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Sling api in aem

By | 04.10.2020

By submitting your feedback, you accept the Adobe Terms of Use. Show Menu. This article explores the major APIs and when and why they should be used. This order is a general rule, meaning exceptions exist. Acceptable reasons to break from this rule are:.

These APIs are supported and should not be avoided, unless com. New abstractions such as Content Fragments and Experience Fragments are built out in the com. The most important concern is maintaining a consistent query language across the code base, to reduce complexity and cost to understand.

OOTB predicates supporting common query requirements. Extensible API, allowing for the development of custom query predicates. To mitigate this leak follow this code sample. Providing security context via the ResourceResolver.

Using Sling APIs to retrieve content from the Adobe Experience Manager Repository

Updating properties via the ModifiableValueMap. Servlet Filters. Event and Job Handlers. Sling Models. Service users. Ensure Sling APIs should not be used instead. OSGi Declarative Services 1. Exceptions to the rule The following are common exceptions to the rules defined above.

While the com. Query APIs AEM QueryBuilder does not support certain query functions such as suggestionsspellcheck and index hints amongst other less common functions. Helpful code snippets The following are helpful Java code snippets that illustrate best practices for common use cases using discussed APIs.

Using this syntax, an explicit call to resourceResolver. Manually closed Sling ResourceResolver ResourceResolvers can be must be manually closed in a finally block, if the auto-closing technique shown above cannot be used. Alternative approach Adapting a resource to an Asset requires the resource itself to be the dam:Asset node.

Alternative approach Adapting a resource to a Page requires the resource itself to be the cq:Page node. Note that this is not a ValueMap, the 2nd parameter default value, and auto-type casting is not supported. In this case, the AEM object may have to be converted into a Sling Resource to efficiently locate the desired property or sub-resource. This can only write to the immediate node relative property paths are not supported.

Note the call to. Create a Sling Resource ResourceResolver supports basic operations for creating resources. Delete a Sling Resource ResourceResolver supports removing a resource. Yes No.Download the package and deploy using package manager.

sling api in aem

The purpose of this code is to show the community these concepts in action. This community code is for teaching purposes only and not meant to go into production as is. A node located in the JCR is considered a resource. For example, a web page is a resource in the JCR. In fact, a resource is a central part of Sling and it assumes everything in the JCR is a resource.

ResourceResolverFactory instance into the service. See Interface ResourceResolverFactory. For example, the adaptTo method converts a resource into an appropriate object representing a certain aspect of this resource.

sling api in aem

For example to translate a Resource object to the corresponding Node object, you invoke the adaptTo method:. An OSGi bundle is created that retrieves a resource, calls the adaptTo method and retrieves a value. A template enables you to define a consistent style for the pages in your application. A template comprises of nodes that specify the page structure. For more information about templates, see Templates.

Right-click the template folder within your applicationselect Create, Create Template. Enter the following information into the Create Template dialog box:.

Add a path to Allowed Paths. Click Next for Allowed Parents. Select OK on Allowed Children. Components are re-usable modules that implement specific application logic to render the content of your web site. You can think of a component as a collection of scripts for example, JSPs, Java servlets, and so on that completely realize a specific function.

In order to realize this functionality, it is your responsibility as a Experience Manager developer to create scripts that perform specific functionality. For more information about components, see Components. By default, a component has at least one default script, identical to the name of the component.

To create a render component, perform these tasks:. Enter the following information into the Create Component dialog box:. Open the templateSling. Enter the following JSP code. Maven manages required JAR files that a Java project needs in its class path. Assign the Maven install location to this environment variable. For example:. Set up a system environment variable to reference Maven. To test whether you properly setup Maven, enter the following Maven command into a command prompt:.

OS name: "windows 7", version: "6. Next, copy the Maven configuration file named settings. You have to configure your settings. Change the command prompt to the generated project. Run the following Maven command:. After you run this command, you can import the project into Eclipse as discussed in the next section.In this tutorial, I have tried to provide very easydetailed and step by step explanation of how sling resource resolution is done in AEM.

After completing this tutorials you will have clear understanding of How a url is mapped to corresponding jcr node in aem. How Sling resource resolution is done. If the component contains. Its only relevance is. Between jsp and html first priority goes to jsp as by default a component is linked to jsp at the time of creation. Note:- If no match is found then it will look for sling:resourceSuperType if available on the component, then it goes to parent component and again run above 5 rules for script resolution.

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sling api in aem

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How Sling Resource Resolution is done in AEM

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Privacy Overview This website uses cookies to improve your experience while you navigate through the website. Privacy Overview.Apache Software Foundation. It serves well as a rapid development environment as it is quickly set up, easy to handle and shows results very easily. Sling on the other hand is based on an OSGi framework and very flexible, allowing the extension of the system in various ways.

Traditional web applications are built around the notion of a traditional application which is converted into an application which may be used using a Web Browser. Web applications consist of a series of servlets and JSP scripts, which are called based on configuration in the web application deployment descriptor. Such applications are generally based on some internal database or some static filesystem content. The Sling API on the other hand looks more like a traditional web server from the outside, which delivers more or less static content.

Response rendering may itself be a multi-step operation. Depending on the Servlets and Scripts, the rendering may include dispatching for child or even foreign Resources.

Unlike the Portlet API, which defines one single level of portlet hierarchy - portlets are just pieces residing besides each other - the Sling API allows for hierarchic structuring of Resources and hence Servlet and Script renderings. To support this structuring, the Sling Framework does not control the rendering process of all elements on the page like the Portlet Container does for the portlets.

With the advent of the Java Collection framework in Java 2, the Enumeration has been superceded by the Iterator. So the natural choice for the Sling API for methods to return enumeratable collection of objects would have be to declare the use of Iterator instances.

