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ASP.Net MVC Tip: URL Anchor Tags

Tuesday, 6 December 2011 7:11 pm Comments off

This is one of those features which should be baked into MVC by default, but isn’t.

Actually, it is partially supported by MVC. This Codeplex answer details it:

 

@Html.ActionLink(
    "Link Text",           // linkText
    "Action",              // actionName
    "Controller",          // controllerName
    null,                  // protocol
    null,                  // hostName
    "fragment",            // fragment
    new { id = "123" },    // routeValues
    null                   // htmlAttributes
)

will produce (assuming default routes):

<a href="/Controller/Action/123#fragment">Link Text</a>

But what if you want the returned redirect of an ActionResult method to include the anchor tag. There is no RedirectAnchorTagResult to return.

 

That same answer does some voodoo to pull it off:

public ActionResult Index()
{
    var url = UrlHelper.GenerateUrl(
        null,
        "Action",
        "Controller",
        null,
        null,
        "fragment",
        new RouteValueDictionary(new { id = "123" }),
        Url.RouteCollection,
        Url.RequestContext,
        false
    );
    return Redirect(url);
}

 

It is this that should be baked into MVC by default. Thats an awful lot of complexity to expose just for the sake of a simple anchor tag. So, yes, a RedirectAnchorTagResult would be a nice addition.

 

Thanks to Darin Dimitrov for providing the answer. Go ahead and upvote his answer.

Categories: Codeplex, MVC, Programming, Tech

Codeplex Projects of the Week.

Wednesday, 30 November 2011 11:00 pm Comments off

Two Codeplex projects have come in quite handy for  me this week and I thought I’d pass them on.

 

WSUS 3.0 – WSUS Smart Approve

I installed Windows Server Update Services on my Windows Home Server 2011 this week.

As usual, I was in a bit over my head. I hit the Approve All Updates nuclear option. Knowledgeable sysadmins are possibly cringing or screaming at me (or both). By the time i figured out that approving updates puts them in the download queue, 4 and a half gigabytes were in the queue. Ordinarily this wouldn’t be a problem. But my broadband has had issues and it’s ridiculously slow (0.85 MBPS) and WSUS was eating up all the bandwidth.

So this was a problem. The solution was, of course to approve and download only needed updates. Amazingly, WSUS has no way of automatically approving needed updates (even as a checkbox buried five or six option screens down and off by default).

So, Codeplex to the rescue!

WSUS Smart Approve does exactly what it says on the tin – automatically approving updates according to certain rules. One of those is, of course, to approve needed updates automatically.

 

MetaWeblogAPI – ooMetaWeblog

One of the nice things about the MetaWeblogAPI is that almost everyone supports it. One of those is, of course, Windows Live Writer 2011.

Using Windows Live Writer as a WYSIWYG editor would be convenient.

There are a number of options to implement a server-side MetaWeblogAPI endpoint. Scott Hanselman has one approach.

I used another approach  – the Matlus.MetaWeblogAPI.

The corresponding Codeplex project is ooMetaWeblog.

 

Hope they come in helpful for somebody.

Why Silverlight Should Stay

Tuesday, 8 November 2011 9:04 pm Comments off

Mary Jo Foley just published a post discussing the future of Silverlight.

I’m not a Silverlight Developer by any stretch of the imagination. I never played with it. Never touched it at all.

Then, for the Flying Shakes website,  I had to have the control below in a web form. Naturally I turned to Silverlight.

image

 

With no knowledge or experience of Silverlight it took me 90 minutes from idea to working control.

And yes, I realise that I could write a HTML5 version of that now. But it would probably take much, much longer (don’t nobody suggest Flash).

Silverlight is good, not just for rich client experiences it allows us to build, but also because its part and parcel of the tools we Visual Studio devs work with every day.

The flip side to this, of course is the user perspective.

Here in the UK we have Sky satellite television. The reason why I like them so much is that they are fairly technology friendly. Besides streaming on the go (iPad, iPhone, etc), you can log on to their Sky Go website to stream on-demand or download and watch on your desktop offline.

This experience is delivered by, wait for it, Silverlight. The impressive part of this whole thing was the Sky Go Desktop Client. Its an offline Silverlight application, popping straight out of the browser and installed silently.  Was downloading from my queue 10 seconds after hitting the download button.

Satisfied does not even begin to describe it.

