- We design and build extraordinary applications for companies looking to make the next great idea a reality.
- learn more
Upcoming Conference: FITC Chicago 2008, June 22-23
Another Chicago area conference coming up: FITC Chicago 2008, from June 22-23 at the Chicago City Centre Hotel & Sports Club, 300 E. Ohio. We're even supporters. 
So what is it beyond the platitudinous "design and technology" event?
Obviously there's going to be lots of talk about how to develop Flex and Flash applications. Also how to develop online/offline apps with Adobe Air. Heck you'd think Adobe was a sponsor. 
If designing RIA's with Flash/Flex/Air is your thing, you want to be here. It's not free, but based on last year's event, well worth the $125-$250 (depending on which sessions you go to).
Update: If you sign up here with our special ninja supporter code of PATH15, you get 15% off.
Topics: Adobe, Adobe AIR, Announcement, Conference, Design, Flash, Flex, Web/Tech
.NET Interface does not allow static/const/readonly fields
In Java, it is perfectly fine to declare an interface with static-final properties as follows:
public interface QuestionFactory
{
public static final int QTYPE_INPUT = 1;
public static final int QTYPE_RADIO = 2;
public static final int QTYPE_CHECKS = 3;
public Question createQuestion(int questionType);
}
This cannot be translated in to .NET as. The following won't work:
public interface IQuestionFactory
{
// won't work in .NET (Err: Interfaces cannot contain fields)
public static readonly int QTYPE_INPUT = 1;
public static readonly int QTYPE_RADIO = 2;
public static readonly int QTYPE_CHECKS = 3;
public Question CreateQuestion(int questionType);
}
The general recommendations in such a scenario is to externalize the const(s) in another class.
public class QuestionType
{
public const int QTYPE_INPUT = 1;
public const int QTYPE_RADIO = 2;
public const int QTYPE_CHECKS = 3;
// disclaimer: I used "const" 'cause I wanted to use it in switch/case.
// However, I assume "static readonly" could have been used as well.
}
Why is this so? The notion seems to be that interfaces cannot have states (they are stateless) and hence do not allow fields. Coming from Java world, I am not entirely sold on this argument though. I prefer one interface with all static readonly/final fields as well method-contracts (that consume those fields).
One may argue use of enum instead of int(s)... but that is a different discussion.
Topics: Web/Tech
The Problem of Encoding H.264 In a Flash Client
Flash Player 9 introduced the ability to decode H.264 video format. However, it cannot encode video as H.264 (although it does encode as H.263).
This is a problem for people who want to take advantage of H.264's ability to encode at a higher quality with a lower bitrate. There are a few vendors out there who propose to offer a solution, but some of the solutions require an extra download which isn't necessarily cross platform.
With the release of AIR, Adobe seems to be targeting the Desktop market as one of their future goals. Many existing desktop applications already support H.264 encoding (see iChat for a good example). If Adobe wants to keep up with the desktop application market, it might be prudent to add support for encoding as H.264 soon.
Topics: Web/Tech
.NET 3.5 Linq to Sql and IBatis.NET
I've been looking at some of the new features in the .NET 3.5 framework and have found Object Relation Mapping (ORM) very similar to IBatis.NET and NHibernate. In .NET 3.5, they use attribute based mapping between the underlying data table and entity class (Domain Object). For instance
using System.Data.Linq;
using System.Data.Linq.Mapping;
[Table="Books"]
public class Book {
[Column="Name"]
public string _Name;
[Column="ISBNNo"]
public string _isbn;
...
}
What you notice is the the class Book is mapped to a table called Books using the Table attribute and particular table columns are mapped using the column attribute on the Book class instance fields. Compared with IBatis.NET XML files; you would have to:
- Reference the Book class using the <typedalias type="Namespace.Book, Namespace"/>
- Create a ResultMap that exposes the Book class internal fields using <property name="ISBN" Column="ISBN">
- Create the sql statement that references the resultmap for the Book class so IBatis.NET and hydrate the results. Below is sample sqlmap.xml file for Ibastis.net
<sqlMap namespace="Surveys" xmlns="http://ibatis.apache.org/mapping">
<alias>
<typeAlias alias="Book" type="Namespace.Books, AssemblyName"/>
</alias>
<resultMaps>
<resultMap id="BookMap" class="Book">
<result property="Name" column="Name"/>
<result property="ISBN" column="ISBN"/>
</resultMap>
</resultMaps>
<statements>
<select id="GetBooks" parameterClass="map" resultMap="BookMap">
select name, isbn from books
</select>
</statements>
</sqlMap>
Furthermore, much of the guesswork required to create the parameterizes queries used to pull information from the database and load a collection of Book objects has been added. Simply creating a new Linq DataContext object, passing the connection string to the database and calling the generic GetTable<T> (where T is class name. in this case Book) is all you need to get the results, versus creating the individual sql in the xml file and calling one of the QueryForObject or QueryForList methods found for IBatis.NET.
Last but not least, Linq provides the programmer with built-in sql like keywords used to build expressions that sort, aggregate and limit the original result set to some more specific or limited result result set without going back to the underlying database.
