Atom VB.NET Reference Documentation

Atom

Current Version: 9.5.0.73

Represents an Atom document. The Atom API allows one to download, create and modify Atom documents.

Object Creation

Dim obj As New Chilkat.Atom()

Properties

AbortCurrent
AbortCurrent As Boolean (ReadOnly)
Introduced in version 9.5.0.58

When set to True, causes the currently running method to abort. Methods that always finish quickly (i.e.have no length file operations or network communications) are not affected. If no method is running, then this property is automatically reset to False when the next method is called. When the abort occurs, this property is reset to False. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)

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DebugLogFilePath
DebugLogFilePath As String

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

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LastErrorHtml
LastErrorHtml As String (ReadOnly)

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorText
LastErrorText As String (ReadOnly)

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorXml
LastErrorXml As String (ReadOnly)

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastMethodSuccess
LastMethodSuccess As Boolean
Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of True indicates success, a value of False indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = True and failure = False.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to True. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

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NumEntries
NumEntries As Integer (ReadOnly)

Number of entries in the Atom document.

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VerboseLogging
VerboseLogging As Boolean

If set to True, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is False. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
Version As String (ReadOnly)

Version of the component/library, such as "9.5.0.63"

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Methods

AddElement
Function AddElement(ByVal tag As String, ByVal value As String) As Integer

Adds a new element to the Atom document. The tag is a string such as "title", "subtitle", "summary", etc. Returns the index of the element added, or -1 for failure.

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AddElementDate
Function AddElementDate(ByVal tag As String, ByVal dateTime As Date) As Integer
This method is deprecated. It will be removed in a future version.

Adds a new date-formatted element to the Atom document. The tag is a string such as "created", "modified", "issued", etc. Returns the index of the element added, or -1 for failure.

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AddElementDateStr
Function AddElementDateStr(ByVal tag As String, ByVal dateTimeStr As String) As Integer

Adds a new date-formatted element to the Atom document. The tag is a string such as "created", "modified", "issued", etc. The dateTimeStr should be an RFC822 formatted date/time string such as "Tue, 25 Sep 2012 12:25:32 -0500". Returns the index of the element added, or -1 for failure.

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AddElementDt
Function AddElementDt(ByVal tag As String, ByVal dateTime As CkDateTime) As Integer

Adds a new date-formatted element to the Atom document. The tag is a string such as "created", "modified", "issued", etc. Returns the index of the element added, or -1 for failure.

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AddElementHtml
Function AddElementHtml(ByVal tag As String, ByVal htmlStr As String) As Integer

Adds a new HTML formatted element to the Atom document. Returns the index of the element added, or -1 for failure.

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AddElementXHtml
Function AddElementXHtml(ByVal tag As String, ByVal xmlStr As String) As Integer

Adds a new XHTML formatted element to the Atom document. Returns the index of the element added, or -1 for failure.

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AddElementXml
Function AddElementXml(ByVal tag As String, ByVal xmlStr As String) As Integer

Adds a new XML formatted element to the Atom document. Returns the index of the element added, or -1 for failure.

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AddEntry
Sub AddEntry(ByVal xmlStr As String)

Adds an "entry" Atom XML document to the caller's Atom document.

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AddLink
Sub AddLink(ByVal rel As String, ByVal href As String, ByVal title As String, ByVal typ As String)

Adds a link to the Atom document.

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AddPerson
Sub AddPerson(ByVal tag As String, ByVal name As String, ByVal uri As String, ByVal email As String)

Adds a person to the Atom document. The tag should be a string such as "author", "contributor", etc. If a piece of information is not known, an empty string or NULL value may be passed.

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DeleteElement
Sub DeleteElement(ByVal tag As String, ByVal index As Integer)

Removes the Nth occurrence of a given element from the Atom document. Indexing begins at 0. For example, to remove the 2nd category, set tag = "category" and index = 1.

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DeleteElementAttr
Sub DeleteElementAttr(ByVal tag As String, ByVal index As Integer, ByVal attrName As String)

Remove an attribute from an element.The index should be 0 unless there are multiple elements having the same tag, in which case it selects the Nth occurrence based on the index ( 0 = first occurrence ).

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DeletePerson
Sub DeletePerson(ByVal tag As String, ByVal index As Integer)

Deletes a person from the Atom document. The tag is a string such as "author". The index should be 0 unless there are multiple elements having the same tag, in which case it selects the Nth occurrence based on the index. For example, DeletePerson("author",2) deletes the 3rd author.

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DownloadAtom
Function DownloadAtom(ByVal url As String) As Boolean

Download an Atom feed from the Internet and load it into the Atom object.

Returns True for success, False for failure.

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DownloadAtomAsync (1)
Function DownloadAtomAsync(ByVal url As String) As Task

Creates an asynchronous task to call the DownloadAtom method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns Nothing on failure

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GetElement
Function GetElement(ByVal tag As String, ByVal index As Integer) As String

Returns the content of the Nth element having a specified tag.

Returns Nothing on failure

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GetElementAttr
Function GetElementAttr(ByVal tag As String, ByVal index As Integer, ByVal attrName As String) As String

Returns the value of an element's attribute. The element is selected by the tag name and the index (the Nth element having a specific tag) and the attribute is selected by name.

Returns Nothing on failure

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GetElementCount
Function GetElementCount(ByVal tag As String) As Integer

The number of elements having a specific tag.

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GetElementDate
Function GetElementDate(ByVal tag As String, ByVal index As Integer) As Date
This method is deprecated. It will be removed in a future version.

Returns an element's value as a date/time.