The org. SlingHttpServletRequest interface defines the basic data available from the client request to both action processing and response rendering. The SlingHttpServletRequest extends the javax. This section describes the data available from the SlingHttpServletRequest.

The following information is represented for reference. The SlingHttpServletRequest objects are only valid during the time of request processing.

Servlets and Scripts must not keep references for later use. As such, the SlingHttpServletRequest interface and its extensions are defined to not be thread safe. Be aware, though that Sessions are server side sessions and hence violate the sessionless principle of REST and therefore should be used with care. It is almost always possible to not use sessions. SlingHttpServletResponse interface extends the javax. HttpServletResponse interface and is currently empty.

It merely exists for symmetry with the SlingHttpServletRequest. Resource represents the data addressed by the request URL.

sling api in aem

Resources may also be retrieved through the org. Usually this interface is not implemented by clients. In certain use cases we call synthetic Resource if may be usefull to define a simple object implementing the Resource interface. The Sling Framework does not care about the concrete implementation of the Resource interface and rather uses the defined methods to access required information.

The interface defines the following methods:. Component interface defines the API implemented to actually handle requests. Like those other interfaces, the Component interface provides methods for life cycle management: init ComponentContext contextdestroy. The Content object and a Component form a pair, in which the Content object takes the passive part of providing data to the Component and the Component takes the active part of acting upon the Content object.

As a consequence, there always exists a link between a given implementation of the Content interface and a given implementation of the Component interface. This link is manifested by the Component identifier available from the Content object through the Content. On the other hand, the link is manifested by the getContentClassName and createContentInstance methods of the Component interface. When a Component instance is created and added to the Component framework, the init ComponentContext method is called to prepare and initialize the Component.

If this method terminates abnormally by throwing an exception, the Component is not used.Newbie question, we are doing the same thing with OSGI and sling servlet then what exactly is the difference between both of them Thanks. A component is the fundamental unit of code in OSGi. The concept of Servlets is not specific to OSGi.

I hope this is helpful. Post a Comment. By Anirudh Sharma. In Sling, servlets can be registered as services. A SlingServletResolver listens for Servlet services and - given the correct service registration properties - provides the servlets as resources in the virtual resource tree. Such servlets are provided as ServletResource instances which adapt to the javax. Servlet class. If neither is set, the Servlet service is ignored.

Using Resource Types - Using this way, we use the sling:resourceType property of the node. For this, we need to hit the path in the browser for which the sling:resourceType is the given one. Using Paths - Using this way, we can directly use the path specified in the request and our servlet will be executed. Registering a servlet via a path is relatively easier than registering it via a resource type but it is still recommended to use resource types instead of paths.

Below are the reasons why. If we use paths, then we need to be extra careful as we do not want to give any path randomly. No suffix handling in the path bound servlets. We also need to specify the paths to the servlet consumers and change in the path can have a serious impact. Types of Servlets There are two types of servlets in Sling which are nothing but the classes we need to extend while creating our servlet. SlingSafeMethodsServlet - If we want to use only the read-only methods then we use this.

This base class is actually just a better implementation of the Servlet API HttpServlet class which accounts for extensibility.

So extensions of this class have great control over what methods to overwrite.Sling Models let you map Java objects to Sling resources. Download the package and deploy using package manager. The purpose of this code is to show the community these concepts in action. This community code is for teaching purposes only and not meant to go into production as is. Note: This article is for AEM 6 and 6. That is, when developing an AEM project, you can define a model object a Java object and map that object to Sling resources.

For more information, see Sling Models. The data members Fields use Inject annotations. These data members map to node properties. Consider the following Java class named UserInfo. Likewise, each data member in the UserInfo class is annotated using Inject. This Java class is mapped to a Sling resource, like the one shown in the following illustatration. Notice that the class members in the UserInfo class map to the String properties that belong to the slingmodel node.

This article walks you through creating a Sling Servlet that uses a Sling Model to map to resources. The following illustration shows the output of the Sling Servlet that uses Sling Models. Notice that the values in the node properties are displayed. Note: If you deploy the package that is shown at the start of this artilce, you can skip these steps and read the article to understand the concepts. The following describes each application folder:. To create an application folder structure:.

A CQ template enables you to define a consistent style for the pages in your application. A template comprises of nodes that specify the page structure.Note: To build an application using Apache Sling watch this video. The client can manipulate the resource through the representations provided they have the permissions.

Each message sent between the client and the server is self-descriptive and includes enough information to describe how it is to be processed.

Rule of Thumb:

The hypermedia that is hyperlinks and hypertext act as the engine for state transfer. Stateless Interactions — none of the clients context is to be stored on the server side between the request. All of the information necessary to service the request is contained in the URL, query parameters, body or headers.

Cacheable — Clients can cache the responses. The responses must define themselves as cacheable or not to prevent the client from sending the inappropriate data in response to further requests. Client-Server — The clients and the server are separated from each other thus the client is not concerned with the data storage thus the portability of the client code is improved while on the server side the server is not concerned with the client interference thus the server is simpler and easy to scale.

Layered System — At any time client cannot tell if it is connected to the end server or to an intermediate. The intermediate layer helps to enforce the security policies and improve the system scalability by enabling load-balancing. Code on Demand — an optional constraint where the server temporarily extends the functionality of a client by the transfer of executable code.

SOAP uses services interfaces to expose the business logic. SOAP defines its own security. RESTful web services inherits security measures from the underlying transport. What is sling resolution? The following diagram explains Sling script resolution: it shows how to get from HTTP request to content node, from content node to resource type, from resource type to script and what scripting variables are available. For more information watch this video. The data members Fields use Inject annotations.

These data members map to node properties. Sling is content-centric. This means that processing is focused on the content as each HTTP request is mapped onto content in the form of a JCR resource a repository node :.

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