Three Awesome Months
Posted by bsstahl on 2019-02-26 and Filed Under: event
The next few months are going to be absolutely amazing. We've got some great events coming up in March and April right here in the Valley of the Sun. In addition, I currently have 4 conferences scheduled in 4 different countries on 2 continents.
AZGiveCamp IX - Presented by Quicken Loans - March 8th-10th
The most important occasion coming up is the 9th AZGiveCamp Hackathon of Help. This year, we're very fortunate to have Quicken Loans presenting our event and hosting it at their new facility in downtown Phoenix. At AZGiveCamp, Arizona's finest technologists will put their skills to work creating software for some great local charity organizations. We help them help our community by using our skills to create tools that help them further their mission.
Visual Studio 2019 Arizona Launch - April 16th
Another fun event for developers in the valley is the Visual Studio 2019 Arizona Launch event being hosted at Galvanize. We'll have some great speakers talking about how Visual Studio 2019 is a more productive, modern, and innovative environment for building software.
Around the World
In March, I'll be visiting opposite ends of the east coast of North America.
First, on March 2nd, I'll be attending the always amazing South Florida Code Camp in Fort Lauderdale. This event is right up there with the biggest community conferences in the country and is always worth attending. This will be the 7th year I've presented at SoFlaCC. If you're in the area I hope you'll attend.
Later in March, I cross the border into Canada to attend ConFoo Montreal. This will be my first trip ever to Montreal so I hope the March weather is kind to this 35 year Phoenix resident. The event runs from March 13th - 15th and there will be 2 Canadiens games during the time I am there so I should be able to get to at least one of them.
In May I get to do a short tour of Europe, spending 2 weeks at conferences in Budapest, Hungary (Craft Conference), and Marbella, Spain (J on the Beach). While I have done some traveling in Europe before, I have never been to Spain or Hungary so I am really looking forward to experiencing the history and culture that these two cities have to offer.
Keep up With Me
I maintain a list of my presentations, both past and upcoming, on the Community Speaker page of this blog. I also try to document my conference experiences @email@example.com. If you are going to be attending any of these events, please be sure to ping me and let me know.
SoCalCodeCamp Slide Decks
Posted by bsstahl on 2018-11-10 and Filed Under: event
The slide decks for my two talks at SoCalCodeCamp USC from November 10, 2018 are below.
Thanks to all of the organizers and attendees of this always amazing event.
Desert Code Camp – October 2017
Posted by bsstahl on 2017-10-16 and Filed Under: event
Another great Desert Code Camp is in the books. A huge shout-out to all of the organizers, speakers & attendees for making the event so awesome.
I was privileged to be able to deliver two talks during this event:
A Developer’s Survey of AI Techniques: Artificial Intelligence is far more than just machine learning. There are a variety of tools and techniques that systems use to make rational decisions on our behalf. In this survey designed specifically for software developers, we explore a variety of these methods using demo code written in c#. You will leave with an understanding of the breadth of AI methodologies as well as when and how they might be used. You will also have a library of sample code available for reference.
AI that can Reason "Why": One of the big problems with Artificial Intelligences is that while they are often able to give us the best possible solution to a problem, they are rarely able to reason about why that solution is the best. For those times where it is important to understand the why as well as the what, Hybrid AI systems can be used to get the best of both worlds. In this introduction to Hybrid AI systems, we'll design and build one such system that can solve a complex problem for us, and still provide information about why each decision was made so we can evaluate those decisions and learn from our AI's insights.
Please feel free to contact me @firstname.lastname@example.org with any questions or comments on these or any of my presentations.
An Example of a Hybrid AI Implementation
Posted by bsstahl on 2017-10-13 and Filed Under: development
I previously wrote about a Hybrid AI system that combined logical and optimization methods of problem solving to identify the best solution to an employee shift assignment problem. This implementation was notable in that a hybrid approach was used so that the optimal solution could be found, but the system could still indicate to the users why a particular assignment was, or wasn’t, included in the results.
I recently published to GitHub a demo of a similar system. I use this demo in my presentation Building AI Solutions that can Reason Why. The code demonstrates the hybridization of multiple AI techniques by creating a solution that iteratively applies a combinatorial optimization engine. Different results are obtained by varying the methods of applying the constraints in that model. In the final (4th) demo method, an iterative process is used to identify what the shortcomings of the final product are, and why they are necessary.
These demos use the Conference Scheduler AI project to build a valid schedule.
