Is there a good way to canonicalize XML with MSXML6?
I have an XML document that I load into a IXMLDOMDocument object. I need to perform an operation like singing or hashing on the document. I would like to put it into XML canonical form a la C14N or similar standard. IXMLDOMDocument has a save to file method, but I don't think that canonicalizes it first nor does it really provide any knobs to control how it writes the file. There is the MXXMLWriter60 that lets you control some stuff like indention, encoding format, etc., but it doesn't seem like it has everything to do the complete the C14N standard. The .net framework has XmlDsigC14NTransform which seems idea, but obviously not usable from where I am in the stack. It seems like MSXML does have some support for XMLDSIG so that code should canonicalize stuff, but it doesn't expose any of that.
Any suggestions?
The short answer is no, MSXML 6.0 doesn't have a cannonicalizer you can use. If old versions of MSXML with canoncalizers existed, they are not included in modern Windows.
Windows does ship inbox components that can canonicalize XML per the c14n standard and many others; however, they are not exposed by any public APIs.
Hope this helps!
Related
Im starting a new project. The aim of the project is to create a e-authoring tool for building courses in SCORM Complaint. Im new to this domain and I have little idea on this. I have taken a view on authoring tool in Articulate, which my customer requires to do the same. I understood the content creation, but I am trying to understand How can I export this as SCORM compliant course? In between I learned about xAPI as well And understood it is a kind of enhanced SCORM.
Could any one guide me to understand this,
1) How can create content from my custom authoring tool and export as SCORM complaint
2) Is it better to use xAPI or SCORM.
3) How is the SCORM pacakge communicate with my custom made LMS?
4) Heard about LRS,
My custom authoring tool will be made in React and store would MondDB
Any help would be greatly appreciated. Thankyou!
That is a lot to take on, particularly all at once.
1) The SCORM spec is made up of multiple parts. There is a packaging portion and a runtime portion. The basics are that your package needs to be a zip file, and that zip needs to include specific files that indicate to the LMS what type of standard it is along with other metadata about the package. For SCORM this will be called an imsmanifest.xml file. For xAPI you are most likely going to use a cmi5.xml (see cmi5) or a tincan.xml file (what Articulate Storyline exports when it says "xAPI"). The other parts of the package will depend on what standard and version of that standard (for SCORM 1.2, 2004 2nd, 3rd, or 4th edition) you are targeting, realizing that different LMSs support different standards and different degrees of those standards.
Once you have a package constructed that will import, the content itself (usually an HTML file) will need to locate the JavaScript API provided by the SCORM player (from the LMS) and make specific calls depending on what the content is needing to store or read, this is the runtime portion. The calls will again depend on the standard and version. For xAPI based packages (either tincan.xml packages or cmi5 packages) the content will communicate directly to the LRS based on the information provided on the URL at launch time (there is no built in JavaScript API).
2) This entirely depends on what your customer base looks like and the types of data that you intend to capture. SCORM is a more mature landscape and has wider adoption and is more heavily specified, if the information you need to capture fits into its limited information model then it is still an excellent choice. If you need significant data portability and/or the information you need to capture goes beyond compliance data (pass/fail, complete, and score) and/or interaction data (questions + answers) then you should consider xAPI, specifically via cmi5.
3) The LMS must provide a JavaScript API (specified by the SCORM runtime) which the content will use as its interface. The storage/retrieval of data is implementation specific for the LMS beyond what is included in the specification for the JavaScript API.
4) You didn't really include a question here.
I would suggest familiarizing yourself with the two sets of standards via http://scorm.com and http://xapi.com. And although it is a plug for my company's product, you may want to consider the Rustici Driver as it is a product (library) specifically designed to make it easy for an authoring tool to export content as SCORM 1.2, 2004, AICC, cmi5 or Tin Can (the latter two being xAPI). Once you have your tool up and running with minimal standards support you should consider testing it on Rustici's SCORM Cloud (it is free for this purpose), see http://cloud.scorm.com.
The format is huge, there is no quick reference guides. And different authoring tools have different scorm-support depths. You should probably start with this document
Sounds like you're talking about designing editable content; and the content "framework" itself.
This is a massive effort! This is massive support! That said, people do it.
Having built a CMS system for many supporting subject matters I had to divide and conquer this task.
Few ways I'd think to digest this beast- data, data, data
Requirements on Activities (Interaction types)
Design (static/dynamic) on these interactions
The view/facade displaying can change. Tech moves at the speed of light. Need to come up with a super solid data model.
I'd think about how these can be generic, and how they can be extended to meet the customers goals/needs. All depends how much customization (if any) can happen.
I start mapping all this to SCORM CMI Object level calls. Scoring, Progress, Interactions, Objectives etc...
