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Hosting WCF Services in an ASP.NET Web Application

By Steve Ives, Posted on July 1, 2011 at 3:39 pm

There are several ways that you can use Synergy/DE tools to expose WCF services, but regardless of which way you decide to create a service, the next decision you have to make is how to host it. By hosting a WCF service you expos the service and make it possible to use it from other applications. In this post I will introduce you to one way that WCF services may be hosted, via an ASP.NET web application and an IIS web server. In a later post I will show you how to host WCF services without this requirement for an IIS web server.

This is the third in a series of posts relating to the various ways in which Synergy developers can use of Windows Communication Foundation (WCF) when building their applications. The posts in the series are:

Building Distributed Apps with Synergy/DE and WCF
Exposing WCF Services using xfNetLink .NET
Hosting WCF Services in an ASP.NET Web Application (this post)
Exposing WCF Services using Synergy .NET Interop
Self-Hosting WCF Services
Exposing WCF services using Synergy .NET

A WCF service is simply a collection of one or more classes in an assembly, but the whole point of implementing a WCF service is to make those classes available to be used by other applications. And those applications will often be located on different networked systems from the service itself. So, in order for a WCF service to be useful, it needs to be “hosted” somewhere, and that somewhere needs to be available on a network.

There are three basic ways that WCF services can be hosted:

Inside a Web application located on a Web server.
Using Windows Process Activation Services (WAS). This mechanism was introduced in Windows Server 2008 and provides a mechanism for hosting WCF services without requiring a Web server.
Services can be “self” hosted by some custom .NET application. For example, developers often host WCF services inside a Windows Service application.

In this post I will show you the basics of hosting a WCF service in an ASP.NET web application. In a future post I will go on to show how to self-host services.

Setting up basic hosting for a WCF service inside an ASP.NET Web application is very easy, but as Synergy .NET doesn’t have support for creating Web applications. You’ll have to use another .NET language, either C# or VB.NET. However, don’t worry about that too much, because there won’t actually be any code in the Web application!

Start Visual Studio 2010 and create a new ASP.NET application:
- From the menu, select File > New > Project.
- Under Installed Templates, select Visual C# > Web > ASP.NET Empty Web Application.
- Chose the name and location for your new Web application.
- Click the OK button to create the new project.
Add a new WCF Service to the project:
- From the menu, select Project > Add New Item.
- Under Installed Templates, select Visual C# > Web > WCF Service.
- Enter the name for your new service. The name will be part of the service endpoint URI that the client connects to, so pick something meaningful. For example, if your service allows orders to be placed then you might name the service something like OrderServices.svc.
- Click the Add button to add the new service to the project.

You will notice that three files were added to the project:

In addition to the service (.svc) file that you named, you will see two C# source files. These files were added because Visual Studio provided all of the files that you would need in order to expose a new WCF service that would be manually coded in these files. But what we’re trying to do is host a WCF service that already exists in another .NET assembly.

Delete the two C# source files by right-clicking on each and selecting delete.

In order to expose a WCF service that exists in another assembly, the first thing we need to do is add a reference to that assembly, to make the classes it contains available within the new Web application.

From the menu select Project > Add Reference and then select Browse.
Locate and select the assembly containing your WCF service and add a reference to your project.
If the assembly you selected was created using xfNetLink .NET then you will also need to add a reference to the xfnlnet.dll assembly, as is usual when using xfNetLink .NET

You’ll need to know that namespace and class name of the WCF service in your assembly. If you can’t remember this that double-click on the assembly that you just referenced and then use Object Browser to drill into the assembly and figure out the names. All that remains is to “point” the service file at your WCF service class.

Double-click on the service (.svc) file to edit it. You should see something like this:

Edit the file as follows:

Change Language=”C#” to Language=”Synergy”.
Change Service=”…” to Service=”YourNamespace.YourWcfClass” (obviously replacing YourNamespace and YourWcfClass with the namespace and class name of your WCF service).
Remove the CodeBehind=”…” item … there is no code-behind, the code is all in the other assembly.
Save the file.

So you should now have something like this:

If your service is based on an assembly created using xfNetLink .NET then you have one final configuration step to perform. You need to tell xfNetLink .NET how to connect to xfServerPlus. You can do this by using the Synergy xfNetLink .NET Configuration Utility (look in the Windows Start Menu) to edit the new web applications Web.config file. If your xfServerPlus service is not on the same machine as your new web application then you must specify a host name or IP address, and if xfServerPlus is not using the default port (2356) then you must also specify a port number. When you’re done, the Web.config file should contain a section like this:

That’s it, you’re done. You should now have a working WCF service!

