The module code is already available on Epicode SVN, the relevant wiki pages will be following as soon as documentation is complete.

The use case is as follows:

• The client wants the site to look exactly as in a template provided as a image,
• the text is using a non standard font that is not available on 60% of Windows machines,
• the site does not use flash.
• the site needs to be equally good looking in IE6 (more about it later)

The solution was to generate images, but how to do it the right way? This has presented us with a once-in-a-lifetime :) opportunity to create a virtual path provider, do something good and learn something new & cool in the process.

Creating a new virtual path provider.

this functionality in itself is fairly well documented on MSDN one thing to pay attention to is to remember to pass the control to the next provider in the provider queue if your provider does not want to serve the request, so in my case:

        public override VirtualFile GetFile(string virtualPath)
        {
            if (IsPathVirtual(virtualPath))
                VirtualFile file = new TextImageVirtualFile(this, virtualPath);
                return file;
            else
                return Previous.GetFile(virtualPath);
        }

this is necessary so you don’t have to have all-or nothing solution (your provider either serving everything the user requests or not being accessible at all) and honestly I’ve spent quite a while before I found out that… I was just being silly – thinking the technology by itself will resolve that ;)

If your Virtual path provider does not actually implement directories you don’t have to make the very provider to do a lot of complicated things. you are perfectly fine to limit the implementation to providing a custom constructor so that EPiServer passes you the configuration data and a couple of methods to tell whether a file is what you want to handle or not

// this one is actually really cool - whatever values you set in your web.config 
// will be passed to you in the collection so you can really make your VPP 
// as configurable as necessary
public TextImageVirtualPathProvider(string name, NameValueCollection configAttributes)

// This one resolves if the file can be generated
public override bool FileExists(string virtualPath) { /* ... */ }
 
// Pretty much only passes the info that directory was not found 
// found if the virtual path matches a path that we should handle
public override bool DirectoryExists(string virtualDir) {  /* ... */  }
 
// Retrieves the virtual file that generates the image if the
// Virtual path matches our pattern or disregards the request if it doesn't
public override VirtualFile GetFile(string virtualPath) {  /* ... */  }
 
// Again this is only a pass through method as we don't support directories
public override VirtualDirectory GetDirectory(string virtualDir) {  /* ... */ }

Now that we have ASP passing the request to us we need to wonder how to format the request in a way that is intuitive to the user, I wanted the URL to be straightforward and follow the path of EPiServer’s friendly URL-S so that they are easily formed by editors. So how about:

http://my.server.com/color/font-name/font-size/The%20text%20i%20want%20to%20print.gif

Ok.. well…, that won’t fly for GIFs – the font will be plain ugly if I don’t use antialiasing and if I do I will have an ugly black background underneath it. The solution to that would be using translucent PNG (which the VPP supports) but IE6 does not support those with transparency without ugly hacks. So I need to replace the blacks with a hint so that it generates a background colour when it merges the background with the font for antialiasing. For the sake of this article let’s assume it was an easy switch (IT WASN’T!) and let’s extend the URL to:

http://my.server.com/color/antialias-hint-color/font-name/font-size/The%20text%20i%20want%20to%20print.gif

But I need the font to be bold! Ok… ok…

http://my.server.com/color/antialias-hint-color/font-name/font-size/font-formatting/The%20text%20i%20want%20to%20print.gif

Can I have the image rotated too? Sigh….

http://my.server.com/color/antialias-hint-color/font-name/font-size/font-formatting(optional)/transformatio(optional)/The%20text%20i%20want%20to%20print.gif

The image rotation follows the RotateFlipType enumeration so you can specify any string that is defined in the MSDN documentation for the enumeration.

