Server-Sent Event Parser

Parse a complete Unicode event stream into dispatched events, preserving last-event IDs and discarding an unterminated final event.

Description

Server-sent events are line-based records dispatched at blank lines.

Server-sent events are line-based records dispatched at blank lines. Event IDs persist across records, while repeated data lines form one newline-joined payload.^[1]

Parse a complete Unicode event stream into dispatched events, preserving last-event IDs and discarding an unterminated final event.

When to use Server-Sent Event Parser

Use this tool to parse a complete Unicode event stream into dispatched events, preserving last-event IDs and discarding an unterminated final event.

Choose the URL, decoded source text, header value or explicit byte list requested by this tool. Paste the complete relevant input and follow its parsing and encoding conventions.

How to use Server-Sent Event Parser and understand its results

Choose the URL, decoded source text, header value or explicit byte list requested by this tool. Paste the complete relevant input and follow its parsing and encoding conventions.
Enter stream using the field table and calculation rules, then run the tool.
Read events, lastEventId, retryMs. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
stream	Complete decoded UTF-8 event stream.	string; maximum length: 1000000	Required

Paste a complete already decoded UTF-8 event stream. Remove an initial BOM and process terminated CRLF, CR or LF lines. Ignore comments, strip one leading field-value space, default event type to message and persist accepted IDs. NUL-containing IDs are ignored; digit-only safe-integer retry values update retryMs. Return dispatched records and final ID/retry state.

on terminated blank line: dispatch if dataLines exist; data=join(dataLines,'\n')

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
events	Dispatched events.	list of object; minimum entries: 0; maximum entries: 100000
lastEventId	Most recent valid event ID.	string; maximum length: 1000000
retryMs	Last safe reconnection interval, or null if no valid retry was supplied.	JSON value

json

{
  "input": {
    "stream": "id: 7\nevent: update\ndata: first\ndata: second\n\nretry: 1500\n\n"
  },
  "output": {
    "events": [
      {
        "event": "update",
        "data": "first\nsecond",
        "id": "7"
      }
    ],
    "lastEventId": "7",
    "retryMs": 1500
  }
}

Limitations and assumptions

An unterminated final line or undispatched final event is discarded. This does not maintain incremental parser state across runs, connect to a server or schedule reconnection.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Extremely large text inputs are rejected. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Meta Tag Parser: Extract named meta entries from HTML source in document order, preserving repeated keys. For a complementary task, use Subresource Integrity Hash Generator: Hash explicit UTF-8 text with SHA-256, SHA-384, or SHA-512 and emit Base64 Subresource Integrity metadata.

References

Server-Sent Event Parser — tool.io

Similar or alternative tools

Meta Tag Parser
Extract named meta entries from HTML source in document order, preserving repeated keys.
Subresource Integrity Hash Generator
Hash explicit UTF-8 text with SHA-256, SHA-384, or SHA-512 and emit Base64 Subresource Integrity metadata.