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GetElementDateStr
Function GetElementDateStr(ByVal tag As String, ByVal index As Integer) As String

Returns an element's value as a date/time in an RFC822 formatted string, such as such as "Tue, 25 Sep 2012 12:25:32 -0500".

Returns Nothing on failure

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GetElementDt
Function GetElementDt(ByVal tag As String, ByVal index As Integer) As CkDateTime

Returns an element's value as a date/time object.

Returns Nothing on failure

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GetEntry
Function GetEntry(ByVal index As Integer) As Atom

Returns the Nth entry as an Atom object. (Indexing begins at 0)

Returns Nothing on failure

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GetLinkHref
Function GetLinkHref(ByVal relName As String) As String

Returns the href attribute of the link having a specified "rel" attribute (such as "service.feed", "alternate", etc.).

Returns Nothing on failure

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GetPersonInfo
Function GetPersonInfo(ByVal tag As String, ByVal index As Integer, ByVal tag2 As String) As String

Returns a piece of information about a person. To get the 2nd author's name, call GetPersonInfo("author",1,"name").

Returns Nothing on failure

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GetTopAttr
Function GetTopAttr(ByVal attrName As String) As String

Returns the value of an attribute on the top-level XML node. The tag of a top-level Atom XML node is typically "feed" or "entry", and it might have attributes such as "xmlns" and "xml:lang".

Returns Nothing on failure

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HasElement
Function HasElement(ByVal tag As String) As Boolean

True (1) if the element exists in the Atom document. Otherwise 0.

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LoadXml
Function LoadXml(ByVal xmlStr As String) As Boolean

Loads the Atom document from an XML string.

Returns True for success, False for failure.

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NewEntry
Sub NewEntry()

Initializes the Atom document to be a new "entry".

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NewFeed
Sub NewFeed()

Initializes the Atom document to be a new "feed".

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SaveLastError
Function SaveLastError(ByVal path As String) As Boolean

Saves the last-error information (the contents of LastErrorXml) to an XML formatted file.

Returns True for success, False for failure.

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SetElementAttr
Sub SetElementAttr(ByVal tag As String, ByVal index As Integer, ByVal attrName As String, ByVal attrValue As String)

Adds or replaces an attribute on an element.

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SetTopAttr
Sub SetTopAttr(ByVal attrName As String, ByVal value As String)

Adds or replaces an attribute on the top-level XML node of the Atom document.

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ToXmlString
Function ToXmlString() As String

Serializes the Atom document to an XML string.

Returns Nothing on failure

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UpdateElement
Sub UpdateElement(ByVal tag As String, ByVal index As Integer, ByVal value As String)

Replaces the content of an element.

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UpdateElementDate
Sub UpdateElementDate(ByVal tag As String, ByVal index As Integer, ByVal dateTime As Date)
This method is deprecated. It will be removed in a future version.

Replaces the content of a date-formatted element.

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UpdateElementDateStr
Sub UpdateElementDateStr(ByVal tag As String, ByVal index As Integer, ByVal dateTimeStr As String)

Replaces the content of a date-formatted element. The index should be an RFC822 formatted date/time string.

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UpdateElementDt
Sub UpdateElementDt(ByVal tag As String, ByVal index As Integer, ByVal dateTime As CkDateTime)

Replaces the content of a date-formatted element.

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UpdateElementHtml
Sub UpdateElementHtml(ByVal tag As String, ByVal index As Integer, ByVal htmlStr As String)

Replaces the content of an HTML element.

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UpdateElementXHtml
Sub UpdateElementXHtml(ByVal tag As String, ByVal index As Integer, ByVal xmlStr As String)

Replaces the content of an XHTML element.

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UpdateElementXml
Sub UpdateElementXml(ByVal tag As String, ByVal index As Integer, ByVal xmlStr As String)

Replaces the content of an XML element.

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UpdatePerson
Sub UpdatePerson(ByVal tag As String, ByVal index As Integer, ByVal name As String, ByVal uri As String, ByVal email As String)

Replaces the content of a person. To update the 3rd author, call UpdatePerson("author",2,"new name","new URL","new email"). If a piece of information is not known, pass an empty string or a NULL.

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Events

AbortCheck
Event OnAbortCheck

Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200.

Args are passed using Chilkat.AbortCheckEventArgs

Event callback implementation:

Dim WithEvents atom As Chilkat.Atom

Private Sub atom_OnAbortCheck(sender As Object, args As Chilkat.AbortCheckEventArgs) Handles atom.OnAbortCheck

    ...

End Sub
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PercentDone
Event OnPercentDone

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.

The abort output argument provides a means for aborting the operation. Setting it to True will cause the method to abort and return a failed status (or whatever return value indicates failure).

Args are passed using Chilkat.PercentDoneEventArgs

Event callback implementation:

Dim WithEvents atom As Chilkat.Atom

Private Sub atom_OnPercentDone(sender As Object, args As Chilkat.PercentDoneEventArgs) Handles atom.OnPercentDone

    ...

End Sub
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ProgressInfo
Event OnProgressInfo

A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.

Args are passed using Chilkat.ProgressInfoEventArgs

Event callback implementation:

Dim WithEvents atom As Chilkat.Atom

Private Sub atom_OnProgressInfo(sender As Object, args As Chilkat.ProgressInfoEventArgs) Handles atom.OnProgressInfo

    ...

End Sub
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TaskCompleted
Event OnTaskCompleted

Called in the background thread when an asynchronous task completes.

More Information and Examples

Args are passed using Chilkat.TaskCompletedEventArgs

Event callback implementation:

Dim WithEvents atom As Chilkat.Atom

Private Sub atom_OnTaskCompleted(sender As Object, args As Chilkat.TaskCompletedEventArgs) Handles atom.OnTaskCompleted

    ...

End Sub
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