Due to several requests, I added a Bookshelf to my website. This has a listing of many of the books that I have read over the last several years. My ultimate goal is to create a searchable Silverlight application, but I'm waiting for Silverlight 4 to come out before I get started on that. In the meantime, we'll have to settle for a static list.
If you have any books that you are fond of, feel free to drop me a note.
Happy Coding!
Tuesday, April 6, 2010
Monday, April 5, 2010
BackgroundWorker Component Questions
I recently received an e-mail with a few questions regarding the BackgroundWorker Component (original article). I decided to share the answers here.
Page Navigation with the BackgroundWorker
Question: I want to navigate to another page in the BackgroundWorker thread -- for example: "frameNavigator.Navigate(new OtherPage());" in the DoWork method. I tried this, but an exception occurred because the Page class uses the main thread whereas the BackgroundWorker uses a separate thread. How can I get around this?
Answer: As you noticed, things like Pages, Winodws and ListBoxes are all items on the UI thread (and they need to stay on the UI thread). And the BackgroundWorker component processes items on a different thread (not the UI thread). So, you will not be able to do things like "Navigate" in the DoWork method.
But here's what you should do: try to figure out why the navigation process is slow. This is usually due to something that happens when your new Page loads -- it could be loading data from a database, transferring a file across the network, or calling a web service. So, even though you cannot put the "Navigate" into the background, you may be able to take whatever is in your Page Load process and put that in the background. In this type of scenario, you could put the database call method or the file transfer method into the background, not the entire Page object. This will have the effect of keeping your UI thread running and responsive while your data loads in the background.
Using the Progress Bar
Question: I want to get the progress completed from the actual process time, not from a predetermined time as you used in the walkthrough. The application must know how much time the BackgroundWorker process will take to navigate to the target page and then show a progress bar based on this information. How can I accomplish this?
Answer: Progress is a tricky subject. In the example in my walkthrough, I am not technically doing the progress bar based on a predetermined time; I am calculating the progress (a percentage) based on the number of iterations completed in the loop. I purposely kept my background process simple so that I could focus on the methods, events and properties of the BackgroundWorker component itself. But you can use the progress event for anything you can calculate a percentage complete for. For a more complex example, you can look at the BackgroundWorker examples on MSDN: http://msdn.microsoft.com/en-us/library/c8dcext2.aspx. One in particular, calculates a Fibonacci sequence using a recursive method call and calculates a percentage for a progress bar.
As an example of a calculation: if you are doing a file transfer, you can calculate a percentage based on the number of bytes received compared to the total number of bytes. So, if you have received 257 bytes of a 1,356 byte file, you are 19% complete. The limitation is that you have to know how far along you are in the process. If you are doing something like making a database call or a web service call, you may not know how long it will take to complete or how much data you are getting back. In those situations, you cannot calculate a percentage and so you may be better off using a "busy animation" (and there are plenty of examples available on the web for WPF and Silverlight).
Complex Results
Question: I don't like examples of BackgroundWorker using results of "string" or "int". I want a real object. How would I do this?
Answer: The e.Result parameter in the DoWork and RunWorkerCompleted can be as simple or as complex as you like. In my example, I simply use an "int", but e.Result is of type "object", so you can put whatever you want in there (including an entire database result set). There are a few limitations such as the objects that need to be on the UI thread (like we mentioned above). As another option, you can use a separate variable (or set of variables) that is accessible to both the UI and the background process. If you do this, you will want to look into the "lock" method to ensure that you don't end up with multiple processes trying to modify the value at the same time.
Round Up
The BackgroundWorker component is not the right solution for everything. But it can be helpful in quite a few situations. As we saw above, you may not be able to do exactly what you want (such as navigating in the background), but if you think about the problem a little differently, you can often come up with a workable solution.
Happy Coding!
Page Navigation with the BackgroundWorker
Question: I want to navigate to another page in the BackgroundWorker thread -- for example: "frameNavigator.Navigate(new OtherPage());" in the DoWork method. I tried this, but an exception occurred because the Page class uses the main thread whereas the BackgroundWorker uses a separate thread. How can I get around this?
Answer: As you noticed, things like Pages, Winodws and ListBoxes are all items on the UI thread (and they need to stay on the UI thread). And the BackgroundWorker component processes items on a different thread (not the UI thread). So, you will not be able to do things like "Navigate" in the DoWork method.