A sample result for the URL:

http://my.server.com/TextImages/Blue/white/Courier%20New/40/BUI/rotate270flipnone/Hello$eol$from$eol$Cognifide!.gif

Will look as follows

For the curious

The final string format matching regular expression looks as follows:

Regex regex = new Regex(
    @"^(?<colour>                  # The first match - starting form the beginning of the string
    ([0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[a-zA-Z]*))   # match either a 6 hex digit string or a name of a known color - this is for text color
    /                             # now we expect the first separating slash
    (?<hint>                      # next match group is about background hint for antialiasing
    ([0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[a-zA-Z]*))   # match either a 3 or 6 hex digit string or a name of a known color - this is for antialiasing color hint
    /                             # again separating slash
    (?<font>[\w\s]*)              # font family name - accept white spaces
    /                             # yet another separating slash
    (?<size>[\d]{0,3})            # font size 
    /                             # oh noes! another slash!
    ((?<style>[BIUSRN\s]*)        # font style Bold, Italic, Underline, Strikethrough
    /){0,1}                       # this group is optional.
    ((?<transform>[\w]*)          # transformation name as specified with System.Drawing.RotateFlipType - this group is optional
    /){0,1}                       # this group is optional too.
    (?<text>[\s\S]*[^\.])         # the text to render - basically anything but a dot - use relacement strings for dots
    [\.]                          # separating dot - now that's a nice change!
    (?<extension>(png|gif))       # the file extension - so that we know whether to generate png or gif
    $                             # everything comes to an end  
    ", 
    RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace | RegexOptions.CultureInvariant);

Usability concerns

The Colours can be provided as both named Colours (red, green, etc..) or html hex formatted colours (e.g. ff00bb, fob, fff, badfoo) both 6 and 3 hex digits strings are accepted.

The URL accepts spaces, and whatever text string that cannot be passed as a part of the url or is invalidated by EPiServer can be escaped by defining a token for it in web.config so for example as you can see in the above url the end of line “\n” character has been escaped into $eol$.

Obviously the font selection is limited to what is installed on your server.

Performance concerns

The basic concern that comes to mind is – how does this impact the server performance if the image is generated every time? Even though the performance impact seemed to be negligible I’ve decided to cache content. These things simply pile up if you have a high load site so why take the chance? Once an URL is called it is saved on first generation asserting the uniqueness of each parameter. Colours like black and 000 will be treated as same colour and cached only once.

Security concerns

So what was done to prevent our server to be an open server for generating images for everyone on the Internet? The VPP only allows for the images to be generated if the request referrer is in a domain or a host that is specified in the web.config. Additionally for testing you can enable the referrer to be null (direct call to images, as opposed to referring to them from a page).

Also as a seconds line of defence, it’s wise to define the cache folder on a share with a quota so we don’t get our server filled up with images should the referrer limiting measure fail for some reason.

The module code is already available on Epicode SVN, the relevant wiki pages will be following as soon as documentation is complete.

The use case is as follows:

• The client wants the site to look exactly as in a template provided as a image,
• the text is using a non standard font that is not available on 60% of Windows machines,
• the site does not use flash.
• the site needs to be equally good looking in IE6 (more about it later)

The solution was to generate images, but how to do it the right way? This has presented us with a once-in-a-lifetime :) opportunity to create a virtual path provider, do something good and learn something new & cool in the process.

Creating a new virtual path provider.

this functionality in itself is fairly well documented on MSDN one thing to pay attention to is to remember to pass the control to the next provider in the provider queue if your provider does not want to serve the request, so in my case:

        public override VirtualFile GetFile(string virtualPath)
        {
            if (IsPathVirtual(virtualPath))
                VirtualFile file = new TextImageVirtualFile(this, virtualPath);
                return file;
            else
                return Previous.GetFile(virtualPath);
        }

this is necessary so you don?t have to have all-or nothing solution (your provider either serving everything the user requests or not being accessible at all) and honestly I?ve spent quite a while before I found out that? I was just being silly ? thinking the technology by itself will resolve that ;)

If your Virtual path provider does not actually implement directories you don?t have to make the very provider to do a lot of complicated things. you are perfectly fine to limit the implementation to providing a custom constructor so that EPiServer passes you the configuration data and a couple of methods to tell whether a file is what you want to handle or not

// this one is actually really cool - whatever values you set in your web.config 
// will be passed to you in the collection so you can really make your VPP 
// as configurable as necessary
public TextImageVirtualPathProvider(string name, NameValueCollection configAttributes)

// This one resolves if the file can be generated
public override bool FileExists(string virtualPath) { /* ... */ }
 
// Pretty much only passes the info that directory was not found 
// found if the virtual path matches a path that we should handle
public override bool DirectoryExists(string virtualDir) {  /* ... */  }
 