To see if the service has really been hosted, right-click on the service (.svc) file and select View In Browser.

You should see the service home page, which will look something like this:

If you see this page then your service is up and running. By the way, the URI in your browsers address window is the URI that you would use to add a “Service Reference” to the service in a client application … but we’ll get on to that in a later post.

Of course, all we have actually done here is set up a web application to host a WCF service, but we’re using Visual Studio’s built in development web server (Cassini) to actually host the service. If you were doing this for real then you’d need to deploy your new web application onto a “real” IIS web server.

We’re not done with the subject of hosting WCF services; in fact we’ve only really scratched the surface. One step at a time!

In my next post in this series I will show you how to Expose a WCF services using Synergy .NET Interop.

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Tags: .NET, ASP.NET, Silverlight, SPC, Synergy/DE 9.5, Visual Studio, WCF, Web Development, Web Services, xfNetLink, xfServerPlus

Exposing WCF Services using xfNetLink .NET

By Steve Ives, Posted on at 1:40 pm

Following a recent enhancement to the product in Synergy 9.5.1, developers can now use xfNetLink .NET to create and expose Windows Communication Foundation (WCF) services. In this post I will describe how to do so.

This is the second in a series of posts relating to the various ways in which Synergy developers can use of Windows Communication Foundation (WCF) when building their applications. The posts in the series are:

Building Distributed Apps with Synergy/DE and WCF
Exposing WCF Services using xfNetLink .NET (this post)
Hosting WCF Services in an ASP.NET Web Application
Exposing WCF Services using Synergy .NET Interop
Self-Hosting WCF Services
Exposing WCF services using Synergy .NET

The basic approach is pretty easy; in fact it’s very easy. In 9.5.1 we added a new -w command line switch to the gencs utility, and when you use the new switch you wind up with a WCF service. I told you it was easy!

So, what changes when you use the gencs –w switch? Well, the first thing that changes are the procedural classes that are generated, the ones that correspond to your interfaces and methods in your method catalog, change in the following ways:

Three new namespaces (System.Runtime.Serialization, System.ServiceModel and System.Collections.Generic) are imported.
The class is decorated with the ServiceContract attribute. This identifies the class as providing methods which can be exposed via WCF.
Methods in the class are decorated with the OperationContract attribute. This identifies the individual methods as being part of the service contract exposed by the class, making the methods callable via WCF.
If any methods have collection parameters, the data type of those parameters is changed from System.Collections.ArrayList to System.Collections.Generic.List. Changing the collection data type is not strictly necessary in order to use WCF, but results in a more strongly prototyped environment which is easier to use, and offers more benefits to developers in terms of increased IntelliSense, etc.

The next thing that changes are any data classes, the ones that correspond to the repository structures that are exposed by the parameters of your methods, that are generated. These data classes change in the following ways:

Two new namespaces are imported. These namespaces are System.Runtime.Serialization and System.ServiceModel.
Each data class (which corresponds to one of your repository structures) that is generated is decorated with the DataContract attribute. This identifies the data class as a class which can be used in conjunction with a WCF service, and which can be serialized for transmission over the wire.
Each public property (which corresponds to a field in the structure) is decorated with the DataMemeber attribute. This attribute identifies each property within the class as one which will be serialized, and as a result will be visible to client applications which use the WCF service.

By the way, if you use a Workbench “.NET Component Project” to create your xfNetLink .NET assemblies then there isn’t currently an option in the component information dialog to cause the new –w switch to be used. So, for the time being, what you can do is add the switch to the Workbench “Generate C# Classes” tool command line. To do this you would go into project properties for the component project, go to the Tools tab, select the “Generate C# Classes” tool, then add the –w at the end of the command line, like this:

We’ll be adding a new checkbox to the component information dialog in 9.5.3 later this year.

By the way, by using the gencs –w switch you make it possible to use the resulting classes as a WCF service, but you don’t have to do so … you can continue to use the classes as a regular xfNetLink .NET assembly also. Why would you want to do that? Well, I sometimes use gencs –w just to turn my collection parameters into generic lists!

I have submitted a working example to the Synergy/DE CodeExchange, contained within the zip file called ClientServerExamples.zip. Within the example, the following folders are relevant to exposing and consuming a WCF Service using xfNetLink .NET:

Folder / Project	Description
xfServerPlus	Contains the Workbench development environment for xfServerPlus and the exposed Synergy methods. If you wish to actually execute the examples then you must follow the setup instructions in the readme.txt file.
xfNetLink_wcf	Contains the Workbench project used to create the xfNetLink .NET client assembly with the WCF attributes.
3_xfpl_xfnl_wcf_service	Contains the Visual Studio 2010 solution containing an ASP.NET web application used to host the WCF service, as well as three example client applications, written in Synergy .NET, C# and VB.

