THE TERMS AND CONDITIONS OF WHICH SHALL PREVAIL IN GOVERNING YOUR RIGHTS OF USE. BY CLICKING THE "BECOME A MEMBER" BUTTON, THE INDIVIDUAL OR ENTITY LICENSING THE PRODUCT ("YOU") IS CONSENTING TO BE BOUND BY AND IS BECOMING A PARTY TO THIS AGREEMENT. IF LICENSEE DOES NOT AGREE TO ALL OF THE TERMS OF THIS AGREEMENT, THE BUTTON INDICATING "BECOME A MEMBER" MUST NOT BE SELECTED, AND LICENSEE MUST NOT INSTALL OR USE THE SOFTWARE.
"VTC" refers to Virtual Training Company,
"You" refers to the user or subscriber.
"Software" refers to the VTC training content and software.
2. LICENSE: VTC hereby grants to You a worldwide, non-royalty bearing, non-exclusive license to use the Software according to the provisions contained herein and subject to payment of the applicable subscription fees.
3. RESTRICTIONS: You may not do any of the following:
Save the Software to Your hard disk or other storage
medium; permit others to use the Software except as specified by addendum;
modify, reverse engineer, decompile, or disassemble the Software; make
derivative works based on the Software; publish or otherwise disseminate
the Software. VTC, Inc., VTC Online University, and the Virtual Training
Company site is owned and operated by VTC, Inc. as a corporation of
All materials on this site are the property of VTC unless otherwise specified. No material from these pages may be copied, reproduced, republished, downloaded, uploaded, posted, transmitted, or distributed in any way. Modification of the materials or use of the materials for any other purpose is a violation of U.S. copyright law and other proprietary rights. For purposes of this Agreement, the use of any such material on any other web site or networked computer environment is prohibited.
4. FEES: The rights granted under this Agreement
are effective only upon payment of the subscription fees, which are
strictly non-refundable other than as expressly provided herein. The
term "monthly subscription" is defined as any 30 day period.
The term "yearly subscription" is defined as one 365 day
period. A yearly subscription ends on the same numerical date as it
began (example July 28, 2004 to July 28, 2005).
The VTC Online University is access to every VTC training tutorial in our library. You pay a flat fee for access to these titles. You are billed according to your renewal selection below, and can renew monthly, yearly, or in any other increment offered. If you choose to be billed monthly, you will be billed every 30 days for the subscription until you request the subscription be cancelled. Our terms of service state that you must cancel a monthly subscription at least two business days before your renewal date. These two days give us enough time to ensure that you will not be charged again.
5. LIMITED WARRANTY: VTC warrants that the Software, if operated as directed, will substantially achieve the functionality described. VTC does not warrant, however, that Your use of the Software will be uninterrupted or that the operation of the Software will be error-free or secure. In addition, the security mechanisms implemented by the Software have inherent limitations, and You must determine that the Software sufficiently meets Your requirements. VTC also warrants that the media containing the Software, if provided by VTC, is free from defects in material from the date You acquired the Software. VTC's sole liability for any breach of this warranty shall be, in VTC's sole discretion: (i) to replace Your defective media or Software; or (ii) to advise You how to achieve substantially the same functionality with the Software as described; or (iii) if the above remedies are impracticable, to refund the subscription fee You paid for the Software. Only if You inform VTC of Your problem with the Software during the applicable subscription period will VTC be obligated to honor this warranty. VTC will use reasonable commercial efforts to repair, replace, advise, or refund pursuant to the foregoing warranty within thirty (30) days of being so notified. If any modifications are made to the Software by You during the warranty period; if the medium is subjected to accident, abuse, or improper use; or if You violate the terms of this Agreement, then this warranty shall immediately terminate. This warranty shall not apply if the Software is used on or in conjunction with hardware or software other than the unmodified version of hardware and software with which the Software was designed to be used as described.
THIS IS A LIMITED WARRANTY, AND IT IS THE ONLY WARRANTY MADE BY VTC OR ITS SUPPLIERS. VTC MAKES NO OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NONINFRINGEMENT OF THIRD PARTIES' RIGHTS. YOU MAY HAVE OTHER STATUTORY RIGHTS. HOWEVER, TO THE FULL EXTENT PERMITTED BY LAW, THE DURATION OF STATUTORILY REQUIRED WARRANTIES, IF ANY, SHALL BE LIMITED TO THE ABOVE LIMITED WARRANTY PERIOD. MOREOVER, IN NO EVENT WILL WARRANTIES PROVIDED BY LAW, IF ANY, APPLY UNLESS THEY ARE REQUIRED TO APPLY BY STATUTE NOTWITHSTANDING THEIR EXCLUSION BY CONTRACT. NO DEALER, AGENT, OR EMPLOYEE OF VTC IS AUTHORIZED TO MAKE ANY MODIFICATIONS, EXTENSIONS, OR ADDITIONS TO THIS LIMITED WARRANTY.