But here's what you should do: try to figure out why the navigation process is slow. This is usually due to something that happens when your new Page loads -- it could be loading data from a database, transferring a file across the network, or calling a web service. So, even though you cannot put the "Navigate" into the background, you may be able to take whatever is in your Page Load process and put that in the background. In this type of scenario, you could put the database call method or the file transfer method into the background, not the entire Page object. This will have the effect of keeping your UI thread running and responsive while your data loads in the background.
Using the Progress Bar
Question: I want to get the progress completed from the actual process time, not from a predetermined time as you used in the walkthrough. The application must know how much time the BackgroundWorker process will take to navigate to the target page and then show a progress bar based on this information. How can I accomplish this?
Answer: Progress is a tricky subject. In the example in my walkthrough, I am not technically doing the progress bar based on a predetermined time; I am calculating the progress (a percentage) based on the number of iterations completed in the loop. I purposely kept my background process simple so that I could focus on the methods, events and properties of the BackgroundWorker component itself. But you can use the progress event for anything you can calculate a percentage complete for. For a more complex example, you can look at the BackgroundWorker examples on MSDN: http://msdn.microsoft.com/en-us/library/c8dcext2.aspx. One in particular, calculates a Fibonacci sequence using a recursive method call and calculates a percentage for a progress bar.
As an example of a calculation: if you are doing a file transfer, you can calculate a percentage based on the number of bytes received compared to the total number of bytes. So, if you have received 257 bytes of a 1,356 byte file, you are 19% complete. The limitation is that you have to know how far along you are in the process. If you are doing something like making a database call or a web service call, you may not know how long it will take to complete or how much data you are getting back. In those situations, you cannot calculate a percentage and so you may be better off using a "busy animation" (and there are plenty of examples available on the web for WPF and Silverlight).
Complex Results
Question: I don't like examples of BackgroundWorker using results of "string" or "int". I want a real object. How would I do this?
Answer: The e.Result parameter in the DoWork and RunWorkerCompleted can be as simple or as complex as you like. In my example, I simply use an "int", but e.Result is of type "object", so you can put whatever you want in there (including an entire database result set). There are a few limitations such as the objects that need to be on the UI thread (like we mentioned above). As another option, you can use a separate variable (or set of variables) that is accessible to both the UI and the background process. If you do this, you will want to look into the "lock" method to ensure that you don't end up with multiple processes trying to modify the value at the same time.
Round Up
The BackgroundWorker component is not the right solution for everything. But it can be helpful in quite a few situations. As we saw above, you may not be able to do exactly what you want (such as navigating in the background), but if you think about the problem a little differently, you can often come up with a workable solution.
Happy Coding!
Friday, April 2, 2010
Target Practice Live Demo
I have finally posted a live demo of the Silverlight 3 Target Practice demo application: Target Practice Live Demo.
As a reminder, this is a mini-app created entirely with XAML (no code-behind). The original article is here: Silverlight Target Practice.
And you can get the source code here: SilverlightTargetPractice.zip
Happy Coding!
As a reminder, this is a mini-app created entirely with XAML (no code-behind). The original article is here: Silverlight Target Practice.
And you can get the source code here: SilverlightTargetPractice.zip
Happy Coding!
Monday, March 1, 2010
Book Review: ASP.NET MVC Framework Unleashed
I just finished reading ASP.NET MVC Framework Unleased by Stephen Walther. It was an extremely fast read: I finished it in a little under two weeks. Unfortunately, I was able to finish it so quickly because it contained very little information. I was rather disappointed by the content. I really don't like giving bad reviews, but I feel like I should get my thoughts down for other folks who may be interested in this topic. Please note, this is a review of the book itself, not the underlying ASP.NET MVC technology.
Beginner, Intermediate, or Advanced?
My biggest problem with Unleashed is that it cannot decide what level it is targeted at. The cover lists it as "User Level: Intermediate-Advanced," but the actual content seems to jump from one level to another. For example, there are step-by-step instructions on configuring and using the ASP.NET Membership Database (ASPNETDB.mdf). I would consider this to be "beginner" level content. For the majority of real-world applications, you will not use the ASPNETDB.mdf database for your user authentication / authorization, instead going for a more robust security model such as implementing a custom MembershipProvider. This is not covered, however.
