History of HTL history-of-htl

For long time users of AEM, this document gives the background on HTL, how it replaces JSP, and the change of name from Sightly.

Formerly Known As Sightly sightly

HTML Template Language (HTL) is the preferred and recommended server-side template system for HTML in Adobe Experience Manager. It takes the place of JSP (JavaServer Pages) as used in previous versions of AEM.

HTL over JSP htl-over-jsp

It is recommended for new AEM projects to use the HTML Template Language, as it offers multiple benefits compared to JSP. For existing projects though, a migration only makes sense if it is estimated to be less effort than maintaining the existing JSPs for the coming years.

But moving to HTL is not necessarily an all-or-nothing choice, because components written in HTL are compatible with components written in JSP or ESP. Meaning that existing projects can without a problem use HTL for new components, while keeping JSP for existing components.

Even within the same component, HTL files can be used alongside JSPs and ESPs. Following example shows on line 1 how to include an HTL file from a JSP file, and on line 2 how a JSP file can be included from an HTL file:

<cq:include script="template.html"/>
<sly data-sly-include="template.jsp"/>

Frequently Asked Questions frequently-asked-questions

These are some questions commonly asked by experienced AEM developers new to HTL.

Does HTL have any limitations that JSP doesn’t? limitations

HTL doesn’t really have limitations compared to JSP in the sense that what can be done with JSP should also be achievable with HTL. However, HTL is by design stricter than JSP in several aspects. What can be achieved all in a single JSP file, might need to be separated into a Java class or a JavaScript file to be achievable in HTL. But this is generally desired to ensure a good separation of concerns between the logic and the markup.

Does HTL support JSP Tag Libraries? tag-libraries

No, but as shown in the Loading Client Libraries section of the Getting Started document, the template & call statements offer a similar pattern.

Can the HTL features be extended on an AEM project? extended

No, they cannot. HTL has powerful extension mechanisms for reuse of logic (the Use-API) and of markup (the template & call statements), which can be used to modularize the code of projects.

What are the main benefits of HTL over JSP? benefits

Security and project efficiency are the main benefits, which are detailed on the Overview.

Will JSP eventually go away? go-away

There are no plans along these lines.

What’s in a name? what-is-in-a-name

In AEM 6.0 and 6.1, HTL was referred to as Sightly. Adobe renamed it to HTML Template Language or HTL to clarify what the specification is for and to align with Adobe’s naming guidelines in general. This naming change was effective as of August 2016 and applies to AEM version 6.0 and forward.

To find out more about HTL and a great place to begin is our official Getting Started with HTML Templating Language (HTL) Guide.