Rss Unicode C Reference Documentation

Rss

Represents an RSS document or sub-part of a document such as a channel, image, or item. The RSS API allows one to download, create and modify RSS documents.

Create/Dispose

HCkRssW CkRssW_Create(void);

Creates an instance of the HCkRssW object and returns a handle (i.e. a "void *" pointer). The handle is passed in the 1st argument for the functions listed on this page.

void CkRssW_Dispose(HCkRssW handle);

Objects created by calling CkRssW_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function. Also, any handle returned by a Chilkat "C" function must also be freed by the application by calling the appropriate Dispose method, such as CkRssW_Dispose.

Callback Functions

Callback Functions are Introduced in Chilkat v9.5.0.56

void CkRssW_setAbortCheck(HCkHttp cHandle, BOOL (*fnAbortCheck)());

Provides the opportunity for a method call to be aborted. If TRUE is returned, the operation in progress is aborted. Return FALSE to allow the current method call to continue. This callback function is called periodically based on the value of the HeartbeatMs property. (If HeartbeatMs is 0, then no callbacks are made.) As an example, to make 5 AbortCheck callbacks per second, set the HeartbeatMs property equal to 200.

C Example using Callback Functions

void CkRssW_setPercentDone(HCkHttp cHandle, BOOL (*fnPercentDone)(int pctDone));

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 callback is only called 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 methods 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).

This callback counts as an AbortCheck callback, and takes the place of the AbortCheck event when it fires.

The return value indicates whether the method call should be aborted, or whether it should proceed. Return TRUE to abort, and FALSE to proceed.

void CkRssW_setProgressInfo(HCkHttp cHandle, void (*fnProgressInfo)(const wchar_t *name, const wchar_t *value));

This is a general callback that provides name/value information about what is happening at certain points during a method call. To see the information provided in ProgressInfo callbacks, if any, write code to handle this event and log the name/value pairs. Most are self-explanatory.

void CkRssW_setTaskCompleted(HCkHttp cHandle, void (*fnTaskCompleted)(HCkTask hTask));

Called in the background thread when an asynchronous task completes. (Note: When an async method is running, all callbacks are in the background thread.)

Properties

void CkRssW_getDebugLogFilePath(HCkRssW cHandle, HCkString retval);

void CkRssW_putDebugLogFilePath(HCkRssW cHandle, const wchar_t *newVal);

const wchar_t *CkRssW_debugLogFilePath(HCkRssW cHandle);

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.

void CkRssW_getLastErrorHtml(HCkRssW cHandle, HCkString retval);

const wchar_t *CkRssW_lastErrorHtml(HCkRssW cHandle);

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.

void CkRssW_getLastErrorText(HCkRssW cHandle, HCkString retval);

const wchar_t *CkRssW_lastErrorText(HCkRssW cHandle);

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.

void CkRssW_getLastErrorXml(HCkRssW cHandle, HCkString retval);

const wchar_t *CkRssW_lastErrorXml(HCkRssW cHandle);

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.

BOOL CkRssW_getLastMethodSuccess(HCkRssW cHandle);

void CkRssW_putLastMethodSuccess(HCkRssW cHandle, BOOL newVal);

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.

int CkRssW_getNumChannels(HCkRssW cHandle);

The number of channels in the RSS document.

int CkRssW_getNumItems(HCkRssW cHandle);

The number of items in the channel.

BOOL CkRssW_getVerboseLogging(HCkRssW cHandle);

void CkRssW_putVerboseLogging(HCkRssW cHandle, BOOL newVal);

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.

void CkRssW_getVersion(HCkRssW cHandle, HCkString retval);

const wchar_t *CkRssW_version(HCkRssW cHandle);

Version of the component/library, such as "9.4.1.42"

Methods

HCkRssW CkRssW_AddNewChannel(HCkRssW cHandle);

Adds a new channel to the RSS document. Returns the Rss object representing the Channel which can then be edited.

HCkRssW CkRssW_AddNewImage(HCkRssW cHandle);

Adds a new image to the RSS document. Returns the Rss object representing the image, which can then be edited.

HCkRssW CkRssW_AddNewItem(HCkRssW cHandle);

Adds a new Item to an Rss channel. Returns the Rss object representing the item which can then be edited.

BOOL CkRssW_DownloadRss(HCkRssW cHandle, const wchar_t *url);

Downloads an RSS document from the Internet and populates the Rss object with the contents.

Returns TRUE for success, FALSE for failure.

Example: Read RSS Feed

HCkTaskW CkRssW_DownloadRssAsync(HCkRssW cHandle, const wchar_t *url);

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

How to Run an Asynchronous Task

BOOL CkRssW_GetAttr(HCkRssW cHandle, const wchar_t *tag, const wchar_t *attrName, HCkString outStr);

const wchar_t *CkRssW_getAttr(HCkRssW cHandle, const wchar_t *tag, const wchar_t *attrName);

Returns the value of a sub-element attribute. For example, to get the value of the "isPermaLink" attribute of the "guid" sub-element, call item.GetAttr("guid","isPermaLink").

