In SDL Web 8.5 we saw the introduction of replacement tokens in the content delivery configuration files. Whereas previously we'd simply had XML files with attributes and elements that we filled in with the relevant values, the replacement tokens allowed for the values to be provided externally when the configuration file is used. The commonest way to do this is probably by using environment variables, but you can also pass them as arguments to the java runtime. (A while ago, I wasted a bunch of time writing a script to pass environment variables in via java arguments. You don't need to do this.)

So anyway - taking the deployer config as my example, we started to see this kind of thing:

<Queues>
 <Queue Id="ContentQueue" Adapter="FileSystem" Verbs="Content" Default="true">
  <Property Value="${queuePath}" Name="Destination"/>
 </Queue>
 <Queue Id="CommitQueue" Adapter="FileSystem" Verbs="Commit,Rollback">
  <Property Value="${queuePath}/FinalTX" Name="Destination"/>
 </Queue>
 <Queue Id="PrepareQueue" Adapter="FileSystem" Verbs="Prepare">
  <Property Value="${queuePath}/Prepare" Name="Destination"/>
 </Queue>

Or from the storage conf of the disco service:

<Role Name="TokenServiceCapability" Url="${tokenurl:-http://localhost:8082/token.svc}">

So if you have an environment variable called queuePath, it will be used instead of ${queuePath}. In the second example, you can see that there's also a syntax for providing a default value, so if there's a tokenurl environment variable, that will be used, and if not, you'll get http://localhost:8082/token.svc.

This kind of replacement token is very common in the *nix world, where it's taken to even further extremes. Most of this is based on the venerable Shell Parameter Expansion syntax.

All this is great for automated deployments and I'm sure the team running SDL's cloud services makes full use of this technique. For now, I'm still using my own scripts to replace values in the config files, so a recent addition turned out to be a bit inconvenient. In Tridion Sites 9, the queue Ids in the deployer config have also been tokenised. So now we have this kind of thing:

<Queue Default="true" Verbs="Content" Adapter="FileSystem" Id="${contentqueuename:-ContentQueue}">
  <Property Name="Destination" Value="${queuePath}"/>
</Queue>

Seeing as I had an XPath that locates the Queue elements by ID, this wasn't too helpful. (Yes, yes, in the general case it's great, but I'm thinking purely selfishly!) Shooting from the hip I quickly updated my script with an awesome regex :-) , so instead of

$config = [xml](gc $deployerConfig)

I had

$config = [xml]((gc $deployerConfig) -replace '\$\{(?:.*?):-(.*?)\}','$1')

About ten seconds after finishing this, I realised that what I should be doing instead is fixing my XPath to glom onto the Verbs attribute instead, but you can't just throw away a good regex. So - I present to you, this beautiful regex for converting shell parameter expansions (or whatever they are called) into their default values while using the PowerShell. In other words, ${contentqueuename:-ContentQueue} becomes ContentQueue.

How does it work? Here it comes, one piece at a time:

'            single quote. Otherwise Powershell will interpret characters like $ and {, which you don't want
\            a slash to escape the dollar from the regex
$            the opening dollar of the expansion espression
\{           match the {, also escaped from the regex
(?:.*?)      match zero or more of anything, non-greedily, and without capturing
:-           match the :-
(.*?)        match zero or more of anything non-greedily. No ?: this time so it's captured for use later as $1
\}           match the }
'            single quote 

 The second parameter of -replace is '$1', which translates to "the first capture". Note the single quotes, for the same reason as before

So there you have it. Now if ever you need to rip through a bunch of config files and blindly accept the defaults for everything, you know how. But meh... you could also just not provide any values in the environment. I refuse to accept that this hack is useless. A reason will emerge. The universe abhors a scripting hack with no purpose.

A month or so ago, Amsterdam was again host to the Tridion Developer Summit. This is a great event for anyone involved with Tridion, and each year it goes from strength to strength. This year, a lot of the focus, understandably, was on the forthcoming release of Tridion Sites 9, which will be part of Tridion DX. We heard speakers from SDL and from the wider community talking on a variety of topics. In one sense, I suppose, the usual mixture, but there's always a certain excitement when a new major release is coming out. (Yes, I know we don't call them major's any more, but still, we're looking at brand new APIs that none of us have used yet: that's a major in my book!)