I HTML 5 may be the bees knees, but there is still a business case for keeping Silverlight around.

I’ll consider HTML 5 a contender when we have the same level of support and tooling for it as we have now for Silverlight.

LINQ + Google Charts + MVC : Pie Chart

Tuesday, 1 November 2011 3:52 pm 1 comment

A couple of weeks ago, I pointed out a LINQ snippet that was running against the Google Charts API.

This week, I’m back with my implementation of  the Pie Chart.

I’ve started with the Pie chart because its relatively simple and will lay the foundation for dealing with the complexities of the other charts.

Building Blocks

Since this is MVC, I created a new ChartsService class in the Services namespace of the project.

If you look at the snippets in the original ACM article, you’ll notice an extension method called “SeparatedBy”. So our first task is to create this extension method.

There are, of course, a number of ways to concatenate a list of string with a separator. This being an exercise in LINQ, we are going to use the LINQ Aggregate method.

   
public static string SeparatedBy(this List<String> list, string seperator)
{ 
return list.Aggregate((current, next) => current + seperator + next); 
}

 

I’m sure that you’ll agree with me when i say that it’s a nice and clean approach to what could be a messy block of code.

However, that extension method will only concatenate the list of strings passed to it. Why is this a problem? Because we are going to want to concatenate lists of int objects as well. So that extension method will just not do. We  could do some fancy work with generics, but the simplest thing to do is to supply to an overloaded method that accepts lists of type int.

public static string SeparatedBy(this List<int> list, string seperator)

List<string> thelist = list.ConvertAll<string>(x => x.ToString());

 return thelist.Aggregate((current, next) => current + seperator + next); 
}

There is one additional difference between these and our original method – the call to ConvertAll. Rather than have a foreach loop that does the conversation, we simply supply an inline lambda function that gets executed against each item  in the list and returns a list of the desired type. Again, very clean.

 

So, armed with these extension methods, we can now declare our classes.

Data

Google charts offers a wide range of functionality and many different kinds of charts. Each chart has a host of differing options and settings available to it. So when creating classes to represting thse charts kinds we have to bear in mind that there will be unique functionality not common to other charts that will come up.

Charts logically are made up of a number of  smaller complements:  bar charts have columns, pie charts have slices and so on and so forth. So we’ll represent these first.


public class Slice
{
public int Value { get; private set; }
public string Legend { get; private set; }

public Slice(int value, string legend)
 this.Value = value;
this.Legend = legend;
}

} 

Lets first look at the Pie class itself now.

Pie Class


public List<Slice> Slices { get; set; }
public string Title { get; private set; 
public Double Height { get; private set; }
public Double Width { get; private set; }

public Pie(string title, double height, double width)
{
this.Slices = new List<Slice>();
this.Title = title;
this.Height = height;
this.Width= width;
}

We start by declaring a number of properties and a constructor. In the constructor we initialize our list of Slices. This is where we see a departure from the snippets of he ACM article.  We do not pass the slices into the constructor. Of course, this is an issue of style over substance. There is no reason why we could not have generated the slices before the creating the chart and then passed the slices.


public string Compile()
{
var tt = Title.Split(' ').ToList().SeparatedBy(' ');
var p = new List<string>(){
this.Slices.Select(slice =>slice.Legend).ToList().SeparatedBy("|"),
this.Slices.Select(slice =>slice.Value).ToList().SeparatedBy(",")};

return string.Format(@"http://chart.googleapis.com/chart?cht=p&chtt={0}&chs={3}x{4}&chl={1}&chd=t:{2}", tt, p.ElementAt(0), p.ElementAt(1), this.Width, this.Height)
}

This is where all the important stuff happens.

Line 3 properly formats the title by putting a + sign to signify spaces between words. Note that we are using the extension method we wrote earlier.

Line 4 creates a new list of strings, each string being the comma or | delimited list of values and legends. Using a List gives us greater flexibility later on when our implementation will handle multiple data series and legends

Line 8 uses String.Format to merge all this data into a url that we can use to call the Google Charts API with. For an explanation of what each of these parameters mean, see the Google Charts API Parameter List

 

ViewModel

Now, this being MVC, the way to display stuff is by using a ViewModel. So lets create one:


public class MonthlyReportsViewModel
{
public MonthlyReports Details { get; set; }
public Pie Chart { get; set; }
 }

The one property we are interested in here is the Chart Property.