// Retrieves the virtual file that generates the image if the
// Virtual path matches our pattern or disregards the request if it doesn't
public override VirtualFile GetFile(string virtualPath) {  /* ... */  }
 
// Again this is only a pass through method as we don't support directories
public override VirtualDirectory GetDirectory(string virtualDir) {  /* ... */ }

Now that we have ASP passing the request to us we need to wonder how to format the request in a way that is intuitive to the user, I wanted the URL to be straightforward and follow the path of EPiServer?s friendly URL-S so that they are easily formed by editors. So how about:

http://my.server.com/color/font-name/font-size/The%20text%20i%20want%20to%20print.gif

Ok.. well?, that won?t fly for GIFs – the font will be plain ugly if I don?t use antialiasing and if I do I will have an ugly black background underneath it. The solution to that would be using translucent PNG (which the VPP supports) but IE6 does not support those with transparency without ugly hacks. So I need to replace the blacks with a hint so that it generates a background colour when it merges the background with the font for antialiasing. For the sake of this article let?s assume it was an easy switch (IT WASN?T!) and let?s extend the URL to:

http://my.server.com/color/antialias-hint-color/font-name/font-size/The%20text%20i%20want%20to%20print.gif

But I need the font to be bold! Ok? ok?

http://my.server.com/color/antialias-hint-color/font-name/font-size/font-formatting/The%20text%20i%20want%20to%20print.gif

Can I have the image rotated too? Sigh?.

http://my.server.com/color/antialias-hint-color/font-name/font-size/font-formatting(optional)/transformatio(optional)/The%20text%20i%20want%20to%20print.gif

The image rotation follows the RotateFlipType enumeration so you can specify any string that is defined in the MSDN documentation for the enumeration.

A sample result for the URL:

http://my.server.com/TextImages/Blue/white/Courier%20New/40/BUI/rotate270flipnone/Hello$eol$from$eol$Cognifide!.gif

Will look as follows

For the curious

The final string format matching regular expression looks as follows:

Regex regex = new Regex(
    @"^(?<colour>                  # The first match - starting form the beginning of the string
    ([0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[a-zA-Z]*))   # match either a 6 hex digit string or a name of a known color - this is for text color
    /                             # now we expect the first separating slash
    (?<hint>                      # next match group is about background hint for antialiasing
    ([0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[a-zA-Z]*))   # match either a 3 or 6 hex digit string or a name of a known color - this is for antialiasing color hint
    /                             # again separating slash
    (?<font>[\w\s]*)              # font family name - accept white spaces
    /                             # yet another separating slash
    (?<size>[\d]{0,3})            # font size 
    /                             # oh noes! another slash!
    ((?<style>[BIUSRN\s]*)        # font style Bold, Italic, Underline, Strikethrough
    /){0,1}                       # this group is optional.
    ((?<transform>[\w]*)          # transformation name as specified with System.Drawing.RotateFlipType - this group is optional
    /){0,1}                       # this group is optional too.
    (?<text>[\s\S]*[^\.])         # the text to render - basically anything but a dot - use relacement strings for dots
    [\.]                          # separating dot - now that's a nice change!
    (?<extension>(png|gif))       # the file extension - so that we know whether to generate png or gif
    $                             # everything comes to an end  
    ", 
    RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace | RegexOptions.CultureInvariant);

Usability concerns

The Colours can be provided as both named Colours (red, green, etc..) or html hex formatted colours (e.g. ff00bb, fob, fff, badfoo) both 6 and 3 hex digits strings are accepted.

The URL accepts spaces, and whatever text string that cannot be passed as a part of the url or is invalidated by EPiServer can be escaped by defining a token for it in web.config so for example as you can see in the above url the end of line ?\n? character has been escaped into $eol$.

Obviously the font selection is limited to what is installed on your server.

Performance concerns

The basic concern that comes to mind is ? how does this impact the server performance if the image is generated every time? Even though the performance impact seemed to be negligible I?ve decided to cache content. These things simply pile up if you have a high load site so why take the chance? Once an URL is called it is saved on first generation asserting the uniqueness of each parameter. Colours like black and 000 will be treated as same colour and cached only once.