There are 4 examples, each of which reside in a separate test method:
The 1st method in BasicExamplesDemo.cs shows an unconstrained model where only the hardest of constraints are excluded. That is, the only features of the schedule that are considered by the scheduler are those that are absolute must-haves. Since there are fewer hard constraints, it is relatively easy to satisfy all the requirements of this model.
The 2nd method in BasicExamplesDemo.cs shows a fully constrained model where all constraints are considered must-haves. That is, the only schedules that will be considered for our conference are those that meet all of the scheduling criteria. As you might imagine, this can be difficult to do, in this case resulting in No Feasible Solution being found. Because we use a combinatorial optimization model, the system gives us no clues as to which of the constraints cause the infeasibility, or what to do that might allow it to find a solution.
The 3rd method in BasicExamplesDemo.cs shows the solution when the true must-haves are considered hard constraints but preferences are not. The AI attempts to optimize the solution by satisfying as many of the soft constraints (preferences) as possible. This results in an imperfect, but possibly best case schedule, but one where we have little insight as to what preferences were not satisfied, and almost no insight as to why.
The final demo, and the only method in AddConstraintsDemo.cs, builds on the 3rd demo, where the true must-haves are considered hard constraints but preferences are not. Here however, instead of attempting to optimize the soft constraints, the AI iteratively adds the preferences as hard constraints, one at a time, re-executing the solution after each to make sure the problem has not become infeasible. If the solution has become infeasible, that fact is recorded along with what was being attempted. Then that constraint is removed and the process continues with the remaining constraints. This Hybrid process still results in an imperfect, but best-case schedule. This time however, we not only know what preferences could not be satisfied, we have a good idea as to why.
The Hybrid Process
The process of iteratively executing the optimization, adding constraints one at a time, is show in the diagram below. It is important to remember that the order in which these constraints are added here is critical since constraining the solution in one way may limit the feasibility of the solution for future constraints. Great care must be taken in selecting the order that constraints are added in order to obtain the best possible solution.
The steps are as follows:
- Make sure we can solve the problem without any of the soft constraints. If the problem doesn’t have any feasible solutions at the start of the process, we are certainly not going to find any by adding constraints.
- Add a constraint to the solution. Do so by selecting the next most important constraint in order. In the case of our conference schedule, we are adding in speaker preferences for when they speak. These preferences are being added in the order that they were requested (first-come first-served).
- Verify that there is still at least 1 feasible solution to the problem after the constraint is added. If no feasible solutions can be found:
- Remove the constraint.
- Record the details of the constraint.
- Record the current state of the model.
- Repeat steps 2 & 3 until all constraints have been tried.
- Publish the solution
- The resulting schedule
- The constraints that could not be added. This tells us what preferences could not be accommodated.
- The state of the model at the time the failed constraints were tried. This give us insight as to why the constraints could not be satisfied.
Note: The sample data in these demos is very loosely based on SoCalCodeCamp San Diego from the summer of 2017. While some of the presenters names and presentations come roughly from the publicly available schedule, pretty much everything else has been fictionalized to make for a compelling demo, including the appearances by some Microsoft rock stars, and the "requests" of the various presenters.
If you have any questions about this code, or about how Hybrid AIs can be used to provide more information about the solutions to problems than strictly optimization or probabilistic models, please contact me @email@example.com.
Building AI Solutions with Google OR-Tools
Posted by bsstahl on 2017-09-28 and Filed Under: development
My presentation from the #NDCSydney conference has been published on YouTube.
We depend on Artificial Intelligences to solve many types of problems for us. Some of these problems have more than one possible solution. Handling those problems with more than one solution while building a modern AI system is something every developer will be asked to do over the course of his or her career. Figuring out the best way to utilize the capacity of a device or machine, finding the shortest path between two points, or determining the best way to schedule people or events are all problems where mathematical optimization techniques and tooling can be used to quickly and efficiently find solutions.
This session is a software developers introduction to using mathematical optimization in Artificial Intelligence. In it, we will explore some of the foundational techniques for solving these types of problems, and use the open-source Google OR-Tools to put them to work in our AI systems. Since this is a session for developers, we'll keep it in terms that work best for us. That is, we'll go heavy on the code and lighter on the math.
Posted by bsstahl on 2017-05-06 and Filed Under: event
The slide deck for my presentation “Examples of Microservice Architectures” can be found here.