Although, this is a very simplicity view of mapping a database table to .NET class. This does give you a good picture to the additional overhead required to using IBatis.NET xml file mapping versus Microsoft's Linq to Sql attribute base mapping, and demonstrates how ORM is now built right into the .NET Framework. And, you be happy to know that your .NET 3.5 Linq to Sql applications will still run on .NET 2.0 because the new features are specific to the specific 3.5 .NET compiler.
Topics: Web/Tech
Callback interfaces in Java == delegates in .NET (a Java developer’s journey into .NET world)
After several years in Java/J2EE world, I recently started working on a .NET project. The motivation was to get to know the pros and cons of both world and leverage better ideas from each going forward.
Having used Apache Commons/Collections in Java, I longed for similar library in .NET. I am not sure if one already exists (quick google didn't turn up any result). However, considering that fact that Commons/Collections uses Callback interfaces a lot, it was clear that any such attempt would leverage .NET's "delegate" feature extensively. I couldn't resist trying to implement it myself. Here is what I ended up with.
So, in my case, I wanted CollectionUtils.collect() method, which transforms a list of object into a list of some other type of objects. This is a handy utility to unwrap/wrap an exising list into another list. So, for example, I have a List<StringWrapper> object in which each StringWrapper object is simply a wrapper around a "String" object. And let's say that I need to get a List<String> from List<StringWrapper> object.
In Java's Commons Collection I would use a call like this:
class StringWrapper {
public String a;
public StringWrapper(String a) {
this.a = a;
}
}
...
List<StringWrapper> aColl = new ArrayList<StringWrapper>();
aColl.add(new StringWrapper("x"));
aColl.add(new StringWrapper("y"));
aColl.add(new StringWrapper("z"));
List result = CollectionUtils.collect(aColl, new Transformer() {
public Object transform(Object o) {
return ((StringWrapper) o).a;
}
});
...
Here CollectionUtils.collect() would be something like (a very lame version of what is in Apache's Commons/Collection library):
class CollectionUtils {
public static <T, N> List<N> collect(List<T> list, Transformer<T,N> transformer) {
List<N> result = new ArrayList<N>();
for(T t: list) {
result.add(transformer.transform(t));
}
return result;
}
}
// Callback interface
interface Transformer<T,N> {
public N transform(T o);
}
In .NET, we could replicate this code 1-for-1 and get the same result. However, .NET's delegate keyword helps cut the fat and provides for a lean implementation as follows:
public class Collections
{
// a 'delegate' defines a method signature. Any method with same method signature can be used as callback method.
public delegate N Transformer<T,N>(T o);
// a function that takes a delegate method whose signature is declared by 'Transformer'
public static IList<N> Collect<T, N>(IList<T> originalList, Transformer<T,N> transformer)
{
IList<N> returnList = new List<N>();
foreach (T oo in originalList)
{
returnList.Add(transformer(oo));
}
return returnList;
}
}
Here, a delegate is like an abstract method and my concrete implementation could be like:
string transform(StringWrapper str) // this method's signature should match the delegate declaration
{
return str.a;
}
And the client call then becomes:
...
IList<string> result = Collections.Collect<StringWrapper, string>(listOfStringWrappers, transform);
...
Or I can do away with an anonymous delegate implementation as:
...
IList<string> result = Collections.Collect<StringWrapper, string>(listOfStringWrappers, delegate(StringWrapper str) { return str.a; });
...
Topics: Web/Tech
Qualification of a Pair Programmer: A Good Listener
Be a Good Listener. We've all heard this phrase. As I experienced recently, it applies readily to pair programming as well.
I am currently helping a student learn Java while she is taking an algorithms class. Having had teaching experience in the past, I was able to teach her the basic stuff fast and well. It was mostly a one way street where I talked and she listened. As she grew more comfortable with Java, she starting asking non-trivial questions. I quickly realized that it was no longer a one way street. I had to make conscious effort to not discount what she said/asked and say what I had to say. It took us longer to arrive at a solution _together_ if I talked more than I listened. I had to resist the temptation to arrive at a solution _alone_ and bring her along; at her speed. To bring her along, I had to listen more and make an effort to understand what she understood and where she missed. This may seem counter-intuitive but I realized that it was best (in terms of code quality and long term sustainability of happy pairing relationship) when I listened to her and gave her just enough information to find her way instead of imposing my way onto her.
I understand that pairing with a newbie is distinct from pairing with your co-developer. But still, being able to align yourself to someone else's thoughts goes a long way in achieving better results.
Happy Pairing !
Topics: Web/Tech
Plug: Designing Invisible Interfaces Webinar
My colleagues Matt Nolker and Shalom Sandalow have put together a nice little webinar entitled "This Won’t Hurt a Bit": Designing the Invisible Interface.. For those of us writing Web 2.0 applications, there are some key insights here, such as: "interacting with the software is not the primary goal or responsibility of the user." So when you use those nifty Ajax widgets, think about whether you are placing a usability burden on the user or are using the power of Ajax to make the interface disappear.
Technorati Tags: uxd, webinar, invisible interfaces, usability
Topics: Web/Tech
Hibernate Gotcha: java.lang.IndexOutOfBoundsException: Remember that ordinal parameters are 1-based!
This can occur for several different reasons. For example, http://opensource.atlassian.com/projects/spring/browse/SPR-1598. Here is how I came across: Missing hibernate mapping file (hbm.xml) in hibernate SessionFactory.