Now that we have our ViewModel, we have to populate it. So, in our ActionResult method:


<pre>Pie chart = new Pie("This is my chart",200);
chart.Slices.Add(new Slice(25, “Slice 1”));
chart.Slices.Add(new Slice(25, “Slice 2”));
chart.Slices.Add(new Slice(25, “Slice 3”));
chart.Slices.Add(new Slice(25, “Slice 4”));
model.Chart = chart;
return View(model);

 

View

In our View itself, we’re going to have to render out the chart. Since the call to Google Charts API will return an image, we can simply do the following:


<img src = "@Model.Chart.Compile()" alt ="">

 

What one could do is to put the actual rendering code in a Helper Method and call the Helper Method from your view, like so:


@GoogleCharts.PieChart(@Model.Chart)

That, of course, further abstracts the code. It does have the advantage of being much cleaner and easier to do.

 

Conclusion

As you can see, using LINQ to abstract away the complexity of what your code is actually doing is not just the province of database code. One thing what I've enjoyed about working with LINQ is how code always comes out looking fresh, clean and crisp. Having worked extensively with LINQ and Lambda expressions, using foreach loops  to process Lists looks so much messier.

Next time, we’ll take a look at the somewhat more complicated Bar Chart. I’ll not cover every single possible piece of functionality, but I’ll cover the basics. All I want to show is how the foundation laid down today can easily translate over. My current implementation of bar charts is sufficient only for the limited functionality the app needs and nothing more. 

At some point in the future, I’d also like to implement Line charts.

 

Postscript

I must say that apart from working with LINQ, its been a very satisfying experience for me to implement a C# version of a web API.

There is GoogleChartsSharp on Codeplex that Implements a whole lot more of the functionality of Google Charts. I did indeed use it for a while before implementing it on my own.

So its been a satisfying experience for me to implement an API that allows me to work the way I want to work. Not only did I write something simpler and easier to work with, but I dropped a dependency in the process and that made me happier than I think its safe to admit. 

Writing against something requires you, the writer, to pay extra attention to the small details. It requires you to think of the relationship between your code,the web API  calls and the documentation that supports it. When one uses an already baked implementation such as GoogleChartSharp, its like working with a giant black box  you have no idea what goes on inside. And you really don’t want to know the finer details. But writing the API, you create a white box. And you HAVE to understand those finer details.

So while the LINQ is nothing special in and of itself,nothing earth shattering or ground-breaking, it is the experience and the satisfaction gained from it that makes this a worthwhile post to write.

Categories: Google, LINQ, MVC, Programming, Projects, Tech, Web

LINQ Goodness: Google Charts Edition

Monday, 3 October 2011 7:35 pm Comments off

My day job (one of them, anyway) is to design*, run and maintain Flying Shakes

If someone had told me when I started  that 90% of the code (and 87.653% of all stats are made up, but you get my drift) I’d write would be for the administration side of things, I’d never have believed it.

 

Anyway, to cut a long story short, it was in this context that I came across a fascinating article from the Association for Computing Machinery (and no, I have not heard of them before either). I came across this a month or so ago, but lost the link.

 

With a little bit of Google-fu, I’ve found it once again: The World According to LINQ.

While its a fascinating article that appeals to the Computer Scientist in me (supposedly useless classes on in-depth database theory tend to do that), what caught my eye was the code sample right at the bottom for generating Google Chart Url’s.

That sample is going to come in very handy for me and I thought I’s share it with you.

Go ahead and read the article.

 

*If you see me ranting on Twitter or Google+ about CSS, this is probably why.

Categories: LINQ, Programming, Software, Tech

WCF Chat Update: Long Polling

Tuesday, 30 August 2011 7:28 pm Comments off

Updating WCF chat continues slowly but surely. I have not made any commits yet, so you’ll have to wait to see the changes.

In addition to the changes to Authentication, there are changes to the callback mechanism that I originally wrote.

 

When i originally wrote the chat application, the callback was one of the first pieces of code that i wrote. The fact of the matter is, the the only requirement for it was to work across the local network (or even simply between instances on the local machine). So when I wrote the Cloud version, suddenly callbacks had to work across NAT to let the application function across the internet.

 

Now, there are a number of possible design patterns that would allow the server to execute a callback on a remote client. 