There isn't one clear answer to the question "what does a micro-service architecture look like?" so it can be very enlightening to see some existing implementations. In this presentation, we will look at 2 different applications that would not traditionally be thought of as candidates for a service-oriented approach. We'll look at how they were implemented and what benefits the micro-services architecture brought to the table for each application.
Demo Code for Testing in Visual Studio 2017
Posted by bsstahl on 2017-03-16 and Filed Under: event
The demo code for my presentation on Testing in Visual Studio 2017 at the VS2017 Launch event can be found on GitHub. There are 2 branches to this repository, the Main branch which holds the completed demo, and the DemoStart branch which holds the starting point of the demonstration in case you would like to implement the sample yourself.
The demo shows how Microsoft Fakes (formerly Moles) can be used to create tests against code that does not implement a reusable interface. This can be done without having to resort to integration style tests or writing extra wrapper code just to implement an interface. During my launch presentation, I also use this code to demonstrate the use of Intellitest (formerly Pex) to generate exploratory tests.
A Busy October and November
Posted by bsstahl on 2016-10-05 and Filed Under: event
The next two months are packed with tons of great technical events that I am really looking forward to. Below are some of the events that I am involved with and will be attending between now and the end of November. I hope to run into you at these events. If you see me, please don’t hesitate to say “hi”. I do love to talk tech.
Desert Code Camp makes its triumphant return from hiatus this weekend at Chandler-Gilbert Community College in the south-east valley. I will be delivering my talk, “A Developer’s Guide to Finding Optimal Solutions” which is an introduction to combinatorial optimization designed specifically for software developers, at 9:45 am in room CHO-110.
IT/DevConnections – Las Vegas NV– October 10th-13th 2016
One of my favorite large conferences of the year is IT/DevConnections in Las Vegas. This year marks my 4th attendance at this event, the 2nd as a speaker. I will be delivering the talk, “Dynamic Optimization – One Algorithm All Programmers Should Know”, a programmer’s introduction to Dynamic Programming, at 2:15 pm on October 13th in Brislecone 2 at the Aria Resort.
This year marks my 2nd attendance at the Atlanta Code Camp. My 1st experience there, last year when I presented on Dynamic Programming, was a big part of the inspiration for drilling deeper into the topic of combinatorial optimization. As such, I return to Atlanta this year with my new talk on the subject, “A Developer’s Guide to Finding Optimal Solutions”.
NWVDNUG & SEVDNUG – Phoenix AZ – Oct 26th and 27th
It is not yet confirmed as of this publication but I have a really great, internationally renown speaker lined-up for the Northwest Valley and Southeast Valley .NET User Groups this month. Final arrangements are currently being made so keep an eye on meetup.com for each group for the details to be published as soon as they are finalized.
SoCalCodeCamp – Los Angeles CA, November 12th – 13th 2016
I have attended many instances of the Southern California Code camp, but this will only be my 2nd time at the Los Angeles incarnation of this event. My 1st time there, last year, I was struck by the old-school beauty of the old school campus and facilities at USC when I presented my talk on Dynamic Programming. This year, I will follow that up with my new, more general overview on the subject of finding optimal solutions.
NWVDNUG & SEVDNUG – Phoenix AZ – Nov 16th and 17th
Our good friend Jeremy Clark (blog, twitter) makes his annual tour of the Valley’s .NET User Groups to talk to us, once again, about many of the things you need to know about .NET and Software Engineering to make your development better. Jeremy will give a different talk each night so be sure to sign-up at the meetup sites and come to both meetings.
Dynamic Optimization Presentation
Posted by bsstahl on 2015-10-21 and Filed Under: event
I hope you’ve had an opportunity to see my presentation, “Dynamic Optimization – One Technique all Programmers Should Know” at a Code Camp or User Group near you. If so, and you want to have a copy of the slide deck for your very own, you can see it embedded below, or use the direct link to the Powerpoint here.
The subject of this presentation is using a technique called Dynamic Programming to solve problems that have more than one possible solution. This technique works very well when used to solve problems that are recursive in nature. One of the best things about this technique is that it guarantees that the solution it produces is the best possible solution.
We look at three examples during the presentation, the first is done only “on paper” and is an example of using this technique to solve a knapsack problem. The second example is done in pseudo-code and solves a linear best-path problem in the game of Chutes & Ladders. Finally, we drop into Visual Studio to solve a 2-dimensional best-path problem. Sample code for both of the last 2 examples can be found in GitHub.