So, the gencs –w command line switch you make it possible to use the resulting classes to directly expose a WCF service, but there is still the matter of how to “host” the service in order to make it accessible to remote client applications, and that’s what I will begin to address in my next posting.

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Tags: .NET, ASP.NET, Silverlight, SPC, Synergy/DE 9.5, Visual Studio, Web Development, Web Services, xfNetLink, xfServerPlus

Another TechEd Sticky Note

By , Posted on June 10, 2010 at 11:58 pm

The other night, I discovered the way to beat the heat while here in New Orleans. It’s a fruity little concoction known as the Hurricane, and while it doesn’t actually affect the climate around you, it sure makes feeling hot and sticky a lot more enjoyable. I’m also pretty sure how it got its namesake: in the morning, you find yourself trying to reconstruct the previous 12 hours of your life by putting together the pieces and fragments of your memory.

TechEd 2010 draws to a close this evening, and though it’s been increasingly difficult to find sessions that seem pertinent to we Synergexians, it’s still been a worthwhile experience.
I’ve learned a lot just by watching presenters step through the build of a Silverlight UI using Microsoft Expression, or show off the latest features of Visual Studio 2010 and how it can be used to quickly create a web app, or walk through the use of new simplified Windows Communication Foundation 4 features.I’ve even filled in the holes in my schedule with sessions on interesting (to me) topics, such as IPv6, trends in cybercrime, and hacker techniques.

Which all brings me to the point of this little blog entry: It seems to me that the value of conferences lies not in the number of sessions that directly apply to you, but in the quantity and quality of the little tidbits you pick up each day. It’s in the discussions you have with other developers and like-minded individuals – whether they take place while sitting down over a cup of coffee, or simply during a quick ride in the elevator. It’s in the creative ideas that spring up when you see a clever implementation and wonder if you can apply the same techniques to an unrelated solution of your own. It’s in the tips, tricks and techniques that you pick up, which will not only save you hours, days, and even weeks of effort in the year ahead, but which can also be shared with the rest of your team to make them more productive as well.

Just a sales pitch for SPC2010? Perhaps…but that wasn't the intent. After all, this is my blog, and with it I get to share helpful experiences from my time “out in the field.” If writing about it all means I’ll get to see more of you when we set up shop in October at the Citizen Hotel, then so much the better. But in the end, my little revelation about the value of coming to TechEd – even with so much focus on technologies that I can’t use – is helping me to sit back and enjoy this final day of the conference, secure in the knowledge that I’m going to be learning something interesting at every turn. And isn’t that what attending the conference is all about?

That, and the Hurricanes, of course…

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Tags: Microsoft, Silverlight, SPC, TechEd, Visual Studio

Preparing for Windows Phone 7

By Steve Ives, Posted on at 7:59 pm

By Steve Ives, Senior Consultant, Synergex Professional Services Group

Later this year, probably, Microsoft are releasing a new version of their phone operating system, and it’s going to be a BIG change for developers who have created applications for the earlier Windows Mobile operating systems. The new O/S is called “Windows Phone 7”, and although under the covers it’s really still Windows CE, on the surface things will look VERY different.

Perhaps the largest single change will be the user interface of Windows Phone 7 devices, which will be entirely driven by Microsoft Silverlight. That’s potentially great news for existing Silverlight or WPF developers, but will of course mean a total re-write of the UI for developers with existing applications which were essentially based on a subset of Windows Forms.

Using Silverlight will mean that we can expect some dazzling UI from applications, and indeed the O/S and the standard applications provided with it already look pretty cool, but there will definitely be a learning curve for anyone who has not developed Silverlight applications before.

Part of the good news is that the basic tools that you need to develop Windows Phone 7 applications are free. You can download Visual Studio Express Phone Edition and have pretty much what you need to develop applications. At the time of writing though, these tools are in a “pre-beta” form, and as such you can probably expect some issues, and need to update the tools pretty regularly.

There is, in my humble opinion at least, also some bad news, not least of which is that Microsoft seem to have turned the Windows Phone platform into, essentially, another iPhone! While developers can use free development tools (or full versions of Visual Studio) to create their applications (just like with the iPhone) they will have to sign up for a $99 annual “Windows Phone Developer “subscription in order to have the ability to deploy their application to their physical phone for testing (just like with the iPhone).