Security concerns

So what was done to prevent our server to be an open server for generating images for everyone on the Internet? The VPP only allows for the images to be generated if the request referrer is in a domain or a host that is specified in the web.config. Additionally for testing you can enable the referrer to be null (direct call to images, as opposed to referring to them from a page).

Also as a seconds line of defence, it?s wise to define the cache folder on a share with a quota so we don?t get our server filled up with images should the referrer limiting measure fail for some reason.

The module code is already available on Epicode SVN, the relevant wiki pages will be following as soon as documentation is complete.

The use case is as follows:

• The client wants the site to look exactly as in a template provided as a image,
• the text is using a non standard font that is not available on 60% of Windows machines,
• the site does not use flash.
• the site needs to be equally good looking in IE6 (more about it later)

The solution was to generate images, but how to do it the right way? This has presented us with a once-in-a-lifetime :) opportunity to create a virtual path provider, do something good and learn something new & cool in the process.

Creating a new virtual path provider.

this functionality in itself is fairly well documented on MSDN one thing to pay attention to is to remember to pass the control to the next provider in the provider queue if your provider does not want to serve the request, so in my case:

        public override VirtualFile GetFile(string virtualPath)
        {
            if (IsPathVirtual(virtualPath))
                VirtualFile file = new TextImageVirtualFile(this, virtualPath);
                return file;
            else
                return Previous.GetFile(virtualPath);
        }

this is necessary so you don?t have to have all-or nothing solution (your provider either serving everything the user requests or not being accessible at all) and honestly I?ve spent quite a while before I found out that? I was just being silly ? thinking the technology by itself will resolve that ;)

If your Virtual path provider does not actually implement directories you don?t have to make the very provider to do a lot of complicated things. you are perfectly fine to limit the implementation to providing a custom constructor so that EPiServer passes you the configuration data and a couple of methods to tell whether a file is what you want to handle or not

// this one is actually really cool - whatever values you set in your web.config 
// will be passed to you in the collection so you can really make your VPP 
// as configurable as necessary
public TextImageVirtualPathProvider(string name, NameValueCollection configAttributes)

// This one resolves if the file can be generated
public override bool FileExists(string virtualPath) { /* ... */ }
 
// Pretty much only passes the info that directory was not found 
// found if the virtual path matches a path that we should handle
public override bool DirectoryExists(string virtualDir) {  /* ... */  }
 
// Retrieves the virtual file that generates the image if the
// Virtual path matches our pattern or disregards the request if it doesn't
public override VirtualFile GetFile(string virtualPath) {  /* ... */  }
 
// Again this is only a pass through method as we don't support directories
public override VirtualDirectory GetDirectory(string virtualDir) {  /* ... */ }

Now that we have ASP passing the request to us we need to wonder how to format the request in a way that is intuitive to the user, I wanted the URL to be straightforward and follow the path of EPiServer?s friendly URL-S so that they are easily formed by editors. So how about:

http://my.server.com/color/font-name/font-size/The%20text%20i%20want%20to%20print.gif

Ok.. well?, that won?t fly for GIFs – the font will be plain ugly if I don?t use antialiasing and if I do I will have an ugly black background underneath it. The solution to that would be using translucent PNG (which the VPP supports) but IE6 does not support those with transparency without ugly hacks. So I need to replace the blacks with a hint so that it generates a background colour when it merges the background with the font for antialiasing. For the sake of this article let?s assume it was an easy switch (IT WASN?T!) and let?s extend the URL to:

http://my.server.com/color/antialias-hint-color/font-name/font-size/The%20text%20i%20want%20to%20print.gif

But I need the font to be bold! Ok? ok?

http://my.server.com/color/antialias-hint-color/font-name/font-size/font-formatting/The%20text%20i%20want%20to%20print.gif

Can I have the image rotated too? Sigh?.

http://my.server.com/color/antialias-hint-color/font-name/font-size/font-formatting(optional)/transformatio(optional)/The%20text%20i%20want%20to%20print.gif

The image rotation follows the RotateFlipType enumeration so you can specify any string that is defined in the MSDN documentation for the enumeration.

