 | Level: Intermediate Katie Horn (K4@engineering.phenomenauts.com), Developer, Freelance
15 Apr 2008 The popular open source Zend Framework just got some slick enhancements. Learn
what's new in V1.5 and how upgrades, including Zend_Form,
Zend_Layout, and Zend_View,
enhanced support for GData Web services, and improved Ajax support can help PHP
developers easily roll out cutting-edge Web applications.
A software framework is a collection of code libraries designed to take care of all the
basics required in an application in a standardized way so application developers can
spend their time developing, instead of constantly having to reinvent the wheel.
There are dozens of open source PHP development frameworks out there to choose from, and
of all those available, the Zend Framework is perhaps the most popular.
Zend stands out by putting a huge emphasis on best practices, which appeals to
those of you who value sustainability. Zend also makes a point of constructing the
framework in a remarkably modular fashion: Most of the individual Zend Framework
components can be pulled completely out and used on their own, which appeals to
developers who only need a fraction of the available libraries. Zend's flexibility,
combined with the solid standardization that comes with emphasizing best practices,
makes it a practical framework for a broad spectrum of purposes.
The already-powerful Zend Framework has gained several entirely new components and
component enhancements in V1.5. The upgrades make developing complicated PHP
applications even easier and more maintainable down the road due to the implementation
of standards in things like form-validation routines and even front-end layout
creation. Let's start by taking a look at the Zend_Form component and all it has to offer.
Zend_Form
One of the more exciting additions to the Zend Framework is the Zend_Form component.
Web applications are pretty useless without the ability to take input data and act on
it, and the easiest way to get data from the user is through a form. Of course, forms
can easily turn into the most tedious aspect of developing and maintaining a Web
application: You must validate everything that comes in, make sure it's what you
thought you were getting, and process every single piece of incoming data individually.
All that is assuming you don't have to generate error messages and start the whole thing
over, which, of course, you will — quite a daunting task to perform
manually, without the ability to reuse code.
The new form component does more than simply allow you to create a form and form
elements programmatically. Zend_Form is capable of performing complex validation and
displaying error messages on your form when validation fails.
Using Zend_Form is pretty straightforward. First, the form
object is instantiated, and its action and method are set. Then, form elements are
added to the form object, and form element validators and
filters are applied to the individual form elements. The completed form object is rendered and used in the application, and the results
are validated and filtered. See Listing 1 for an example of a simple form.
Listing 1. A simple form
require_once 'Zend/Form.php';
$form = new Zend_Form(array(
'method' => 'post',
'elements' => array(
'name' => array('text', array(
'required' => true,
'label' => 'Name',
'validators' => array('alpha')
)),
'age' => array('text', array(
'required' => true,
'label' => 'Age',
'validators' => array('digits')
)),
'submit' => array('submit', array(
'label' => 'Send'
))
),
));
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The results of Listing 1 are shown in Figure 1.
Figure 1. The form
Zend_Form comes with the following elements: button, checkbox, hidden, image,
multichckbox, multiselect, password, radio, reset, select, submit, text, and textarea.
Zend_Form is not limited to the elements that ship with it: The built-in Zend_Form_Element class allows you to create your own elements.
You can instantiate the form elements manually and attach them to the form or let the
form object create and instantiate a new form element of the requested type for you.
Every element is individually configurable as required or not, with individual sets of
validators and filters that can be attached to their form elements any time prior to
the finished form being rendered, before or after the individual elements have been
attached to the form object.
There are 19 standard validation types that come ready to use with your form elements.
These validators can check for just about every data type you would regularly need to
collect — from simple data-type verification to regular-expression matching to e-mail
address validation that can be configured to make sure the top-level domain exists, and
has an MX record. By default, when a validator returns false, the remaining validation
checks are aborted, but that parameter is also configurable for each individual validator.
In Listing 1, an alpha-validator was applied to the name field, and the digit's
validator was applied to the age field. When you enter data that fails these validation
tests, Figure 2 shows the results of what happens entirely by default.
Figure 2. The form with failed validation tests
Once the validators are in place, the next step is applying filters. If validators can
be said to act like bouncers at a club, filters behave more like personal stylists:
Filters take the data in a form element, filter out what you don't want to see on the
other side, and pass on what's left. There are 12 standard built-in filter types for
doing things like stripping out whitespace, trimming the alpha from the numeric,
changing text to uppercase, converting special characters to HTML entities, and
stripping disallowed tags. Use a filter when you know the data you want is present in
the field, but it badly needs a haircut and a bit of a makeover.