 

The first is ,indeed, the design pattern we use at the moment. Where we actually have a callback. the enabler for this is actually found in WCF. The wsHTTPDuplexBinding allows for dual HTTP connections – one in each direction. This allows you to invoke an operation on the client. However, in order for this to work, you need to have an instance of WCF server on a per-instance basis. So. Every new client session will spawn a new instance of the server. This means that you are going to end up with dozens ( or hundreds etc) of long-lived instances. The question here is scalability. Is this scalable?

It might seem somewhat arrogant to talk about scalability, but if you design with scalability in mind, you’re not going to end up dealing with it later.

 

The other is something that, while not new, really hit the big-time after Friendfeed released its Tornado server. Tornado supports long polling http connections. Long polling is not in and of itself new. The basic design pattern involves a client making a call ( http or otherwise) to a server. The server receives the connection and keeps it open until it has something to return. Some long polled connections eventually time out and this is the implicit signal for the client to immediately open another connection. Others, such as the Friendfeed implementation, keep them open indefinitely.

 

There are probably more that you can think of, but these are the two that I considered for the Chat Application. As with most things, the choice is between a Push model (where notifications are pushed to the client) and the Pull model (where information, Notifications or otherwise, is pulled from the server by the client).

 

The fact of the matter is that I like both. Both are Cool. And both are supported intrinsically by WCF – no coding voodoo to make thins work.

Of the two, I’ve begun implementing the long polling method. Although it s radical departure, it will allow the overall design of to server-side to remain the same. The WCF server remains as a Single Instance service, and so the implementation remains the same.

The WCF stack is written in such a way that when you mark a OperationContract as needing the Async Pattern, WCF with start the Asyc operation and then go off and handle another request until that method returns. The End method that receives the results then returns the data to the client. In other words, its non-blocking.

I’ve not sorted out the exact specifics of implementation, but there will be changes to both the server and the client to accommodate  this. In saying that, I’m doing  a lot of simplification to the class structure. So hopefully what emerges from all these changes will be better than the current setup. Even I had to go back and follow the inheritance tree to figure things out.

These changes are happening in parallel with the changes to the authentication scheme.

 

So, while I’ve got no code, I leave you with this MSDN blog post on Async programming with WCF and this post that adapts it to long-polling specifically.

Some Interesting Code – your thoughts required

Thursday, 18 August 2011 11:22 am Comments off

Without going to into a long story, I found some interesting code here to convert anonymous types to any strongly typed, well, type.

 

public static object ToType<T>(this object obj, T type)
{

    //create instance of T type object:
    var tmp = Activator.CreateInstance(Type.GetType(type.ToString())); 

    //loop through the properties of the object you want to covert:          
    foreach (PropertyInfo pi in obj.GetType().GetProperties()
    {
      try 
      {   

        //get the value of property and try 
        //to assign it to the property of T type object:
        tmp.GetType().GetProperty(pi.Name).SetValue(tmp, 
                                  pi.GetValue(obj, null), null)
      }
      catch { }
     }  

   //return the T type object:         
   return tmp; 
}

From this codeproject article.

Anyone have any thoughts on this?  Is it good? Bad? Inefficient? Crap??

Categories: Programming, Software, Tech

WCF Server Chat Update:

Tuesday, 19 July 2011 11:38 am 1 comment

I just left this reply to a comment on my last post on this project:

Hi there,

No, I Haven’t been able to make in any changes sine my last comit.

However, I have been taking a look at it over the past week, since there are issues with it. As you say authentication and authorisation are one of them.

I’ve been looking at the possibility of using Forms authentication. This brings ASP.Net Membership, Profiles and Roles to the table and these can be used.

This of course requires a SQL server as a back end. And requires the use of SSL.

This requires significant changes to the code base, to move from the current storage model (XML in the case of the Windows service, and Azure Tables in the case of the Windows Azure role). And since authorisation and authentication are now handled separately, those WCF method calls that currently handle this aren’t required.

Also, since the codebase is effectively two separate projects, these changes need to be made twice.

The client will also need to be changed.

These changes do make a lot of sense and I’m well along in implementing them. So look out for a post soon on them.

 

I thought I’d let everyone know that this is the direction I’m taking things in.

 

Life is busy, which why I haven’t been able to update things as much as I’d like.

There is one other particular problem with the WCF Server chat that I would have liked to have solved in my last comitt.