6. PROPRIETARY RIGHTS: VTC reserves all proprietary rights in and to the Software, is protected by copyright and other intellectual property laws and by international treaties. VTC, Inc.
Trademark Notice: VTC, Virtual Training Company,
Inc., The VTC Logo, and VTC Online University, are trademarks of VTC,
Inc. All other company and product names may be trademarks of their
The information contained herein is subject to change without notice. Copyright © 1995 - 2005 VTC, Inc. All rights reserved.
7. TERMINATION: This Agreement shall automatically terminate if You fail to comply with the restrictions described herein. Your obligations to pay outstanding subscription fees shall survive any termination of this Agreement.
8. LIMITATION OF LIABILITY: UNDER NO CIRCUMSTANCES
AND UNDER NO LEGAL THEORY, TORT, CONTRACT, OR OTHERWISE, SHALL VTC
OR ITS SUPPLIERS OR RESELLERS BE LIABLE TO YOU OR ANY OTHER PERSON
FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES OF
ANY CHARACTER, INCLUDING WITHOUT LIMITATION, DAMAGES FOR LOSS OF GOODWILL,
WORK STOPPAGE, COMPUTER FAILURE OR MALFUNCTION, OR ANY AND ALL OTHER
COMMERCIAL DAMAGES OR LOSSES. IN NO EVENT WILL VTC BE LIABLE FOR ANY
DAMAGES IN EXCESS OF THE AMOUNT VTC RECEIVED FROM YOU FOR A LICENSE
TO THE SOFTWARE, EVEN IF VTC SHALL HAVE BEEN INFORMED OF THE POSSIBILITY
DAMAGES, OR FOR ANY CLAIM BY ANY OTHER PARTY. THIS LIMITATION OF LIABILITY SHALL NOT APPLY TO LIABILITY FOR DEATH OR PERSONAL INJURY RESULTING FROM VTC'S NEGLIGENCE TO THE EXTENT APPLICABLE LAW PROHIBITS SUCH LIMITATION. SOME JURISDICTIONS DO NOT ALLOW THE EXCLUSION OR LIMITATION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THIS EXCLUSION AND LIMITATION MAY NOT APPLY TO YOU.
9. Links To Other Materials: Linked sites found at the VTC site are not under the control of VTC, and we are not responsible for the content of any linked site or any link contained in a linked site. VTC may change links based solely on our discretion, and we reserve the right to terminate any link or linking program at any time. VTC does not, by linking to sites, endorse companies or products to which it links and reserves the right to note as such on its web pages. If you decide to access any of the third party sites linked to this site, you do this entirely at your own risk.
Forums, and Chat are not always screened by VTC, and we are not responsible for the content of any public or open forum content at the site. VTC may change these public forums based solely on our discretion, and we reserve the right to terminate any forum at any time. VTC does not, by allowing these forums, endorse companies or products which may be mentioned in these forums, and reserves the right to note as such on its web pages. If you decide to access any of the public forums in this site, or linked to this site, you do this entirely at your own risk.
9. GOVERNING LAW & DISPUTE RESOLUTION: This Agreement is governed by Virginia law. All disputes between You and VTC shall be finally resolved through arbitration in Winchester, Virginia. This site is controlled by VTC from its offices within the United States of America. VTC makes no representation that materials in the site are appropriate or available for use in other locations, and access to them from territories where their content is illegal is prohibited. Those who choose to access this site from other locations do so on their own initiative and are responsible for compliance with applicable local laws. You may not use or export the Materials in violation of U.S. export laws and regulations. Any claim relating to the Materials shall be governed by the internal substantive laws of the Commonwealth of Virginia, USA.
VTC may revise these Terms at any time by updating this posting. You should visit this page from time to time to review the then-current Terms because they are binding on you. Certain provisions of these Terms may be superseded by expressly designated legal notices or terms located on particular pages at this Site.
If you have any questions regarding this policy,
or your information specifically,
you may email us at:firstname.lastname@example.org.