Visual Studio Design Mode Changing your Html

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/visual_studio_design_mode_changing_your_html.htm]

Occasionally Visual Studio (2003) changes the Html when you go to design mode. While it reformats it, it may also add certain closing tags. This can be counter-productive if you're doing certain techniques where you want the Html to be the way you initially made it. I've heard rumors that 2005 guarantees that your Html won't get altered.

I see this Html changing in two categories:

1. Ways you can solve it by adding extra html, such as multiple nested tables
2. Ways that Visual Studio is just wrong

The problem with the first is that any extra html you add must be transported over the wire and rendered on the client, so it slows performance. The only helpful technique I know to avoid needing that extra overhead is to make Visual Studio open in Html view by default.  Goto: Tools > Options > Html Designer > General, and set the options to open in Html instead of Design view. Ideally your UI is refactored enough (with user controls, base pages, custom controls, possibly #includes, etc...) that the Html can be managed in Html view. I can then save my page, "peek" in design view to check the overall layout, disregarding any potential changes from Visual Studio.

In the second category, one (seemingly) blatant bug I came across in Visual Studio was when I had a custom control with custom attributes, and the attribute didn't have a value (kind of like "nowrap" - it only needs the attribute, not any associated value). Something like:

...

kept getting maligned to something like below when I went to design view. The attribute values got disjointed from the attributes:

...

However if I put the value-less attribute at the end, then I could toggle back and forth between Html and Design view:

...

I'm not sure what causes this - it could be something with the custom control, value-less attribute, affect from other attributes, or something else, but it solved that particular problem.

System.Web.HttpException: External component has thrown an exception

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/systemwebhttpexception_external_component_has_thrown_an_exce.htm]

As far as debugging difficulty goes, anything that you can reproduce and step through with the debugger is likely simple. Sometimes you'll get an error that occurs before the codebehind is even hit, and you therefore can't debug it like "normal". One such error is: "System.Web.HttpException: External component has thrown an exception."

Web pages integrate both the aspx and codebehind pages. What may be happening is that some control in the html of the aspx page has an onserver attribute that references a non-existent server event. For example, you may have copied from a similar page that had a LinkButton with attribute onserverclick="AddLink_Click". The WebForm expects an "AddLink_Click" method in the codebehind. The original page may have had this method, but perhaps the target page does not. Therefore when you try to load the page, it can't "merge" the aspx and codebehind correctly and therefore crashes before even going to a breakpoint in the CodeBehind's Page_Load.

The solution (in this case) is to ensure that any attributes set in the aspx page are consistent with the codebehind.

Why I love XmlSpy with XSD Schema Editor.

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/why_i_love_xmlspy_with_xsd_schema_editor.htm]

Before coming to Ameripay's  Software Engineering department, I used to do consulting. Because with consulting, everything (such as what software you have licenses for) is project-driven, my software was often on the cheap. Clients and managers were very hesitant to pay for licenses for "frivolous" software, especially with the previous IT recession. Therefore certain things, like editing Xml Schemas, I often did the harder, manual way. For simple schemas this works, but it just becomes draining (You can learn the basics of Xml Schema at the online W3Schools).

Now I have XmlSpy installed, and it's great if even just for the schema editor. I've heard many good things about this popular tool, but never got the chance to check it out myself. The help section even has a step-by-step tutorial. It looks like Altova even offers a free XmlSPy Home Edition to get you started.

Yet another tool I wish I had had before.

Batch code generation with CodeSmith Console

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/batch_code_generation_with_codesmith_console.htm]

I'm always keeping my eyes open for practical tools that save time and mental sanity. One of the most mentally-draining tasks is repetitious modifying of simple code. For example, many simple CRUD (Create-Read-Update-Delete) stored procedures, and their accompanying DAL and Business Objects are redundant. Ideally we could just auto-generate this given the inputs. Auto code generation is a great time saver, which frees us from boring tasks to focus on interesting ones.

CodeSmith is a great code generator. It has both a free and purchase version, it has a large support community, is time tested (been out for several years now), and has great functionality. It's based around writing templates with ASP syntax, which is much more friendly then using XSL or writing your own C# app to assemble the target code. Therefore part of a CodeSmith template may look like:

private void <%= SampleStringProperty %>() {     // <%= GetSomething() %>     // Do something }

There are plenty of tutorials about auto-generating your data access layer. But one thing I really like about CodeSmith is its batch processing. These are features I'd like in batch processing:

• Ability to call the tool from a command line, passing in an Xml config file
• Extend step 1 to generate many objects from a single Xml file, as opposed to calling the exe each time.
• Ability to merge your changes into an existing, non-generated document.
• Ability to auto-generate a document, but leave certain sections open to customization

The first two help with batch processing, such that you could generate an entire layer at once. The last two help with versioning and customization. You need to both made custom modifications to templates, and then not have those overwritten upon re-running the tool.