The talks covered everything from the new user interface, to the combined play with structured content that the DX platform will offer, to new services based on GraphQL (which is probably becoming the "must study" topic). Other speakers covered integrations and extension points and javascript and, well, you name it. If you spoke, and I haven't mentioned your bit, please don't take offence!

It was a great conference, which I thoroughly enjoyed; not least because of the chance to catch up with everyone. But a month later, I just want to share the thing that really blew me away and stuck with me. The new product release isn't finished just yet, but the scope is more or less fixed. If a feature isn't already in, then it probably won't be in Tridion sites 9. That said, the guys in R&D are not standing still, and they are already looking forward to the next thing. Which brings me to the buzz moment of this year's summit. I'm not sure if Likhan Siddiquee was even meant to be presenting in the main theatre at that moment, but well... Likhan's an enthusiast. If this guy's got some amazing new tech to show, try and stop him! (Good luck with that!) So he comes in and just kind of tags along after a couple of the other SDL presenters. He's showman enough that it could have all been staged, but he managed to make it seem as though... well... he just had this cool stuff on his laptop and.... did we maybe have five or ten minutes?

So he walks on stage carrying his kid - a babe in arms! Start em young, I suppose. Anyway child-care and work-life balance obviously hold no fears for Likhan. He hands off the baby to his able assistant, and proceeds to unveil the geeky goodies. What did he have? Nothing less than the Tridion kernel running on .NET core! Sure - this was a pre-preview. Hot off the press. No user interface, and only a bare-bones system, but sure enough he got it going from the command prompt with the "dotnet" command and proceded to start hitting service endpoints with a web browser. Wow!

It was a moment in time. You had to be there. I'm sure we'll be waiting a while to see a production version. For sure it won't make it into the 9 release, but who cares? Hey for a lot of people, they won't even notice. Nothing wrong with running Windows Server, is there? Still this will open up lots of possibilities for different kinds of hosting options, and for those of us who like to run a "fifth environment" it's going to be awesome. Everything on linux containers. What's not to like?

Thanks to all those who took part in the Summit. You were all great, but especially thanks Likhan for that inspiring moment!

I've recently been working on an application that will allow members of our content management teams to search within a chosen folder in Tridion for specific content. You might think that's well enough covered by the built-in search functionality, but we're heading towards a search and replace feature, so we pretty much have to process the content ourselves. In the end users' view of the world, a Rich Text field in a component has... well...  a rich text view, and, for the power-users, a Source tab where you can see the underlying HTML. That's all fine, but once you get to the technical implementation, it's a bit more complicated, and we'll end up replicating some of Tridion's own smoke and mirrors to present a view to the users that's consistent with what they are used to. This means not only that we need to be able to translate from text to HTML, but also from "XML in the XHTML namespace" to HTML. One of the bulding blocks we need to do this is the ability to take XML with namespace declarations, and get rid of them so that the result isn't in a namespace. 

A purist (such as myself) might say that the only correct way to parse XML is with an XML parser, and just in case you've never ended up there, I heartily recommend that you read this answer on Stack Exchange before proceding further. Still - in this case, what I want to do is amenable to RegExes, and yes, I know: now I have two problems. Anyway - FWIW - I started this at the office, thinking I'd just quickly Google for a namespace-stripping regex and I'd be on my way. Suffice it to say that the Internet is rubbish at this. I ended up with a page of links to rubbish regexes that just weren't going to float my boat. So I mailed the problem to myself at home, and today, in the quiet of a Sunday morning, it didn't seem quite so daunting. Actually, I'm still considering whether an XML-parser approach, or an XSLT might not be better, and I may end up there if my needs turn out to be more complex, but for now, here's the namespace stripper. 

static Regex namespaceRegex = new Regex(@"    
             xmlns             # literal
             (:[^\s=]+)?       # : followed by one or more non-whitespace, non-equals chars
             \s*               # optional whitespace
             =                 # literal
             \s*               # optional whitespace
             (?<quote>['""])   # Either a single or double quote - giving it the name 'quote' for back-reference
             .+?               # Non-greedily match anything
             \k<quote>         # The end-quote to match the one we found earlier
             ", RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.IgnorePatternWhitespace);

public static string RemoveNamespacesFromDocument(string xml)
{            
      return namespaceRegex.Replace(xml, string.Empty);
}

Of course, this is written in C#, and I'm taking advantage of the IgnorePatternWhitespace feature in .NET regexes, which allows for the copious comments that might well be necessary if I ever have to actually read this code instead of just writing it. 

