pbs-howto-response-size-calculation

Response Length Calculation

Wire format

Each server response is sent as:

4-byte big-endian length prefix + UTF-8 JSON payload

So:

total_bytes = 4 + json_payload_bytes

The response JSON shape is:

{
  "meta": ...,
  "uuid": ...,
  "hits": [...]
}

Important behavior for return_empty

• If hits = 0 and return_empty is false or omitted, the server sends no response
• If hits = 0 and return_empty = true, the server sends an empty response payload

Assumptions Used For The Table

• uuid example: "generated-uuid"
• meta example:

{"source":"python-client","mode":"live"}

• Each returned ID is a 36-byte UUID-like string:

"123e4567-e89b-12d3-a456-426614174000"

Calculation Process

Base payload sizes

1. No uuid, no meta, empty hits

{"meta":null,"uuid":null,"hits":[]}

• JSON bytes: 35
• Framed bytes: 35 + 4 = 39

2. uuid only, empty hits

{"meta":null,"uuid":"generated-uuid","hits":[]}

• JSON bytes: 47
• Framed bytes: 47 + 4 = 51

3. meta only, empty hits

{"meta":{"source":"python-client","mode":"live"},"uuid":null,"hits":[]}

• JSON bytes: 71
• Framed bytes: 71 + 4 = 75

4. uuid + meta, empty hits

{"meta":{"source":"python-client","mode":"live"},"uuid":"generated-uuid","hits":[]}

• JSON bytes: 83
• Framed bytes: 83 + 4 = 87

Per-returned-ID growth

For a 36-byte returned ID:

• First ID adds 38 bytes to the JSON payload
• Each additional ID adds 39 bytes

Reason:

• first item: " + 36 chars + " = 38
• next items: , + " + 36 chars + " = 39

So for n > 0:

hits_bytes(n) = 38 + (n - 1) * 39

Equivalent:

hits_bytes(n) = 39n - 1

Final Formulas

Let n be the number of returned IDs.

No uuid, no meta

total_bytes = 39 + (39n - 1), for n > 0
total_bytes = 39, for n = 0

Simplified:

total_bytes = 38 + 39n, for n > 0
total_bytes = 39, for n = 0

uuid only

total_bytes = 51, for n = 0
total_bytes = 50 + 39n, for n > 0

meta only

total_bytes = 75, for n = 0
total_bytes = 74 + 39n, for n > 0

uuid + meta

total_bytes = 87, for n = 0
total_bytes = 86 + 39n, for n > 0

Results Table

Returned IDs	No uuid, No meta	uuid only	meta only	uuid + meta
0	39	51	75	87
1	77	89	113	125
2	116	128	152	164
3	155	167	191	203
4	194	206	230	242
5	233	245	269	281
6	272	284	308	320
7	311	323	347	359
8	350	362	386	398
9	389	401	425	437
10	428	440	464	476
11	467	479	503	515
12	506	518	542	554
13	545	557	581	593
14	584	596	620	632
15	623	635	659	671

Notes

• These values are for the PBS application payload only
• They do not include TCP, IP, or TLS overhead
• If return_empty=false and there are 0 hits, response size is 0 bytes