Debugging in LINQPad

If you have been reading my blog over the last few months you will no doubt be aware that I am a regular user of LINQPad. I do not have any commercial involvement with LINQPad nor its creators, I just really like it. Recently, I decided to try out the latest release, which adds integrated debugging to the already feature rich tool. This amazingly powerful new feature adds yet another reason why this application should be in every developer's arsenal, regardless of experience and ability (it is a great learning tool for students). Here is a brief overview of this new feature, which is available with the premium license (currently on sale for $85 at time of writing; it may not be the case as you are reading this).

When running the latest LINQPad, the debugging feature adds some new buttons to the familiar toolbar. All the debugging features are available for both statement and program-based queries in C#, VB, and F# (not expressions or SQL languages). The first new button is the Pause button, also known as Break. This works as you might expect, pausing the current code execution. The other two are to specify how exceptions should be handled, informing  the debugger to break on unhandled exceptions and when exceptions are thrown. Breakpoints can be added by clicking in the margin to the left of the code or pressing F9 when the caret is on the desired line.  When a breakpoint is active on a line, it is indicated as a large red circle. For those who regularly use Visual Studio, the breakpoint and general debugger experience will be familiar.

Pressing F5 will run the query (or selected lines) as usual, but now, any breakpoints set on executing lines will cause the code to break. At this point, LINQPad will reveal some familar and not-so-familiar tools for debugging the code. General status information is displayed at the bottom of the LINQPad window, showing things like whether the code is executing or paused, whether the debugger is attached or not, and the process ID.

The next code statement to execute is highlighted in the code with a yellow arrow in the margin (in this case, overlaid on the breakpoint circle), and the code highlighted in yellow. In the lower left portion of the screen, we can see local variables and executing threads. We can also set up our own watches as necessary. Any objects in the Locals and Watch tabs can be expanded using the + glyph to reveal their constituent values. As in Visual Studio, these tabs allow the expansion of just-in-time LINQ queries so you can delve into the deep dark secrets of your code. However, you can also take advantage of LINQPad's fantastic dump feature and dump any value out to the Results tab on the right. If you want to control how far down the object graph a dump will go, you can modify the Dump Depth using the + and - controls in the column header.

The `Dump` output for the `range` variable
The Dump output for the range variable
Specifying the depth of the dump
Specifying the depth of the dump

For more information on LINQPad and its many features, check out the LINQPad website (http://linqpad.net). In my opinion, whether you use the free version or one of the paid upgrades, you will have one of the best coding utilities available for .NET.

Writing A Simple Slack Bot With Node slack-client

Last week, we held our first CareEvolution hackathon of 2015. The turn out was impressive and a wide variety of projects were undertaken, including 3D printed cups, Azure-based machine learning experiments, and Apple WatchKit prototypes. For my first hackathon project of the year, I decided to tinker with writing a bot for Slack. There are many ways to integrate custom functionality into Slack including an extensive API. I decided on writing a bot and working with the associated API because there was an existing NodeJS1 client wrapper, slack-client2. Using this client wrapper meant I could get straight to the functionality of my bot rather than getting intimate with the API and JSON payloads.

I ended up writing two bots. The first implemented the concept of @here that we had liked in HipChat and missed when we transitioned to Slack (they have @channel, but that includes offline people). The second implemented a way of querying our support server to get some basic details about our deployments without having to leave the current chat, something that I felt might be useful to our devops team. For this blog, I will concentrate on the simpler and less company-specific first bot, which I named here-bot.

The requirement for here-bot is simple:

When a message is sent to @here in a channel, notify only online members of the channel, excluding bots and the sender

In an ideal situation, this could be implemented like @channel and give users the ability to control how they get notified, but I could not identify an easy way to achieve that inside or outside of a bot (I raised a support request to get it added as a Slack feature). Instead, I felt there were two options:

  1. Tag users in a message back to the channel from here-bot
  2. Direct message the users from here-bot with links back to the channel

I decided on the first option as it was a little simpler.

To begin, I installed the client wrapper using npm:

The slack-client package provides a simple wrapper to the Slack API, making it easy to make a connection and get set up for handling messages. I used their sample code to guide me as I created the basic skeleton of here-bot.