When we forget to list a hibernate mapping file (*.hbm.xml) during SessionFactory creation, it usually fails fast. This fail fast happens since there is another domain-entity mapping that has many-to-one relationship with this class. However, if a given domain-entity is not being referenced by any other entity mapping file, then Hibernate (obviously) will have no knowledge that this entity-exists.
This is fine, but you expect your query to fail with proper error message when any hibernate query method is called in relation to an unlisted entity. For example, I have a User entity in addition to many other entities. For the sake of argument, let us say that no other entity refers to User entity. So, if I list hibernate mapping files (*.hbm.xml) for all entities except User.hbm.xml, SessionFactory creation won't fail. This is fine since SessionFactory has no magical way to figure out how many entity-classes should have their mapping defined and listed.
However, it should fail when I call methods like Session.createQuery("from com.package.User as s where userName=?"). You would expect Hibernate to fail-fast and complain about un-mapped class (com.package.User in this case). It doesn't. Under these circumstances, trying to execute hql query with positional parameter gives "java.lang.IndexOutOfBoundsException: Remember that ordinal parameters are 1-based!". Trying to run query with named-param will result in 'org.hibernate.QueryParameterException: could not locate named parameter [<paramname>]". None of these errors say anything about the unmapped entity.
Topics: Web/Tech
The BA’s Role on the Agile Team
Wow!
We just changed the model for our current big project, and it's no wonder I thought the BA Role was undefined.
I had been acting as an assistant-deputy-associate project manager, technical writer and QA Manager. Whatever the project needed, by gosh, was OK by me, and still is.
The side benefit is it makes it seem like I'm multi-talented, a very good thing come review time.
But now (drum roll please) there's a defined role for the BA.
Go figure.
In order to get the the base functionality up and working, the pragmatic approach worked very well.
But now, the client needs and wants control of the features, enhancements and repairs for the system to meet the business needs. Right up our alley.
We're moving from month-long sprints into two week sprints.
Sooooo, the first week into the current sprint, the IA and I discuss the requirements with the client for those items likely to be included in the next Sprint. We write 'em up and we frame the wires and get verbal client sign off that first week.
If it's a biggie, I'll slap a functional spec together with the IA's wire frames and work flow requirements.
If it's small, I set it in the issue tracker as an improvement with th details in the description field (I always wondered what that field was used for).
If the developers need more detail or discussions with users, I act as a liaison to get that happening without the client getting barraged by hundreds of IMs and e-mails.
I think I'm going to wish I was issued a stick.
But I gotta make that happen for the DevTeam, otherwise we can't produce what the customer wants.
The second week, I run the requirements by the DevTeam Lead for a sanity test. I'll probably flunk, but better to revise and have items really ready for the Planning Session on the second Friday.
I post the client's wish list in the wiki (can't get away from that dang tool, can I?) by Wednesday of the week before the sprint start.
It says here in The Handy Dandy Agile Methodology Handbook for the Perplexed that the developers have to read them!
In the SPrint Planning/Negotiating/Teeth-Gnashing Meeting on the Friday before the next sprint starts, the Customer ranks the items s/he wants in the sprint.
The DevTeam then huddles, makes interesting noises and then sets team estimates (kinda like liar's poker when you watch it) and commits to a list it can handle.
Me and the PM then negotiate with the Customer to come up with a final list.
We break for coffee and a smoke and then go through a Post Mortum of the sprint just ended.
Here, everyone has to talk and discuss process (not people or finger pointing- as much fun as that might be)- including the customer and his/her team. Fair's fair, right?
If an item's actionable, the PM and I will meet with the appropriate lead and figure out some mitigation strategies or process change.
Then we're off to the races for the next round.
So, the BA's role in an Agile Project isn't all that different from other methodologies.
While 'control' of the project is now in the customer's hands, defining requirements and disseminating them differs only in that we're doing 'just enough' rather than 'kill hundreds of acres of trees with Word.'
Since the developers and the customers aren't running everything through the BA or IA (typical waterfall), we loose the 'translator effect' that intrudes every time technicalese is translated to rich bidness language and vice versa.
Even so, the BA is there to help both sides meet and mesh an understanding both sides can live with and understand.
The complexity is increased with an IA on board, but that complexity is more than offset by the IA handling project foundation work like 'task flow' (work flow to us BA-types) and they can whip up wire frames faster and prettier than I can. Those benefits combined with actual design to make the end user's job easier and more intuitive is well worth the the minor complexity issue.
With that big stick, I think I want a regulation Referee's Shirt as well.
<ding> <ding>
Next Round
Powered by ScribeFire.
Topics: Web/Tech
Afraid of LIE (LazyInitializationException)… Don’t Be.
All the fuss around LIE reminds me of my days when I was scared of NPE (NullPointerException). No matter how hard I tried, I just couldn't write code that couldn't run into NPE. Slowly, I learnt that it is not a question about not running into NPE, it is about implicit awareness about the possibility of any reference being a null at any given place and time in code. Isn't LIE very similar to NPE in that way?
Folks are afraid of switching from Hibernate 2.0 to Hibernate 3.0 because their app starts throwing LIE everywhere as soon as they do. So, instead of trying to figure out the reason for this. They switch back to 2.0.
