DEMO: Services

What a Service Is For

There's another thing on our computer called services — yet another program. So what are services, and what do they look like?

Let's give an example here. I've created a program, and this program is going to monitor the temperature outside and monitor the temperature inside, and based off of that information it might turn on my heat or my AC in my home. So this is just a simple little program that I have. It has a couple of inputs into it, and then it will do something based off of those inputs.

Now with this program, what I have to do is I have to get into my computer, I have to double-click this to open it up, so that way it can start monitoring these two inputs and give that output. Otherwise it's not up and running on the computer. And you can see that that could be problematic, because I could turn on my computer and not have logged in yet, and now this program is not up and running when I want it to be up and running. Whether I'm on the computer or not, I want it to be up and running.

Well, what I can do is I can take this program and turn it into a service. You can take lots of different programs and turn them into a service.

The Services Console

So what I'm going to do is I'm going to open up Windows here, and I'm going to type in services and open up the service console. This service console that I see here has lots of different services that are on it. With that, I can see the status — some of them are running and some of them are not. I can also see the startup type: some of them automatically set up, some of them manually have to be set up and started, and some of them are automatically set up but with a timer, so they're delayed. So I can see that there's different software here that's installed. Each one of these is a program on the computer that's set up as a service.

An Example: the DHCP Client

Let's look at a specific service that's already set up on this machine. What I'm going to do is scroll down to DHCP client. The DHCP client is what goes out and grabs an IP address — connects to the network and says, hey, can you give me an IP address, and then the machine will assign an IP address to it. So the DHCP client is pretty important. On most networks, most networks are not going to statically assign something, so it's going to need to be up and running for the computer to be able to have any kind of connectivity to a network and to the rest of the world.

So this DHCP client is running. I can right-click on this and I can stop the service — in which case, I wouldn't want to do that, but I could — or I could restart it if it's malfunctioning. And then what I can do is I can pull up the properties of it. When I pull up the properties on here, I can see the startup type. So the startup type, I pulled down: I can do automatic with delayed start, I can do automatic, I can do manual, or I can disable this altogether. So this is a way for me to control this service and how this service is going to function.

Turning Your Own Program Into a Service

So with my temp adjust program, what I could do is I could set up the service in here. Now, there is a command that you have to go through, and we're not too concerned about setting that up and demonstrating that at this point, but just know that I could actually create a program and set it up in here so it could be up and running when this computer starts.

A lot of these take effect and activate before you ever even log into the computer, which is pretty important, especially when you're talking about servers. When you're talking about servers, you have lots of these services that get launched before anybody has to sign into that machine, and that's pretty critical for the functionality of a server — and also even for services like DHCP on a regular client machine.