It will no longer be possible to deploy applications via “CAB file” installations, in fact for anything other than developer testing, the ONLY way to get an application onto a Windows 7 Phone will be via the Microsoft “Windows Phone Marketplace” (just like with the iPhone). When a developer publishes an application to the marketplace they can chose whether the application is free, or is to be charged for. With iPhone development developers can submit an unlimited number of free applications, and many do. With Windows Phone 7, developers can only submit five free applications, and after that there will be a charge to submit further free applications. If an application is submitted for sale, Microsoft will take a 30% cut of any proceeds (just like with the iPhone).

Applications submitted for inclusion in the marketplace will be subject to “testing and approval” by Microsoft (just like iPhone apps), and apps may be rejected if they don’t meet the guidelines set by Microsoft (just like with iPhone apps). This inevitably means that some types of applications won’t be allowed. For example, with the iPhone it is not possible (in the US at least) to use “tethering” to enable you to plug your iPhone into your laptop in order to access the Internet via the cell phone network, and I would imagine we’re now going to see similar restrictions on Windows 7 Phone applications.

iPhone applications execute in a very strictly defined sandbox, and while this does afford a lot of protection for the platform (because, for example, one application can in no way interact with the data of another application), it can also seriously limit what applications can do. For example, on the iPhone it is not possible to save an email attachment (say a PDF file) and subsequently open that PDF file in another application, Acrobat Reader for example. While I understand the protections offered by the sandbox approach, as a user of the device I feel that it restricts too far what I can do with the device. The Windows Phone 7 platform is essentially exactly the same.

Other restrictions in the Windows Phone 7 platform that developers will have to come to terms with are:

No access to TCP/IP sockets
No access to Bluetooth communication
No access to USB connections to a host computer
No Windows Forms UI’s
No SQL Express access
No ability to execute native code via pinvoke (except device drivers, which must be approved by Microsoft)
No customization of O/S features (e.g. no alternate phone dialers)

One thing that strikes me as kind of strange is that, apparently, the web browser on Windows Phone 7 will not support Flash, and apparently will not support Silverlight either! The flash thing is kind of expected, both Apple and Microsoft seem to do everything they can to keep Flash of THEIR devices, but not supporting Silverlight (on an O/S where the entire UI is Silverlight) was a surprise … at first. Then I realized that if the browser supported Silverlight there would be a way for developers to circumvent all of the application approval and marketplace restrictions that I talked about earlier!

Another surprise was that, like all versions of the iPhone until iOS 4.0, Windows Phone 7 devices will only execute a single user application at a time. This is one of the main things that iPhone users have complained about through the versions, and Apple just learned the lesson, but it seems that Microsoft have decided not to. For developers this means that it is imperative that applications save their data and state frequently, because the application could be terminated (with notification and the ability to clean up of course) at any time.

One thing is for sure … Microsoft seem to be betting the company on “The Cloud”, and Windows Phone 7 falls straight into this larger scale objective. The vision is that this new device will be a gateway to The Cloud in the palm of your hand. It is expected that many applications may execute directly from The Cloud (rather than being installed locally on the device) and that the device will have the ability to store (and synchronize) data in The Cloud. Apparently these features will be included for free, with a limited (not announced) amount of on-line storage, and presumably fee-based options for increasing the amount of storage available. Of course using things in The Cloud is all well and good, until youfind yourself in a "roaming" situation, paying $20/MB, or more!

On the bright side, Windows Phone 7 devices will be available from a number of different manufacturers, so there will be choice and competition in the marketplace. Windows Phone 7 devices will (in the US at least) be available from a number of cell phone carriers, unlike Apples exclusive deal with AT&T.

While there is no doubt that Windows Phone 7 promises to be a seriously cool new device, and I have no doubt will sell in larger numbers than any of the predecessor Windows Mobile devices ever did, it remains to be seen whether it will have what it takes to be a serious competitor to the mighty iPhone. I can’t help wishing that Microsoft had done at least some things a little bit differently.

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Tags: Mobile Devices, Silverlight, Windows Phone

Silverlight – What’s it all About?

By Steve Ives, Posted on November 18, 2009 at 5:16 pm

Day two at PDC09, and with between ten and twelve concurrent tracks it’s pretty tough to decide which sessions to attend. Luckily there are three of us attending the conference, so with a little planning we can at least attempt to maximize our coverage. But still … so many choices!

I’ve been involved with Web development for a long time now … in fact I’ve been involved with Web development ever since there was such a thing as Web development, so I decided to spend the day trying to make sense of the choices that are now available to Web developers in the Microsoft space.

