This page provides guidelines and best practice recommendations on how to create a custom Java-based REST endpoint with Magnolia.
Java-based custom REST endpoints give access to the full power of Java and provide a high level of flexibility and configurability. REST endpoints in Magnolia also allow fine-grained security.
Endpoints can be used for many purposes, from triggering a third party service to implementing a custom JSON provider. However, there are also other possibilities to get Magnolia content as JSON.
In this page, we assume that you know Java and the basics of Maven or another similar dependency management tool.
What is a Magnolia REST endpoint?
A REST endpoint is a resource located on a server, in our case on a Magnolia instance, which can be accessed with a RESTful URL.
A Java endpoint makes use of the Java API for RESTful Web Services (JAX-RS). The endpoint exposes public methods accessible via distinct URLs. A public method is accessed with a request and produces a response.
Magnolia REST endpoints are JAX-RS endpoints.
REST base path and RestDispatcherServlet
The base path for every Magnolia REST resource is
/<context>/.rest, where <context> is either the name of the webapp or
/ if the webapp is served from the root context. For details about specific paths of specific REST resources, see Understanding
All requests to
/<context>/.rest* are handled by the RestDispatcherServlet, which is installed and configured by the
What do endpoints do?
An endpoint can have several methods accomplishing completely different tasks. Basically endpoints can do anything that is possible with Java.
Each publicly exposed method representing a REST resource must produce a response that contains at least some response headers (the minimum is a proper HTTP response code). Both the request and response may or may not contain a "payload" (JSON or XML) wrapped in the request or response body.
An endpoint should implement at least one method that can be accessed by its specific path with one of the standard HTTP methods:
Data API endpoints
A typical use case for an endpoint is a data API, which can read, create, update or delete content. A data API endpoint must implement at least one method, such as a
GET method to read data.
Typically, methods for data interaction are called with these HTTP methods:
|Data interaction function||Read data||Create data||Update data||Delete data|
|Request has payload||no||yes||yes||no|
|Response has payload||yes||maybe||maybe||no|
Magnolia provides default endpoints to read, create, update and delete nodes and properties of JCR workspaces. For details about the Magnolia default JCR content API, read the section about the
magnolia-rest-services module below or have a look at the REST API page.
Java, Maven and package names
Java classes typically are wrapped in modules. When the Java classes of your endpoint are part of a (Maven) module, you can add the module to your bundle or webapp as a .jar file or manage the dependency with Maven in the .pom file of the webapp.
Creating a Magnolia Maven module with a Maven archetype
Use the Magnolia Maven archetype to create a new Magnolia Maven module that will host your Java REST endpoint.
Before running the Maven
archetype command, please read How to use Magnolia Maven archetypes: Check Maven settings.
If you are not familiar with the Maven archetype plugin, please also read How to use Magnolia Maven archetypes: The archetype plugin.
Here is the archetype command call:
- Always use the latest version of the archetype.
- Provide meaningful values for the
- Provide the
magnolia-bundle-versionthat fits your existing Magnolia bundle(s) best. If you are not sure, use the latest released Magnolia version: 6.1.1.
- The archetype creates a POM file which imports the
magnolia-bundle-parent. This parent manages the versions of Magnolia modules you rely on.
Executing the archetype plugin command
Open a shell and change to the directory where you want the Magnolia Maven module skeleton to be created.
Run the following command:
Maven prompts you to specify values for several parameters. Use values that fit your requirements:
|Maven ||Typically reflects the name or domain of your company or projects.|
|Maven ||Project-specific identifier.|
|Maven artifact ||Project version. Typically, when creating a new project, use the value suggested by Maven, for example |
|Package name for Java classes reflecting both your company (or domain) and the specific project.|
Magnolia version from which your custom project inherits.
|The Java class name of the autogenerated module class.|
After you have entered the values, the archetype plugin displays their list and asks you to confirm it. If you confirm by pressing
ENTER, the plugin generates the skeleton of your archetype. You should see a
BUILD SUCCESS message at the end of the process. If you press
C, nothing is generated.
resources directories contain more subfolders.
Java package name
Example:In this example:
- The package name is
- The class name is
- The fully qualified class name (fqcn) is
If you want to raise the version of the endpoint later on, without disabling the original version, create a package with a higher version such as
Magnolia REST modules and recommended dependencies
We assume that you know the basics about how to manage dependencies, and that you manage these dependencies with Maven.
