Mht VB.NET Reference Documentation
Mht
Current Version: 10.0.0
Chilkat MHT can generate email objects from HTML files and URLs, and convert HTML to MHT or EML files.
Object Creation
Dim obj As New Chilkat.Mht()
Properties
AbortCurrent
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.)
topBaseUrl
When processing an HTML file or string (not a website URL), this defines the base URL to be used when converting relative HREFs to absolute HREFs.
topConnectTimeout
The amount of time in seconds to wait before timing out when connecting to an HTTP server. The default value is 10 seconds.
topDebugHtmlAfter
A filename to save the result HTML when converting a URL, file, or HTML string. If problems are experienced, the before/after HTML can be analyzed to help determine the cause.
topDebugHtmlBefore
A filename to save the input HTML when converting a URL, file, or HTML string. If problems are experienced, the before/after HTML can be analyzed to help determine the cause.
topDebugLogFilePath
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:
- a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
- the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
- there is an internal problem (bug) in the Chilkat code that causes the hang.
DebugTagCleaning
When True causes the Mht class to be much more verbose in its logging. The default is False.
topEmbedImages
Controls whether images are embedded in the MHT/EML, or whether the IMG SRC attributes are left as external URL references. If false, the IMG SRC tags are converted to absolute URLs (if necessary) and the images are not embedded within the MHT/EML.
topEmbedLocalOnly
If True, only images found on the local filesystem (i.e. links to files) will be embedded within the MHT.
topFetchFromCache
If True, page parts such as images, style sheets, etc. will be fetched from the disk cache if possible. The disk cache root may be defined by calling AddCacheRoot. The default value is False.
topHeartbeatMs
The time interval, in milliseconds, between AbortCheck event callbacks. The heartbeat/AbortCheck provides a means for an application to abort any MHT method before completion.
The default value is 0, which means that no AbortCheck events will be fired.
topIgnoreMustRevalidate
Some HTTP responses contain a "Cache-Control: must-revalidate" header. If this is present, the server is requesting that the client always issue a revalidate HTTP request instead of serving the page directly from cache. If IgnoreMustRevalidate is set to True, then Chilkat MHT will serve the page directly from cache without revalidating until the page is no longer fresh. (assuming that FetchFromCache is set to True)
The default value of this property is False.
topIgnoreNoCache
Some HTTP responses contain headers of various types that indicate that the page should not be cached. Chilkat MHT will adhere to this unless this property is set to True.
The default value of this property is False.
topLastErrorHtml
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.
topLastErrorText
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.
LastErrorXml
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.
topLastMethodSuccess
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.
topNoScripts
Only applies when creating MHT files. Scripts are always removed when creating EML or emails from HTML. If set to True, then all scripts are removed, if set to False (the default) then scripts are not removed.
topNtlmAuth
Setting this property to True causes the MHT component to use NTLM authentication (also known as IWA -- or Integrated Windows Authentication) when authentication with an HTTP server.
The default value of this property is False.
topNumCacheLevels
The number of directory levels to be used under each cache root. The default is 0, meaning that each cached item is stored in a cache root directory. A value of 1 causes each cached page to be stored in one of 255 subdirectories named "0","1", "2", ..."255" under a cache root. A value of 2 causes two levels of subdirectories ("0..255/0..255") under each cache root. The MHT control automatically creates subdirectories as needed. The reason for mutliple levels is to alleviate problems that may arise when huge numbers of files are stored in a single directory. For example, Windows Explorer does not behave well when trying to display the contents of directories with thousands of files.
topNumCacheRoots
The number of cache roots to be used for the disk cache. This allows the disk cache spread out over multiple disk drives. Each cache root is a string indicating the drive letter and directory path. For example, "E:\Cache". To create a cache with four roots, call AddCacheRoot once for each directory root.
topPreferIpv6
If True, then use IPv6 over IPv4 when both are supported for a particular domain. The default value of this property is False, which will choose IPv4 over IPv6.
topPreferMHTScripts
This property provides a means for the noscript option to be selected when possible. If PreferMHTScripts = False, then scripts with noscript alternatives are removed and the noscript content is kept. If True (the default), then scripts are preserved and the noscript options are discarded.
topProxy
(Optional) A proxy host:port if a proxy is necessary to access the Internet. The proxy string should be formatted as "hostname:port", such as "www.chilkatsoft.com:100".
topProxyLogin
If an HTTP proxy is used and it requires authentication, this property specifies the HTTP proxy login.
topProxyPassword
If an HTTP proxy is used and it requires authentication, this property specifies the HTTP proxy password.
topReadTimeout
The amount of time in seconds to wait before timing out when reading from an HTTP server. The ReadTimeout is the amount of time that needs to elapse while no additional data is forthcoming. During a long data transfer, if the data stream halts for more than this amount, it will timeout. Otherwise, there is no limit on the length of time for the entire data transfer.