The issue involves the server pinging other clients across NAT. Of course, this could be solved by moving to a pull model rather than a push notification model. While that would be easy, I want to take a good long look at getting push to work properly before trying any other models.

Push notification is where its at. So if anyone has any pointers to implementing it, please send it my way.

Windows Azure Block Blobs

Tuesday, 17 May 2011 11:38 pm 5 comments

In Windows Azure Blob Storage, not all blobs are created equal. Windows Azure has the notion of Page Blobs and Block Blobs.  Each of these distinct blob types aim to solve a slightly different problem, and its important to understand the difference.

To Quote the documentation:

  • Block blobs, which are optimized for streaming.
  • Page blobs, which are optimized for random read/write operations and provide the ability to write to a range of bytes in a blob.

About Block Blobs

Block blobs are comprised of blocks, each of which is identified by a block ID. You create or modify a block blob by uploading a set of blocks and committing them by their block IDs. If you are uploading a block blob that is no more than 64 MB in size, you can also upload it in its entirety with a single Put Blob operation.

When you upload a block to Windows Azure using the Put Block operation, it is associated with the specified block blob, but it does not become part of the blob until you call the Put Block Listoperation and include the block’s ID. The block remains in an uncommitted state until it is specifically committed. Writing to a block blob is thus always a two-step process.

Each block can be a maximum of 4 MB in size. The maximum size for a block blob in version 2009-09-19 is 200 GB, or up to 50,000 blocks.

About Page Blobs

Page blobs are a collection of pages. A page is a range of data that is identified by its offset from the start of the blob.

To create a page blob, you initialize the page blob by calling Put Blob and specifying its maximum size. To add content to or update a page blob, you call the Put Page operation to modify a page or range of pages by specifying an offset and range. All pages must align 512-byte page boundaries.

Unlike writes to block blobs, writes to page blobs happen in-place and are immediately committed to the blob.

The maximum size for a page blob is 1 TB. A page written to a page blob may be up to 1 TB in size.

So, before we determine what blob type we’re going to use, we need to determine what we’re using this particular blob for in the first place.

You’ll notice the above extract is quite clear what to use block blobs for: streaming video. In other words, anything that we don’t need random I/O access to. On the other hand page blobs have a 512-byte page boundary that makes it perfect for random I/O access.

And yes, its conceivably possible for you to need to host stuff such as streaming video as a page blob. When you think about this stuff to much, you end up imagining situations where that might be possible.  So, these would be situations where you are directly editing or reading very select potions of a file. If you’re editing video, who wants to read in an entire 4MB for one frame of video? You might laugh at the idea of actually needing to do this, but that the Rough Cut Editor is web based and works primarily with web-based files. If you had to run that using Blob storage as a backend you’d need to use page blobs to fully realise the RCE’s functionality.

So, enough day-dreaming. Time to move on.

Some groundwork

Now, in our block blob, each individual block can be a maximum of 4MB in size. Assuming we’re doing streaming video, 4MB is not going to cut it.

The Azure API provides the CloudBlockBlob class with several helper methods for managing our blocks. The methods we are interested in are:

  • PutBlock()
  • PutBlockList()

The PutBlock method takes a base-64 encoded string for the Block ID, a stream object with the binary data for the block and a (optional) MD5 hash of the contents. Its important to note that the ID string MUST be base-64 encoded or else Windows Azure will not accept the block. For the MD5 hash, you can simply pass in null.  This method should be called for each and every block that makes up your data stream.

The PutBlockList  is the final  method that needs to be called. It takes a List<string>  containing every ID of every block that you want to be part of this blob. By calling this methods it commits all the blocks contained in the list. This means, then, that you could land up in a situation where you’ve called PutBlock but not included the ID when you called PutBlockList. You then end up with an incomplete and corrupted file. You have a week to commit uploaded blocks. So all is not lost if you know which blocks are missing. You simply call PutBlockList with the IDs of the missing blocks.

There are a number of reasons why this is a smart approach.  Normally, I fall on the side of developer independence, the dev being free to do things as he likes without being hemmed in. In this case, by being forced to upload data in small chuncks, we realise a number of practical benefits. The big one being recovery from bad uploads – customers hate having to re-start gigabyte sized uploads from scratch.

Here be Dragons

The following example probably isn’t the best. I’m pretty sure someone will refactor and post a better algorithm.