The Java API for RESTful Web Services - JAX-RS is defined in the packages
javax.xml.bind. These are interfaces and sufficient for endpoint classes during compilation. However, on runtime, when the REST resources are used, a webapp also requires implementations of the these two mentioned packages. Magnolia uses RESTeasy for this purpose.
The dependencies (for both the interfaces and the implementations) are managed by the
Your module, which depends on Magnolia REST module(s), automatically (transiently) inherits the dependencies from the Magnolia modules.
The Magnolia REST module contains three submodules.
Magnolia REST modules
The REST Integration module installs the integration part of REST. The module:
- Manages the dependencies for the required JAX-RS libraries.
/config/<module-name>/rest-endpointsfor any custom endpoints you want to register. The monitoring mechanism is the same as used for observing registered dialogs, templates and apps.
- Installs a special servlet
RestDispatcherServletwhich dispatches requests to the individual endpoints registered in configuration.
- Lets you define additional providers or marshallers (called
MessageBodyWorkersin RESTeasy) you might need. The providers are responsible for translating the return object into JSON/XML and vice-versa.
- Installs the default
restrole that initially prevents access to unauthorized requests.
<dependency> <groupId>info.magnolia.rest</groupId> <artifactId>magnolia-rest-integration</artifactId> </dependency>
magnolia-rest-services module depends on the
magnolia-rest-integration module. Therefore it provides everything explained in the preceding section.
In addition, it contains the Magnolia default REST endpoints NodeEndpoint and PropertyEndpoint and the CommandEndpoint , which are described on the REST API page.
This module also provides the RepositoryMarshaller , which you can use within your custom endpoint.
<dependency> <groupId>info.magnolia.rest</groupId> <artifactId>magnolia-rest-services</artifactId> </dependency>
This module provides the Delivery endpoint.
<dependency> <groupId>info.magnolia.rest</groupId> <artifactId>magnolia-rest-content-delivery</artifactId> </dependency>
The REST Tools module integrates the swagger tools into the Admin UI. These tools ease the development and testing of REST endpoints.
The module extends the
RestDispatcherServlet with a custom, API-aware servlet that can read API annotations from all available REST endpoints. The servlet enables the endpoints in the Swagger API explorer. If you write your own endpoint you need to add annotations in the code yourself.
The module is used for development and testing purposes only.
<dependency> <groupId>info.magnolia.rest</groupId> <artifactId>magnolia-rest-tools</artifactId> </dependency>
Magnolia REST module versions
Make sure you use the same version for all Magnolia REST modules on which you depend.
The version of the Magnolia REST modules depends on the version of Magnolia you use to run your custom endpoint. We recommend you check the .pom file (or the parent .pom file) of your Magnolia webapp. The .pom file manages the version of the Magnolia REST modules using the property
restVersion. If you are unsure, use the latest released version, which is currently: 2.1.2.
How to create a Java class that acts as a REST resource
To create a Java class that acts as a REST resource, write a Java class — your service — and register this service in the Magnolia
configuration workspace. Registering the service makes sure that the REST resource can be accessed by a default Magnolia servlet.
In this section we create a simple endpoint implementation and explain some important details for every custom Java REST endpoint in the context of Magnolia.
Creating the Java class
Create the class
com.example.rest.service.v1.DemoEndpoint. This is the code for a simple working example:
- Extends AbstractEndpoint (line 13).
- Has at least one method, which (here) has the return type
- Declares its path on both the class and the method level (lines 12, 19).
- Declares its response type(s) (line 21).
- Declares the HTTP methods through which it can be accessed (line 20).
Let's have a closer look at some of these details below.
See line 13 in the example above. By extending AbstractEndpoint , the endpoint can be configured. We will see later on what the configuration and registration looks like. When a request comes to Magnolia mapped to this endpoint, an instance is created via Inversion of Control (IoC). During this process, the IoC framework also creates an instance of EndpointDefinition , which is injected into the constructor of our endpoint class.
If you are not yet familiar with the
package, we recommend you take some time to learn the basics. This package contains many annotations that can be used to declare the details of Java-based REST resources. We will see how to use these annotations below.
javax.ws.rs.core.Response is the standard response type for a Java REST endpoint.
