ServerSentEvent C++ Reference Documentation

CkServerSentEvent

Current Version: 11.5.0

Chilkat.ServerSentEvent

Parse server-sent event text into event name, data, ID, and retry fields.

Chilkat.ServerSentEvent is a small helper class for parsing Server-Sent Events formatted text. Given a multi-line event block, it extracts the event name, data payload, id value, and retry interval into simple read-only properties. It is useful when an application receives event-stream text and needs to work with the structured event fields instead of manually parsing the raw lines.

Load event text

Use LoadEvent to parse a complete multi-line Server-Sent Event block.

Read event name

Inspect EventName to determine the event type supplied by the server, if an event: field is present.

Read event data

Use Data to obtain the event payload, such as JSON text from a streaming API or real-time service.

Track event IDs

Read LastEventId when the event includes an id: field that identifies the event or stream position.

Handle retry hints

Use Retry to read the server-provided retry interval when a retry: field is included.

Diagnostics

Check LastErrorText if event text cannot be parsed or if a parsing result is unexpected.

Relationship to Chilkat.WebSocket: ServerSentEvent does not manage a WebSocket connection or parse WebSocket frames. Instead, it can be used after Chilkat.WebSocket receives a text message whose payload is formatted as a Server-Sent Event. Read the WebSocket text frame, pass the event text to LoadEvent, then use EventName, Data, LastEventId, and Retry to process the event.
Common pattern: Receive or otherwise obtain a complete Server-Sent Event text block, call LoadEvent, then inspect EventName to route the event and Data to process the payload. Use LastEventId and Retry when the stream provides reconnection or event-position information.

Object Creation

// Local variable on the stack
CkServerSentEvent obj;

// Dynamically allocate/delete
CkServerSentEvent *pObj = new CkServerSentEvent();
// ...
delete pObj;

Properties

Data
void get_Data(CkString &str);
const char *data(void);
Introduced in version 9.5.0.58

The data for the server-side event. (If the data field was empty, then this will be empty.)

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DebugLogFilePath
void get_DebugLogFilePath(CkString &str);
const char *debugLogFilePath(void);
void put_DebugLogFilePath(const char *newVal);

If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.

Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.

Possible causes of hangs include:

  • A timeout property set to 0, indicating an infinite timeout.
  • A hang occurring within an event callback in the application code.
  • An internal bug in the Chilkat code causing the hang.

More Information and Examples
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EventName
void get_EventName(CkString &str);
const char *eventName(void);
Introduced in version 9.5.0.58

The name of the server-side event. (If the event field was not present, then this will be empty.)

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LastErrorHtml
void get_LastErrorHtml(CkString &str);
const char *lastErrorHtml(void);

Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorText
void get_LastErrorText(CkString &str);
const char *lastErrorText(void);

Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastErrorXml
void get_LastErrorXml(CkString &str);
const char *lastErrorXml(void);

Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.

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LastEventId
void get_LastEventId(CkString &str);
const char *lastEventId(void);
Introduced in version 9.5.0.58

The content of the id field, if present.

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LastMethodSuccess
bool get_LastMethodSuccess(void);
void put_LastMethodSuccess(bool newVal);

Indicates the success or failure of the most recent method call: true means success, false means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.

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Retry
int get_Retry(void);
Introduced in version 9.5.0.58

The integer value of the retry field, if it exists; otherwise, 0.

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Utf8
bool get_Utf8(void);
void put_Utf8(bool newVal);

When set to true, all const char * arguments and return values are interpreted as UTF-8 strings. When set to false, they are interpreted as ANSI strings.

In Chilkat v11.0.0 and later, the default value is true. Before v11.0.0, it was false.

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VerboseLogging
bool get_VerboseLogging(void);
void put_VerboseLogging(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.

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Version
void get_Version(CkString &str);
const char *version(void);

Version of the component/library, such as "10.1.0"

More Information and Examples
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Methods

LoadEvent
bool LoadEvent(const char *eventText);
Introduced in version 9.5.0.58

Loads the multi-line event text into this object. For example, the eventText for a Firebase event might look like this:

event: put
data: {"path": "/c", "data": {"foo": true, "bar": false}}

Returns true for success, false for failure.

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