Now there are a couple of things to note here.  One bring that I want to illustrate what happens at a lower level of abstraction that we usually work at, so that means no StreamReaders – We’ll read the underlying bytes directly.

Secondly, not all Streams have the same capability. Its perfectly possible to come across a Stream object where you can’t seek. Or determine the length of the stream. So this is written to handle any data stream you can throw at it.

With that out of the way, lets start with some Windows Azure setup code.

StorageCredentialsAccountAndKey key = new StorageCredentialsAccountAndKey(AccountName, Account Key);
CloudStorageAccount acc = new CloudStorageAccount(key, true);

CloudBlobClient blobclient = acc.CreateCloudBlobClient();
CloudBlobContainer Videocontainer = blobclient.GetContainerReference("videos");
Videocontainer.CreateIfNotExist();

CloudBlockBlob blob = Videocontainer.GetBlockBlobReference("myblockblob");

Note how we’re using the CloudBlockBlob rather than the CloudBlob class.

In this example we’ll need our data to be read into a byte array right from the start. While I'm using data from a file here, the actual source doesn't matter.

byte[] data = File.ReadAllBytes("videopath.mp4");

Now, to move data from our byte array into individual blocks, we need a few variables to help us.

            int id = 0;
            int byteslength = data.Length;
            int bytesread = 0;
            int index = 0;
            List blocklist = new List();
  • Id will store a sequential number indicating the ID of the block
  • byteslength is the length, in bytes of our byte array
  • bytesread keeps a running total of how many bytes we’ve already read and uploaded
  • index is a copy for bytes read and used to do some interim calculations in the body of the loop (probably will end up refactoring it out anyway)
  • blocklist holds all our base-64 encoded block id’s

Now, on to the body of the algorthim. We’re using a do loop here since this loop will always run at least once (assuming, for the sake of example, that all files are larger than our 1MB block boundary)

do
            {
                byte[] buffer = new byte[1048576];
                int limit = index + 1048576;
                for (int loops = 0; index < limit; index++)
                {
                    buffer[loops] = data[index];
                    loops++;
                }

The idea (that of using a do loop) here being to loop over our data array until less than 1MB remains.

Note how we're using a separate byte array to copy data into. This the block data that we'll pass to PutBlock. Since we're not using StreamReaders, we have to do the copy byte for byte as we go along.

It is this bit of code would be abstracted away were we using StreamReaders (or, more properly for this application, BinaryReaders)

Now, this is the important bit:

                 bytesread = index;
                string blockIdBase64 = Convert.ToBase64String(System.BitConverter.GetBytes(id)); //1

                blob.PutBlock(blockIdBase64, new MemoryStream(buffer, true), null); //2

                blocklist.Add(blockIdBase64);
                id++;
            } while (byteslength - bytesread > 1048576);

There are three things to note in the above code. Firstly, we're taking the block ID and base-64 encoding it properly.

And secondly, note the call to PutBlock. We're wrapped the second byte array containing just our block data as a MemoryStream object (since that's what the PutBlock methods expects) and we've passed in null rather than an MD5 hash of our block data.

Finally, note how we add the block id to our blocklist variable. This will ensure that the call to PutBlockList will include the ID's of all of our uploaded blocks.

So, by the time this do loops finally exits, we should be in a position to upload our final block. This final block will almost certainly be less than 1MB in size (barring the usual edge case caveats). Since this final block is less than 1MB, our code will need a final change to cope with it.

            int final = byteslength - bytesread;
            byte[] finalbuffer = new byte[final];
            for (int loops = 0; index < byteslength; index++)
            {
                finalbuffer[loops] = data[index];
                loops++;
            }
            string blockId = Convert.ToBase64String(System.BitConverter.GetBytes(id));
            blob.PutBlock(blockId, new MemoryStream(finalbuffer, true), null);
            blocklist.Add(blockId);

Finally, we make our call to PutBlockList, passing in our List array (in this example, the “blocklist” variable).

blob.PutBlockList(blocklist);

All our blocks are now committed. If you have the latest Windows Azure SDK (and I assume you do), the Server Explorer should allow you to see all your blobs and get their direct URL’s.  You can downloaded the blob directly in the Server Explorer, or copy and paste the URL into your browser of choice.

Wrap up

Basically, what we’ve covered in this example is a quick way of breaking down any binary data stream into individual blocks conforming to Windows Azure Blob storage requirements, and uploading those blocks to Windows Azure. The neat thing here is that by using this method not only does the MD5 hash let Windows Azure check data integrity for you, but block ID’s let Windows Azure take care of putting the data back together in the correct sequence.