A sample result for the URL:

http://my.server.com/TextImages/Blue/white/Courier%20New/40/BUI/rotate270flipnone/Hello$eol$from$eol$Cognifide!.gif

Will look as follows

For the curious

The final string format matching regular expression looks as follows:

Regex regex = new Regex(
    @"^(?<colour>                  # The first match - starting form the beginning of the string
    ([0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[a-zA-Z]*))   # match either a 6 hex digit string or a name of a known color - this is for text color
    /                             # now we expect the first separating slash
    (?<hint>                      # next match group is about background hint for antialiasing
    ([0-9a-fA-F]{3}|[0-9a-fA-F]{6}|[a-zA-Z]*))   # match either a 3 or 6 hex digit string or a name of a known color - this is for antialiasing color hint
    /                             # again separating slash
    (?<font>[\w\s]*)              # font family name - accept white spaces
    /                             # yet another separating slash
    (?<size>[\d]{0,3})            # font size 
    /                             # oh noes! another slash!
    ((?<style>[BIUSRN\s]*)        # font style Bold, Italic, Underline, Strikethrough
    /){0,1}                       # this group is optional.
    ((?<transform>[\w]*)          # transformation name as specified with System.Drawing.RotateFlipType - this group is optional
    /){0,1}                       # this group is optional too.
    (?<text>[\s\S]*[^\.])         # the text to render - basically anything but a dot - use relacement strings for dots
    [\.]                          # separating dot - now that's a nice change!
    (?<extension>(png|gif))       # the file extension - so that we know whether to generate png or gif
    $                             # everything comes to an end  
    ", 
    RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace | RegexOptions.CultureInvariant);

Usability concerns

The Colours can be provided as both named Colours (red, green, etc..) or html hex formatted colours (e.g. ff00bb, fob, fff, badfoo) both 6 and 3 hex digits strings are accepted.

The URL accepts spaces, and whatever text string that cannot be passed as a part of the url or is invalidated by EPiServer can be escaped by defining a token for it in web.config so for example as you can see in the above url the end of line ?\n? character has been escaped into $eol$.

Obviously the font selection is limited to what is installed on your server.

Performance concerns

The basic concern that comes to mind is ? how does this impact the server performance if the image is generated every time? Even though the performance impact seemed to be negligible I?ve decided to cache content. These things simply pile up if you have a high load site so why take the chance? Once an URL is called it is saved on first generation asserting the uniqueness of each parameter. Colours like black and 000 will be treated as same colour and cached only once.

Security concerns

So what was done to prevent our server to be an open server for generating images for everyone on the Internet? The VPP only allows for the images to be generated if the request referrer is in a domain or a host that is specified in the web.config. Additionally for testing you can enable the referrer to be null (direct call to images, as opposed to referring to them from a page).

Also as a seconds line of defence, it?s wise to define the cache folder on a share with a quota so we don?t get our server filled up with images should the referrer limiting measure fail for some reason.

We’ve not been talking much about it and that’s partially my fault as well (busy with other projects), but Cognifide has a really cool initiative called Cognifide Labs that we intend to grow over time. The plan is to devote up to 10% company time into side projects that help us grow expertise and allow our devs to dwell into interesting technologies, methodologies and languages and develop their skills.

One of the first projects (that I took part in) is CogniScale – an app that allows FlexiScale users to manage their servers. Here’s the story…

Being the agile company taking part in many EPiServer projects we never seem to have enough environments to test our web-apps and software in general in various scenarios. We find ourselves constantly reinstalling and trying to keep our servers in a state that can can at least remotely be called as stable. After all how many deployments and tearing down of various EPiServer, CruiseControl, TeamCity, SQL Server and other "I need to have" apps can a server take before slowing down to a crawl or collapsing all together (that said I bow before our faithful THOTH for taking all the abuse it does). We definitely needed more servers! And we needed them now!

Early this year we’ve started to talk to the guys at XCalibre that came up with a great idea. What if you could have an unlimited amount of servers available for you at any given time? I mean really what if you could have 0 servers one day and the next day have a rich farm of servers for literally no cost, paying only when you power them up and not paying a bit if you take them down.  This turned out to be quite a project for them that turned to materialize as FlexiScale. (you can read more about it here). Looking at all that I’ve mentioned before while eliminating the cost of maintaining the servers locally we decided to give FlexiScale a spin.