Keep an eye on my Speaking Engagements Page for opportunities to see this presentation live. If you are a user group or conference organizer, you can contact me to schedule an in-person presentation. This presentation is a lot of fun to deliver and has been received extremely well at Code Camps and User Groups across the country.
New OSS Project
Posted by bsstahl on 2014-07-11 and Filed Under: development
I recently started working on a set of open-source projects for Code Camps and other community conferences with my friend Rob Richardson (@rob_rich). In addition to doing some good for the community, I expect these projects, which I will describe in more detail in upcoming posts, to allow me to experiment with several elements of software development that I have been looking forward to trying out. These include:
- Using Git as a source control repository
- Using nUnit within Visual Studio as a test runner
- Solving an optimization problem in C#
- Getting to work on a shared project with and learning from Rob
As an enterprise developer, I have been using MSTest and Team Foundation Server since they were released. My last experience with nUnit was probably about 10 years ago, and I have never used Git before. My source control experience prior to TFS was in VSS and CVS, and all of that was at least 6 or 7 years ago.
So far, I have to say I'm very pleased with both Git for source control, and nUnit for tests. Honestly, other than for the slight syntactical changes, I really can't tell that I'm using nUnit instead of MSTest. The integration with Visual Studio, once the appropriate extensions are added, is seamless. Using Git is a bit more of a change, but I am really liking the workflow it creates. I have found myself, somewhat automatically, committing my code to the local repository after each step of the Red-Green-Refactor TDD cycle, and then pushing all of those commits to the server after each full completion of that cycle. This is a good, natural workflow that gives the benefits of frequent commits, without breaking the build for other developers on the project. It also has the huge advantage of being basically unchanged in a disconnected environment like an airplane (though those are frequently not disconnected anymore).
The only possible downside I can see so far is the risk presented by the fact that code committed to the local repository, is not yet really safe. Committing code has historically been a way of protecting ourselves from disc crashes or other catastrophes. In this workflow, it is the push to the server, not the act of committing code, that gives us that redundancy protection. As long as we remember that we don't have this redundancy until we push, and make those pushes part of the requirements of our workflow, I think the benefits of frequent local commits greatly outweigh any additional risk.
As to the other two items on my list, I have already learned a lot from both working with Rob and in working toward implementing the optimization solution. Even though we've only been working on this for a few days, and have had only 1 pairing session to this point, I feel quite confident that both the community and I will get great benefit from these projects.
In my next post, I'll discuss what these projects are, and how we plan on implementing them.
Code Sample for My TDD Kickstart Sessions
Posted by bsstahl on 2012-02-13 and Filed Under: development
The complete, working application for my .NET TDD Kickstart sessions can be found here.
Unzip the files into a solution folder and open the Demo.sln solution in a version of Visual Studio 2010 that has Unit Testing capability (Professional, Premium or Ultimate). Immediately, you should be able to compile the whole solution, and successfully execute the tests in the Bss.QueueMonitor.Test and Bss.Timing.Test libraries.
To get the tests in the other two test libraries (Bss.QueueMonitor.Data.EF.Test & Bss.QueueMonitor.IntegrationTest) to pass, you will need to create the database used to store the monitored data in the data-tier and integration tests, and enable MSMQ on your system so that a queue to be monitored can be created for the Integration test.
The solution is configured to use a SQLExpress database called TDDDemo. You can use any name or SQL implementation you like, you’ll just need to update the configuration of all of the test libraries to use the new connection. The script to execute in the new database to create the table needed to run the tests can be found in the Bss.QueueMonitor.Data.EF library and is called QueueDepthModel.edmx.sql.
You can install Message Queuing on computers running Windows 7 by using Programs and Features in the Control Panel. You do not need to create any specific queue because the integration test creates a queue for each test individually, then deletes the queue when the test is complete.
If you have any questions or comments about this sample, please start a conversation in the Fediverse @firstname.lastname@example.org or Contact Me.
.NET TDD Kickstart
Posted by bsstahl on 2012-01-26 and Filed Under: event development
I head out to Fullerton tomorrow for the start of my .NET TDD Kickstart world tour.
In this session, the speaker and the audience will "pair up" for a coding session which will serve as an introduction to Test Driven Development in an Agile environment. We will use C#, Visual Studio and Rhino Mocks to unit test code to be built both with and without dependencies. We will also highlight some of the common issues encountered during TDD and discuss strategies for overcoming them.
I will be presenting this session at numerous venues around the country this year, including, so far:
If you are interested in having me present this or another session at your event, please contact me.