Now when I refactor this code for actual production, a couple of things are going to be different. I’ll do the MD5 hash. I’ll upload blocks in parallel to take maximum advantage of upload bandwidth (this being the UK, there not much upload bandwidth, but I’ll take all I can get). And obviously, I’ll use the full capability of Stream readers to do the dirty work for me.

Heres the full code:

StorageCredentialsAccountAndKey key = new StorageCredentialsAccountAndKey(AccountName, Account Key);
CloudStorageAccount acc = new CloudStorageAccount(key, true);

CloudBlobClient blobclient = acc.CreateCloudBlobClient();
CloudBlobContainer Videocontainer = blobclient.GetContainerReference("videos");
Videocontainer.CreateIfNotExist();

CloudBlockBlob blob = Videocontainer.GetBlockBlobReference("myblockblob");

byte[] data = File.ReadAllBytes("videopath.mp4");

int id = 0;
int byteslength = data.Length;
int bytesread = 0;
int index = 0;
List blocklist = new List();

do
            {
                byte[] buffer = new byte[1048576];
                int limit = index + 1048576;
                for (int loops = 0; index < limit; index++)
                {
                    buffer[loops] = data[index];
                    loops++;
                }
                bytesread = index;
                string blockIdBase64 = Convert.ToBase64String(System.BitConverter.GetBytes(id));

                blob.PutBlock(blockIdBase64, new MemoryStream(buffer, true), null);

                blocklist.Add(blockIdBase64);
                id++;
            } while (byteslength - bytesread > 1048576);

            int final = byteslength - bytesread;
            byte[] finalbuffer = new byte[final];
            for (int loops = 0; index < byteslength; index++)
            {
                finalbuffer[loops] = data[index];
                loops++;
            }
            string blockId = Convert.ToBase64String(System.BitConverter.GetBytes(id));
            blob.PutBlock(blockId, new MemoryStream(finalbuffer, true), null);
            blocklist.Add(blockId);
            blob.PutBlockList(blocklist);

Holiday Reading iList

Friday, 13 May 2011 10:52 pm Comments off

While I don’t usually do this before going on holiday, this time I’m not taking any dead tree books with me at all.

Rather, I’m taking my trusty iPad with IBooks and Kindle for iPad installed. Since we’re flying Ryanair, with their stickiness for baggage weights and sizes, he weight saved has been substantial. Usually I take a couple of paperbacks and a hardcover or two, so my bags a lot lighter this time around.

So, that reading list again, split up between iBooks and Kindle.

iBooks:

1. The Void Trilogy – Peter F Hamilton
2. Pandora’s Star – Peter F Hamilton
3. Judas Unchained – Peter F Hamilton
4. Servants of the People – Andrew Rawnsley
5. Life and Death of the Party – Andrew Rawnsley
6. Red November – W. Craig Reed
7. The Hobbit – J.R.R Tolkien
8. Paypal API’s Up and Running – Micheal Balderas

Kindle

1. The Design of Everyday Things – Don Norman
2. Dreaming in Code – Scott Rosenburg

I think that’ll keep me busy for a week :)

As you can see the above list is heavily biased towards iBooks. The ability to buy a book off iBooks without even thinking about it is the probable reason. Amazon Kindle gives you too much pause for thought.

About the Paypal API book. Yes, I’m sad. I do have the tendency to program while on holiday. If you’ll recall, I did some major re-architecting of my Client Server Chat project while is was in Spain in December. So goodness know what I might do this time around.

I hear the Design of Everyday Things is a seminal work and every designer should read it. Jeff Atwood of the Coding Horror blog (and Stackoverflow, StackExchange etc) highly recommends it.

Dreaming in Code is the most readable book about programmers and programming I’ve ever read. Though I must say reading it elicits the same reaction as watching Dennis Nedry screw Jurassic Park’s computer systems up: A Long Loud Cry of NOOOOOOOOOOOOOOOOOOOO!

Sightly changing the subject away from books, I got the Camera Connection Kit for my iPad. It’s works like a swiss car. If I could get Visual Studio on my IPad, I’d leave the laptop at home.

I’ll see you all in a week (and a bit, one always needs a holiday from holiday when you get back)

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