Xebra Documentation

Revision as of 15:19, 29 June 2009 by Sandrod (Talk | contribs) (→‎Example)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

1 Architecture Overview
2 Website Development
3 Xebra Libraries

Architecture Overview

(img)

The Xebra HTTP Plugin (Apache Module or IIS7 Handler) forwards a request from the HTTP server to the Xebra Server and waits for a response.
The Xebra Server forwards a request to the appropriate web application.

Website Development

(img)

The web designer creates xeb files with a html editor. Xeb files consist of html code with The web

Xebra Libraries

Page

The page libraries consists of the core tags needed for page configuration and composition. The Tags are:

Tag	Description
<page:controller class="..." />	Defines the controller which should be used for the xeb page
<page:declare_region id="..." />	Declares a region at the specific point in the xeb page
<page:define_region id="..."> ... </page:define_region>	Defines a region from a template, can only be used inside a page-include tag
<page:include id="..." />	Includes a template
</page:fragment>	If used the page is not transformed to a servlet

Example

This example shows the workings of the template framework. It consists of a master page which acts as a template and three different types of usage of this template.

master.xeb

<html>
<page:controller class="DEFAULT_CONTROLLER"/>
<body>
<h1>
<page:declare_region id="greeting" />
</h1>
<page:declare_region id="form" />
</body>
</html>

The master page is "deferred", since there are page:declare_region tags. The translator detects the undefined regions and doesn't generate a servlet from this xeb file.

slave1.xeb

<page:include template="master">
    <page:define_region id="greeting">
    Hello, I'm Slave 1
    </page:define_region>
    <page:define_region id="form">
    Other region
    </page:define_region>
    </page:include>

slave2.xeb

<html>
    <page:controller class="SLAVE2_CONTROLLER" />
    <page:include template="master"
       <page:define_region id="form">
        Other region 2
        </page:define_region>
    </page:include>
    </html>

slave3.xeb

<page:include template="slave2.xeb">
    <page:controller class="SLAVE2_CONTROLLER" />
        <page:define_region id="greetings">
        </page:define_region>
    </page:include>

With these techniques we would be able to minimize duplicated code and hence errors in the xeb files, which are difficult to debug.

This code will generate exactly three servlets, SLAVE1_SERVLET.e , SLAVE2_SERVLET.e and SLAVE3_SERVLET.e. master.xeb and form.xeb are fragments. SLAVE1_SERVLET inherits the controller from the master page, while SLAVE2_SERVLET "overwrites" this definition and uses SLAVE2_CONTROLLER. All the pages which are deferred (like master.xeb) are not compiled to servlets. Neither are pages which are denoted with the tag page:fragment. Template pages could be used to differentiate views based on roles. For instance one could think of roles like 'guest', 'user' and 'admin'. 'guest' and 'user' would then have pages which inherit from a 'master_page', implementing their own menus. 'admin' in contrast would inherit from 'user', since it is a user with additional rights. So it would have to extend the menu and contents. Sub pages which have been added through page:include could act as master pages as well, further encouraging code reuse.