But just in case you are hardcore, and all that named matches and commenting fuss is for wusses, here's the TL;DR...

@"(?is)xmlns(:[^\s=]+)?\s*=\s*(['""]).+?\2"

What's not to like? :-) 

A couple of weeks ago, this site went down. That happens from time to time. It went down just as I left the country to go on holiday, and it could only be fixed via physical access, so it was down for a week. At least one person has commented that maybe I should stop with this silliness of running my own server on an old Gentoo box in the meter cupboard, and get some proper hosting.

The thing is, that when I started this blog, some years ago now, I went through a detailed requirements analysis, and a full MoSCoWMeh matrix. If you aren't familiar with MoSCoWMeh, this is an enhanced variant of the well-known MoSCoW technique, which also accommodates the needs of private and hobby-run systems.

The requirement for reliable hosting and 5-nines up-time was classified as Meh, and has remained so since. So now you know.

Today, for the first time, I used a helper in a Razor Tridion template. I'd made a fairly standard 'generic link' embedded schema, so that I could combine the possibility of a component link and an external link in a link list, and allow for custom link text. (Nothing to see here, move along now please.)  However, when I came to template the output, I wanted to have a function that would process an individual link. A feature of Razor templating is that you can define a @helper, which is a bit like a function, except that instead of a return value, the body is an exemplar of the required output. There is also support for functions, so to lift Alex Klock's own example:

@functions {
    public string HelloWorld(string name) {
        return "Hello " + name;
    }
}

and

@helper HelloWorld(string name) {
    <div>Hello <em>@name</em>!</div>
}

will serve fairly similar purposes.

What I wanted to do today, however was slightly different; I didn't want to pass in a string, but a reference to my embedded field. All the examples on the web so far are about strings, and getting the types right proved interesting. I started out with some code like this:

@foreach(var link in @Fields.links){
  @RenderLink(link);
}

So I needed a helper called RenderLink (OK - this might be a very trivial use-case, but a real problem all the same.). But what was the type of the argument? In theory, "links" is an EmbeddedSchemaField (or to give it it's full Sunday name: Tridion.ContentManager.ContentManagement.Fields.EmbeddedSchemaField) but what you get in practice is an object of type "Tridion.Extensions.Mediators.Razor.Models.DynamicItemFields". I'd already guessed this by poking around in the Razor Mediator sources, but after a few of my first experiments went astray, I ended up confirming that with @link.GetType().FullName

Well I tried writing a helper like this:

@using Tridion.Extensions.Mediators.Razor.Models 
@helper RenderLink(DynamicItemFields link){
... implementation
}

but that didn't work, because when you try to call the methods on 'link' they don't exist.

And then, just for fun, of course, I tried

@using Tridion.ContentManager.ContentManagement.Fields 
@helper RenderLink(EmbeddedSchemaField link){
... implementation
}

but that was just going off in an even worse direction. Yeah, sure, that type would have had the methods, but what I actually had hold of was a DynamicItemFields. Eventually, I remembered some hints in the mediator's documentation and tried using the 'dynamic' keyword. This, it turns out, is what you need. The 'dynamic' type lets you invoke methods at run-time without the compiler needing to know about them. (At last, I was starting to understand some of the details of the mediator's implementation!)

@helper RenderLink(dynamic link){
... implementation
}

This may be obvious with hindsight (as the old engineers' joke has it ... for some value of 'obvious') . For now, I'm writing another blog post tagged #babysteps and #notetoself, and enjoying my tendency to take the road less travelled.

-- Robert Frost