On line 22 we declare the return type.
On line 23 we use the static method
#ok (without an argument), which ensures that:
- The HTTP response code is 200 (if everything else goes well).
- Since we use the method
#okwith no argument, no payload is created and the response does not have a body, just headers.
On line 21, by using the
@Produces annotation, we can declare a list of possible HTTP response content types.
Note that, in our example, there is no need to declare the HTTP response content type because the method only returns response headers but no response body. However, if the method creates a payload (for instance JSON or XML) to be returned as an HTTP response body, then you should declare the response content type with @Produces.
A method on a REST endpoint has a distinct path to access it with a RESTful URL. A path generally consists of several parts:
- Magnolia REST base path:
If you are running a local development bundle, the base REST path is typically
On a productive environment, where you serve the webapp from the root context, the base REST path is
This path is mapped to the Magnolia REST servlet.
- REST endpoint base path. This path is declared on the class level with the
@Pathannotation; see line 12 on the example above.
This path in our example is
The value of this path can be chosen arbitrarily. Note that it typically contains the version of the endpoint (which is
If your package name reflects the version, you can use the same version identifier on both the package name and the endpoint base path.
- REST endpoint method path. This path is declared on the method level with the
@Pathannotation; see line 19 on the example above.
The example shown is static with the value
/hello. However, the method path can be dynamic in combination with
@PathParam, we will see an example later on.
To summarize, the path to a REST "resource" is a combination of:
|Magnolia REST base path||+||REST endpoint base path||+||REST endpoint method path|
Declaring the HTTP method
On line 20 we use the annotation
@GET. This declares that the REST resource defined by this method can be accessed with the HTTP method GET only.
If you try to access the resources using another method (for example with POST), the resource returns an error HTTP response code. We will test this later on with cURL.
You can only declare one HTTP method per method. The Java compiler shows an error if you try to declare two methods (by using two annotations).
Registering the REST resource in Magnolia
REST resources in Magnolia should be registered within your custom module. This ensures that the REST resource and its configuration are known in the Magnolia EndpointDefinitionRegistry .
Example: Registering the endpoint:
The folder which contains a list of endpoint definitions. The name of the folder must be
The name of the endpoint. The name is arbitrary but must be unique.
The fully qualified class name of the definition class. Typically
The fully qualified class name of the REST endpoint java class.
Granting access to the REST resource in the Security app
The last step before you can access the resource with a client is to grant access to the REST resource in the Security app.
Permissions to issue REST requests are controlled using the standard Magnolia role-based security mechanism .
magnolia-rest-integration module installs a
rest role which has the permission to issue requests to the
properties endpoints by default.
You can extend the existing
rest role to provide web access to the path of your custom REST resource, or you can duplicate the existing role to create a new one just for your use case. In either case, make sure that you assign this role to the users who need to access this resource.
Details of the role
Access Control Lists (ACL):
|Deny||Deny all to begin.|
Allow access to the Swagger tools. This is only required if you have the
Allow access to our custom endpoint whose access path is
Access type meanings:
|Deny||Everything is denied.|
|Get||Only the HTTP method |
|Get&Post||All HTTP methods available are allowed: |
This is the list of roles assigned to superuser:
Depending on your bundle, you may have more roles assigned to
Accessing the resource
Now everything is ready to access the custom endpoint.
cURL is a useful tool to test REST resources. To check if you have it installed, open a command shell and type:When it is installed, the shell displays something like this: Once you have confirmed that cURL works, try the following request: Since we provide the
-ioption, cURL displays the response header. Remember that the requested resource does not produce a payload, so there is no response body. Now try to access the resource via the
POSTmethod: Here are the response headers: This is expected. The method
#hellois annotated with
@GETdeclaring it can only be accessed with the HTTP method
GET. See the section declaring the HTTP method.
Note that you pass the username and password in clear text in this cURL call. This is acceptable when testing on a local machine, however, we advise against doing this to access a production environment server.
About marshalling and data conversion
An endpoint dealing with data must manage two types of data conversion:
- Transforming data into a simple Java bean or POJO (Plain Old Java Object) and vice versa.
- Transforming the POJO into JSON or XML and vice versa.
