In our last post we introduced the topic of HTML5 for GIS web and mobile developers. This post is a continuation of our HTML5 series of posts.
HTML5 introduces the new concept of ‘semantic markup’.
HTML5 introduces new semantically rich elements that can convey the purpose of the element to both developers and browsers.
In order to arrive at these, the W3C undertook a huge mining operation of billions of pages to see which Ids and Class attributes page developers were using to provide meaning to their <div> tags. After throwing out the nonsensical ones, they saw various usage patterns repeated over and over again and implemented these as brand new elements within HTML5.
These new tags help to provide both structure AND meaning to our web pages as can be seen in the markup sample below.
When to Use Semantic Tags
So do these new elements replace the <div> tag? No, they don’t. But they can provide more meaning than a <div> tag if used correctly – both to developers and browsers.
Bear in mind when using the new HTML5 tags that you are not obliged to use them to make your document valid HTML. In fact, often it won’t make sense to use them. For instance, we probably don’t want to re-purpose our map control, so we can still carry on using <div>s with appropriate ID and class names to define their meaning.
However, these semantic tags are very useful for common page elements such as those in the typical web page structure shown on the left in the image below. Let’s look at some of these in more detail and then we’ll show them in action in a demo.
The <header> and <hgroup> Tags
From the HTML5 spec, the <header> element (not to be confused with the <head> element) refers to :
“a group of introductory or navigational aids. A header element typically contains the section’s heading (an h1–h6 element or an hgroup element), but can also contain other content, such as a table of contents, a search form, or any relevant logos.”
A good place to include a header is at the beginning of your page as shown in the first piece of markup below. But you are not limited to just one header element per page. You can use multiple headers, each of which will then become the <header> for a new section of the document. This is semantic markup in action. Your browser understands how your content is organized and other user agents could re-purpose that content if required.
If you have only got a simple title with a single heading element (<h1>–<h6>), you do not need an <hgroup>.
If you have a title with subtitle(s) or tag lines (i.e., more than one consecutive <h1>–<h6>), group them in an <hgroup>.
If you have a title with subtitle(s) and other metadata associated with the section or article, place both the <hgroup> and the metadata within a single <header> element.
The <footer> Tag
The <footer> tag is similar to the <header> tag in that it can be used in the whole page or in individual sections. However, the footer tag denotes the end of the page or section. (Actually, the <footer> tag does not have to be at the end of the page or section, but it usually is.)
The footer tag can be used to give information about who wrote the section, copyright information and perhaps even links to related resources. Note how we’ve used another new semantic tag in HTML5 – the <address> tag – to include contact information.
The <nav> Tag
Use the <nav> tag to define an area of your page containing major links to other areas of your site.
Not all links need to be hosted within your <nav> tag. For instance, the <footer> element discussed earlier is often used for links to key parts of a site
I think it’s fair to say that there is still a bit of confusion around when to use the <nav> tag. Perhaps a useful test would be this: If you were building your page in HTML4, would you consider including a <div> with an id of ‘nav’ or similar? If so, you probably need a <nav> tag!
The <section> Tag
It’s tempting to use the section element to wrap content to style it, or to somehow distinguish your main content from the other areas of your page such as the <header>, <nav>, <footer> and so on. However this is wrong! You could (and should) use a <div> instead.
In general, a section is just a piece of content which you could store as an individual record in a Content Management System. Not all content lends itself to being a section, so if in doubt just use a <div>.
Here are some rules of thumb for using the <section> element:
Don’t use it just as hook for styling or scripting; that should be a <div>
Don’t use it unless there is a natural heading at the start of a section
Don’t use it if another tag like <article> or <aside> would be a better fit
The <article> Tag
The <article> tag is one of the easiest ones to get your head around. Basically, it’s just a self-contained piece of prose that would still make sense if you took it out of the page and, say, copied it into Notepad. And that’s the whole idea behind the <article> tag, that it could be used to repurpose content.
Think in terms of news stories, blog posts, etc.
The <aside> Tag
The <aside> tag defines content related to but not included in the content that surrounds it.
So to use the <aside> tag correctly, you need to consider what element on the page it is providing more information about.
The W3c recommends the following usage pattern:
When the <aside> tag is used within an article element, it needs to be related to the article.
And when it is used outside an article it needs to relate to the site as a whole.
For more information on the use of semantic tags and other HTML5 topics for GIS web and mobile developers please consider our HTML5 and CSS3 for GIS Web Developers course.
2010 – HTML5 Takes Off
Google, Microsoft and Apple have all been shouting from the rooftops about HTML5 since around 2010 and have already started implementing HTML5 features in the latest versions of their browsers even though the standard won’t be complete for several years yet. You can test support within your current browser at www.html5test.com. Whether HTML5 will be the saving grace of the web remains to be seen. What is certain though is that the public interest in HTML5 is huge and growing all the time.