Follow these simple rules and we can avoid LIE in most places:
- Use OpenSessionInViewFilter (OSIV), it is your friend (as described here and here): Atleast in web applications, this ensures that you have a valid session in all layers - controller, service and finally view. One argument I came across recently against OSIV-filter is that it couples your application with Hibernate and makes it harder to replace persistence layer with some other persistence mechanism. An interesting thought! But does it really stick? Think about it. Any persistense framework will either not use lazy loading (like hibernate 2.0 did) or have some mechanism for loading object on demand ("lazy" that is).
- Avoid keeping reference to a hibernate managed entity outside of a hibernate session: If you need to keep an object around longer than a request (http-request or any other request), create a data-transfer-object out of your hibernate object. There are few common situations where this occurs most often. Currently Logged in user's information is retrieved from database when the user logs in and is kept in HttpSession. It is very easy to get into the habit of modifying this User object in HttpSession and trying to save it which will run you into Hibernate Merge issues. The easier (and Hibernate mechanism independent) solution is to create UserDTO and keep that in HttpSession. Another common situation is when you need to use caching to reduce database load. Again, why not use DTO(s) inside cache and not hibernate managed entities. It can be argued that this promotes struts action-form like anti-pattern ("bridge" anti-pattern?). However, I prefer keeping a known entity (fully initialized with a controlled hierarchy depth) around than a magical entity (hibernate object that may not have been fully initialized).
Just like NPE, once we ensure that an open connection to database (hibernate session) exists whenever we deal with a hibernate managed entity, we can avoid LIE.
Topics: Web/Tech
Wiki? I Don’t Need No Stinkin’ Wiki!
So my first project here at PathFinder Development is to move an existing application from .NET 1.0 to 2.0. Seemed simple.
I started the usual As-Is Decomposition modeling while looking at the existing application.
It turned out to be a prototype that didn't type.
Hmmm.
OK, abandon As-Is and concentrate on To Be.
The Functional Requirements template worked just fine in Word. Everybody loved it. Everybody thought it was real snazzy. Of course it was. I'm the English Major Alice referred to in her fine blog on Design.
Everybody, that is, except our Technical Architect.
"I want you to put this on our wiki," he said calmly.
????
"And we'll all be able to edit it."
!!!!
I'm the document master on this project, Mister. I determine what the developers see and how they see it. I create the catalogs, baby. I talk to the customer, dude- keep the developers behind that curtain- they might pull out a slide rule when the suits are around. I'm the technical to business and business to technical translator, fella. I run the JAD sessions and the interviews, pal.
Well. I've only been here a coupla weeks. And they're payin' me real good. And they seem pretty smart...
So as I was groaning and moaning learning the new tool, and doing it over to the technical guy's satisfaction (who ever allowed a developer or Technical Architect to have an opinion on formatting and word use? You ever try to read one of their documents?).
And then did it again to satisfy the slave driver.
The he rubbed salt into the wound by telling me to add <previous> and <next> links at the bottom of each page.
I tricked him.
I looked at the mark-up language for our instance and found some cool tags that generated them automatically. Hah!
If I post this, I thought, and anybody on the team can edit it, what the heck do they need me for? Mebbe it's time to get the old resume revised, even though I've only been here a few weeks.
"You'll write the Functional Specifications and we'll all edit them as we develop the feature," My team-mate turned Agile Coach told me.
Oh. I'll add the use cases, data maps and controls to these 'Specifications.' Yeah, I can see how that'd work.
"No, we don't long use cases that no one will read- plop in some activity diagrams, we'll list the use cases as 'scenarios' and you read up on User Stories."
!!!
"Agile is 'just enough' documentation," he said patiently, "Read up on that, too."
$%^#@!
My hesitant, but analytical hold on the world started caving in.
None of my closely held writing, analysis or PM skills were being used, much less valued, in this Agile stuff.
It was akin to moving from the world of daily journalism into a help desk- all the moves and instincts I used in news were, at one fell swoop, totally and absolutely wrong.
- I know UML I cried out.
- I can split a 45 page Use Case into 13 different documents and set them all at different levels!
- I can create To-Be and As-Is Decompositions PowerPoints that make people cry!
- My Vision and Charter documents are so clean there no one sues anyone else, I declaimed.
- My VISIO charts are animated art works fer gosh sakes with drop shading and colored boxes so the executives has something in color to look at.
Then I started to read. I like getting paid regular.
I started with the Manifest for Agile Software Development.
- People oriented. Hmmm.
- Working Code? Never been on a project that actually worked the first time to the customer's satisfaction.
- Actually listen to the people who use it? I've been demanding that since I started this BA stuff.
Not bad.
Went to the links.
- Iterative- excellent- works best that way.
- Feature driven with add ons as able- just the way I've designed in the past.
- Self-organizing? Only high level folks? WOW!
Cool.
Got me some books.
- Good for small to medium sized projects- coordination and traceability issues otherwise, makes sense
- Scrum? Who invented that word? Oh. Rugby. Nasty game. Ah, everyday status/obstacles/plan- good idea.
- Prototyping with actual code? Great Idea.
- User Stories? Hmmm. makes a lot of sense- after all, we're not gonna use this...
Excellent.
But no mention of the need, want or value added to the Agile Team by a Business Analyst or User Experience except for some upfront JAD or interview work in Iteration Zero.