Read the rest of this article »

This article is a part of the series describing the faceted navigation system for EPiServer that we have developed in Cognifide and that’s already proven to be a robust solution for delivering tagged content a heavy traffic site. The engine will be released shortly as an open source project.

So how is the faceted engine structured?

Read the rest of this article »

This article is the second of a series describing the faceted navigation system for EPiServer that we have internally developed in Cognifide, that’s already proven to be a robust solution for delivering tagged content a heavy traffic site, which will be released shortly as an open source project.

First of all we have to explain the nomenclature as it is going to be used quite a bit. A few terms we use pretty extensively are:

• Facet – this is roughly an elaborate version of an EPiServer (or WordPress) category. One of the problem with EPiServer category is that it is just that and absolutely nothing more. There is no way for attaching metadata and conditional structuring of the category tree. There is no way to assign them roles. Facets provide you with much, MUCH more.

Read the rest of this article »

…with an unconventional approach to data fetching.

This article is a first of a series describing the faceted navigation system for EPiServer that we have internally developed in Cognifide and that’s already proven to be a robust solution for delivering tagged content a heavy traffic site, which will be released shortly as an open source project. The article outlines some pitfalls of EPiServer that we’ve run into and the nature of the project in which the module was used first and which influenced a lot of our design decisions.

This article and the Faceted Navigtation module is developed on EPiServer 4.61 and not the latest version 5 of the CMS so far, so mind that some of my reservations may not be a problem if you’re just starting to work on a brand new project and have the luxury of using new features of it.

Also (which may be a good thing) our sites uses a different approach to navigation the content, we do not really care much for the tree structure, but we treat all EPiServer pages equally when looking for content because of how the site is designed from the creative point of view.

Read the rest of this article »

This is a slightly dated post (written around November last year), that I forgot to post some time ago, so bare in mind, we’ve already started working on the faceted navigation getting open source status and I’ve updated the first sentece to include Adam Matusiak joining our team – Welcome Adam!

Over the last month or two  our hive mind has assimilated two new voices, our thoughts have become one with Greg’s, and Adam’s.

But seriously, the EPiServer (and consequently the .Net) part is getting really strong with eight nine(!) developers on that side currently working on a number of projects and that’s just developers!

What I really like is that we’re not just consuming the APIs, we already have developed some very cool technologies and the best part is that we’re starting to look seriously at open-sourcing some of our technologies to make the EPiServer community benefit from our experience. As a part of Cognifide Labs (that we hope to evolve in shape of Google’s “Pet projects”, I’m really looking forward to that). I’ll be working in my spare time on making our page commenting engine as well as our faceted navigation engine public consumption ready and ultimately add to the EPiCode experience. These are some modules that we’ve been working on for a long time, but just so busy with the various project development we’ve never been able to make them commented and documented enough for it to be a viable for a 3rd party developers to grasp. But already the technologies proven to be robust, scalable and extensible to support sites with over 6 million page views per month and growing and the site being fast and responsive just like you were the only person visiting it, thanks to using our data caching/fetching routines. All of that despite of a number of content pages counted in tens of thousands now.

It’s good to be a part of the hive mind, especially as brilliant as this one, so give in …resistance is futile, you will be assimilated!

Would you be interested in working with us on the technologies? How much need do you have for an elaborate faceted navigation in your projects? Did you have a need to add a commenting (site wide) to a site that already works, in a way that is not intrusive and that allows you to moderate comments in with the EPiServer editing mode integration? Which one would you find more interesting for us to start working on making public?

Just a daily time saver, for reuse at another time.

Any old time windows developer, will remember the fun of using the ini files with GetPrivateProfileString. As much as ini files sucked there is one nice aspect of that call – you can setup a default value it is to return in case a value is not specified in the file. Similarly in a daily episerver programming you usually want to read a value but if one is not epcified you will usually want to use another value and just move along with the progress, and not really care to have an if there to do the filling in. Not to limit the property to any specific type – the task can be nicely solved with generics to handle pretty much any type of property.