Returns TRUE for success, FALSE for failure.

HCkRssW CkRssW_GetChannel(HCkRssW cHandle, int index);

Returns the Nth channel of an RSS document. Usually there is only 1 channel per document, so the index argument should be set to 0.

int CkRssW_GetCount(HCkRssW cHandle, const wchar_t *tag);

Return the number of sub-elements with a specific tag.

BOOL CkRssW_GetDate(HCkRssW cHandle, const wchar_t *tag, SYSTEMTIME *outSysTime);

This method is deprecated. It will be removed in a future version.

Return the value of a sub-element in date/time format.

Returns TRUE for success, FALSE for failure.

BOOL CkRssW_GetDateStr(HCkRssW cHandle, const wchar_t *tag, HCkString outStr);

const wchar_t *CkRssW_getDateStr(HCkRssW cHandle, const wchar_t *tag);

The same as GetDate, except the date/time is returned in RFC822 string format.

Returns TRUE for success, FALSE for failure.

HCkRssW CkRssW_GetImage(HCkRssW cHandle);

Return the image associated with the channel.

int CkRssW_GetInt(HCkRssW cHandle, const wchar_t *tag);

Return the value of a numeric sub-element as an integer.

HCkRssW CkRssW_GetItem(HCkRssW cHandle, int index);

Return the Nth item of a channel as an RSS object.

BOOL CkRssW_GetString(HCkRssW cHandle, const wchar_t *tag, HCkString outStr);

const wchar_t *CkRssW_getString(HCkRssW cHandle, const wchar_t *tag);

Return the value of an sub-element as a string.

Returns TRUE for success, FALSE for failure.

BOOL CkRssW_LoadRssFile(HCkRssW cHandle, const wchar_t *filePath);

Load an RSS document from a file.

Returns TRUE for success, FALSE for failure.

BOOL CkRssW_LoadRssString(HCkRssW cHandle, const wchar_t *rssString);

Loads an RSS feed document from an in-memory string.

Returns TRUE for success, FALSE for failure.

BOOL CkRssW_MGetAttr(HCkRssW cHandle, const wchar_t *tag, int index, const wchar_t *attrName, HCkString outStr);

const wchar_t *CkRssW_mGetAttr(HCkRssW cHandle, const wchar_t *tag, int index, const wchar_t *attrName);

Get an attribute value for the Nth sub-element having a specific tag. As an example, an RSS item may have several "category" sub-elements. To get the value of the "domain" attribute for the 3rd category, call MGetAttr("category",2,"domain").

Returns TRUE for success, FALSE for failure.

BOOL CkRssW_MGetString(HCkRssW cHandle, const wchar_t *tag, int index, HCkString outStr);

const wchar_t *CkRssW_mGetString(HCkRssW cHandle, const wchar_t *tag, int index);

Get the value of the Nth occurance of a sub-element. Indexing begins at 0.

Returns TRUE for success, FALSE for failure.

BOOL CkRssW_MSetAttr(HCkRssW cHandle, const wchar_t *tag, int idx, const wchar_t *attrName, const wchar_t *value);

Set an attribute on the Nth occurance of a sub-element.

Returns TRUE for success, FALSE for failure.

BOOL CkRssW_MSetString(HCkRssW cHandle, const wchar_t *tag, int idx, const wchar_t *value);

Set the value of the Nth occurance of a sub-element. Indexing begins at 0.

Returns TRUE for success, FALSE for failure.

void CkRssW_NewRss(HCkRssW cHandle);

Clears the RSS document.

void CkRssW_Remove(HCkRssW cHandle, const wchar_t *tag);

Removes a sub-element from the RSS document.

BOOL CkRssW_SaveLastError(HCkRssW cHandle, const wchar_t *path);

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

Returns TRUE for success, FALSE for failure.

void CkRssW_SetAttr(HCkRssW cHandle, const wchar_t *tag, const wchar_t *attrName, const wchar_t *value);

Sets the value of a sub-element attribute.

void CkRssW_SetDate(HCkRssW cHandle, const wchar_t *tag, SYSTEMTIME *dateTime);

This method is deprecated. It will be removed in a future version.

Sets the value of a date/time sub-element.

void CkRssW_SetDateNow(HCkRssW cHandle, const wchar_t *tag);

Sets the value of a date/time sub-element to the current system date/time.

void CkRssW_SetDateStr(HCkRssW cHandle, const wchar_t *tag, const wchar_t *dateTimeStr);

The same as SetDate, except the date/time is passed as an RFC822 string.

void CkRssW_SetInt(HCkRssW cHandle, const wchar_t *tag, int value);

Sets the value of an integer sub-element.

void CkRssW_SetString(HCkRssW cHandle, const wchar_t *tag, const wchar_t *value);

Sets the value of a sub-element.

BOOL CkRssW_ToXmlString(HCkRssW cHandle, HCkString outStr);

const wchar_t *CkRssW_toXmlString(HCkRssW cHandle);

Returns the RSS document as an XML string.

Returns TRUE for success, FALSE for failure.