To demonstrate filters in action on our simple form, let's change the elements array.
Listing 2. Applying a filter to the elements array
'elements' => array(
'name' => array('text', array(
'required' => true,
'label' => 'Name',
'validators' => array('alpha'),
'filters' => array('StringToUpper')
)),
'age' => array('text', array(
'required' => true,
'label' => 'Age',
'validators' => array('digits'),
'filters' => array('digits')
)),
'submit' => array('submit', array(
'label' => 'Send'
))
),
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As you can see, we added a filter to change the name field to all uppercase and another
to strip out everything from the age that isn't digits. Now, when we submit these
values, we see the results below.
Figure 3. The form with a filter applied
When we hit Send, we end up with the following values after they pass
validation and go through the filters, as shown below.
Figure 4. The form after validation and filters applied
The age input, the filter, validator, and required attribute in that particular
combination effectively guarantee a value will pass validation if and only if there's a
digit in there somewhere and that no garbage that might have tried to get in with the
digits will get passed through to the server. It should be noted that the only way to
pass validation on the name field is to give it all alpha-characters to begin with
because, in that case, the filter does nothing to help the value get past the bouncer.
Rendering the finished form can be accomplished in a few ways. The form has a render
method that can be used or echoed directly. Most forms, however, use a Zend_View helper.
Zend_Layout and
Zend_View
The new Zend_Layout and the enhanced Zend_View components in Zend Framework V1.5 are
often mentioned in the same breath and for good reason. Working together, these two
components can be used to successfully decouple the presentation from the controller in
PHP applications and standardize that presentation in such a way that facilitates rapid development and maintainability.
What does that all mean?
It means that a standardized and far less painful method of maintaining a consistent
front end is now available, as long as you go along with the spirit of the thing and keep your code modular.
Zend_Layout does not have to be used with the Model-View-Controller (MVC). As with most
of the Zend Framework, Zend_Layout can be pulled out and used on its own. However, when
it is used with the MVC, it becomes a convenient sort of adapter between Zend_View and the controller, effectively compartmentalizing the
presentation in a two-step view and making site layouts more universal.
Whether you are using the MVC or pulling out Zend_Layout as a stand-alone component,
you will need to create at least one layout script. Sometimes called templates in other
implementations, layout scripts define the basic front-end structure of a Web page, but
instead of static data, they place variables on the page anywhere the displayed data
may differ from page to page (or, more accurately: action to action). These placeholder
variables in the layout script are populated by assigning the values needed in the
layout script to the layout, telling the layout which particular layout script you want
to use and finally rendering it as a page.
The actual rendering is done by Zend_View. So as far as
Zend_Layout is concerned, you
get all the Zend_View functionality for free. Layout scripts should be positively
riddled with view helpers, or you're almost certainly not doing it right. View helpers
are precisely where a significant portion of the convenience and standardization comes in to the mix.
When you have worked out your layout script(s), you can create an instance of
Zend_Layout in your bootstrap and set your layout's configuration options. After it has
been instantiated in this manner, you'll be able to access and reconfigure the Zend_Layout object from the action, via an action helper. Inside the
action, you can change programmatically which layout script you want the instance of
Zend_Layout to use, and re-populate the current variables each layout script will need.
From the controller's perspective, all the data that ends up going to the user simply
get shoved into a handy-dandy adapter, which takes it away to be used in an entirely different scope.
OpenID and InfoCard (Web 2.0)
OpenID is a decentralized identification protocol designed to be used across many Web
sites. Rather than require a correct username and password combination, the user is
prompted for a URL or XRI, obtained from an existing OpenID provider. The provider
performs the authentication. One way the providers are able to perform the
authentication is by requesting an InfoCard. When the provider communicates successful
authentication to the requesting site, that user is considered logged in, and additional
information may be retrieved from his personal URL.
Zend Framework V1.5 supports the use of OpenID and InfoCard, not only as a client site
but as an OpenID provider. These components are completely separate and have no
dependencies on each other. Strange as it may seem, with Zend Framework V1.5, you may
develop an OpenID provider that is not OpenID-enabled or vice versa (which makes more
sense). There is also an InfoCard component built into the framework, which provides
relying-party (or OpenID-enabled) support for InfoCards used in conjunction with OpenID.
