Category Archives: Topics

Posts on technical topics. The sub-category provides the specific area of interest.

C#, MongoDB, Projects, Sandbox

Started adding mongodb support to C# code

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I started adding in concrete MongoDB support to the tool code I’m building. Last night I incorporated the drivers into the solution and set up the connection code for the database. My initial attempt to directly use the C++/CLI object to push a record into the database failed but I expect to add a class that is properly serializable to BSON tonight and get volume information persistence working. I still need to get a better handle on updates in MongoDB. I know there are various sorts of atomic test and set sorts of operations on documents and in order to make this work properly with concurrent access, I need to understand those operations and use them to ensure that updates don’t ‘walk’ on themselves.

When I have a bit more time to type, I’ll add in more details on the MongoDB driver work and the approaches I’m using.

Daily Blog, General Technical, Topics

VirtualBox supports multiple monitors…

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I’ve been using VirtualBox pretty heavily to partition things out on my systems where some tasks require setups that clash at the OS level.

I generally find multiple monitors to be exceptionally helpful in software development settings. I’ve been running with my Virtual Box VMs on one monitor and using the other monitors for host OS based windows…and this has worked pretty well.

This morning I decided to take a look at the configuration settings for my main VM and to my delight I found that it is possible to configure additional monitors and place them on the desktop. This should streamline things when developing on a VM as it allows me to keep my IDE full screen on one screen while using a second for other activities.

Now if I can only figure out how to make Docker and Virtual Box live together in harmony at home (Docker wants Hyper-V while Virtual Box can’t run under that hypervisor) I’ll be feeling pretty happy.

C++, Projects, Sandbox, Topics

JSON over Stdin/Stdout for small local components.

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I’m looking at adding a local control capability to my little C++ based file and volume identifier tool. I’ve run into a number of small functions that would be well served by tools written in specific languages that have access to specialized APIs but would benefit from a local interface with somewhat decent performance.

Unix style text in/text out is limiting as the command/response format lacks structure and the performance (with one process start per request) is potentially unacceptable.

Adding in a command line switch that sets the tool into ‘json in/json out’ mode and keeps the program alive until the pipes drop or an exit command is received should address these issues.

Ideally, the stdin and stdout would transport UTF-8 data containing complete JSON entities…one as a request and one containing the complete response. This can continue until the hosting program sends an EOF or drops the pipes.

I’m wrapping together a very lightweight JSON generator/parser to support this effort and will be following that up with some testing of C++/Java/C# (and perhaps others) sub-process and pipe management coding. If all goes well, I should have a nice little approach for wrapping small pieces of code that need to run in a particular language but must be hosted elsewhere with decent performance and a robust communications format.

Daily Blog, Python, Thoughts, Topics

Native extensions to Python

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I spent a little time last night looking at the coding requirements for creating native (C essentially) extensions to Python. This has come up previously in conversations as another way to make native code accessible functions available for scripting by folks who aren’t development engineers.

The facility appears similar in style to that provided for writing perl extensions or JNI. No surprise here. I’ll probably try playing with this a little bit sometime soon just to get a feel for the full series of steps. The process involved in getting the *.dll or *.so file into the right spot to be usable seems a little bit opaque, but perhaps it is just so automated that it isn’t much of an issue.

I’m not a huge fan of Python but it has a huge following and seems to be a useful intermediate step between shell scripting sorts of activity and full powered implementation languages (C++/C#/Java).

I wish python had not chosen such a poorly conserved item as white-space to represent block scoping (the tabs/spaces issues are not generally fixable without making the representation issues worse). They also seem to have created a permanent 2.x/3.x schism where quite a few years after the major version upgrade there is still a substantial amount of code on either side of the divide. Perl 5/6 had a similar issue, but perl 6 never seems to have taken off so the impact is much smaller.

Some links that seemed useful:

Daily Blog, Java, JavaFX, Thoughts, Topics

JavaFX Event Handling

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I’m finding myself needing a better understanding of JavaFX UI event handling and my basic JavaFX books seem to ignore most of that aspect of the system. It looks as if the wiring of UI events is buried deep enough and the handling is automated enough that most of the time there’s no need to directly interact with events.

I need to perform an action when a given UI panel is exposed after being hidden…a simple enough activity in most cases. I expect I’ll find the right controls soon enough, just a bit surprised that they’re not talked about as directly as I’m used to.