This code defines a connection to Slack using the token that is assigned to our bot by the bot integration setup on Slack's website. It then sets up a handler for the open event, where the groups and channels to which the bot belongs are output to the console. In Slack, I could see the bot reported as being online while the code executed and offline once I stopped execution. As bots go, it was not particularly impressive, but it was amazing how easy it was to get the bot online. The slack-client package made it easy to create a connection and iterate the bot's channels and groups, including querying whether the groups were open or archived.

For the next step, I needed to determine when my bot was messaged. It turns out that when a bot is the member of a channel (including direct message), it gets notified on each message entered in that channel. In our client code, we can get these messages using the message event.

Using the slack-client's useful helper methods, I turned the message channel and user identifiers into channel and user objects. Then, if the message is a message (it turns out there are other types such as edits and deletions), I send the details of the message to the console.

With my bot now listening to messages, I wanted to determine if a message was written at the bot and should therefore alert the channel users. It turns out that when a message references a user, it actually embeds the user identifier in place of the displayed @here text. For example, a message that appears in the Slack message window as:

Is sent to the message event as something like3:

It turns out that this special code is how a link to a user or channel is embedded into a message. So, armed with this knowledge and knowing that I would want to mention users, I wrote a couple of helper methods: the first to generate a user mention embed code from a user identifier, the second to determine if a message was targeted at a specific user (i.e. that it began with a reference to that user).

Using these helpers and the useful slack.self property, I could then update the message handler to only log messages that were sent directly to here-bot.

The final stage of the bot was to determine who was present in the channel and craft a message back to that channel mentioning those online users. This turned out to be a little trickier than I had anticipated. The channel object in slack-client provides an array of user identifiers for its members; channel.members. This array contains all users present in that channel, whether online or offline, bot or human. To determine details about each user, I would need the user object. However, the details for each Slack user are provided by the slack.users property. I needed to join the channel member identifiers with the Slack user details to get a collection of users for the channel. Through a little investigative debugging4, I learned that slack.users was not an array of user objects, but instead an object where each property name is a user identifier. At this point, I wrote a method to get the online human users for a channel.

Finally, I crafted a message and wrote that message to the channel. In this update of my message event handler, I have trimmed the bot's mention from the start of the message before creating an array of user mentions, excluding the user that sent the message. The last step calls channel.send to output a message in the channel that mentions all the online users for that channel and repeats the original message text.

Conclusion

Example

My @here bot is shown below in its entirety for those that are interested. It was incredibly easy to write thanks to the slack-client package, which left me with hackathon time to spare for a more complex bot. I will definitely be using slack-client again.

 


  1. or ioJS, if you would prefer 

  2. I find hackathons to be a bit like making a giant pile of sticks in the middle of a desert; it's an opportunity to get creative and build something where there seems to be nothing…using sticks…or in my case, a Node package and Slack 

  3. I totally made up the user identifier for this example 

  4. I used WebStorm 9 from JetBrains to debug my Node code, a surprisingly easy and pleasant experience 

Some of my favourite tools

Update: This post has been updated to recognise that CodeLineage is now maintained by Hippo Camp Software and not Red Gate Software as was originally stated.

If you know me, you might well suspect this post is about some of the idiots I know, but it is not, this is entirely about some of the tools I use in day-to-day development. This is by no means an exhaustive list, nor is it presented in any particular order. However, assuming you are even a little bit like me as a developer, you will see a whole bunch of things you already use, but hopefully there is at least one item that is new to you. If you do find something new and useful here, or you have some suggestions of your own, please feel free to post a comment.

OzCode

OzCode is an add-in for Visual Studio that provides some debugging super powers like collection searching, adding computed properties to objects, pinning properties so that you don't have to go hunting in the object tree, simpler tracepoint creation, and a bunch more. I first tried this during beta and was quickly sold on its value. Give the 30-day trial a chance and see if it works for you.

Resharper

This seems to be a staple for most C# developers. I was a late-comer to using this tool and I am not sure I like it for the same reasons as everyone else. I actually love Resharper for its test runner, which is a more performant alternative to Visual Studio's built-in Test Explorer, and the ability to quickly change file names to match the type they contain. However, it has a lot of features, so while this is not free, give the trial a chance and see if it fits.

Web Essentials

Another staple for many Visual Studio developers, Web Essentials provides lots of support for web-related development including enhanced support for JavaScript, CSS, CoffeeScript, LESS, SASS, MarkDown, and much more. If you do any kind of web development, this is essential1.