/// <summary>
/// Gets a property from a page by its name - if a property does not exist or is not set - returns a default value.
/// </summary>
/// <typeparam name="T">The type of the property</typeparam>
/// <param name="page">The page to pull the data from</param>
/// <param name="propertyName">The name of the property</param>
/// <param name="defaultValue">The value to be returned if the property does not exist or is not set.</param>
/// <returns>The value of the property.</returns>
public static T GetPropertyDefault<T>(PageData page, string propertyName, T defaultValue)
{
    PropertyData property = page.Property[propertyName];
    if (property == null || property.Value == null)
    {
        return defaultValue;
    }
    else
    {
        return (T) property.Value;
    }
}

It’s hard not to appreciate how clean that resolve is (with strong typing being forced with use of generics):

string link = PageUtility.GetPropertyDefault(CurrentPage, "ALink", "#top");

Another speedup coming from the TryParse background – when I want to deviate from the normal execution if a property is not defined but still have a clean code and strong typing…

/// <summary>
/// Gets a property from a page by its name - if a property does not exist or is not set, 
/// returns the presence status of the property existence as a boolean value.
/// </summary>
/// <typeparam name="T">The type of the property.</typeparam>
/// <param name="page">The page to pull the data from</param>
/// <param name="propertyName">The name of the property</param>
/// <param name="value">The value to be returned if the property exist and has a value, 
/// if the proeprty does not exist or is not set the value witll remain unchanged.</param>
/// <returns>True if the property was retrieved succesfully, false otherwise.</returns>
public static bool TryGetProperty<T>(PageData page, string propertyName, ref T value)
{
    PropertyData property = page.Property[propertyName];
    if (property == null || property.Value == null)
    {
        return false;
    }
    value = (T)property.Value;
    return true;
}

As much as I seem to be enjoying my trip with EpiServer there are some little things I don’t seem to appreciate all that much and I’m not quite sure how to work around some of them in an elegant way.

EpiServer has a fairly advanced way of dealing with properties but it also seems to be a bit tough on the developer whenever you try to do something more than just strictly using its API-s. One of the areas I don’t really enjoy is the dealing with the pages that are expired or generally unavailable for the user for various reasons.

In the project that we’ve been implementing recently we needed to store page ids for further reference in numerous places and although this generally works, accessing a page that’s been deleted, expired or not published yet, has proven to be a challenge and I can’t seem to be able to find an elegant solution around it.

For instance, we have a list of bloggers, that are stored in our faceted navigation with links to their pages, our system lists them and the links to their pages, should someone’s page be unpublished yet – we run into problems.

Another good sample of where this is needed is a list of pages (A multi-page property of sorts). There seems to be no implementation of a multi-page property in EpiServer and the only reasonable implementation that I’ve been able to find is available through EpiCode. The following is it deals with the pages going in or out of the system, which leads me to think that the only way of checking whether a page is available for me is to instantiate it with all the consequences of it:

// get the page with error handling for 
// access denied or deleted page
try
{
    PageData page = Global.EPDataFactory.GetPage(pageref);
    isExternalLink = (page.StaticLinkURL != multipageLinkItem.Url);
 
    if (page != null && isExternalLink == false)
        _selectedPages.Add(page);
}
catch (PageNotFoundException notFoundEx)
{
    // We should not add the page if it
    // does not exist
}
catch (EPiServer.Core.AccessDeniedException accessDeniedEx)
{
    // User is not allowed to see page, skip it
}
catch (Exception ex)
{
    // The page could not be loaded, for some other
    // reason.
    System.Diagnostics.Debug.Write("Page could not be loaded: " + pageref.ToString(), "PropertyMultiPage");
}

What I do not like about this part (of an otherwise remarkable piece) of code is that exceptions are not supposed to be the driving force of the program flow. But in this case they seem to have been forced to do it. It’s like I had to open a file to check its size or whether it even exists.

I can see why the system will not let me visit the page if I’m not allowed to do it as a user, but the fact that the API frowns at me whenever I even try to instantiate it just to check its existence or my rights to it has proven to be quite problematic. After all a user is not supposed to see a login screen in the list of pages, but rather when he/she enters a page that he/she no no rights to. Better yet, give me a way to check whether I even can access it.

Is there one already? Has anyone heard? Did anyone see?