When building reusable components in JavaServer Faces (JSF), developers often choose between composite components and custom classic components. Both approaches have distinct use cases and benefits, depending on your application’s requirements.

What Are JSF Composite Components?

Composite components are XML-based reusable components designed to simplify the inclusion of a group of related tags, components, or HTML into a single unit. These are ideal for:

• Grouping related UI elements into a single component.
• Rapid prototyping and reuse of existing tags/components.

Example Use Case:

You need a reusable form that combines an input field, label, and validation message into one component. This is a great fit for composite components because:

• It requires no custom Java code.
• It leverages existing JSF tags.

Composite Component Example:

<ui:component xmlns="http://xmlns.jcp.org/jsf/component"
              xmlns:cc="http://xmlns.jcp.org/jsf/composite">
    <cc:interface>
        <cc:attribute name="label" />
    </cc:interface>
    <cc:implementation>
        <h:outputLabel for="input" value="#{cc.attrs.label}" />
        <h:inputText id="input" />
        <h:message for="input" />
    </cc:implementation>
</ui:component>

What Are JSF Custom Classic Components?

Custom classic components are Java-based components designed for situations where existing JSF tags/components cannot meet your requirements. These components allow you to create advanced custom behavior and functionality, such as:

• Implementing custom input types (<input type="file">, <input type="range">).
• Adding server-side processing or validations.

Example Use Case:

You need to implement a file upload field in JSF, which is not natively supported. Custom components are the only way to achieve this.

How to Create a Custom Component:

1. Create a Java class extending UIComponent or UINamingContainer.
2. Implement the component’s behavior in Java.
3. Use <cc:interface componentType> to bind the Java class to a composite.

Key Differences Between Composite and Custom Components

When to Use Tag Files Instead

Sometimes a composite component isn’t the right choice. For example, if you want a reusable <h:column> for a dataTable, a tag file is a better option. Tag files are XML-based but are optimized for use in such cases.

Conclusion

• Use composite components for simple grouping and reuse of existing JSF tags.
• Use custom classic components for advanced functionality or when JSF lacks native support.
• Consider tag files when neither composite nor custom components fit perfectly, such as in reusable <h:column> cases.

Would you like examples of tag files or more detailed instructions on creating custom components? 😊

Ahmad Gohar

With over 18 years of experience in software architecture, Java technologies, and leadership, I specialize in crafting scalable, future-proof solutions for global organizations. Whether it’s transforming legacy systems, building cutting-edge cloud-native applications, or mentoring teams to excel, I’m committed to delivering value-driven results.

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