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new 51cdc76 Update GZIPLayer to document new layer variable
compressionLevel
51cdc76 is described below
commit 51cdc7634b648389d9021097d0f94825539c6089
Author: Guichard Desrosiers <[email protected]>
AuthorDate: Fri Jun 5 16:52:32 2026 -0400
Update GZIPLayer to document new layer variable compressionLevel
---
site/layers.md | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/site/layers.md b/site/layers.md
index ff0b287..129a0fa 100644
--- a/site/layers.md
+++ b/site/layers.md
@@ -608,7 +608,17 @@ The entire fixed length region of the data will be pulled
into a byte buffer in
- Name: gzip
- Namespace URI: urn:org.apache.daffodil.layers.gzip
-- Parameter Variables: None
+- Parameter Variables
+ - `compressionLevel` an integer specifying the gzip compression level used
+ when unparsing. Valid values are:
+ - `0` — no compression
+ - `1 to 9` — amount of compression, ranging from 1 (fastest with least
compression)
+ to 9 (slowest with best compression)
+ - `-1` — use implementation default, usually level 6. This is the default
parameter
+ value if the variable is not set.
+
+ This variable is declared with `external="true"`, so it can be
overridden
+ externally without having to modify the schema.
- Result Variables: None
- Import Statement:
```
@@ -618,14 +628,6 @@ The entire fixed length region of the data will be pulled
into a byte buffer in
This layer uses the `java.util.zip.GZIPInputStream` and
`java.util.zip.GZIPOutputStream`
libraries to decode and encode.
-Prior to Java 16, the `java.util.zip.GZIPOutputStream` wrote a value of zero
for the OS field
-in the header (byte index 9).
-In Java 16, this was changed to a value of 255 to better abide by the GZIP
specification.
-Unfortunately, this means unparsed data using a GZIP layer might have a single
byte difference,
-depending on the Java version used.
-To avoid inconsistent behavior of test failures that expect a certain byte
value this layer
-always writes a consistent header (header byte 9 of 255) regardless of the
Java version.
-
----
## Line Folded Layers