Get your self a wicked SCORM Content API library or write one yourself. You'll be re-using a lot of these calls, no sense baking them into all your interactions
Get up on SCORM Packaging .. much of this has to be defined at author time. Lots of reading, and a lot of features you need to pick thru if your customers even use. Don't dev in places that have .1% market need. The low hanging fruit get you to market.
Surround yourself with passionate great people. You'll need them.
As far as the standards go, it's all about portability. SCORM works directly with a LMS if thats where your customer goes. Others use a LRS which is coded to work with one they set at author time. You can even do both.
Aside from React and MongoDB, you'll need something that can do the lift and shift of all this content.
I have implemented a report in standard WPF controls and have also implemented a DocumentPaginator to take these controls and convert them into a document for printing.
I have also implemented some code which uses the document paginator to render the pages to images and write them out to a PDF using PDFSharp, however this does not allow for copying and pasting, also the image quality is questionable.
I have experimented with the GhostXPS utility and was thinking of using it by saving out to an XPS document and then using GhostXPS to convert it to a PDF, this was promising, however the current version contains a bug that renders data copied from the generated PDF useless...
So I thought I would ask here to try and find a efficient method for doing this, Can someone please suggest a good way to take a DocumentPaginator and either save it directly out to a PDF, with copy/paste functionality or convert it from an XPS document to a PDF with this functionality?
Thanks,
Alex.
EDIT - PDFSharp fix:
Ok as requested here is what I did to compile the fix for the PDFSharp 1.31 XPS converter:
1) I downloaded the source from here:
PDFSharp - SourceForge
2) I followed the instruction in this post:
PSFSharp Fix
XpsParser.ImageBrush.cs (ln 22, added): brush.Opacity = 1;
PdfContentWriter.cs (ln 526, changed): if (opacity <= 1)
3) Then just compile the source, first open the 'PdfSharp-WPF.csproj' and build that, then open the 'PdfSharp.Xps.csproj' and build it as well, the relevent libraries are 'PdfSharp-WPF.dll' and 'PdfSharp.Xps.dll'
Note upon trying to build the source you will likely receive a few errors depending on which version of .NET you are targeting, these are simple to fix if you just read the error messages.
EDIT(2): NJones created a blog post with more details on the PdfSharp fix: Output to PDF in WPF
There is an XPS Converter that was included with PDFsharp 1.31. It's a beta version, but AFAIK it supports nearly everything and may work for your needs.
PDFsharp 1.31 can be downloaded from SourceForge or CodePlex.
If a commercial SDK would be an option, there is one company I came across that has a professional XPS to PDF conversion option (and more).
http://www.nixps.com
Warning: I'm not affiliated with this company nor have I tried their products. I have on the other hand heard good things about them.
I use Telerik Reporting which handles document pagination and allows you to create reports in a designer similar to creating a GUI. I decided to just buy a 3rd party product because I didn't want to spend development time writing my own paginator, etc. Also, this tool is probably more bug proof then a custom solution and allows a lot of flexibility for how you want to design your printout/report. In the future if you have more complicated printing or reports required, this tool does a lot more. I do not work for Telerik, but there product is good.
It allows exporting to PDF, Word, Excel, HTML, PowerPoint, PNG, etc. etc.
IMHO, you've got the right idea: XPS is, in my mind, the simplest method of serializing the data into a usable format, especially for conversion.
As for a third party tool, I've a peer (as in, not myself,)who's used CheckPrixa with some measure of success; it's freeware and it offers command line conversions. (i.e. serializing a document and converting a la generated .bat file.)
It also allows you to handle keywords, titles, etc. along with more important items like even pagination.
As far as I'm aware, there are no known discrepancies.
Alternatively, if converting the MSXPS is what's giving you headaches, you might want to look at XpsConverter, it converts MSXPS to OpenXPS, and as a Window's driver, it's available on any machine using .NET 3 and above.
Keep us updated with whatever solution you try, virtual reports are a growing deal.
I'm communicating with a logic analyzer (HP 1660A) over RS232. I issue a command which tells the analyzer to print screen its display and send it over to the controller (my pc) through serial communication. I'm saving the result (which is usually abut 25kB) to my computer and I would like to view it as a TIFF or other format. The problem is that the response from the analyzer comes in PCL format, therefore suitable to be sent to a printer and printed directly, but not to be opened as an image. I have tried a few PCL to image converters to do the job, I found one which does it properly, however I've used the trial version and I am reluctant to purchase it. I've given you the background of my labour. I would appreciate any kind of help, a reference to the commands in pcl 1 and what should I do in order to extract the data and format it properly from the PCL file. I have no experience with PCL and image processing whatsoever, so please, give me a hand here. Thank you.