Looking as if the easy route to this may be to name the top level pane in a given area and then attach a ‘show’ handler to that pane. Hoping this works as this would make it pretty easy to do what I need to get done.

Some links that I’m recording for later convenience (some just interesting here not directly relevant):

The charting and 3D API items are of interest, but not part of this, but I’m trying to keep notes on where things were found so that I can go back and dig deeper later…a small amount of clutter for convenience…

C++, Daily Blog, Thoughts, Topics

New Version of the C++ Templates Book

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There is a new edition of C++ Templates: The Complete Guide (2nd Edition) out. This has actually been in print for around a year, but I’ve been a bit focused on C#, Java and Javascript and not paying all that much attention to C++ developments for the last couple of years.

I’ve created plenty of template classes and functions in C++ but have not done much more than a bit of reading on the powerful template metaprogramming capabilities provided by the C++ template facility. With C++ 2011/2014/2017 and its language and runtime library enhancements, these sorts of approaches have  become more powerful and less complex.

I expect to buy a copy of this and read it through sometime soon as a complement to The C++ Programming Language, 4th Edition, The C++ Standard Library: A Tutorial and Reference (2nd Edition) and Effective Modern C++: 42 Specific Ways to Improve Your Use of C++11 and C++14 1st Edition. I’m still considering dropping money on a copy of the standard itself (ISO/IEC 14882:2017 Programming languages — C++, main page here) as the comments on the final draft that is freely available seem to suggest it is more of a mess than is usual. Interesting…the ANSI copy is at $116.00 which is significantly less expensive than I had thought.

C++, Daily Blog, Thoughts, Topics

JSON over stdin/stdout

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I’m looking at adding a json over standard I/O pipes option to my tool from last weekend. I’m thinking of this as an intermediate option between interop type solutions (jni, pinvoke and such) and simple command line execution.

Adding in a –jsonrpc option to the tool that selects a mode where json object are read from stdin and json results are emitted to stdout seems like a pretty good option. This should provide an abstracted but tightly coupled interface between a piece of code running as a separate process and a language that may not have access to the APIs needed to get the job done.

This does imply that there will be one subprocess per parent process that needs access. The upside of this is that things remain modular where a problem with one subprocess has no effect on others in the system. We sacrifice a bit of efficiency along the way, but I can’t see that as a major issue in most cases.

C++, Daily Blog, Thoughts, Topics

Adding Boost to the mix…

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I’ve built and used boost before and had good results. I’m going to add boost to my home C++ tools mix and I suspect I may find a workable json parser/generator in there. Grabbing the pieces now, but I don’t expect that I’ll have a usable build for a day or two given available cycles/time.

Built b2 and now I’ve bootstrapped the zip archive of boost. We’ll see what is there in the morning after the .\b2 run finished. I think I may wind up missing some interesting bits that require optional extras, but I should have a decent subset and can likely add in the missing pieces as needed.

C++, Daily Blog, Thoughts, Topics, Win32

A bit of C++ over the weekend

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I spent a good bit of time over the weekend digging into some java coding for work. Wrapping some things up and the extra time will help.

I noticed that there is a third edition of effective java out there. I have the older edition, but it is really too old to be helpful with the current state of the java world. The ‘effective’ books overall have tended to be very helpful with usage, idioms and anti-patterns beyond the basic so I’m looking forward to reading this volume and seeing what it has to offer.

I spent a good piece of today writing up a free-standing command line tool to display the unique file id for windows files. The API that provides this is exceptionally useful when working with file cleanup in systems where there are mount points, symbolic links and other reparse points present. This API is not directly accessible from languages such as java or C# and thus an invokable command line tool seems handy. Interop and jni would also offer access, but the command line tool seems the most general purpose (if perhaps low on the performance scale).

I wound up writing a small command line option parser to support this work (though only used a little at this point). I’ll likely keep this around and use it in other tools going forward.

I’m also looking at adding a json output generation option and a stream in/stream out switch to make this little tool more useful for higher volume solutions with programmatic interfaces. It seems as if a json based programmatic interface using standard I/O streams would offer significant performance while also providing enough ‘traction’ to make program to program use of the tool practical.

I ran into a small hiccup this evening as I was unable to upload the code to github as github appeared to be suffering from some sort of relatively serious failure. Hoping that tomorrow morning things will be in better shape and I can push the code up then.

I will probably build a simple json library for local use over the next couple of days (I’ve done this before and it is relatively straightforward as json is a very regular and simple format). I need small and easy more than capable and fast so something coded locally seems best.