Windows services management

-

Wow, it's been a long time since I last updated the blog. Life, you know.

OK, today I bring you a very simple library to manage the Windows services you may have created (either with LabVIEW or in another language, it doesn't matter). These VIs allow to install and uninstall the service, as well as running it, stopping it and getting its current status. A lot of extra functionalities could be added if ever needed, you'll see they're extremely easy to use and modify.

Download Services LLB (library and class for LabVIEW 2016)

The main part of the library is made up of service.lvclass, a LabVIEW class that wraps the provided functions: install, start, stop, get status and uninstall. Maybe using GOOP here is overkill, but it's easier this way, just deploy init and close to create and dispose an instance and call the other VIs in between. This class uses .NET methods inside and as such is only valid for a Windows OS, but we are talking about Windows services here, so no problem 😉.

Now, if you open service.lvlib (the tree screenshot is on the right) you'll see that, aside from the LV class, there are some non .NET functions (up in the tree). They rely in command-line execution and Windows registry access, and are needed at least to install and uninstall the service. There are also some methods for starting, stopping and getting the service status through CLI; as I said before the class uses .NET for the same functionalities but I thought you may still find them useful as standalones and so I have put them outside the class.

Alright, let's go with the operation. If your service is already installed, you just need its name to identify it. Be careful, the service name is not the name that appears on the service list (services.msc), that's just the public name. Right-click on the service and select "properties" to retrieve the actual service name. Pass this name to init.vi and go ahead running it or whatever you want.

If the service is not installed the class initialization will go on, but obviously you won't be able to do anything with the service. Install it through install.vi and pass as inputs the public name, the associated exe file and, optionally, its dependencies (these are already installed services that this service will depend upon). Once this is done, continue as previously, for example running it.

And that's it. Play with the functions and remember that adding new ones (for advanced service management) will be as easy as deploying the appropriate .NET methods and properties.

Comentarios

Publicar un comentario

Entradas populares de este blog

SNMP library for LabVIEW

-
Imagen
SNMP (Simple Network Management Protocol) is a fairly common protocol for communicating with network equipment. It's fast, lightweight and standardized. Unfortunately it's not quite as simple as its name implies and LabVIEW doesn't support it natively. Some years ago I was in the necessity of using SNMP from a LabVIEW system to control some hardware. I started looking for already implemented solutions and found a library developed by Mark Yedinak (great work!). It was useful since it demonstrated it could be done and how, but I needed more control over the operations, so I had to read the protocol down to the low level bytes and implement what I need by myself. Yeah, pretty hard and with time constraints no less. Anyway, here it is. Download (Library in LLB file for LabVIEW 2016) See the examples folder to grasp the basic use. Probably you'll need no more than these sets of VIs to send and retrieve data and to get traps sent by your equipment. To integrate
Leer más

Base64 Encoding

-
Imagen
Long time no see! Today I'm here to talk about Base64 encoding and how to do it in LabVIEW. What is Base64 and what is used for? Base64 is a six-bit based encoding mechanism that uses only printable characters from the ASCII table (lower and upper case letters, numbers, and three more characters, usually "+/="). This means it can be represented in any textual environment, though obviously adds an overhead respect to the original code since two bits of every byte are unused. You will find B64 mainly in mail applications (to send attachments), but lately it's been popular in URLs and HTML too. The concept is to insert small chunks of data directly as B64 text to avoid recurrent callings for files through the web. For example, you can embed an image inside your HTML or CSS file. It's not my intention to delve too deep in this aspect, but for an image tag the resulting HTML code would look like this (let's assume a JPG file): <img src="data:imag
Leer más

Retrieve CPU temperature

-
Imagen
Lately I had to check the CPU temperature in a critical acquisition system, and I thought it could be a good thing to share here. I know there are several applications to do this and much more, but getting it from our code allows to react conveniently to any event. Now, IMPORTANT, the VI doesn't work on its own. First you must download the Open Hardware Monitor . Extract OpenHardwareMonitorLib.dll from the zip file and put it in the same folder the VI is located. The objects exposed in it use .NET Framework 2.0 and above, but that shouldn't be a problem in any modern machine. On the other hand, this works only for Windows , obviously. And remember, the application (either an .exe or the LabVIEW IDE) must run with administrator rights (otherwise you'll get error 1172 ). Download (VI for LabVIEW 2016) Now, if you haven't worked with .NET functions in LabVIEW, this can be a good opportunity to familiarize with them. Let's take a look at the code. First we
Leer más