P.S. I've obtained the PCL file from the analyzer, both in C# and matlab... I have one slight problem in C# with the serial port control, some images have some uninterpreted characters in the image, when using the above converters. I say all these because I need an algorithm or some indications, no matter the programming language, so please feel free to post.
PCL is complex to read. There are only a handful of tools out there that do a good job of this. We have lots of PCL expertise and still often look to other to supply conversion to PDF and other formats. If the PCL is quite simple, that is, just text, a few fonts, and a graphic or two, a couple of RegEx commands could deal with the extraction of the text and then you could mock up a new document using whatever tools you wish.
Looking at these files in stackoverflow might be tough. If you can get them on an ftp and post a link I can take a quick look and post my findings/thoughts here. The other option is to look to an outside tool. There are a few we've had success with. Our needs are broad so I've settled on one that works the best with many different PCL streams (some PCL coding is better than others). As you are dealing with a known quantity of PCL you may have a few options. Here are a few we've used and had some success with (in order of usefulness to us)
PCLWorks by PageTech (they have a GUI viewer and complete SDK)
VeryPDF PCL Converter (command line tool)
SwiftView
There are others, and even an opensource variant of Ghostscript that handles PCL (we've never had much luck as the PCL we use often contains very custom fonts, symbol sets, and tons of macros which seem to choke it.
GhostPCL
EDIT: Most recently we've been working with LincPDF (http://www.lincolnco.com/). This is also an excellent product with has one big benefit, deployment is simple. Some of the other tools have complex software installations. This solution is very easy for us to deploy as a feature in an application. It's also faster then any tools we've tested to date (at least with the PCL that we generate from our apps which is quite complex as they include specialized fonts and macros).
According to the spec sheet for the HP 1660 (pdf) series can send the TIFF,PCX and postscript.
Wouldn't it be easier to use TIFF?
The project was put on hold for a while, but I would like to offer a complete and usable solution.
#Adrian
You can save the image to a floppy disk, I've done that, saved it as TIFF and everything worked fine. Unfortunately, it sends only PCL through RS232. The idea to save the print screen over serial communication was to avoid using too much the floppy disk, which the device uses in order to boot.
#Douglas
Thank you for your elaborate answer. I'll take a look at the indicated tools, however, my desire is to offer a complete front-end solution, which yields directly the graphic. I've put some files from my tests here in order to see the complexity of the PCL constructions. Do you have any knowledge of a possible API that I could integrate into my application, which can parse the file and interpret the PCL?
Regards,
Cosmin
We capture the serial input via a serial spooler that watches COM1:. It's called SSpool.exe. It redirects the PCL as input to PCLXForm. PCLXForm converts it into any raster format (TIFF, JPG, PDF, BMP, etc.) However, we can also extract the text during the conversion and we can extract individual raster objects from the PCL for re-arrangement in the downstream application. Our pricing model is positioned for licensee's that need to convert up to 50,000 pages of invoices into indexed PDF's per month. However, this type of application normally requires a custom license in order to get our pricing down to the level required. In order to do so, we often have to restrict our product to convert unlimited files, but only up to the 20th page within any one PCL print file. That provides enough page volume and gives us the ability to reduce the pricing per unit. To demo, you would need the PCLTool SDK.
I'm implementing an Apache 2.0.x module in C, to interface with an existing product we have. I need to handle FORM data, most likely using POST but I want to handle the GET case as well.
Nick Kew's Apache Modules book has a section on handling form data. It provides code examples for POST and GET, which return an apr_hash_t of the key+value pairs in the form. parse_form_from_POST marshalls the bucket brigade and flattens it into a buffer, while parse_form_from_GET can simply reference the URL. Both routines rely on a parse_form_from_string routine to walk through each delimited field and extract the information into the hash table.
That would be fine, but it seems like there should be an easier way to do this than adding a couple hundred lines of code to my module. Is there an existing module or routines within apache, apr, or apr-util to extract the field names and associated data from a GET or POST FORM into a structure which C code can more easily access? I cannot find anything relevant, but this seems like a common need for which there should be a solution.
I switched to G-WAN which offers a transparent ANSI C scripts interface for GET and POST forms (and many other goodies like charts, GIF I/O, etc.).
A couple of AJAX examples are available at the GWAN developer page
Hope it helps!
While, on it's surface, this may seem common, cgi-style content handlers in C on apache are pretty rare. Most people just use CGI, FastCGI, or the myriad of frameworks such as mod_perl.
Most of the C apache modules that I've written are targeted at modifying the particular behavior of the web server in specific, targeted ways that are applicable to every request.
If it's at all possible to write your handler outside of an apache module, I would encourage you to pursue that strategy.