Lucene advanced searches
Lucene is an open source information-retrieval search engine, best known for its
full-text indexing capabilities and its ability to search the Internet. The
Zend_Search_Lucene component delivers the functionality of a built-in full-text
advanced search engine to Zend Framework V1.5. It should be noted that while Lucene is a
search engine, it has no crawling capability. You must manually add all relevant
content into the Zend_Search_Lucene's index manually. (See Resources for developerWorks articles about Lucene.)
Zend Framework V1.5 is not the first appearance of the Zend_Search_Lucene component. A
previous version of the search engine had already been implemented. However, the
release of Zend Framework V1.5 does mark a significant upgrade from V1.9 to V2.2. With
that upgrade, the Lucene component gained three powerful advanced-search options.
Both single and multiple wildcard searches are now supported, as are range searches
and fuzzy searches. A range search will look for a value in a specified field between
an upper and lower boundary, and a fuzzy search will look for words similar to
the term supplied by the user. For instance, a fuzzy search on "Mike" might
return "bike" and "mire."
While the Lucene component did get upgraded, the old functionality is still there, and
all pre-existing indexes will be automatically upgraded the first time the enhanced
Zend_Search_Lucene component touches them.
LDAP authentication
Lightweight Directory Access Protocol (LDAP) has only just started to be supported in
the Zend Framework. This is good news for quite a lot of developers who need to create,
say, a company intranet application that uses an existing set of official company
credentials. It is noted in the Zend Framework's current documentation that the current
level of support is really just a bare-bones implementation, delivering just the
minimum functionality required to be able to make Zend_Auth_Adapter_LDAP work.
In your config.ini file, information about your LDAP server is specified.
When the user wants to authenticate, the supplied username and password combination,
along with some additional Zend_LDAP options, are then sent to the LDAP server
specified in the .ini file for authentication. Just like all the other authorization
adapters, Zend_Auth_Adapter_Ldap returns a Zend_Auth_Result as soon as it's managed to get one from the server,
with the following methods: getCode() will return a code for
whatever happened (pass or fail); getIdentity(), which
returns the identity of the authentication attempt; getMessages(), which will only contain messages on a failed
authentication; and isValid(), which will return true if the
user was successfully authenticated.
Nirvanix, Technorati, and SlideShare Web services
Three new Web service components made their way into Zend Framework V1.5: Nirvanix,
Technocrati, and SlideShare.
Nirvanix is an Internet-based file storage system that allows registered users to
store, manipulate, and access files through their APIs. Nirvanix is designed to handle
larger media files (such as video) and make them accessible anywhere you are able to
authenticate over the Internet.
Technorati is a search engine for blogs, and its Web services allow you to make several
different queries against their database, including regular keyword searches,
tag searches, top-tag searches, sum totals of daily blogs featuring a given keyword,
"cosmos" searches that return results that contain links to specific URLs. With
Technorati, you will be able to quickly find out what's hot out on the wire today and stay on top of it.
Slideshare.net is a Web site that hosts slideshows for registered users. With the
Slideshare component, you can embed slideshows hosted by slideshare within your PHP
applications, view slideshows that have been shared with you, and upload new slideshows
to your Slideshare account.
These three components join the list of Web services already supported by the Zend
Framework. This growing library of Web-service components enables you to quickly and
easily integrate content from more than a dozen popular Web sites into any PHP
application. The fact that these Web-service components can be installed individually,
without the presence of the rest of the Zend Framework, will be of particular appeal to
those who are new to the world of PHP development, as well as seasoned PHP developers
who simply prefer working in a different framework.
Next, we'll take look at feature enhancements that are noteworthy updates to features
and components that existed before, but that needed to be modified to better address
the new needs of the ever-changing Internet landscape.
Google GData
The Zend_GData component is basically giant adapter for various Google services that
support the GData API. The revised list of GData services accessible by the Zend_GData component includes:
- Google Base
- Google Blogger
- Google Calendar
- Google Codesearch
- Google Documents List
- Google Notebook
- Google Provisioning
- Google Spreadsheets
- Picasa Web Albums
- YouTube
Perhaps the most anticipated new Web service support in all of Zend Framework V1.5 is
support for the YouTube API. Now, with Zend_GData, you can search through and access
YouTube videos matching a large variety of criteria, access video feeds and
subscriptions, look up user profiles, see all of a particular user's videos and
favorites, and retrieve comments. With the existing functionality, appropriate YouTube
content can be found and integrated seamlessly into your PHP applications.
