Ubiquitous Technology

Work has been quite demanding lately but hopefully I will be able to post more regularly now.

I had planned to integrate eBay into SiteFinity via custom user controls but I decided to instead write the integration in Flex and integrate that into SiteFinity. It will make it easier for my client to add new versions since I only need to give them the SWF file and they can upload it themselves. I already know that we will need to support both search functionality for eBay auctions and ability to list items for auction and possibly other types of functionality. I decided to create a POC first and integrate that into SiteFinity before adding more interesting functionality. I focused on getting the infrastructure set up before making it look spiffy. In this post I'll show how to create the Flex binary. The SWF and source code has been posted here.



I decided to use one of the Flex MVC frameworks because I already know I will need to support several screens and it will make it easier to support. I picked the Mate framework, because it fits so nicely into Flex and it's non-intrusive. Mate strongly encourages you to separate the logic into views, event maps, events and business objects shown below.



The communication between the view and event handlers is handled via the Event Bus. An event is dispatched from the view and the event bus figures out which event map that listens for the event that was dispatched. The event map calls services and/or business objects. Commonly the event map also have injectors that binds properties in the view to business objects.

The event map in my POC is relatively simple displayed below.



This event map listens for the event SearchRequestEvent.GET and calls a business class SearchInvoker. This class makes a call to eBay using their Flash based API and dispatches either a success event or a fault event that gets handled inside the event map.

The event map also has Injectors that sets up the binding between properties in the view to the SearchManager. These injectors are initialized first before any custom events gets dispatched from the view.



The next step will be to add the SWF to SiteFinity.

It seems like everyone is getting a bad customer experience these days. I bought a MEAP early access book from Manning last year called "Unlocking Facebook". In October, the author wrote that Manning had cancelled the book. I was going to contact Manning but you can only contact them by calling them so I gave up. This week they sent me an email and let me have a refund OR two books of same type! Now that is great customer service!

I'm going to be busy reading Nhibernate In Action and ASP.NET MVC In Action now. Good stuff.

Work has been quite challenging as of late but I finally have some spare time on the weekends again. One of my planned tasks have been to integrate Ebay listings into SiteFinity. This was something that our charity originally requested during the charity event in January but we never got to it. Now after I've had a chance to look into Ebay's API, I can tell it would have been impossible unless I had known then what I know now about their API's.

Ebay has a developer web site which describes all the various API's they have available and sample code. They have different types of API's depending on what I intend to do, i.e. if you want to sell or buy or look at historical data and so forth. They also have a number of different stacks you can use depending on your platform: library based, SOAP based, XML over HTTP and REST. Their site is a little messy and I couldn't find anywhere where they show all the options you have, you have to dig around. I decided to use the Trading API based on what I am interesting in doing and decided to use the SOAP API.

I first downloaded the SDK for .Net with samples to take a quick look. Apparently, all the samples appears to be using their library. Surprisingly, the samples were built with VS 2003/.Net 1.1 and it was not a smooth process to VS 2008/.Net 3.5. Apparently they have a dependency on the J# Redistributable Package so I had to search their forums and download the Redistributable Package just to be able to even compile the sample. Bad customer experience. However, they have some samples that are more up-to-date in the Knowledgebase and other sections at their developer web site.

I'm a little surprised how companies like Ebay and Amazon appear to be pushing their libraries if you want to integrate with them. Is that what developers actually ask for or is it just a bad idea conceived by someone in their marketing departments? I don't like to add a dependency on a third party library unless it has a compelling set of features that really makes everything so much easier. In this case because it appears that they want to have some of the assemblies in the GAC and my code will be hosted at a hosting provider, it seemed like a bad idea to me. Maybe I haven't looked into it in enough depth but I don't see that it's much easier than just using one of their other API's directly.

I decided to either to use their SOAP API or their REST API. I'm inclined to call their "REST" API a STREST API since it's not resource based at all, you just dump the request at one service endpoint which really defeats the purpose of using REST. Their SOAP API is not a lot better, it consists of one single massive 4 MB WSDL file. Their API's just seem to be based on their old XML over HTTP technology and the only thing that is different if you use a different API is the notation. You have to specify both the operation you want to invoke and the authentication in the service endpoint like this:

https://api.ebay.com/
wsapi?callname=AddItem&siteid=0&appid=myappid&version=511&Routing=new

This is a poor design IMO, there's no reason why they can't derive the operation and authentication from the message. If you use their SOAP API, you have to specify both authentication and the operation you want to invoke in the SOAP body as well. I'm disappointed in their design decisions and I hope no one uses Ebay as a good example to follow. Frankly, I had expected a lot more based on their good reputation in general.

If you decide to use their SOAP API or their REST API, I recommend you use a web service testing tool to verify that your calls work correctly instead of having to write a bunch of code and running into issues and either having serialize the request or have to use a HTTP Proxy tool to be able to troubleshoot it. I prefer using soapUI because the rich feature set and that they have a free version but there are a number of other tools you can use, I'm not aware of any other free tools though. SoapUI also has a professional version with more features but I have never looked into that. Here's an example of the GetCategories call in soapUI:



However, some of their other operations are quite complex like AddItem. It might be more benefical to just use a tool like this to easily see all the options instead of trying to get it to run because of the large number of options. Thankfully, they have really good documentation online that describes all the various options and the available values when it's restricted.