I have not yet tried any solution, since I found this SO question as a result of my own frustration with the example in the "Apache Modules" book as well. But here's what I've found, so far. I will update this answer when I have researched more.
Luckily it looks like this is now a solved problem in Apache 2.4 using the ap_parse_form_data funciton.
No idea how well this works compared to your example, but here is a much more concise read_post function.
It is also possible that mod_form could be of value.
I'm hearing more and more about domain specific languages being thrown about and how they change the way you treat business logic, and I've seen Ayende's blog posts and things, but I've never really gotten exactly why I would take my business logic away from the methods and situations I'm using in my provider.
If you've got some background using these things, any chance you could put it in real laymans terms:
What exactly building DSLs means?
What languages are you using?
Where using a DSL makes sense?
What is the benefit of using DSLs?
DSL's are good in situations where you need to give some aspect of the system's control over to someone else. I've used them in Rules Engines, where you create a simple language that is easier for less-technical folks to use to express themselves- particularly in workflows.
In other words, instead of making them learn java:
DocumentDAO myDocumentDAO = ServiceLocator.getDocumentDAO();
for (int id : documentIDS) {
Document myDoc = MyDocumentDAO.loadDoc(id);
if (myDoc.getDocumentStatus().equals(DocumentStatus.UNREAD)) {
ReminderService.sendUnreadReminder(myDoc)
}
I can write a DSL that lets me say:
for (document : documents) {
if (document is unread) {
document.sendReminder
}
There are other situations, but basically, anywhere you might want to use a macro language, script a workflow, or allow after-market customization- these are all candidates for DSL's.
DSL stands for Domain Specific Language i.e. language designed specifically for solving problems in given area.
For example, Markdown (markup language used to edit posts on SO) can be considered as a DSL.
Personally I find a place for DSL almost in every large project I'm working on. Most often I need some kind of SQL-like query language. Another common usage is rule-based systems, you need some kind of language to specify rules\conditions.
DSL makes sense in context where it's difficult to describe\solve problem by traditional means.
If you use Microsoft Visual Studio, you are already using multiple DSLs -- the design surface for web forms, winforms, etc. is a DSL. The Class Designer is another example.
A DSL is just a set of tools that (at least in theory) make development in a specific "domain" (i.e. visual layout) easier, more intuitive, and more productive.
As far as building a DSL, some of the stuff people like Ayende have written about is related to "text parsing" dsls, letting developers (or end users) enter "natural text" into an application, which parses the text and generates some sort of code or output based on it.
You could use any language to build your own DSL. Microsoft Visual Studio has a lot of extensibility points, and the patterns & practices "Guidance Automation Toolkit" and Visual Studio SDK can assist you in adding DSL functionality to Visual Studio.
DSL are basic compilers for custom languages. A good 'free and open' tool to develop them is available at ANTLR. Recently, I've been looking at this DSL for a state machine language use on a new project . I agree with Tim Howland above, that they can be a good way to let someone else customize your application.
FYI, a book on DSLs is in the pipeline as part of Martin Fowler's signature series.
If its of the same standard as the other books in the series, it should be a good read.
More information here
DSL is just a fancy name and can mean different things:
Rails (the Ruby thing) is sometimes called a DSL because it adds special methods (and overwrites some built-in ones too) for talking about web applications
ANT, Makefile syntax etc. are also DSLs, but have their own syntax. This is what I would call a DSL.
One important aspect of this hype: It does make sense to think of your application in terms of a language. What do you want to talk about in your app? These should then be your classes and methods:
Define a "language" (either a real syntax as proposed by others on this page or a class hierarchy for your favorite language) that is capable of expressing your problem.
Solve your problem in terms of that language.
DSL is basically creating your own small sublanguage to solve a specific domain problem. This is solved using method chaining. Languages where dots and parentheses are optional help make these expression seem more natural. It can also be similar to a builder pattern.
DSL aren't languages themselves, but rather a pattern that you apply to your API to make the calls be more self explanatory.
One example is Guice, Guice Users Guide http://docs.google.com/View?docid=dd2fhx4z_5df5hw8 has some description further down of how interfaces are bound to implementations, and in what contexts.
Another common example is for query languages. For example:
NewsDAO.writtenBy("someUser").before("someDate").updateStatus("Deleted")
In the implementation, imagine each method returning either a new Query object, or just this updating itself internally. At any point you can terminate the chain by using for example rows() to get all the rows, or updateSomeField as I have done above here. Both will return a result object.
I would recommend taking a look at the Guice example above as well, as each call there returns a new type with new options on them. A good IDE will allow you to complete, making it clear which options you have at each point.
Edit: seems many consider DSLs as new, simple, single purpose languages with their own parsers. I always associate DSL as using method chaining as a convention to express operations.