LinqPad

I was late to the LinqPad party, but gave it a shot during Ann Arbor Give Camp 2013 and within my first hour or two of using it, dropped some cash on the premium version (it is very inexpensive for what you get). Since then, whether it is hacking code or hacking databases, I have been using LinqPad as my standard tool for hacking.

For code, it does not have the overhead of creating projects and command line, WinForms or WPF wrapper tools that you would have to do in Visual Studio. For databases, LinqPad gives you the freedom to use SQL, C#, F# or VB for querying and manipulating your database as well as support for many different data sources beyound just SQL Server, providing an excellent alternative to SQL Management Studio.

LinqPad is free, but you get some cool features if you go premium, and considering the sub-$100 price, it is totally worth it.

JustDecompile

When Red Gate stopped providing Reflector for free, JetBrains and Telerik stepped up with their own free decompilers for poking around inside .NET code. These are often invaluable when tracking down obscure bugs or wanting to learn more about the code that is running when you did not write it. While JetBrains' dotPeek is useful, I have found that JustDecompile from Telerik has a better feature set (including showing MSIL, which I could not find in dotPeek).

Chutzpah

Chutzpah is a test runner for JavaScript unit tests and is available as a Nuget package. It supports tests written for Jasmine, Mocha, and QUnit, as well as a variety of languages including CoffeeScript and TypeScript. There are also two Visual Studio extensions to provide Test Explorer integration and a handy context menu. I find the context menu most useful out of these.

Chutzpah is a great option when you cannot leverage a NodeJS-based tool-chain like Grunt or Gulp, or some other non-Visual Studio build process.

CodeLineage

CodeLineage is a free Visual Studio extension from Hippo Camp Software2. Regardless of your source control provider, CodeLineage provides you with a simple interface for comparing different points in the history of a given file. The simple interface makes it easy to select which versions to compare. I do not use this tool often, but when I need it, it is fantastic.

FileNesting

This Visual Studio extension from the developer of Web Essentials makes nesting files under one another a breeze. You can set up automated nesting rules or perform nesting manually.

I like to keep types separated by file when developing in C#. Files are cheap and it helps discovery when navigating code. However, this sometimes means using partial classes to keep nested types separate, so to keep my solution explorer tidy, I edit the project files and nest source code files. I also find this useful for Angular directives, allowing me to apply the familiar pattern  of organizing code-behind under presentation by nesting JavaScript files under the template HTML.

Whether you have your own nesting guidelines or want to ensure generated code is nested under its corresponding definition (such as JavaScript generated from CoffeeScript), this extension is brilliant.

Switch Startup Project

Ever hit F5 to debug only to find out you tried to start a non-executable project and have to hunt for the right project in the Solution Explorer? This used to happen to me a lot, but not since this handy extension, which adds a drop down to the toolbar where I can select the project I want to be my startup project. A valuable time saver.

MultiEditing

Multi-line editing has been a valuable improvement in recent releases of Visual Studio, but it has a limitation in that you can only edit contiguous lines at the same column location. Sometimes, you want to edit multiple lines in a variety of locations and with this handy extension, you can. Just hold ALT and click the locations you want to multi-edit, then type away.

Productivity Power Tools

Productivity Power Tools for Visual Studio have been a staple extension since at least Visual Studio 2008. Often the test bed of features that eventually appear as first class citizens in the Visual Studio suite, Productivity Power Tools enhances the overall Visual Studio experience.

The current version for Visual Studio 2013 provides support for colour printing, custom document tabs, copying as HTML, error visualization in the Solution Explorer, time stamps in the debug output margin, double-click to maximize and dock windows, and much more. This is a must-have for any Visual Studio user.


  1. yes, I went there 

  2. though it was maintained by Red Gate when I first started using it 

Debugging IIS Express website from a HyperV Virtual Machine

Recently, I had to investigate a performance bug on a website when using Internet Explorer 8. Although we are fortunate to have access to BrowserStack for testing, I have not found it particularly efficient for performance investigations, so instead I used an HyperV virtual machine (VM) from modern.IE.

I had started the site under test from Visual Studio 2013 using IIS Express. Unfortunately, HyperV VMs are not able to see such a site out-of-the-box. Three things must be reconfigured first: the VM network adapter, the Windows Firewall of the host machine, and IIS Express.