2015 – Final Specification Due
HTML5 is an evolving standard which is not expected to be finalized until 2015. For an amusing countdown visit http://www.ishtml5readyyet.com. With browser manufacturers competing to adopt HTML5 features right away, this means that there is likely to be a fair bit of discrepancy around how HTML5 is implemented. Nevertheless, HTML5 is here. Whether it will really achieve as much as is claimed remains to be seen, but as Web GIS developers we need to know about this stuff!
So What Exactly is HTML5?
HTML5 is not exactly a new standard, because it really is just a loose collection of enhancements that have or will be made to the HTML 4.01 spec. It’s just easier to refer to these collectively as HTML5.
It’s not like the internet needs to upgrade. Everything that was coded in HTML4 continues to work quite happily without modification. However, as browsers continue to adopt new features offered by HTML5, web developers will be more inclined to use them – either to take advantage of new functionality, or to make it easier to accomplish what they could already do in HTML4.
Key New Features of HTML5
Let’s cover some of the core enhancements offered by HTML5 which developers can start to use right away in supported browsers.
First of all, HTML5 introduces a whole bunch of new tags. Some of these are what are known as ‘semantic’ tags which allow other computers to discover not just what a page element is but what it means which makes it easier to re-purpose content. We’ll cover semantic tags in the next post in this series.
There are new tags for embedding audio and video in a web page without relying on plugins like Flash and Quicktime.
There is improved support for forms such as auto-completion as the user types and automatic focusing on fields to make data entry easier.
There are new APIs, or Application Programming Interfaces too which encapsulate brand new functionality.
The Canvas API allows you to draw rich graphics natively within the browser and apply gradients, fills and other effects.
The Geolocation API can provide the location of a connected device via its IP address, by triangulation with local wi-fi hotspots or GPS (if supported)
Local Storage improves on the current idea of using ‘cookies’ – small data files that are stored on the user’s hard drive to persist session information, user preferences and so on. In HTML5 you can store up to 5MBdata locally, making it possible to improve performance by caching. For example, you could store a document locally as the user edits it before submitting the changed version to the server.
Offline Web Applications – as demonstrated in the past by Google Gears – let users run our web applications without being connected to the Internet. HTML5 coordinates the download of all the data they need and its subsequent upload when they are back online.
In the next post in this series we’ll cover semantic markup in HTML5.
There are essentially three types of mobile application development including native, web, and hybrid solutions. What most people associate with mobile applications or apps are native applications. These are applications developed specifically for a particular mobile operating system platform. For example, most people associate apps in the Apple Store as native applications. As we’ll see this isn’t always the case though. Web applications developed for the mobile platform are run in the browser on the mobile device (Safari for example). Finally, Hybrid applications are a combination of the two, and as you’ll see they may well be the preferred method of mobile application development for most applications moving forward. In this post we’ll examine each of these application development types.
Native Mobile Applications
Native applications are developed specifically for the mobile device that it will be run on. For example, applications that you download from the Apple Store are often native applications for the iPhone or iPad. Different languages are used to develop these native applications. Applications developed for the iOS are created with Objective C, C, or C++. Android applications are developed with the Java programming language. These applications will run more efficiently than web or hybrid applications because they are compiled specifically for the operating system where they will run. Natively developed applications can also use all the phone’s features including the camera, geolocation, the users’ address book, and more. You don’t have access to all these functions when developing web mobile applications.
As I mentioned, native application development must use the language specific to the platform for which you’ll develop the application. The most common mobile development environments and their programming languages are illustrated below.
Native Application Development Process
The source code for natively developed application is written in the specific language for the platform being used. This course code is then compiled into an executable file. This is similar to traditional desktop application development. Any resources that need to be bundled with the application are then combined with the binary output from the compiler to produce a distribution package. Resources are typically things like images and icons that are used in your application. The distributable package is then ready for inclusion in the app store specific to your environment. App stores vary in their requirements for applications, but all include some sort of approval process which can be time consuming.
Image from Worklight.com
Native applications have full access to the operating system API on which they are developed. Your source code makes calls into the OS specific API to access the various services available on the platform. This will vary by platform, but all natively developed applications have full access to the functions provided. This includes functions such as data storage, location, camera, speaker, microphone, and others.
Image from Worklight.com
Native applications have a number of advantages. As I mentioned these applications have full access to all features of the mobile device so they are able to offer the full range of functionality. Native applications also do not have to be connected to the web to be used. They can be used in offline mode. In contrast, web applications always need access to the internet. This is changing though as you’ll see later. Finally, native applications get good visibility with consumers because they are distributed through the phone manufacturer’s app store.
