ServerSentEvent PowerBuilder Reference Documentation
ServerSentEvent
Current Version: 11.6.0
Chilkat.ServerSentEvent
Use
Inspect
Use
Read
Use
Check 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
LoadEvent to parse a complete multi-line
Server-Sent Event block.
Read event name
EventName to determine the event type supplied by
the server, if an event: field is present.
Read event data
Data to obtain the event payload, such as JSON text from
a streaming API or real-time service.
Track event IDs
LastEventId when the event includes an
id: field that identifies the event or stream position.
Handle retry hints
Retry to read the server-provided retry interval when a
retry: field is included.
Diagnostics
LastErrorText if event text cannot be parsed or if a
parsing result is unexpected.
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.
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
oleobject loo_ServerSentEvent
integer li_rc
loo_ServerSentEvent = create oleobject
li_rc = loo_ServerSentEvent.ConnectToNewObject("Chilkat.ServerSentEvent")
if li_rc < 0 then
destroy loo_ServerSentEvent
MessageBox("Error","Connecting to COM object failed")
return
end if
// ... use loo_ServerSentEvent ...
destroy loo_ServerSentEventPowerBuilder uses the Chilkat ActiveX through an oleobject: declare the variable, create it, connect it to the Chilkat class with ConnectToNewObject, and destroy it when finished. A negative return code from ConnectToNewObject means the ActiveX is not registered, or the registered ActiveX does not match the bitness (32-bit or 64-bit) of the PowerBuilder target.
Objects returned by methods (such as an HttpResponse or JsonObject) are also oleobject variables and must likewise be destroyed. A method that fails to return an object returns null; test with IsNull(). In the signatures on this page, the Chilkat class name identifies which object is expected or returned; the PowerBuilder variable type is always oleobject.
To bind to a specific major version of Chilkat, append the major version number to the ProgID, such as ConnectToNewObject("Chilkat.ServerSentEvent.11") for Chilkat v11.*.*.
Members typed blob exchange binary data as a Variant byte array. The PowerBuilder examples instead use the BinData-based alternatives (methods ending in Bd), which keep binary data inside Chilkat objects.
Properties
Data
The data for the server-side event. (If the data field was empty, then this will be empty.)
DebugLogFilePath
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.
EventName
The name of the server-side event. (If the event field was not present, then this will be empty.)
LastBinaryResult
This property is mainly used in SQL Server stored procedures to retrieve binary data from the last method call that returned binary data. It is only accessible if Chilkat.Global.KeepBinaryResult is set to 1. This feature allows for the retrieval of large varbinary results in an SQL Server environment, which has restrictions on returning large data via method calls, though temp tables can handle binary properties.
LastErrorHtml
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.
topLastErrorText
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.
LastErrorXml
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.
topLastEventId
The content of the id field, if present.
LastMethodSuccess
Indicates the success or failure of the most recent method call: 1 means success, 0 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.
LastStringResult
In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. It is accessible only when Chilkat.Global.KeepStringResult is set to TRUE. SQL Server has limitations on string lengths returned from methods and properties, but temp tables can be used to access large strings.
LastStringResultLen
The length, in characters, of the string contained in the LastStringResult property.
topRetry
The integer value of the retry field, if it exists; otherwise, 0.
VerboseLogging
If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
Methods
LoadEvent
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 1 for success, 0 for failure.