Length Field Frame Joiner
Join bounded byte payload frames with explicit unsigned length prefixes and byte order; output stream is limited to 128 bytes.
Description
Join bounded byte payload frames with explicit unsigned length prefixes and byte order; output stream is limited to 128 bytes.
A sequence of byte payloads can be serialized by prefixing each with its own fixed-width length.
When to use this tool
Join bounded byte payload frames with explicit unsigned length prefixes and byte order; output stream is limited to 128 bytes.
- Prepare the supplied framesJson, lengthBytes, littleEndian fields for this operation.
- Compare the complete example with the representation used by your own input before carrying the result into another step.
How to use the tool and how it works
- Enter framesJson, lengthBytes, littleEndian. Use the exact text syntax, units and index conventions explained below.
- Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
- Read result.bytes. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
Parse framesJson as byte arrays and choose lengthBytes from 1 to 4. Encode each payload length in the selected endian order, concatenate prefix and payload for each frame and reject totals above 128 bytes.1
| Input field | Meaning and representation | Accepted input |
|---|---|---|
| framesJson | JSON text, entered as one text field. The decoded structure is illustrated below; it is not a separate file. | Text |
| lengthBytes | length bytes. | Integer from 1 to 4 inclusive |
| littleEndian | Explicit choice for little endian; supply a boolean rather than a text label. | true or false |
For the JSON text fields, the following decoded structures show the example records before they are serialized into input strings. Keep field names, list nesting and value types as shown.
[
{
"field": "framesJson",
"decoded": [
[
1,
2
],
[
3
]
]
}
]| Output field | Interpretation |
|---|---|
| result | Object containing the named outputs below. |
| result.bytes | The bytes list in the ordering and representation described above. |
{
"input": {
"framesJson": "[[1,2],[3]]",
"lengthBytes": 1,
"littleEndian": false
},
"output": {
"result": {
"bytes": [
2,
1,
2,
1,
3
]
}
}
}Limitations and assumptions
- Lengths exclude their prefix; zero-length frames are allowed. No delimiter, checksum or transport action is added.
- All declared input fields are required and unexpected top-level fields are rejected. Numbers must be finite; lists are limited to 128 entries and ordinary text fields to 8,192 UTF-16 code units, with tighter limits where stated.
- JSON text inputs must parse within bounded nesting and size limits. Numeric outputs outside the safe finite range are rejected; large exact integer results use decimal strings. Indexes and half-open spans are zero-based unless a rank is explicitly described as one-based.
Alternative or Complementary methods
Use a stateful protocol parser when processing partial streams or validating complete packets. Retain the declared prefix width, byte order and payload-versus-frame boundary convention when composing these operations.
References
Similar or alternative tools
- Length Field Frame Splitter
Split a complete length-field byte stream with explicit 1–4 byte unsigned payload lengths and byte order; truncation is rejected, no checksum or sync inference.
- Byte Frame Prefix Length Audit
Compare a leading unsigned byte length field against the complete remaining frame payload; mismatch is evidence, not a thrown truncation error.