c# create barcode image Exceptions and State Management in .NET

Use Quick Response Code in .NET Exceptions and State Management

With one major exception, all Windows NT-based operating systems support the same basic security constructs, although the richness of the semantics has changed, notably starting with Windows 2000. The major exception is that Active Directory, available in server versions starting with Windows 2000, supports a very different feature set than the client versions and prior versions of Windows NT.

Objective 1.4: Troubleshoot DHCP 13-39

The ValidationEventHandler Event The XmlValidatingReader class contains a public event named ValidationEventHandler, which is defined as follows: public event ValidationEventHandler ValidationEventHandler; This event is used to pass information about any DTD, XDR, or XSD schema validation errors that have been detected. The handler for the event (also named ValidationEventHandler) has the following signature: public delegate void ValidationEventHandler( object sender, ValidationEventArgs e ); The ValidationEventArgs class is described by the following pseudocode: public class ValidationEventArgs : EventArgs { public XmlSchemaException Exception; public string Message; public XmlSeverityType Severity; } The Message field returns a description of the error. The Exception field, on the other hand, returns an ad hoc exception object (XmlSchemaException) with details about what happened. The schema exception class contains information about the line that originated the error, the source file, and, if available, the schema object that generated the error. The schema object (the SourceSchemaObject property) is available for XSD validation only. The Severity field represents the severity of the validation event. The XmlSeverityType defines two levels of severity Error and Warning. Error indicates that a serious validation error occurred when processing the document against a DTD, an XDR, or an XSD schema. If the current instance of the XmlValidatingReader class has no validation event handler set, an exception is thrown. Typically, a warning is raised when there is no DTD, XDR, or XSD schema to validate a particular element or attribute against. Unlike errors, warnings do not throw an exception if no validation event handler has been set. The XmlValidatingReader in Action Let's see how to validate an XML document. As mentioned, the XmlValidatingReader class is still a reader class, so it proceeds with an incremental validation as nodes are actually read. The caller is notified of any schema exception found for a node by raising the ValidationEventHandler event. This section describes in detail how to validate an XML document, including initializing an XML reader, handling validation errors, and setting and detecting the validation types. Initialization of the Reader To validate the contents of an XML file, you must first create an XML text reader to work on the file and then use this reader to initialize an instance of a validating reader. A validating reader can be initialized using a living instance of an XmlReader class typically, an XmlTextReader object or using an XML fragment taken from a stream or a memory string, as shown here: 65

A. Creating and populating a table in Design view B. Displaying data from a collection in a grid format c. Creating a table of static images stored in a folder on your site D. Providing layout for dynamically generated controls

SET NOCOUNT ON; USE testdb; GO SET LOCK_TIMEOUT 30000; DECLARE @j AS INT; BEGIN TRAN UPDATE dbo.T2 SET col1 += 1; UPDATE dbo.T2 SET col1 += 1; UPDATE dbo.T2 SET col1 += 1; WAITFOR DELAY '00:00:05'; WHILE 1 = 1 BEGIN SET @j = (SELECT SUM(col1) FROM dbo.T1); WAITFOR DELAY '00:00:01'; END

Used to delay the call of the subsequent method in a method chain. You pass the number of milliseconds you want to delay to the method. Allow you to fade an element into view (as long as it is set to have no display in the markup), out of view, or to another element, as in .fadeTo(). Turns off all jQuery effects for the page. Allow you to show or hide one or more selected elements. This method shows or hides an element by fading it into or out of view, providing a rudimentary form of animation. Allow you to animate the showing of an item, fading it into view in a sliding motion. Note that .slideToggle() allows you to fade an element into and out of view (and toggle the current shown or hidden state).

When ToString is called, it attempts to translate the numeric value into its symbolic equivalent. The numeric value is 0x0003, which has no symbolic equivalent. However, the ToString method detects the existence of the [Flags] attribute on the Actions type, and ToString now treats the numeric value not as a single value but as a set of bit flags. Because the 0x0001 and 0x0002 bits are set, ToString generates the following string: "Read, Write". If you remove the [Flags] attribute from the Actions type, ToString would produce the following string: "3". I discussed the ToString method in the previous section, and I showed that it offered three ways to format the output: "G" (general), "D" (decimal), and "X" (hex). When you re formatting an instance of an enumerated type by using the general format, the type is first checked to see whether the [Flags] attribute is applied to it. If this attribute is not applied, a symbol matching the numeric value is looked up and returned. If the [Flags] attribute is applied, a symbol matching each 1 bit is looked up and concatenated to a string; each symbol is separated by a comma. If you prefer, you could define the Actions type without the [Flags] attribute and still get the correct string by using the "F" format:

int conferenceId = Integer.parseInt(request.getParameter("id")); ConferenceSummary conference = conferenceService .getConferenceSummary(conferenceId); return new ModelAndView("conferenceDetail", "conference", conference); } private ConferenceService conferenceService; public void setConferenceService(ConferenceService conferenceService) { this.conferenceService = conferenceService; } } Finally, the view conferenceDetail.jsp shows the dates for which the conference is accepting abstracts for presentation, as well as list of the tracks available for the conference. Again, as previously done, JSTL tags are used to format the dates and iterate over retrieved collections, as shown in Listing 6-38. Listing 6-38. JSP View for Conference Detail View (conferenceDetail.jsp) <%@ page contentType="text/html; charset=UTF-8" %> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %> <table width="100%"> <tr> <td> <h4>Abstract Submissions</h4> </td> </tr> <tr> <td> Abstracts accepted from <fmt:formatDate value="${conference.abstractSubmissionStartDate}" type="date" dateStyle="full" /> until <fmt:formatDate value="${conference.abstractSubmissionEndDate}" type="date" dateStyle="full" />

Important In general, a client machine should be pointing at one of your internal DNS servers rather than using your ISP DNS server settings.