---
id: object/codeunit/421
type: object
title: Codeunit 421 "Data Compression Impl."
summary: Codeunit 421 "Data Compression Impl." in System Application (System.IO). 16 public procedures. Present since at least BC23, still in BC30.
tier: official
language: en
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  - system application
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object_type: codeunit
object_id: 421
name: Data Compression Impl.
namespace: System.IO
app: System Application
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first_version: "23"
last_version: "30"
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---

# Codeunit 421 "Data Compression Impl."

> Codeunit 421 "Data Compression Impl." in System Application (System.IO). 16 public procedures. Present since at least BC23, still in BC30.

System Application · System.IO · BC23-30 · [source at ea08af5e](https://github.com/microsoft/BCApps/blob/ea08af5ef2d6a9b5c5af4a029288abbe2c883220/src/System%20Application/App/Data%20Compression/src/DataCompressionImpl.Codeunit.al) · facts from BC29

## Properties

| Property | Value |
|---|---|
| Access | Internal |

## Procedures

- `CreateZipArchive()`
- `GZipCompress(InputInStream: InStream; CompressedOutStream: OutStream)`
- `GZipDecompress(InputInStream: InStream; DecompressedOutStream: OutStream)`
- `OpenZipArchive(InputInStream: InStream; OpenForUpdate: Boolean)`
- `OpenZipArchive(InputInStream: InStream; OpenForUpdate: Boolean; EncodingCodePageNumber: Integer)`
- `OpenZipArchive(TempBlob: Codeunit "Temp Blob"; OpenForUpdate: Boolean)`
- `SaveZipArchive(OutputOutStream: OutStream)`
- `SaveZipArchive(var TempBlob: Codeunit "Temp Blob")`
- `CloseZipArchive()`
- `IsZip(InputInStream: InStream): Boolean`
- `IsGZip(InputInStream: InStream): Boolean`
- `GetEntryList(var EntryList: List of [Text])`
- `ExtractEntry(EntryName: Text; OutputOutStream: OutStream; var EntryLength: Integer)`
- `ExtractEntry(EntryName: Text; var TempBlob: Codeunit "Temp Blob"): Integer`
- `AddEntry(InStreamToAdd: InStream; PathInArchive: Text)`
- `RemoveEntry(PathInArchive: Text)`

## Calls

From the extracted call graph of BC29 (graphify-al on the snapshot checkout): calls whose target is known from a declared type or an `Object::"Name"` argument. Interface dispatch and calls through events are not counted, so the list is not complete.

- [Codeunit 4100 "Temp Blob"](../codeunit/4100.md) (2 calls: `CreateZipArchive → CreateOutStream`, `SaveZipArchive → CreateInStream`)

## Called by

- [Codeunit 425 "Data Compression"](../codeunit/425.md) (12 calls: `AddEntry → AddEntry`, `CloseZipArchive → CloseZipArchive`, `CreateZipArchive → CreateZipArchive`, …)

## Across versions

- Present in: BC23-30
- Changed (declaration) in: none

Source: AL metadata extracted from the code (names, ids, signatures, properties); no code bodies (D10).

## Ask your agent

Procedure bodies are not stored here (D10). The call sections above are our own, per object, from the BC29 call graph. For a procedure body or the calls of one procedure, ask bc-code-atlas (external, by Stefan Maron, MIT; default corpus w1-28), which the bc-observatory plugin connects: `bcatlas_resolve_node(object_type: "codeunit", object_name: "Data Compression Impl.")`, then `bcatlas_get_procedure_body` or `bcatlas_get_neighbors` on the returned id.