If the endpoint handles both read (GET) and write (PUT to create and POST to update) actions, marshalling and data conversion must also work in both directions.
In this section we focus on some aspects of this kind of data conversion.
Converting a data object into a POJO and vice versa
Regardless of the type of data you deal with, in the context of a REST endpoint, at some point you typically transform "data" into a POJO (and vice versa).
There is no "one size fits all" for transforming a data object into a POJO and vice versa. The best solution for you depends on your use case.
JCR to POJO
magnolia-rest-services module provides classes to transform JCR nodes and properties into POJOs and vice versa.
- RepositoryMarshaller is the transformer.
- RepositoryNode is the type of the POJO.
The Magnolia endpoints PropertyEndpoint and NodeEndpoint use these classes. You also can use the classes for your custom endpoints. However, note that the structure of the POJO and of the resulting payload after marshalling may not cover your requirements.
Marshalling and unmarshalling - creating and receiving payload
Marshalling is handled by the REST framework by the JAX-RS API implementation.
However, when dealing with payload (XML or JSON) in your endpoint, note the following:
- To create payload, you must
PUTa POJO into the response of the endpoint method.
- When receiving payload from a request, the responsible method must have an appropriate signature in order to initiate unmarshalling.
Adding POJOs to the REST response to deliver payload
Imagine you have a POJO with the name
Lunch and two properties:
lunchpayload. Endpoint method(s) providing a
Lunchobject would look like this: Note that the snippet shows two methods:
#lunch2. Both produce the same payload when called from outside, however, their implementation is slightly different.
- Uses the generic return type
- Puts the POJO (of the type
Lunch) into this response; see line 6.
This approach provides high flexibility concerning the response code, for instance you can do things like this:
- Uses the specific POJO as return type. Here it is
- Returns the POJO directly on the method.
Note that both method produce the same response headers and identical payload (structure, in this example only the values of the food and beverage properties differ).
#lunchNote that the payload also contains the property
id. This property comes from the super class
Lunch; we will need this id later on.
Both approaches to produce payload with POJOs shown here work in more complex scenarios. For example: you could return a list of POJOs; the properties of the POJO could also be POJOs; and so on.
Receiving payload and getting the POJO
Endpoint methods that receive a payload (JSON or XML) are typically used to create or update an object.
Let's imagine an example where the endpoint allows you add a lunch object to a store. In the context of a data store, adding is like creating. To create an object, a REST service is called with the the HTTP method
This code snippet shows the method to add a lunch:
Line 140: It is generally considered good practice to tell the service what type of data it consumes. However, it is not required.
Line 143: The most important point in the current context is the method signature.
The method must contain a parameter of the type to which the payload should be mapped to.
- Line 146: If the mapping was successful, we add the lunch POJO to the store. The
storeactually is a mock store, it does not really store data in the example. (See
BlackboxDatastoreon Git.). However,
store#addmay throw an exception if it fails.
- Line 147: Build the response with the response code 200 (ok), and also put the lunch object into the payload, it now carries the object id too. Giving back the just created object could be used on a client to render an update UI or to summarize the successful add action.
- Line 148-150: These lines handle the exception thrown by the store. You can provoke this by sending a payload to the method where the property
foodhas the value
You can test the new method using cURL.
Now provoke an error with "Bad food":The "Bad food" was rejected. No payload was returned and the HTTP response code is 406 (Not Acceptable).
Implementing a method to update an object (and using the HTTP method
POST) works in a similar way. In such a case, the payload sent to the REST endpoint must contain the object id in order to update the correct item on the data store.
The same-origin policy problem
Let's assume you want to use a data API endpoint to serve content managed with Magnolia apps to independent applications located "outside" of Magnolia. For example, you want to use an AngularJS application to display your content.
We also assume Magnolia and the Angular application are hosted on completely different systems.
According to the same-origin policy:
(...) a web browser permits scripts contained in a first web page to access data in a second web page, but only if both web pages have the same origin.
Therefore, if your application resides within a domain that is different from the domain that hosts your data, the web browser will actively prevent accessing content stored under the host domain.
An elegant solution to solve the same-origin policy without changing Apache configuration is the Magnolia Add HTTP Headers filter. This fiter is available out-of-the-box; you only need to configure it.
Sample code on GIT
The sample code for the examples on this page is available on the Magnolia GIT repository.