Migrating API Proxies | MuleSoft Documentation
# Migrating API Proxies
## Performing a Proxy Migration
To perform a proxy migration, this example uses the Mule Migration Assistant (MMA). The procedure requires that you meet the Prerequisites for the tool. For complete user documentation on MMA, see Migration to Mule 4 (on GitHub).
The MMA command for migrating proxies uses the standard command-line options (on GitHub) for migrating a Mule app:
Command-line Invocation:
```
$ java -jar mule-migration-assistant-runner-0.5.1.jar \
 -projectBasePath /Users/me/AnypointStudio/workspace-studio/my-mule3-proxy/ \
 -muleVersion 4.1.5 \
 -destinationProjectBasePath /Users/me/my-dir/my-migrated-proxy
```

Note that the MMA creates the directory for the migrated project through the `-destinationProjectBasePath` option. The `my-migrated-proxy` must _not_ exist before you invoke the command. If you point to a folder that exists already, the migration will fail an error like this: `Exception: Destination folder already exists.`
When the migrator runs successfully, you see a message something like this:
Successful Migration
```
Executing migration...
...
========================================================
MIGRATION SUCCESS
========================================================
Total time: 11.335 s
Migration report:
/Users/me/my-dir/my-migrated-proxy/report/summary.html
```

After migration completes successfully, the destination folder contains:
  * A proxy POM file.
  * The `report` directory containing the Mule Migration Report (on GitHub) (`summary.html`). Note that the same information provided in the report can be found as comments in the proxy XML file.
  * The `mule-artifact.json` file, with a `minMuleVersion` value that matches the `-muleVersion` value set in the MMA command.
  * The `src` directory, which contains the migrated content.


The `src` directory contains subdirectories `main` and `test`. Inside `main`, the `mule` directory is the proxy XML file. At the same level as the `mule` directory, MMA will create a `resources` directory for any DataWeave files or other files that the migrated proxy needs. Note that the configuration file defined in the proxy XML must be present in the `resources` directory for the artifact to be deployed correctly. The `test` directory contains test configuration files.
After a successful migration, you need to modify the POM file as explained in POM Migration. Once the POM file has the correct organization ID, you can compile with `mvn clean install`. If the compilation is successful, you can upload the migrated proxy to Exchange using `maven clean deploy`. You can find a more detailed explanation of uploading a custom app in Publish and Deploy Exchange Assets Using Maven.
### POM Migration
The POM file migration modifies the file to include the elements necessary for uploading the custom proxy to Exchange.
_After_ the migration:
  * Replace the `{orgId}` value in the `<groupId/>` and `<exchange.url/>` elements with the organization ID found in Anypoint Platform.


For more information on how to obtain the organization ID, see Uploading a Custom Policy to Exchange.
By default, the Exchange URL is set to the production environment.
```
<groupId>{orgId}</groupId>
<properties>
 <exchange.url>https://maven.anypoint.mulesoft.com/api/v1/organizations/{orgId}/maven</exchange.url>
</properties>
```

Note that for the EU version of the URL, you need to set the URL manually after the migration:
  * URL template for EU: `https://maven.eu1.anypoint.mulesoft.com/api/v1/organizations/{orgId}/maven`


If the MMA does not find a POM file for the proxy, MMA will create a new POM file. In this file, the `artifactId` for the proxy is the name of the base directory for the proxy app. For example, for a proxy in `mytestproxy/src/main/app/proxy.xml`, the `artifactId` is `mytestproxy`.
### Dependency and Plugin Versions
Dependency and plugin versions are set by default by the MMA, and you can change them manually, as needed.
### Un-Migrated Elements
Several elements are not migrated from Mule 3 to Mule 4:
Element | Reason  
---|---  
`api-platform-gw:tags` | API auto-create is disabled in Mule 4.  
`api-platform-gw:description` | API auto-create is disabled in Mule 4.  
For each of these elements, the child elements are removed, as well.
### Common Migration Issues
If proxy files are not found during the migration, the MMA prints a message like this one:
Unsuccessful Migration
```
Executing migration...
...
===============================================================================
MIGRATION FAILED
===============================================================================
Total time: 3.008 s
Exception: Cannot read mule project. Is it a Mule Studio project?
com.mulesoft.tools.migration.engine.exception.MigrationJobException: Cannot read mule project. Is it a Mule Studio project?
	at com.mulesoft.tools.migration.engine.project.MuleProjectFactory.getMuleProject(MuleProjectFactory.java:50)
	at com.mulesoft.tools.migration.engine.MigrationJob.generateSourceApplicationModel(MigrationJob.java:116)
	at com.mulesoft.tools.migration.engine.MigrationJob.execute(MigrationJob.java:80)
	at com.mulesoft.tools.migration.MigrationRunner.main(MigrationRunner.java:83)
===============================================================================
```

### POM Migration Issues
If the MMA does not find the POM model for the proxy, the MMA will either generate the model from an existing POM in Mule 3, or if there is no Mule 3 POM, the MMA will create the model. If MMA uses an existing POM, any incorrect POM definition that the MMA encounters will cause POM model creation process to fail. For information about a POM model failure, you need to check for any preceding error messages regarding MMA steps on modifying the POM model.
### RAML Proxy Migration
RAML proxy elements are migrated to REST proxy elements:
`proxy:raml-proxy-config`. | `rest-validator:config`.  
---|---  
`proxy:raml`. | `rest-validator:validate-request`.  
`apikit:mapping-exception-strategy`. | `error-handler` with `on-error-continue` elements in the flow containing the `rest-validator:validate-request` element.  
The `error-handler` element contains the following types for `on-error-continue` elements:
Type | Status Code  
---|---  
REST-VALIDATOR:BAD_REQUEST  
REST-VALIDATOR:RESOURCE_NOT_FOUND  
REST-VALIDATOR:METHOD_NOT_ALLOWED  
HTTP:TIMEOUT  
Exceptions that are not found in the Mule 3 element are autocompleted by the Mule Migration Assistant.
### WSDL Proxy Migration
WSDL proxy migration consists of migrating the attribute values for WSDL properties. In Mule 3, most values are extracted using the function defined as attribute value. In Mule 4, there is no equivalent process, so most properties are migrated to a default value and require manual configuration with values from the WSDL file, which start with the `service` keyword.
Some properties are renamed to extract the value in a more transparent way, for example:
`![wsdl(p['wsdl.uri']).services[0].preferredPort.name]` | `${service.port}`  
---|---  
`![wsdl(p['wsdl.uri']).targetNamespace]` | `${service.namespace}`  
`![wsdl(p['wsdl.uri']).services[0].name]` | `${service.name}`  
Other properties, such as the following, are migrated to a DataWeave expression that uses the WSDL Functions Extension dependency, provided by MMA, to extract the expected values:
`![wsdl(p['wsdl.uri']).services[0].preferredPort.addresses[0].port]` | `#[Wsdl::getPort('${wsdl.uri}','${service.name}','${service.port}')]`  
---|---  
`![wsdl(p['wsdl.uri']).services[0].preferredPort.addresses[0].host]` | `#[Wsdl::getHost('${wsdl.uri}','${service.name}','${service.port}')]`  
`![wsdl(p['wsdl.uri']).services[0].preferredPort.addresses[0].path]` | `#[Wsdl::getPath('${wsdl.uri}','${service.name}','${service.port}')]`  
## See Also
Migrating API Gateways
Migrating API Gateways: Autodiscovery
Migrating API Gateways: Mule Runtime Configuration
Core Components Migration
Publish and Deploy Exchange Assets Using Maven