If you look across the entire industry there are many and varied Web development platforms available, some well proven, some relatively new. When Microsoft first introduced Active Server Pages (ASP) back in 1996 they changed the game. Web development was taken to a whole new level, and in my humble opinion they have lead the game ever since.

Until recently the choice was clear. The Web development platform of choice was ASP.NET’s WebForms environment. Thanks in part to very rich developer support in Visual Studio, and an absolutely vast array of excellent third-party plug-ins and controls, the ASP.NET WebForms environment was, and still is absolutely dominant in the industry.

However, things are changing. In 2007 Microsoft unveiled a new technology called Silverlight, and while it is fair to say that initial adoption was slow, Silverlight could today be considered to be a key part of Microsoft's vision for the future of computing generally!

Silverlight is essentially a browser plug-in that allows Web browsers to render rich user interfaces. It started out as a relatively simple plug-in which allowed browsers to display streamed video content, much like Adobe Flash, but that is no longer the case today. The technology is less than two years old at this point, and today Microsoft announced the beta for the fourth major release of the product in that short time. Clearly a lot of dedicated effort has been put into into Silverlight … there must be a “bigger picture” here!

Let’s take a step back. A browser plug-in is a software component that allows a Web browser to do something that is not inherently supported by the Web (i.e. by HTTP and HTML). The issue here is that HTTP and HTML were designed as a mechanism for a client system (a browser) to safely display “content” from a server system. That server system could be located anywhere, and owned and operated by anyone. In that situation, how do you trust the publisher of the content? The simple answer is … you can’t. So for that reason early browsers didn’t allow the Web “applications” to interact with the client system in any way … they simply displayed static content.

Of course clever software developers soon found ways around that restriction, but only if the user of the client system gave their permission. That permission is typically granted by allowing the installation of third-party plug-ins on the client system. Once a plug-in is present it can be detected by the browser, and in turn detected by the Web server, which can then take advantage of the capabilities of the plug-in. And because a plug-in is a piece of software that was explicitly allowed to be installed on the client system by the user of the client system, it is not subject to the normal “restrictions” (sandbox) placed on the Web browser … plug-ins can do anything!

Silverlight isn’t the first product that Microsoft has introduced in this arena. Many years ago they introduced support for ActiveX controls to be embedded within Web pages, and the technology was very cool. It allowed very rich and highly interactive user interfaces to be rendered within a web browser, it allowed the web “application” to interact with the “resources” of the client system, and for a while ActiveX in the browser showed a lot of promise. The problem was that the ActiveX technology was only available in the Internet Explorer browser, and at that time IE didn’t have a big enough market penetration for ActiveX in the browser to become a serious player.

Today though, things are different. Internet Explorer is by far the most dominant Web browser in use (although Firefox, Safari and Google Chrome continually eat away at that market lead). But this time around the difference is that Microsoft took a different approach … they made Silverlight plug-ins available for Firefox … and Safari … and today even announced the development of a plug-in for Google Chrome in the up-coming Silverlight 4 release. This is pretty impressive, because the current version of Chrome doesn’t even support plug-ins!

Today during the PDC09 keynote presentations Silverlight was front and center, and I’ll be completely honest here … the demos that I saw totally blew me away! Silverlight can now be used to render fabulous interactive user interfaces which can equal anything that can be achieved in a desktop application, and with appropriate permissions from the user of the client system Silverlight applications can fully interact with the local client system as well. It’s even possible (in the current release) to execute Silverlight applications outside of a traditional web browser, allowing them to appear to the user exactly as desktop applications would … but with no installation required (other than the Silverlight plug-in).

So why is Silverlight so important to Microsoft? And why might it be so important to all of us as software developers, and as software users? Well, the answer to that question is related to my last post to this blog … it’s all about the Cloud! The perfect model for a Cloud application is a Web application, but even with all of the advances in Web technologies it’s still really hard to make a web application that is as feature-rich and capable as a modern desktop application … unless you use a tool like Silverlight.

Now don’t get me wrong, ASP.NET WebForms is still a fabulous technology, and still very much has a place. If you have an ASP.NET WebForms application today … don’t panic, you’re in good shape too. The point here is that you now have options. In fact, there is a third option also … it’s called ASP.NET MVC, and I’ll talk about that in another blog post soon.

If you want to see examples of Silverlight in action then check out the Silverlight Showcase Samples (of course you'll need the Silverlight plug-in installed, but the site will offer it to you if you don't have it), and if you can also get more information about the PDC09 Silverlight 4 (beta) demos.

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Tags: ASP.NET, MVC, PDC, Silverlight, Web Development, WebForms