But the text does not qualify as Intermediate or Advanced as there is very little actual content. The majority of the book is code samples. Code samples are generally a good thing, but the code samples here are full-files. This means that when looking at the various elements (such as Views and Controllers), you end up seeing the same "boiler-plate" code over and over again. Many times there are only a few unique lines of code in a 30 line listing. In addition, descriptions of the code samples are limited to a paragraph or two with no in-depth description of the concepts at hand. This is combined with listings in both C# and VB (again, not necessarily a bad thing). I often felt like I was "skimming" a 30 page chapter in just 10 minutes or so due to the use of code samples and lack of description.
As a final example, there are 2 chapters devoted to AJAX and jQuery. In the introduction to the book, the author assumes that the reader is familiar with HTML and .NET (either C# or VB). However, it does not mention AJAX or jQuery as pre-requisites. AJAX is used much differently in ASP.NET MVC than it is in Web Forms, yet there is no discussion of those differences. There is just a handful of samples with little explanation.
Lack of Focus
Another problem is the lack of focus. ASP.NET MVC has many unique features, but many of the concepts are shared with ASP.NET Web Forms and the .NET framework at large. I wanted the book to focus on the concepts that differ from non-ASP.NET MVC applications, but there was a lot of overlap.
To expand on the example above (the Membership database), the security concepts (users, roles, principles, etc.) are the same as ASP.NET Web Forms applications, but there were several large sections dedicated to authentication. And as noted above, this was only at the "beginner" level and did not touch on intermediate or advanced topics.
As another example, Unleashed spends a lot of time with the Entity Framework. There are step-by-step instructions on creating a SQL Express database and setting up Entity Framework entities. In addition, it also spends a bit of time talking about the Repository pattern and Service layers of the application. These all related to the "M" (Model) of MVC. But the point of the "M" is that you can implement your model in an infinite number of ways. Again, this may be appropriate for a "beginner" level book, but it should go beyond merely mentioning other options if it is trying to be something more.
Ironically, I think that the topic covered best by this book is Test Driven Development (TDD). Throughout the text, there is a focus on the "Red / Green / Refactor" methodology of TDD. And the final part of the book (6 chapters on building a sample application) is a very good walkthrough of using the test-first method to fulfill the use cases. Had this book been called Test Driven Development with ASP.NET MVC, I would probably give this book a much better review.
Summary
Ultimately, the only reason that I was able to follow this book is because I went through ASP.NET MVC training. But the reason that I purchased the book was so that I could have a reference with more detail. As an example, I was looking for details on HTML Helpers, both the helpers "in the box" and custom helpers. The book has a few mentions of the existing helpers, but does not go into any detail on the options and parameters available. As for creating custom helpers, there is an example of it, but nothing much beyond the sample code.
I really don't like giving bad reviews. I realize that putting any technical book together is a lot of work. However, technical books are also my life-blood. They are my primary source of in-depth learning. In addition, they are quite expensive. I do have enough information to complete my project (which was the primary goal of training + book), but I'm still looking for a good reference book. Since ASP.NET MVC version 2 is just around the corner (releasing with .NET 4.0 in April), I'll probably hold out before purchasing another.
In working with ASP.NET MVC, I'm becoming a fan of it. So, I'll be posting more about the technology topic in the future. I'll also keep you informed of other useful resources that I run across.
[Update: I have found a good book on this topic: Pro ASP.NET MVC 4 by Adam Freeman. You can see my review here: Book Review: Pro ASP.NET MVC 4.]
Happy Coding!
Beginner, Intermediate, or Advanced?
My biggest problem with Unleashed is that it cannot decide what level it is targeted at. The cover lists it as "User Level: Intermediate-Advanced," but the actual content seems to jump from one level to another. For example, there are step-by-step instructions on configuring and using the ASP.NET Membership Database (ASPNETDB.mdf). I would consider this to be "beginner" level content. For the majority of real-world applications, you will not use the ASPNETDB.mdf database for your user authentication / authorization, instead going for a more robust security model such as implementing a custom MembershipProvider. This is not covered, however.
But the text does not qualify as Intermediate or Advanced as there is very little actual content. The majority of the book is code samples. Code samples are generally a good thing, but the code samples here are full-files. This means that when looking at the various elements (such as Views and Controllers), you end up seeing the same "boiler-plate" code over and over again. Many times there are only a few unique lines of code in a 30 line listing. In addition, descriptions of the code samples are limited to a paragraph or two with no in-depth description of the concepts at hand. This is combined with listings in both C# and VB (again, not necessarily a bad thing). I often felt like I was "skimming" a 30 page chapter in just 10 minutes or so due to the use of code samples and lack of description.