In my case, the operations that are of interest to me is GetCategories to get all the various categories and AddItem which lists an item at Ebay. Now when I have figured out exactly what operations I need to invoke for the functionality I am interested in, I will try to get it to work in SiteFinity.

At the We Are Microsoft charity event last weekend, our team decided to implement a solution using a CMS product so they easily would be able to update the content. We decided to use Telerik SiteFinity based on the repution of Telerik and the fact that they had developer training the first day. Perhaps not the strongest reasons to pick a product but in our case we did not regret picking SiteFinity. The Web CMS Report have categorized the most well known CMS products, SiteFinity is categorized "Mid Market Challengers" which from what I can tell is an accurate categorization.

We used SiteFinity version 3.5 SP 1. The intial setup was a bit painful because the MSI installer didn't work too well on my Vista laptop but thankfully evengalist Gabe Sumner pointed out during the training that you can download a SiteFinity Visual Studio solution from sitefinity.com . The solution file is a Visual Studio Web Site template, I would have preferred a Web Application Project but I assume it's easy enough to change if you really want to change it.

SiteFinity plugs into the regular VS template pretty nicely. You will without a doubt want to add your own master page and the good news is that you just add it like you would in a normal ASP.NET web site. You need to add a script manager in the markup though like this:







You also need to add a theme to the App_Themes folder. This is where you put your css files and images that you use in the header/body/footer via your master page. Once you restart your worker process or the web server if you use Cassini, both the master page (template) and your theme should be visible once you edit a page. If you select a the template and the theme you created earlier, you should get the look and feel your expecting.





This is the basics to set it up, I will go into more detail after adding more functionality.

What I like about SiteFinity so far:

• WSIWYI Editor for editing content.
• Very easy for non-technical people to learn to use with a little training. Of course, you still need to know some basic HTML to make it look right.
  
• Workflow enginge in the Standard version, which is nice to have. I haven't had a chance to use it yet though.
  
• User controls hooks into SiteFinity in a nicely, allowing drag-and-drop in the GUI. You do have to add an entry into the web.config file though.
  
• It's relatively inexpensive, I don't think $899 is much money for a commercial organization for a CMS product where you get support.
  

What I don't like:

• All pages appear to use ViewState by default, whether it's static text only or a form. I think ViewState in general is way overused in ASP.NET web forms in general, I wish Telerik didn't fall into this trap as well but perhaps there's a good reason.
  
• I really don't understand why even images must use an Httphandler ASHX but perhaps it's not as heavy handed as it seems to be.
• Error handling seems a little sparse. Both during the setup and if it can't find the database when you run it, you get uncaught exceptions.
• ASP.NET 3.5 has been out for a good while now, you expect products to use 3.5 instead of 2.0 by now.
  

All in all, I really like this product and I'm glad I got a chance to try it out. The road map for version 4 looks pretty interesting. I wish they would have mentioned using the ASP.NET MVC framework instead of the ASP.NET Web Forms though.

I just got back from the charity event We Are Microsoft hosted in Dallas. It was a wonderful event, so many charities that all were worthwhile causes. I met a bunch of wonderful people, it is amazing that so many people were willing to give up a full weekend away from their families. I think the final tally was over 170 people including developers, designers, charities and event staff. It was very exhausting weekend of coding and little sleep but great to see that all charities actually received a fully working web site. Chris Koenig and Toi Wright put together a really great event plus all the volunteers.

Our team built a web site for the shelter New Beginning Center using Telerik Sitefinity as the CMS of choice. The new website isn't quite ready yet but will hopefully be up in the next few weeks as we're working on the finishing touches.

None of the guys on our team had any prior experience using SiteFinity but thankfully it was relatively easy to use. Telerik also had two great developer evengalists, Gabe Sumner and Todd Anglin who really knew the product well and were great at providing feedback. I will post later this week what I liked and disliked about SiteFinity.

Like so many others in the .Net community, I've been looking at the ASP.NET MVC framework lately which as of this writing is currently in beta. I really like what I've seen so far but YMMV. It seems like many developers that have experience using MonoRail have raised quite a few concerns. Obviously, MonoRail has been around for quite a while and have a lot more features and some of the design decisions may make MonoRail more extensible than ASP.NET MVC ever will be.

I've used the User Interface Process (UIP) Application Block previously in some projects and ASP.NET MVC is quite impressive compared to UIP :-). I really like that you can replace the view engine and that the aspx pages are so much more lightweight compared to Web Forms.