"That's because they had customer buy-in at the start with dedicated, empowered customer buy-in," The suddenly wise and no longer job threatening Agile Coach explained, "You're gonna do much of that with interaction with Subject Matter Experts and our User Experience team member as we implement this feature."
Um, How do we handle Scope Creep?
"We only deal with the feature we did last week (bug fixing), what we're working on now (design, specification and code) and what we're going to do next week," My Agile Coach explained, "And we let the visionary blog, add to the wiki in a Blue Sky section to his/her heart's content, but we only deal with that stuff as we begin designing that feature."
Mark Twain was right, your father seems like the biggest dope in the world when you're 18 and you become amazed athow smart he became in 7 years when you're 15. This turn around only took a month or so.
Ah. Thank you Sensei.
Next Up: My First Agile Project's Process Flow
Powered by ScribeFire.
Topics: Web/Tech
Writing Technical Requirements: The First Commandment
Business Analysts seem to come from two areas:
- Developers who want to be Writers
- Writers who want to be Developers
Coming from the second group myself, I've often been asked to help neophyte writers improve their skills. Trading writing tips for tech points is a good thing for me since I can abstract and write from today until tomorrow- but unless I understand what I'm writing about, it's more than obvious. Hence my 'quickie writer's course, the Ten Commandments to Writing Technical Requirements.
Here's the First Commandment:
I. Thou Shall Always
Address the Audience's Needs
You have three major audiences for and Requirements
Documentation:
- · Developers/IT Professionals
- · Business and Project Managers
- · Quality Assurance Staffers
Each audience has a different educational and experiential background and their own jargon.
To address each audience's needs, follow these guidelines:
1. Eliminate
jargon. You may know what SQL means,
but the VP of Order Management may not and you do not want to make that person feel inadequate nor do you really want to explain what SQL is- I usually say 'queries the database' and leave it at that.
2. Clearly
and effectively organize and label the elements of your document. We'll get into this very important area in a future blog, suffice it to say here you can get a big head start by:
- Splitting your material into logical groups your reader can easily understand
- Properly labeling each group so your reader can scan the doc to find what s/he wants.
- Use an outline- revise the outline when needed, but use it.
3. Use
consistent terms and phrases throughout the document. Don't call it 'The Application' in one are and 'The System' in another. pick one and stick with it.
4. Eliminate
buzzwords. Don't use 'initiate' when you mean 'start.' Don't use 'terminate' when you mean 'end.' And, one of my pet peeves- 'entitle' is not a fancy word for 'title.' If you are entitled to something- it means you deserve or earned it.
5. Avoid
clauses. If you need to use one, put it at the beginning, but not in the middle since the reader can't parse it that well, or end of a sentence, if you use one clause in a sentence you can put it at the end, but that should be your second choice. See what I mean?
6. Avoid
passive voice- see Commandment V. For now, just remember "Boy paints the fence" is ACTIVE voice and "The fence was painted by the boy" is PASSIVE. Note both sentences mean exactly the same thing. It has nothing to do with verb tense, it has to do with who's doing what in the sentence.
7. When
using the command form, use "must," not "shall."
"Shall" is regal and antiquated. Better yet- ignore all those 'The System must....' statements entirely and just start writing after the word 'must.'
Writing is organized thought. If you can design it, you can
write it. Write it as though you were explaining it in a conversation with your
non-technical parent. Except my mother. Ain't no way that'll happen. In such a case, you do not talk down to them,
but try to make them understand.
This is the first rule of any writing.
Next Up: Knowledge.
Topics: Web/Tech
An Interview with ZK Creator Tom Yeh
Anyone who has been following the development of AJAX frameworks has heard of ZK, the server-side component GUI framework that allows you to write applications like you would a desktop app. It has become one of the most popular projects on sourceforge and has been nominated for a 2006 Sourceforge.net Community Choice Award.
Recently I talked with one of ZK's creators, Tom Yeh of Potix, about the Framework's popularity and future.
ZK Background
DK: How did you come up with the idea for ZK, i.e. an AJAX framework that allows you to write webapps like you would a desktop app?
TY: As I mentioned in http://zk1.sourceforge.net/faq.html#Why, it is the result of frustration.
I was a fan of thin-client computing since leading a wonderful team to develop Network Computer and Window Terminal in 1995. I truly believe in the so-called utility computing. Accessing applications should be as simple as using tap water.
It is crazy that someone should carry tons of water when traveling, since tap water is available everywhere. However, we still travel with notebooks, even though Internet connectivity is everywhere. Similarly, the Web edition of MS Outlook has been available for years, but we are still using the desktop version. Why? Frustrated user experiences and excessive development costs. In other words, it is too costly to develop a Web UI from scratch or add-on to 'legacy' apps, and people won't use the Web UI even if it is provided.
After trying different ways to apply Ajax in the projects on which we consulted, we found that applying Ajax at the client side, as most frameworks did, only solved the half of the problem -- though it did result in a lovely interface. That is why ZK was born.
DK: Who is Potix?
TY: Potix is a consulting firm providing expertise in Web development and project management. We also develop applications on an ODM-basis. ZK is the consequence of this work. However, due to strong demand, we mainly focus on ZK now.