HyperV VM Network Adapter

HyperV Virtual Switch Manager
HyperV Virtual Switch Manager

In HyperV, select Virtual Switch Manager… from the Actions list on the right-hand side. In the dialog that appears, select New virtual network switch on the left, then Internal on the right, then click Create Virtual Switch. This creates a virtual network switch that allows your VM to see your local machine and vice versa. You can then name the switch anything you want; I called mine LocalDebugNet.

New virtual network switch
New virtual network switch

To ensure the VM uses the newly created virtual switch, select the VM and choose Settings… (either from the context menu or the lower-right pane). Choose Add Hardware in the left-hand pane and add a new Network Adapter, then drop down the virtual switch list on the right, choose the switch you created earlier, and click OK to accept the changes and close the dialog.

Add network adapter
Add network adapter
Set virtual switch on network adapter
Set virtual switch on network adapter

Now the VM is setup and should be able to see its host machine on its network. Unfortunately, it still cannot see the website under test. Next, we have to configure IIS Express.

IIS Express

Open up a command prompt on your machine (the host machine, not the VM) and run ipconfig /all . Look in the output for the virtual switch that you created earlier and write down the corresponding IP address1.

Command prompt showing ipconfig
Command prompt showing ipconfig

Open the IIS Express applicationhost.config file in your favourite text editor. This file is usually found under your user profile.

Find the website that you are testing and add a binding for the IP address you wrote down earlier and the port that the site is running on. You can usually just copy the localhost binding and change localhost to the IP address or your machine name.

You will also need to run this command as an administrator to add an http access rule, where <ipaddress>  should be replaced with the IP you wrote down or your machine name, and <port>  should be replaced with the port on which IIS Express hosts your website.

At this point, you might be in luck. Try restarting IIS Express and navigating to your site from inside the HyperV VM. If it works, you are all set; if not, you will need to add a rule to the Windows Firewall (or whatever firewall software you have running).

Windows Firewall

The VM can see your machine and IIS Express is binding to the appropriate IP address and port, but the firewall is preventing traffic on that port. To fix this, we can add an inbound firewall rule. To do this, open up Windows Firewall from Control Panel and click Advanced Settings or search Windows for Windows Firewall with Advanced Security and launch that.

Inbound rules in Windows Firewall
Inbound rules in Windows Firewall

Select Inbound Rules on the left, then New Rule… on the right and set up a new rule to allow connections the port where your site is hosted by IIS Express. I have shown an example here in the following screen grabs, but use your own discretion and make sure not to give too much access to your machine.

New inbound port rule
New inbound port rule
Specifying rule port
Specifying rule port
Setting rule to allow the connection
Setting rule to allow the connection
Inbound rule application
Inbound rule application
Naming the rule
Naming the rule

Once you have set up a rule to allow access via the appropriate port, you should be able to see your IIS Express hosted site from inside your VM of choice.

As always, if you have any feedback, please leave a comment.


  1. You can also try using the name of your machine for the following steps instead of the IP 

CiviCRM deployment on IIS WordPress

At Ann Arbor Give Camp this year, I worked on a team looking into donation management options for non-profits. Thanks to Dr. Milastname (it would be inappropriate to reveal his true identity), we found CiviCRM and spent much of the weekend getting familiar with its deployment and functionality inside of WordPress. CiviCRM integration with WordPress is a relatively new feature, so it was not totally unsurprising that we encountered one or two issues. The first and by far the biggest problem we encountered was the White Screen of Death (WSOD).

After some debugging (which involved editing a couple of PHP files inside of the WordPress and CiviCRM systems), we discovered that a PHP add-in used by CiviCRM for templating was relying on the open_basedir variable and this was not set on our IIS-based system. This caused the templating add-in to fail, halting the rendering of the CiviCRM admin screen and resulting in the WSOD.

To rectify this problem, I edited wp_config.php to introduce the open_basedir variable just before the require statement for wp_settings.php. I set the variable to the path of the WordPress deployment (ABSPATH) and refreshed the CiviCRM admin screen.

This fixed the WSOD and enabled us to continue our evaluation of CiviCRM1. We also raised an issue against the CiviCRM project and added a post to the CiviCRM forms, ensuring the lessons we learned would benefit future users of CiviCRM.


  1. And discover a bug that I had introduced all by myself