One of the more fascinating sample applications that I have seen come from Microsoft as long as I can remember is the MVC StoreFront by Rob Conery. It is so refreshing to finally see a sample application that has some complexity. It takes quite a bit of time to go through all the video's but is well worth it where Rob goes through using ASP.NET MVC and concepts like Dependency Injection, TDD, Mocking and even Domain Driven Design. It's a little bit confusing that the first 23 video's are at ASP.NET / MVC while also all the previous and new episodes (25 and forward) with topics like Domain Driven Design is at Rob's blog. There are a ton of good comments at his blog so that's the best place to go to.

The MVC StoreFront is just a tremendous learning experience using a variety of frameworks that may be useful in your projects. Extra plus that Rob doesn't just "pimp" Microsoft solutions and educate the use of some OSS frameworks.

See part 1 for the introduction of this web slice implementation where we set up the order web page. In the order page we showed where we set the RSS feed that we want to point to. In this part we will implement the Httphandler and RSS feed.

There's plenty of information available on how Httphandlers work, I won't go into the details about that. Our Httphandler listens for requests coming in to our SalesOrderWeb web site that takes the form http://localhost/SalesOrderWeb/123/OrderTracking.rss where "123" is the SalesOrderId of an order in the AdventureWorks database we want to look up.

The IHttpHandler interface have one method and one property that must be implemented:

• IsReusable
• ProcessRequest

The IsResuable property has confused many developers due to very sparse documentation about it. It can be set to true if multiple requests can process the HttpHandler at the same time, i.e. we don't have any private data or similar that could inadvertily be shared between two requests that run at the same time. Clear as mud? Good. Our HttpHandler does not have any data that is shared between requests so we can set IsResuable to true.

The ProcessRequest method will process the requests for us and output the processed data when we are done. This sequence diagram shows roughly the sequence of events that takes place.



The actual ProcessRequest method in our HttpHandler looks like this:

public void ProcessRequest(HttpContext context)
{

if (ValidateParameters(context) == false) // Not good
{
context.Response.StatusCode = 500;
context.Response.End();

return;
}

string[] requestPath = context.Request.Path.Split((char)'/');
string salesOrderNumber = requestPath[2];

FeedChannel chan = new FeedChannel(salesOrderNumber);
string feed = chan.GetRSSFeed();

context.Response.ContentType = "text/xml";
context.Response.Write(feed);
}

The first thing we need to do is to validate the input which is handled in the ValidateParameters method. In this sample we're just checking that we have what appears to be a SalesOrderId and then we get the salesOrderId out of the request.

Next, we instantiate the FeedChannel which loads the SalesHeader and SalesDetail for this sales order and we build the html that will be displayed in the "Description" field in the RSS item. In this implementation we only will have one single FeedItem but it's possible to have more than one FeedItem for every channel if you have aggregate data that you want to display in your feed.

We call the GetRSSFeed method which will create the XML we want to output and display in the web slice. We use the XmlDocument in .Net and the associated classes to help build the request in this case.

public string GetRSSFeed()
{         
 XmlElement workNode = null;
 XmlElement itemNode = null;

 // Get the custom section which contains the default values for the RSS feed.
 SalesOrderConfigSection soSection = SalesOrderConfigSection.GetConfig();

 XmlDocument doc = new XmlDocument();
 XmlProcessingInstruction pi =
     doc.CreateProcessingInstruction("xml-stylesheet",
         string.Format("type='text/css' href='http://{0}/SalesOrderWeb/css/rss.css'"
             , Dns.GetHostName()));
 doc.AppendChild(pi);

 XmlElement docNode = doc.CreateElement("rss");
 XmlAttribute attribute = doc.CreateAttribute("version");
 attribute.Value = "2.0";
 docNode.Attributes.Append(attribute);
 doc.AppendChild(docNode);

 // Create the channel element and its subelements:
 XmlElement channelElement = doc.CreateElement("channel");
 docNode.AppendChild(channelElement);                     

 AddElement(doc, channelElement, "title", string.Format(_title, SalesOrderId));
 AddElement(doc, channelElement, "link", string.Format(soSection.URL,
                             Dns.GetHostName(), SalesOrderId));
 AddElement(doc, channelElement, "description", soSection.Description);
 AddElement(doc, channelElement, "ttl", soSection.ttl);

 // Add the information about each line item.
 foreach (FeedItem feedItem in _feedItems)
 {
     itemNode = doc.CreateElement("item");
     channelElement.AppendChild(itemNode);
     workNode = doc.CreateElement("title");
     workNode.InnerText = string.Format(feedItem.Title, SalesOrderId);
     itemNode.AppendChild(workNode);
     workNode = doc.CreateElement("description");
     workNode.InnerText = feedItem.Description;
     itemNode.AppendChild(workNode);
     workNode = doc.CreateElement("link");
     workNode.InnerText = string.Format(soSection.URL, Dns.GetHostName(), SalesOrderId);
     itemNode.AppendChild(workNode);            
 }

 return doc.OuterXml;
}

The returned xml is written into the HttpResponse, formatted as text/xml and returned to the browser.

context.Response.ContentType = "text/xml";
context.Response.Write(feed);

The feed is a fairly normal RSS feed that can be viewed in the browser, in a separate RSS Reader or in the web slice as the intent was in this case.