The default value is 20 seconds.
topRequireSslCertVerify
If True, then the HTTP client will verify the server's SSL certificate. The certificate is expired, or if the cert's signature is invalid, the connection is not allowed. The default value of this property is False.
topSocksHostname
The SOCKS4/SOCKS5 hostname or IPv4 address (in dotted decimal notation). This property is only used if the SocksVersion property is set to 4 or 5).
topSocksPassword
The SOCKS5 password (if required). The SOCKS4 protocol does not include the use of a password, so this does not apply to SOCKS4.
topSocksPort
The SOCKS4/SOCKS5 proxy port. The default value is 1080. This property only applies if a SOCKS proxy is used (if the SocksVersion property is set to 4 or 5).
topSocksUsername
The SOCKS4/SOCKS5 proxy username. This property is only used if the SocksVersion property is set to 4 or 5).
topSocksVersion
SocksVersion May be set to one of the following integer values:
0 - No SOCKS proxy is used. This is the default.
4 - Connect via a SOCKS4 proxy.
5 - Connect via a SOCKS5 proxy.
UnpackDirect
If True, then the UnpackMHT and UnpackMHTString methods will unpack the MHT directly with no transformations. Normally, the related parts are unpacked to a "parts" sub-directory, and the unpacked HTML is edited to update references to point to the unpacked image and script files. When unpacking direct, the HTML is not edited, and the related parts are unpacked to sub-directories rooted in the directory where HTML file is created (i.e. the unpack directory). When unpacking direct, the "partsSubDir" argument of the UnpackMHT* methods is unused.
Note: It is only possible to directly unpack MHT files where the Content-Location headers DO NOT contain URLs. The MHT must be such that the Content-Location headers of the related items contain relative paths.
Note: The default value of this property is False.
topUnpackUseRelPaths
Controls whether absolute or relative paths are used when referencing images in the unpacked HTML. The default value is True indicating that relative paths will be used. To use absolute paths, set this property value equal to False.
topUpdateCache
Controls whether the cache is automatically updated with the responses from HTTP GET requests. If True, the disk cache is updated, if False (the default), the cache is not updated.
topUseCids
Controls whether CID URLs are used for embedded references when generating MHT or EML documents. If UseCids is False, then URLs are left unchanged and the embedded items will contain "content-location" headers that match the URLs in the HTML. If True, CIDs are generated and the URLs within the HTML are replaced with "CID:" links.
The default value of this property is True.
topUseFilename
If True, a "filename" attribute is added to each Content-Disposition MIME header field for each embedded item (image, style sheet, etc.). If False, then no filename attribute is added.
The default value of this property is True.
topUseIEProxy
If True, the proxy host/port used by Internet Explorer will also be used by Chilkat MHT.
topUseInline
If True, an "inline" attribute is added to each Content-Disposition MIME header field for each embedded item (image, style sheet, etc.). If False, then no inline attribute is added.
The default value of this property is True.
topVerboseLogging
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.
topVersion
WebSiteLogin
(Optional) Specifies the login if a a Web page is accessed that requires a login
topWebSiteLoginDomain
The optional domain name to be used with NTLM authentication.
topWebSitePassword
Optional) Specifies the password if a a Web page is accessed that requires a login and password
topMethods
AddCacheRoot
If disk caching is used, this must be called once for each cache root. For example, if the cache is spread across D:\cacheRoot, E:\cacheRoot, and F:\cacheRoot, an application would setup the cache object by calling AddRoot three times -- once with "D:\cacheRoot", once with "E:\cacheRoot", and once with "F:\cacheRoot".
AddCustomHeader
Adds a custom HTTP header to all HTTP requests sent by the MHT component. To add multiple header fields, call this method once for each custom header.
topAddExternalStyleSheet
(This method rarely needs to be called.) Includes an additional style sheet that would not normally be included with the HTML. This method is provided for cases when style sheet names are constructed and dynamically included in Javascript such that MHT .NET cannot know beforehand what stylesheet to embed. MHT .NET by default downloads and embeds all stylesheets externally referenced by the HTML
topClearCustomHeaders
Removes all custom headers that may have accumulated from previous calls to AddCustomHeader.
topExcludeImagesMatching
(This method rarely needs to be called.) Tells Chilkat MHT .NET to not embed any images whose URL matches a pattern. Sometimes images can be referenced within style sheets and not actually used when rendering the page. In cases like those, the image will appear as an attachment in the HTML email. This feature allows you to explicitly remove those images from the email so no attachments appear.
topGetAndSaveEML
Creates an EML file from a web page or HTML file. All external images and style sheets are downloaded and embedded in the EML file.