Potix is also a house of old dogs. Most of us have more than 15 year of experience, ranging from developing Windows/Linux/Web applications, to embedded OS and GUI frameworks. ZK is my second OSS project; the first one, called OpenPam (GUI for embedded devices), was not very popular.
DK: How are you planning on making money with ZK? Nextapp, the makers of Echo2, sells an Eclipse plugin for around $400. Is that a business model you are examining?
TY: Dual license (as MySQL did). You might also take a look at one of my posts: http://sourceforge.net/forum/message.php?msg_id=3605162
Other Frameworks
DK: Echo2 seems to be the only other server-side AJAX framework out there. How would you compare yourself with Echo2?
TY: Echo2 assumes UI designers are Swing programmers, while ZK assumes many of them are not programmers.
Markup languages, like HTML, XUL and XAML, scripting languages, like PHP and Ruby, and the object oriented approach are the three most important developments since GUI was introduced. Unfortunately, Echo2, WebOnSwing and similar frameworks only focus on the object-oriented approach.
In addition to BeanShell, we are looking at the possibility of using Ruby and PHP in zscript. It looks to be, so far, quite feasible.
DK: There's lots of talk now about the Google Web Toolkit. Do you see it as a competitor to ZK or a complement?
TY: Both.
From a technological viewpoint, it is a complement. GWT is a client-side solution and quite good for developing Ajax components. On the other hand, it is never a good idea to replicate the business logic to the client, which eventually brings us back to the maintenance headache of fat clients. In addition, loading huge JavaScript files into the client and executing them there is not fun at all. At the end, you need a server-side solution to handle the business logic and presentation tier.
It would be great if we can leverage GWT's power to simplify the effort of component development (as we did with DOJO and FCKeditor).
From a perception level, users might see it as a competitor. Google is now at a sweet spot with plenty of resources and a good reputation, as Microsoft was in the 1980s. Developers love to explore any kit Google puts out there and exaggerate what it can do as if Google was the first to invent it.
DK: Do you envision developers writing ZK components using GWT?
TY: Sure, GWT does a good job for non-JavaScript programmers who want to develop Ajax components. I expect that some results of this will show up in next few months.
However, what makes Ajax programming difficult is not JavaScript itself. Rather, it is the incompatible and buggy API (to communicate with DOM). The ability to do Java-to-JavaScript is important, but I am also hoping for some benefits from the standards efforts of OpenAjax.
The true value of ZK is its architecture. We look forward to adapting components to ZK as decent (client-side) Ajax components become available.
DK: What other AJAX tools, frameworks or technologies do you think are noteworthy or interesting?
TY: DOJO has an amazing set of components, though it is too heavy (one of the reason we didn't build the ZK Client Engine upon it). Atlas has great integration with Visual Studio. Anyone who wants to provide an authoring tool should take it as an example. Google Spreadsheets is an excellent Ajax application. You should unplug the network connection and see how it reacts, though. It's cool nonetheless.
Strengths and Weaknesses
DK: What would you say are the strengths and weaknesses of the ZK framework?
TY: Strengths: boundless. But seriously, great richness and excellent productivity, if we can put in a sentence.
Many of ZK users appreciate that they can design a rich Web application without programming. Many have thanked us for the intuitive event model and feature rich components that have saved them countless hours. Many enjoy the power of prototyping so they can change the look and function right in front of their customers. For more information, you could take a look at the executive summary (http://zk1.sourceforge.net/wp/ZK-exesum.pdf).
Weaknesses:
- Stops working if the connection is broken. It would be better if a subset of functions still worked (such as read only viewing).
- Round-trip latency, though hardly observable. To minimize the effect of this, we plan to, in addition to Client Side Action, add visual effects that execute solely at the client and notify the server only when necessary.
One other weakness shared by all HTTP-based solutions is the lack of Server-side push. Though someone has implemented so-called "reverse Ajax", it introduces too much overhead on the server. This -- server-side push -- is the next important step beyond Ajax.
DK: There aren't any production applications out there using ZK. Do you see that as a problem and, if so, what are you doing to address it?
TY: According to the profile of our customers, adopting ZK is still in the development (and evaluation) phase. By and large, adopting Ajax for most companies is still in an early stage. It is just a matter of time. I'm not really that concerned about it as long as the growth of ZK's acceptance is strong.
DK: Right now, the framework doesn't seem to allow for easy customization of the look and feel (window color, font, etc.). First, is that correct and, if so, do you have any plans to address it?
TY: Not correct. The look and feel are well separated by CSS and molds. What prevents users from customizing the look is the lack of documentation and samples. Also, the customization of the sophisticated components is sometimes not intuitive. It forces users to look at DSP files (the templates used to generate HTML tags). We realize this is an issue and we will provide documentation in the Developer Reference guide.
DK: I've noticed in the code that you spawn another thread to handle events. Can you explain the design to me? Also, how does this fit in with the Servlet standard and doesn't this make it difficult to cluster a ZK application if the user session has non-serializable information and context?
TY: It is common that an application has to confirm with users about, say, whether to delete a file. It is unbelievably costly for Web developers to implement such functions. Why? Users get no response until the servlet has completed, while the servlet requires user's confirmation to decide whether to proceed further.