As a final example, there are 2 chapters devoted to AJAX and jQuery. In the introduction to the book, the author assumes that the reader is familiar with HTML and .NET (either C# or VB). However, it does not mention AJAX or jQuery as pre-requisites. AJAX is used much differently in ASP.NET MVC than it is in Web Forms, yet there is no discussion of those differences. There is just a handful of samples with little explanation.
Lack of Focus
Another problem is the lack of focus. ASP.NET MVC has many unique features, but many of the concepts are shared with ASP.NET Web Forms and the .NET framework at large. I wanted the book to focus on the concepts that differ from non-ASP.NET MVC applications, but there was a lot of overlap.
To expand on the example above (the Membership database), the security concepts (users, roles, principles, etc.) are the same as ASP.NET Web Forms applications, but there were several large sections dedicated to authentication. And as noted above, this was only at the "beginner" level and did not touch on intermediate or advanced topics.
As another example, Unleashed spends a lot of time with the Entity Framework. There are step-by-step instructions on creating a SQL Express database and setting up Entity Framework entities. In addition, it also spends a bit of time talking about the Repository pattern and Service layers of the application. These all related to the "M" (Model) of MVC. But the point of the "M" is that you can implement your model in an infinite number of ways. Again, this may be appropriate for a "beginner" level book, but it should go beyond merely mentioning other options if it is trying to be something more.
Ironically, I think that the topic covered best by this book is Test Driven Development (TDD). Throughout the text, there is a focus on the "Red / Green / Refactor" methodology of TDD. And the final part of the book (6 chapters on building a sample application) is a very good walkthrough of using the test-first method to fulfill the use cases. Had this book been called Test Driven Development with ASP.NET MVC, I would probably give this book a much better review.
Summary
Ultimately, the only reason that I was able to follow this book is because I went through ASP.NET MVC training. But the reason that I purchased the book was so that I could have a reference with more detail. As an example, I was looking for details on HTML Helpers, both the helpers "in the box" and custom helpers. The book has a few mentions of the existing helpers, but does not go into any detail on the options and parameters available. As for creating custom helpers, there is an example of it, but nothing much beyond the sample code.
I really don't like giving bad reviews. I realize that putting any technical book together is a lot of work. However, technical books are also my life-blood. They are my primary source of in-depth learning. In addition, they are quite expensive. I do have enough information to complete my project (which was the primary goal of training + book), but I'm still looking for a good reference book. Since ASP.NET MVC version 2 is just around the corner (releasing with .NET 4.0 in April), I'll probably hold out before purchasing another.
In working with ASP.NET MVC, I'm becoming a fan of it. So, I'll be posting more about the technology topic in the future. I'll also keep you informed of other useful resources that I run across.
[Update: I have found a good book on this topic: Pro ASP.NET MVC 4 by Adam Freeman. You can see my review here: Book Review: Pro ASP.NET MVC 4.]
Happy Coding!
Tuesday, February 23, 2010
New to Me: ASP.NET MVC
ASP.NET MVC was New 18 Months Ago
I first heard about ASP.NET MVC in October 2008 (at the VSLive! conference). Scott Hanselman gave a keynote that presented an overview and announced the beta release. At that point, it looked interesting, but with all of the new technologies that have been thrown at us over the last several years, I couldn't devote any time to look into it. Plus, I was comfortable with WebForms, having spent the previous 3 years developing fairly significant web apps.
So, here we are a year and a half later. I was struggling with a project at work. I knew that I could accomplish the task with WebForms, but all of my UI designs that I had worked through on the whiteboard seemed to come out as a mess. I had a nagging feeling that ASP.NET MVC was the solution to this problem. I took some time to look into it some more, and it turns out that it was the right direction.
Why ASP.NET MVC was the Answer
My main problem is that I needed to present data to the user in a different format depending on the record type. And I wouldn't know the record type until run time. ASP.NET WebForms is a "page first" model. This means that the user requests a particular page (through a URL). The page is then processed on the server which then presents the output to the user. ASP.NET MVC is an "action first" model. This means that instead of requesting a physical page, the user requests an action (also through a URL). This action is processed by a Controller. In my situation, the Controller can instantiate the Model (from my business layer) and then, based on the record type, can present the specific View (aspx page) that is appropriate.
So, I've taken a crash course in ASP.NET MVC. After going through some on-line training and working through a simple test app, I'm convinced that this is the right solution for this particular project. The design is much cleaner and will be easier to maintain.