Currently, the Zend Framework YouTube API support is read-only.
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UTF-8 character support in Adobe PDF
Another improved feature in Zend Framework V1.5 is the addition of the UTF-8 character set
to the native PDF support already provided by previous versions of the Zend Framework. This
greatly increases the number of valid characters, and by extension, the number of
languages supported by the PDF component. Additionally, it is now possible to extract
fonts from loaded PDF files, making incremental updates a whole lot less painful to perform. |
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Improved Ajax support: ContextSwitch helper and REST
Asynchronous JavaScript + XML (Ajax) has had a profound impact on the way information
can be delivered to a client's browsing session. Very simply: With Ajax client-side
JavaScript can request and receive information from an external source without
navigating away from the main window location or reloading. Ajax is heavily used in
Web applications like Gmail, which update information on a fairly constant basis without
reloading the entire window.
Zend Framework V1.5 has improved native Ajax support with the ContextSwitch helper and
the Zend_REST component.
The ContextSwitch helper, part of Zend_Controller, is used to deliver existing content
in a different format or context. For instance, say you had constructed a controller to
create a page, which lists in detail all the breakfasts you had consumed for the past
three weeks. Normally, it would display the page with a layout and view consistent with
the rest of your browser-friendly Web site. Now imagine someone in the world asks if
you can serve up that same list in XML. With ContextSwitch, you no longer have to
create a separate controller. Simply tell the helper that it can display
XML and create an XML view script for it to use instead of the normal context view
script. It will make sure the document extension and headers are
all appropriate and well formed, and serve up all your breakfasts in Ajax-friendly XML.
And now it's even simpler than that: In Zend Framework V1.5, there is an AjaxContext helper that exists solely to switch context to XML specifically for the construction of Ajax responses.
The extended Ajax support continues to expand with the Zend_REST component, which
contains both REST client and full REST server functionality. Zend_REST can be used to
roll your own Web services or access and parse Web services. Of course, XML Web
services you publish can be easily accessed with — you guessed it — Ajax.
Summary
As we have seen, there are quite a few exciting new developments in Zend Framework
V1.5. Some of the updates simply make routine tasks easier to set up correctly than
they ever have been, and other updates make options readily accessible that would have
been otherwise daunting at best to try and cook up by oneself. All of these things help
to put more power in your hands, and that's never a bad thing.
Resources Learn
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See the Zend Framework's Programmer's Reference Guide.
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Read an overview of the new features in V1.5.
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Read the Zend_Layout Component Proposal.
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Read about the shared identity service OpenID.
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Read about Lucene, the free/open
source information-retrieval library.
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The Zend Framework site maintains the latest documentation, as well as installation FAQs.
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For in-depth coverage of the Zend Framework, see the nine-part developerWorks series
"Understanding
the Zend Framework."
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The PHP Function List is a valuable resource.
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PHPPatterns explains MVC from the PHP point of view.
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See the developerWorks tutorial "Apache Lucene
quick-start guide" to learn the ropes of Apache Solr V1.2, an Apache Lucene subproject.
-
See the developerWorks article "Beef up Web search
applications with Lucene" to learn how to create a robust Web search application.
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PHP.net is the central resource for PHP developers.
-
Check out the "Recommended PHP reading list."
-
Browse all the PHP content on developerWorks.
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Expand your PHP skills by checking out IBM developerWorks' PHP project resources.
-
To listen to interesting interviews and discussions for software developers, check out developerWorks podcasts.
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Using a database with PHP? Check out the Zend Core for
IBM, a seamless, out-of-the-box, easy-to-install PHP development and production environment that supports IBM DB2 V9.
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Stay current with developerWorks' Technical events and webcasts.
-
Check out upcoming conferences, trade shows, webcasts, and other Events around the world that are of interest to IBM open source developers.
-
Visit the developerWorks Open source zone for extensive how-to information, tools, and project updates to help you develop with open source technologies and use them with IBM's products.
-
Watch and learn about IBM and open source technologies and product functions with the no-cost developerWorks On demand demos.
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About the author | | | According to her mother, Katie Horn has spent far too much of her 28 years on the computer. She has a degree in computer science from Chapman University, after which she has mostly enjoyed the jobs with "systems" or "engineer" somewhere in the title. Despite a degree of proficiency in the area, she would prefer never again to be called "network admin." |
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