CodeSmith offers both several help guides, and samples, to assist with these. Check:

• CodeSmith Console Tutorial in the CodeSmith Studio's Help section
• Samples at: "CodeSmith\v3.0\SampleProjects\ConsoleSamples\GenerateCode.bat"

If all you have is a hammer, everything looks like a nail. With a good code-generation tool, you start viewing all those redundant tasks very differently.

AJAX - Asynchronous JavaScript and XML

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/ajax__asynchronous_javascript_and_xml.htm]

Until recently, I assumed that web applications were based on a strict client-server / request-response model. This has several limitations, such as a thin client (your web browser) not being able to do any *real* business logic. For example, say you need to validate against a back-end data source such as ensuring a username-password combo is valid or checking if a city exist within a state. As this is really outside the scope of JavaScript, it would require a hit to the backend, and then re-posting the page.

But what if you could just do a "postback" for the desired field only, leaving the rest of the page unchanged? And what if you could have the server automatically update the client without the client initiating the event?

A technology, Asynchronous JavaScript and XML (AJAX) looks like it can do just that. Quoting from Adaptive Path's Jesse James Garrett:

[Quote]

Ajax isn't a technology. It's really several technologies, each flourishing in its own right, coming together in powerful new ways. Ajax incorporates:

• standards-based presentation using XHTML and CSS;
• dynamic display and interaction using the Document Object Model;
• data interchange and manipulation using XML and XSLT;
• asynchronous data retrieval using XMLHttpRequest;
• and JavaScript binding everything together.
   

[End Quote]

Check out these sites for more detail:

• http://ajax.schwarz-interactive.de/csharpsample/default.aspx - download relevant source code
• http://www.ajaxmatters.com/ - other Ajax links.

This looks like it has a ton of potential, and I'm looking forward to checking it out and doing a future blog post on a sample.

Enterprise Library Tips for Strong Names and Versions

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/enterprise_library_tips_for_strong_names_and_versions.htm]

Previously I offered some tips for configuring Enterprise Library. Today I'll discuss another problematic area - adding strong names.

First, this builds on concepts about Strong Names and PublicKeyTokens.  You may need to add a strong name to the EntLib blocks if you include it in a project that already uses strong names (because this requires that all assemblies being referenced also have strong names).

To add a strong name, you'll need to create a key and reference it in the AssemblyInfo.cs file.

Strong Names and Versioning Tips

0 - You will need to add the key to the source code. Microsoft gives us the source code partially so that we can do things like this.

1 - Put properties (like strong-naming) in the GlobalAssemblyInfo.cs. This requires you to remove (or comment out) the key from the other 38 AssemblyInfo files, however it lets you change it in one place.

2 - Note that there are two places that DLLs are stored.

• C:\Program Files\Microsoft Enterprise Library\bin
• C:\Program Files\Microsoft Enterprise Library\src\\bin

Opening the EntLib solution and compiling creates copies in the \src dir. You still need to copy these to the \bin
Make sure to run the "Copy Assemblies to Bin Directory" script included in the EntLib start menu. If you're not putting DLLs in the GAC,  EntLib's config tool pulls DLLs from the \bin dir. So you'll notice strong-name nightmares if you don't do this. It will set the assembly name (like PublicKeyToken) from those DLLs, not merely the ones used in your project. For example, check the version of the DLLs loaded by the config tool, and make sure that they include the strong name.

Enterprise Library Tips for Configuration

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/enterprise_library_tips_for_configuration.htm]

Enterprise Library is Microsoft's next generation of Application Blocks. It's a free, integrated suite of common architectural components that your project probably needs. It has several good perks:

• Includes all source code
• An auto-config tool to handle the Xml config files.
• 38 projects of well written code - i.e. a good example to learn from
• Full documentation
• A huge community supporting it.

You can download it here. Be sure to check the official blogs:

• Tom Hollander
• Scott Densmore

When I first was playing around with it, I had trouble with creating strong names and config files.

Configuration Tips

1. A single application can have multiple physical config files:

• CachingQuickStart.exe.config (app)
• cachingConfiguration.config (other block)
• dataconfiguration.config (other block)

Furthermore, you'll need to make sure that the correct file is copied to the app's bin. Merely rebuilding or using EntLib's config tool doesn't copy all configs.

2 - For the data access block config, you'll need to set both the connection string as well as the individual params. Config looks like:

3 - For the Caching Block's Data Provider:

• "PartitionName" does not correspond to actual database partitions, but rather a value in the Caching.CachData.PartitionName column. This means that you don't need to create a DB partition for the DB cache to work.
• Make sure that you run the script to create the Caching DB ('Caching').
• Make sure that user has access to the 'Caching' database, and can insert into the CacheData table. Merely running the create script doesn't provide access to custom users.

4 - For the Caching Block's Isolated Storage, this uses System.IO.IsolatedStorage. You do not provide a physical file path name. Partition Name is a folder name like "MyApp".

I'll discuss Strong Names in my next post.