There is much more than an hour’s worth of material to be presented, so instead of trying to rush through everything I want to talk about during this time, I’ve instead taken some questions from this presentation and posted them below. Please contact me if you have any additional questions, need clarification, or if you have an suggestions or additions to these lists.
Update: I have moved the FAQ list here to allow it to be maintained separately from this post.
Demo Code for EF4Ent Sessions
Posted by bsstahl on 2011-06-26 and Filed Under: development
I previously posted the slides for my Building Enterprise Apps using Entity Framework 4 talk here. I can now post the source code for the completed demo application. That code, created for use in Visual Studio 2010 Ultimate, is available in zip format below. This is the same code that was demonstrated at Desert Code Camp 2011.1 and SoCalCodeCamp 2011 as well as the New Mexico .NET User’s Group (NMUG).
Desert Code Camp Presentation
Posted by bsstahl on 2011-04-02 and Filed Under: event development
Thanks to all of the organizers, speakers, sponsors and attendees of Desert Code Camp 2011.1. This is the first time that I’ve presented at a Code Camp and it was a fantastic experience for me. My session, Building Enterprise Apps using Entity Framework 4, was very well attended with 35 people cramming, standing-room-only, into a room with a capacity of 28 (please don’t tell the Fire Marshall). The demos went very well (everything worked as it was supposed to) and the feedback I’ve gotten so far was entirely positive.
I will be posting some additional information from the session shortly, including the sample code and the changes I make to the Microsoft All Rules code analysis ruleset, but I wanted to get the session slides up as quickly as possible.
If you have any additional feedback on the session, please feel free to contact me here, in the Fediverse @email@example.com or by email as shown in the slide deck.
DCC 2011.1 -- Building Enterprise Apps using Entity Framework 4
Looking for Evening Events at Mix11
Posted by bsstahl on 2011-01-30 and Filed Under: event
I won’t be an attendee at the Mix conference this year. Nothing against this conference; it is usually fantastic and I have met many awesome people there. This year, my focus is elsewhere, on SOA and Middleware/Back-End technologies. Not that I’ve ever really been a front-end guy mind you, but I am of the opinion that balance is a good thing and since I consider myself weaker in front-end (UX) technologies, Mix has been a good learning experience for me in the past. However, as I said, this year, my primary focuses are elsewhere.
Not being an attendee doesn’t stop me from wanting to meet with old friends and continue the awesome technical discussions that go on at these events. I have loved meeting with the product teams in the past, both to learn from them and to provide my input into the future directions of the products. So, it is my intent to fly up to Las Vegas (it is less than an hour flight from Phoenix) for at lease 1 evening of the Mix conference, perhaps 2. Right now, I am looking for events to schedule for that (those) evening(s).
I know that I will not be able to go to the attendee party, since I will not be an attendee, and that event occurs on Wednesday the 13th (courtesy of Joe Guadagno’s Mix 11 Events site). This means that the most likely evenings for me to be there are Monday and Tuesday, April 11th and 12th. Do you know of any events going on in Las Vegas during this time that would be awesome for me as a .NET Software Engineer to attend? If so, I would appreciate it if you would let me know. I’ve setup a special email alias just for this purpose, please contact me at
Day 2 AM
Posted by bsstahl on 2003-10-30 and Filed Under: event
The morning sessions of Day 2 were highlighted by drill-downs into Yukon and WinFS. The most impressive demo of the conference so far was done during the WinFS drill-down by Gord Mangione and Tom Rizzo. They used the Information Agents of WinFS to configure their voicemail application so that when a call came in from a client matching specified custom criteria, and the calendar showed that the user was busy, it would respond to the caller with the time the user's calendar next showed him free.
WinFS may finally make good on the decade-old promise of turning the file-system into a relational database. Its metadata features, including extensible schema, appear poised to make the file-system as programmatically accessible as a database server, with many of the same query capabilities including natural language or SQL style queries.
Yukon also appears to be a major improvement in development technology. This next generation of SQL Server provides CLR (Common Language Runtime - AKA, the .NET Framework) in-process to the SQL Server. This will allow developers to separate the application (or system) tiers physically as well as logically, improving performance, scalability, security, maintainability and extensibility. It will also allow queries to be written in any CLR language, provides structured exception handling for those queries (including in T-SQL) and will allow us to build queries that easily integrate data from various sources (including Web Services).
Needless to say, I am rather excited about many of these developments and am looking forward to installing Longhorn and Yukon on development servers when I return to the real world.