There are many solutions to this problem, but the most elegant one is modal dialogs. ZK is one of the first Web framework that really enables the server-side modal dialog. The magic is to process events in another thread. Then, users can suspend and resume the processing anytime they like -- including but not limited to modal dialogs.
It does make clustering difficult if there is a pending thread in a session. We are working on the serialization issue now. A basic idea is to send the application a notification, and it can decide how to handle pending threads. Of course, if there is no pending thread, there is no notification at all.
DK: What is your favorite ZK feature?
TY: Macro components, the threading models, and zscript.
DK: Are there some cases where you wouldn't use ZK to develop an AJAX-based web application?
TY: Hard to imagine unless clients want the application to be functional even if the connection is off. Oh, action games, but it might not be a good idea to use Ajax there at all.
DK: It doesn't appear that you are using JUnit in the ZK code. Is this true? And if so, why?
TY: Only common utilities are tested with JUnit (refer to pxcommonTest in SVN). I am still thinking about which is the best way to test ZK components. We will come out with something in the near future.
Future Plans
DK: What is the biggest feature enhancement request you are getting from the users of ZK?
TY: Safari support and design patterns. By design patterns I mean information on how to really write an application with ZK. An illustration with Pet Store is a common request.
DK: On your road map you mention plans to provide a mobile version of ZK. First, what is the time frame for this? Second, how are you planning to do this architecturally? Can users write one application and dynamically re-target their apps to a different front end?
TY: We originally planned to provide a J2ME-based client engine, but we are keen on developing a Flash-based solution now. Architecturally, we have to do three things to support a new client: client engine, server engine and components. Users have to do two things accordingly: use a different set of components and adjust their UI to fit into small screen. We will keep the component API very similar (and also provide common interfaces that make developer's code polymorphic).
It is possible to let users use the same set of components, where components would be smart enough to detect the client and behave differently. However, we're not considering this approach because it makes the development and maintenance of components too complicated. Of course, we can use the factory pattern to chose the correct implementation, but it makes the instantiation of a component too complex for most users.
DK: You've stated that ZK is at the interface layer. Do you plan to introduce components that punch through to the data layer, sort of like the .NET datagrid?
TY: Yes. We will add more data-layer utilities, such as zkplus's DelegatingVariableResolver, too. After all, most ZK applications will have to access a database. However, we may not do a similar deep integration as Ruby on Rails did -- I don't like to make so many assumptions about how applications might be built.
DK: What do you see as the major challenges facing the AJAX community today?
TY: There are too many frameworks, such that many users prefer to wait. There isn't even a well-recognized categorization for them (such as server vs. client). A comparison chart or something similar would be very useful.
A standard like OpenAjax will help (at the client side), but I've never seen an alliance really work.
DK: Care to share any other plans you have for ZK?
TY: We are interested in adding mega-components, such as spreadsheet, forum and wiki. Part of the success of PHP is because the availability of plenty of off-of-shelf stuff. We won't develop all of these components ourselves. Rather, we prefer to help other developers deliver them either as OSS or commercial components. We will have a ZK.forge website to promote such collaborations.
Topics: Ajax Components, Ajax Frameworks, Ajax Products, Ajax Tools, Ajax Widgets, Design Patterns, Echo2, Flash, GWT, Web 2.0, Web Development, Web/Tech, ZK
Wanted: A Javascript Source Code Search Engine
I use quite a few search engines in my day-to-day work. I expect you do too. There's one that I use quite a bit to see what's happening in the Open Source world. No, it's not Freshmeat. It's Koders.
Koders.com allows you to search the source code of thousands of Open Source projects. It allows you to filter by language (and license). That's really very handy when your looking for coding examples. It also let's you see when and where someone is using a particular Javascript library in their project. Looking for Dojo and Scriptaculous, it is no surprise that Webwork and Rails show up.
Now endless hours of fun can be had with the Koders search engine, but what I'd really like is a search engine that allows me to search all of the Javascript on the web. It's out there, it's readable, it's searchable. Surely google or Yahoo or whoever already slurps in the Javascript in their crawls. Why not add a new google engine for searching Javascript?
To anyone looking for examples of Javascript or AJAX, the utility of such a search engine is self evident. It might make corporate IT managers a little nervous to have all of their logic flapping in the breeze. Let that be a lesson to not put your business logic in the UI.
If anyone know of such a search engine or of any hacks or tricks to make existing search engines give up their secrets, please let me know. Passing xmlhttprequest filetype:js into google gives a less than satisfying result.
Update 1: Building such a search engine shouldn't be all that hard. The pieces are already out there. See the Heritrix web crawler that the Internet Archive uses for it's work.
Topics: Ajax Tools, Application Development, Best Practices, Search, Web 2.0, Web/Tech
Ajax Forms - Enhancing the user experience
The web is filling up quickly with examples of Ajax powered sites that allow us to do things we’ve never been able to do before on the web. From note taking apps, to spreadsheets, photo editors, and online games, Ajax apps like these are continually pushing the boundaries of what is possible, and in the process changing the way we work live and play on the internet.
However, we can also use Ajax to build better user experiences for the tasks we’ve already been performing on the web. One kind of task crying out for Ajax attention is form submittal, in which a user fills in a set of fields and presses the submit button.