There are also a number of disadvantages associated with natively developed applications. Because they are developed for a specific platform (operating system and device) the number of users that can be reached is restricted. For example, if you develop an application for Android devices, Apple users will not be able to access the application unless you specifically write the application for the iOS. This can lead to a lot of duplicate work. Third party approval can also be barrier. You have to wait for approval for the application to be published to the app store so you have limited control over the timing of the distribution. All of this means you’re duplicating work on different patterns. This can be time consuming and costly.
Mobile Web Application Development Process
The web application development process is quite different from native applications. Applications are run through the browser on the mobile device. In this case there is no need for an app store since the application runs through the browser instead. One of the drawbacks of using this type of development process is that you don’t have access to the full array of operating system functions provided by the mobile device. In fact, this set of functions is quite limited on many devices.
Image from Worklight.com
There are some disadvantages to using a mobile web application development process. The primary disadvantage is that you can’t make use of many of the phone’s built in features such as the camera or the address book. They also can’t be deployed to the phone’s marketplace which limits the visibility of the application in some ways.
Hybrid Application Development Process
Image from Worklight.com
PhoneGap has two primary tasks. First, it enables you to take an existing code base and deploy to multiple mobile platforms. This is quite important as it removes the need to re-develop an application for each platform that you intend to use. PhoneGap also provides access to the operating system functionality provided by the mobile device.
Image from Worklight.com
HTML5 is in widespread use in mobile web application development. The top supported features of HTML5 on mobile devices include audio and video, geolocation, offline web application support, web storage, CSS3 selectors, and 2D animations. For an extensive look at mobile compatibility with HTML5 features please visit the link provided on this slide.
This smaller footprint is a great choice for mobile applications including the iPhone and iPad. There are two primary differences between the standard and compact builds of the API. First, the compact build only loads objects that are needed for your application. For example, if you don’t need a Calendar widget then it’s not loaded. The second difference is that the compact build only loads 32 code modules instead of the 80 modules loaded with the standard Dojo build. If you need to use a code module that is not downloaded as part of the compact build then you can use dojo.require to load the specific module you use. You’ll also notice that various user interface components have been altered to make them easier to use on a mobile platform.
So, at some point you will need to make a decision on what type of application development process you intend to use for your application. Your choice may vary depending upon the needs of the application. Considerations include time, budget, and resources available to develop each solution. In general, native applications cost more and take more time to get to market, but the user experience is often better in terms of functionality and performance. Web applications, while they tend to cost less and can be developed more quickly don’t have quite the user experience as they don’t run as fast nor do they have access to the full capabilities of the platform. Hybrid applications provide an excellent alternative by combining the best features of both platforms.
Building Mobile ArcGIS Server Applications
It’s obviously a lot to learn, but our new Building Mobile ArcGIS Server Applications course is designed to get you up to speed with developing hybrid mobile GIS applications. By the end of this class you will be well on your web to developing some great mobile GIS applications. The first session begins April 16th, 2012.
The first session of our Building Mobile ArcGIS Server Applications course will be offered beginning April 16th and runs through May 18th.
There are a tremendous number of mobile application development platforms including iPhone, iPad ,Android devices, Windows 7 devices, Blackberry, and others. Developing applications for each of these platforms can be a time consuming, frustrating process. It is not uncommon to develop the exact same application multiple times; once for each supported platform. What a waste of resources!
* HTML5 and CSS3
* DojoX Mobile
* Capstone Project
The next session of our ArcGIS Server Bootcamp begins February 13th, and we still have a few
seats available for this popular course.
The bootcamp includes the following sections:
This course is taught in a web based format. All materials are available 24×7 and you have
access to the instructor to answer any questions or problems as you work through the materials.
Register by January 31 to take advantage of our early registration price of $799.
The price increases to $999 after that date.
Get free access to the first module in our Programming the ArcGIS Server API for Flex here.
Price for each course is $567 through Oct. 26th. Price increases to $715 after this date.
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Today we are pleased to announce that our Web Mapping Programmers Bundle is now available for purchase.
This bundle of courses will be made available on Monday, July 18th. Links to each of the courses will be sent out on that date.
Through July 22nd you can pre-purchase this bundle for $299.00. After July 22nd the bundle will sell for $399.00.
The next session of our ArcGIS Server Bootcamp begins July 11th and runs through August 19th. The early registration price of $615 is good through June 25th. The regular course price is $999.
We still have seats available.
This is a self-paced, instructor guided course. You do have access to the course for a full year so you can go back and review as necessary or take some extra time to complete the materials if your schedule doesn’t allow you to finish during the course session.
During your one year of access to the course materials you also receive any updates to the course free of charge. This will include our Introduction to Managing ArcSDE course materials slated for completion late this summer.
The bootcamp currently consists of two sections (soon to be 3 with the addition of our ArcSDE