Returns True for success, False for failure.
topGetAndSaveEMLAsync (1)
Creates an asynchronous task to call the GetAndSaveEML 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
topGetAndSaveMHT
Creates an MHT file from a web page or local HTML file. All external images, scripts, and style sheets are downloaded and embedded in the MHT file.
Returns True for success, False for failure.
GetAndSaveMHTAsync (1)
Creates an asynchronous task to call the GetAndSaveMHT 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
topGetAndZipEML
Creates an EML file from a web page or HTML file, compresses, and appends to a new or existing Zip file. All external images and style sheets are downloaded and embedded in the EML.
Returns True for success, False for failure.
topGetAndZipEMLAsync (1)
Creates an asynchronous task to call the GetAndZipEML 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
topGetAndZipMHT
Creates an MHT file from a web page or HTML file, compresses, and appends to a new or existing Zip file. All external images and style sheets are downloaded and embedded in the MHT.
Returns True for success, False for failure.
topGetAndZipMHTAsync (1)
Creates an asynchronous task to call the GetAndZipMHT 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
topGetCacheRoot
Returns the Nth cache root (indexing begins at 0). Cache roots are set by calling AddCacheRoot one or more times.
Returns Nothing on failure
topGetEML
Creates EML from a web page or HTML file, and returns the EML (MIME) message data as a string.
Returns Nothing on failure
topGetEMLAsync (1)
Creates an asynchronous task to call the GetEML 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
topGetMHT
Creates MHT from a web page or local HTML file, and returns the MHT (MIME) message data as a string
Returns Nothing on failure
topGetMHTAsync (1)
Creates an asynchronous task to call the GetMHT 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
topHtmlToEML
Creates an in-memory EML string from an in-memory HTML string. All external images and style sheets are downloaded and embedded in the EML string that is returned.
Returns Nothing on failure
topHtmlToEMLAsync (1)
Creates an asynchronous task to call the HtmlToEML 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
topHtmlToEMLFile
Creates an EML file from an in-memory HTML string. All external images and style sheets are downloaded and embedded in the EML file.
Returns True for success, False for failure.
topHtmlToEMLFileAsync (1)
Creates an asynchronous task to call the HtmlToEMLFile 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
topHtmlToMHT
Creates an in-memory MHT web archive from an in-memory HTML string. All external images and style sheets are downloaded and embedded in the MHT string.
Returns Nothing on failure
topHtmlToMHTAsync (1)
Creates an asynchronous task to call the HtmlToMHT 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
topHtmlToMHTFile
Creates an MHT file from an in-memory HTML string. All external images and style sheets are downloaded and embedded in the MHT file.
Returns True for success, False for failure.
topHtmlToMHTFileAsync (1)
Creates an asynchronous task to call the HtmlToMHTFile 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
topLoadTaskCaller
RemoveCustomHeader
Removes a custom header by header field name.
topRestoreDefaults
Restores the default property settings.
topUnpackMHT
Unpacks the contents of a MHT file. The destination directory is specified by unpackDir. The name of the HTML file created is specified by htmlFilename, and supporting files (images, javascripts, etc.) are created in partsSubDir, which is automatically created if it does not already exist.
Returns True for success, False for failure.
UnpackMHTString
Same as UnpackMHT, except the MHT is passed in as an in-memory string.
Returns True for success, False for failure.
Events
AbortCheck
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 mht As Chilkat.Mht Private Sub mht_OnAbortCheck(sender As Object, args As Chilkat.AbortCheckEventArgs) Handles mht.OnAbortCheck ... End Sub
PercentDone
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 mht As Chilkat.Mht Private Sub mht_OnPercentDone(sender As Object, args As Chilkat.PercentDoneEventArgs) Handles mht.OnPercentDone ... End Sub
ProgressInfo
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 mht As Chilkat.Mht Private Sub mht_OnProgressInfo(sender As Object, args As Chilkat.ProgressInfoEventArgs) Handles mht.OnProgressInfo ... End Sub
TaskCompleted
Called in the background thread when an asynchronous task completes.
Args are passed using Chilkat.TaskCompletedEventArgs
Event callback implementation:
Dim WithEvents mht As Chilkat.Mht Private Sub mht_OnTaskCompleted(sender As Object, args As Chilkat.TaskCompletedEventArgs) Handles mht.OnTaskCompleted ... End Sub