Resources
I was fortunate enough to win a 1-year subscription to the Pluralsight OnDemand! library. In the library is a 10 hour on-line course for ASP.NET MVC, and I took a couple of days last week to go through it. This was an excellent resource. (If you are interested in trying Pluralsight OnDemand! yourself, just stop by the website; they offer 7-day trial subscriptions if you drop them a note.)
In addition, I picked up "ASP.NET MVC Framework Unleashed" by Stephen Walther as a printed reference. I'm still working my way through the book, but I've found a lot of useful information so far.
More to Come
Stay tuned for more to come. My project at work is still in progress. I'll have a lot of learnings from it (as I do with most of my projects). When I run across interesting items, good tips, and pitfalls, I'll be sure to post them here.
Happy Coding!
I first heard about ASP.NET MVC in October 2008 (at the VSLive! conference). Scott Hanselman gave a keynote that presented an overview and announced the beta release. At that point, it looked interesting, but with all of the new technologies that have been thrown at us over the last several years, I couldn't devote any time to look into it. Plus, I was comfortable with WebForms, having spent the previous 3 years developing fairly significant web apps.
So, here we are a year and a half later. I was struggling with a project at work. I knew that I could accomplish the task with WebForms, but all of my UI designs that I had worked through on the whiteboard seemed to come out as a mess. I had a nagging feeling that ASP.NET MVC was the solution to this problem. I took some time to look into it some more, and it turns out that it was the right direction.
Why ASP.NET MVC was the Answer
My main problem is that I needed to present data to the user in a different format depending on the record type. And I wouldn't know the record type until run time. ASP.NET WebForms is a "page first" model. This means that the user requests a particular page (through a URL). The page is then processed on the server which then presents the output to the user. ASP.NET MVC is an "action first" model. This means that instead of requesting a physical page, the user requests an action (also through a URL). This action is processed by a Controller. In my situation, the Controller can instantiate the Model (from my business layer) and then, based on the record type, can present the specific View (aspx page) that is appropriate.
So, I've taken a crash course in ASP.NET MVC. After going through some on-line training and working through a simple test app, I'm convinced that this is the right solution for this particular project. The design is much cleaner and will be easier to maintain.
Resources
I was fortunate enough to win a 1-year subscription to the Pluralsight OnDemand! library. In the library is a 10 hour on-line course for ASP.NET MVC, and I took a couple of days last week to go through it. This was an excellent resource. (If you are interested in trying Pluralsight OnDemand! yourself, just stop by the website; they offer 7-day trial subscriptions if you drop them a note.)
In addition, I picked up "ASP.NET MVC Framework Unleashed" by Stephen Walther as a printed reference. I'm still working my way through the book, but I've found a lot of useful information so far.
More to Come
Stay tuned for more to come. My project at work is still in progress. I'll have a lot of learnings from it (as I do with most of my projects). When I run across interesting items, good tips, and pitfalls, I'll be sure to post them here.
Happy Coding!
Wednesday, February 17, 2010
Jeremy on .NET Rocks! (sort of)
Okay, so now that I have your attention, I wasn't really on .NET Rocks!. But Carl and Richard did read my e-mail on show #525. Here's a link (if you're curious): .NET Rocks! Show #525. You can skip ahead to about 4 minutes in.
And BTW, they are sending me a hoody.
And BTW, they are sending me a hoody.
Saturday, February 13, 2010
Quick Byte: Statement Lambdas
Overview
The first time I came across a lambda expression, I was perplexed. I could tell that something important was going on, but I got stuck on the new syntax. As I studied them some more, I had an "aha" moment, and it all clicked into place. This is a brief runthrough of that process with statement lambdas.
Get It Here
You can get the walkthrough (just a short 3-page one) and sample code here: http://www.jeremybytes.com/Demos.aspx.
Direct Links:
PDF Walkthrough
Code Download
Let me know what you think. If you find this useful (or not), drop me a note at feedback@jeremybytes.com.
Happy Coding!
The first time I came across a lambda expression, I was perplexed. I could tell that something important was going on, but I got stuck on the new syntax. As I studied them some more, I had an "aha" moment, and it all clicked into place. This is a brief runthrough of that process with statement lambdas.
Get It Here
You can get the walkthrough (just a short 3-page one) and sample code here: http://www.jeremybytes.com/Demos.aspx.
Direct Links:
PDF Walkthrough
Code Download
Let me know what you think. If you find this useful (or not), drop me a note at feedback@jeremybytes.com.
Happy Coding!
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