Almost all forms today use the POST action in the SUBMIT button to upload data to the server, where processing gets done, and an entirely new page is sent back to the user. Depending on the results, this might be a “Thank You” message, or it could specify an error in the form submission (more likely when the form is lengthy). Either way, the experience is a poor one.
First, the navigational requirements are increased, as at least two pages are required-one for form and one for result. The result page usually contains no more that a couple of sentences displaying the results of the form submission, and possibly instructions on what next steps to take.
Second, the user has to wait until the end of the form submittal process to receive any error messaging. This increases the likelihood that there will be unnecessary typing and mouse movement/clicking, since incorrectly entered information into one input field may require a user to reenter fields down the entire form.
By using Ajax to asynchronously send the information to a server for processing, form entry and submission can be much more quick and painless.
Information can be uploaded processed and returned as the user enters data into an input field. Since not all the input needs to be sent at one time upon submit button on click, the user is told instantly, say, that the username he just entered is already taken.
Once all the required form data is submitted, the result can be displayed on the same page, allowing the user to move on to other, more enjoyable, tasks more quickly. If the form is small, and shares screen real estate with other content on one page, the user can continue on that page after the form is successfully submitted. No need to hit the back button.
Here is an example of what can be done to build a better Newsletter Signup form.
Ajax continually provides us with new and exciting web based products and services. But is also is a powerful tool for restructuring the way information is presented and manipulated on the web.
About Pathfinder
Recent
- Roles Testing For Security
- Blackbird takes the pain out of JavaScript logging
- Making GWT JSON not Quite so Painful
- IDEA - preconference workshop 06 Oct 08
- HTML5, Ajax history management, and The Ajax Experience 2008 Boston
- A Look Back At Past Posts
- Flash Player on iPhone gossip
- Microsoft to Jump on Board EC2
- TAE Boston 2008: The Unsexy Presentations
- The Ajax Experience 2008: Hope to see you in Beantown
Archives
- October 2008
- September 2008
- August 2008
- July 2008
- June 2008
- May 2008
- April 2008
- March 2008
- February 2008
- January 2008
- December 2007
- November 2007
- October 2007
- September 2007
- August 2007
- July 2007
- June 2007
- May 2007
- April 2007
- March 2007
- February 2007
- January 2007
- December 2006
- November 2006
- October 2006
- September 2006
- August 2006
- July 2006
- June 2006
- May 2006
- April 2006
- March 2006
Topics
.NET
2d physics
3d
3D GPS
3D physics
37signals
Accessibility
actionscript
activerecord
Add new tag
Adium
ADO.NET Entity Framework
Adobe
Adobe AIR
Advertising
agile
Agile Development
AIR
Ajax
Ajax Applications
Ajax Bookmarking
Ajax Components
Ajax Development
Ajax Examples
Ajax Experience
Ajax Frameworks
Ajax history management
Ajax Intervention
Ajax libraries
AJAX Obfuscation
Ajax Performance
Ajax Products
Ajax Tools
Ajax Widgets
Amazon
amf
Analysis
Android
Announcement
Announcements
antennae
Apollo
Application Architecture
Application Development
AS3
ASP.NET
Asynchronous Processing
awards
Back Button
Benchmarking
Best Practices
BitmapData.draw
BJAX
Blaze Advisor
blog
blogging
Books
Browsers
Business
Business Reasons for Ajax
Business Rules
C#
Canvas
Case Studies
chess
Chicago
Cloud Computing
CMS
COBOL
code art
Code Generation
Color
COMET
Conference
Consistency
Content Management
CRM
CruiseControl
CSS
Custom Flex Component
data visualization
Degrafa
Design
Design Patterns
Desktop
Desktop RIA
Developer's Notebook
Diagnose
Dojo
Domain Knowledge
Drools
EC2
Echo2
Echo3
Editorial
ERP
Ethnographic Research
events
externalinterface
Ext JS
Facebook
ferret
FileReference
Firefox
Firefox Extensions
Flash
flash awards
flash player
flash player 10
Flex
flexunit
Flock
Flow
Frameworks
front end
front end development
Games
Gauge Component
getting things done
Git
Google
Google calendar
Google Gears
Grails
Graphics
Greasemonkey
Groovy
GStreamer
GTD
Gwittir
GWT
Healthcare
Hibernate
Hudson
IDE
Ideation
IE
IE6
IE7
IE8
ILOG JRules
Information Architecture
Innovation
Instructional Design
Interaction Design
Interview
iPhone
iTunes
Java
Javascript
JavaScript frameworks
Javascript Libraries
JBoss Rules
Jess
Jetty
JIT
Jobs
jQuery
JSF
JSON
JSR-94
JsUnit
Lazlo
Legacy Systems
lightweight
LinkedIn
LINQ
logging
Logical Model and Conceptual Model
Low Pro
Mac
Mash Note
Mashups
Meebo
MetaWidget
Methodology
Microformats
Microsoft
Mobile
Mootools
mouse scroll
mouse wheel
Mozilla
Music
MVC
MySql
NetNewsWire
Object-Oriented
Object Relation Mapping (ORM)
Office
OOP
Open Screen
Open Source
Opera
Oracle
ORM
osx
pagination
Pair Programming
papervision3d
Patterns
Peer Creation
Performance
Personas
PHP
physics
physics engines
plugin
preloader
process
Web/Tech