DownOperation (Syncany API Documentation)

java.lang.Object
- org.syncany.operations.Operation
- - org.syncany.operations.AbstractTransferOperation
  - - org.syncany.operations.down.DownOperation

```
public class DownOperation
extends AbstractTransferOperation
```
The down operation implements a central part of Syncany's business logic. It determines whether other clients have uploaded new changes, downloads and compares these changes to the local database, and applies them locally. The down operation is the complement to the UpOperation.
The general operation flow is as follows:
1. List all database versions on the remote storage using the LsRemoteOperation (implemented in listUnknownRemoteDatabases()
2. Download unknown databases using a TransferManager (if any), skip the rest down otherwise (implemented in downloadUnknownRemoteDatabases()
3. Load remote database headers (branches) and compare them to the local database to determine a winner using several methods of the DatabaseReconciliator
4. Determine whether the local branch conflicts with the winner branch; if so, prune conflicting local database versions (using findLosersPruneBranch())
5. If the apply-changes-flag is switched on, changes are applied to the local file system using the ApplyChangesOperation.
6. Save local database and update known database list (database files that do not need to be downloaded anymore
See Also:

DatabaseReconciliator

Field Summary

Fields
Modifier and Type Field Description

static java.lang.String ACTION_ID
- Fields inherited from class org.syncany.operations.AbstractTransferOperation
  actionHandler, eventBus, transferManager
- Fields inherited from class org.syncany.operations.Operation
  config

Constructor Summary

Constructors
Constructor Description

DownOperation(Config config)

DownOperation(Config config, DownOperationOptions options)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`DownOperationResult`	`execute()`	Executes the down operation, roughly following these steps: Download the remote databases to the local cache folder Read version headers (vector clocks) Determine winner branch Prune local stuff (if local conflicts exist) Apply winner's branch Write names of newly analyzed remote databases (so we don't download them again)

Methods inherited from class org.syncany.operations.AbstractTransferOperation
finishOperation, getLastRemoteCleanupNumber, getNewestDatabaseFileVersion, otherRemoteOperationsRunning, startOperation

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - ACTION_ID
```
public static final java.lang.String ACTION_ID
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - DownOperation
```
public DownOperation(Config config)
```
  - DownOperation
```
public DownOperation(Config config,
                     DownOperationOptions options)
```
- Method Detail
  - execute
```
public DownOperationResult execute()
                            throws java.lang.Exception
```
    Executes the down operation, roughly following these steps:
    
    Download the remote databases to the local cache folder
    Read version headers (vector clocks)
    Determine winner branch
    Prune local stuff (if local conflicts exist)
    Apply winner's branch
    Write names of newly analyzed remote databases (so we don't download them again)
    Specified by:
    
    execute in class Operation
    
    Returns:
    
    Returns an operation-specific operation result
    
    Throws:
    
    java.lang.Exception - If the operation fails