ServerSentEvent Lua Reference Documentation
chilkat.ServerSentEvent
Current Version: 11.7.0
Markdown version of this page for AI tools (v 11.7.0) · all AI docs
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
local chilkat = require("chilkat")
local server_sent_event = chilkat.ServerSentEvent.new()Creates the object (chilkat.ServerSentEvent() does the same). Lua's garbage collector frees it when it is no longer referenced; server_sent_event:dispose() frees it at once, and in Lua 5.4 and later local server_sent_event <close> = chilkat.ServerSentEvent.new() frees it when the block ends. Calling a method of a disposed object raises an error.
Errors
A method that fails returns nil followed by the error text, as io.open does: local body, err = server_sent_event:method(...), where err is the object's last_error_text. Wrap the call in assert() to raise an error with that text instead. Methods that answer a question return true or false, numbers are returned as they are (check last_method_success where the description says a value means failure), and property reads and writes never fail for Chilkat reasons.
Misuse raises a Lua error: a wrong argument type or a missing argument (bad argument #1 to ...), an unknown property name, a write to a read-only property, an out-of-range integer, or an object of the wrong class.
Names are Chilkat's in snake_case: QuickGetStr is quick_get_str, LastErrorText is last_error_text. Properties are fields (server_sent_event.verbose_logging = true) and methods use the colon (server_sent_event:method(...)). Strings are UTF-8; binary data is a Lua string of bytes. Indexes are 0-based, as in every Chilkat API. Unlocking: call chilkat.unlock_bundle("...") once at startup.
Properties
Data
local strVal = server_sent_event.data
The data for the server-side event. (If the data field was empty, then this will be empty.)
DebugLogFilePath
local strVal = server_sent_event.debug_log_file_path
server_sent_event.debug_log_file_path = strVal
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
local strVal = server_sent_event.event_name
The name of the server-side event. (If the event field was not present, then this will be empty.)
LastErrorHtml
local strVal = server_sent_event.last_error_html
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
local strVal = server_sent_event.last_error_text
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
local strVal = server_sent_event.last_error_xml
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
local strVal = server_sent_event.last_event_id
The content of the id field, if present.
LastMethodSuccess
local boolVal = server_sent_event.last_method_success
server_sent_event.last_method_success = boolVal
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.
Retry
local intVal = server_sent_event.retry
The integer value of the retry field, if it exists; otherwise, 0.
VerboseLogging
local boolVal = server_sent_event.verbose_logging
server_sent_event.verbose_logging = boolVal
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.
Version
local strVal = server_sent_event.version
Methods
LoadEvent
-- ok is true, or nil and err on failure
local ok, err = server_sent_event:load_event(event_text)
Loads the multi-line event text into this object. For example, the event_text for a Firebase event might look like this:
event: put
data: {"path": "/c", "data": {"foo": true, "bar": false}}
Returns true on success, nil, err on failure. The second return value, err, is the object's last_error_text; wrap the call in assert() to raise an error instead.