Subtitles of the Movie

Artifacts, nodes and communication paths give information about the physical topology of your system, but often you need to know more then which software is deployed to which hardware or execution environment in order to get the software to execute. And that's where the subject of this movie, deployment specifications comes into play. A deployment specification is a special kind of artifact that lets you specify the configuration parameters needed for the software to run. A deployment specification thus adds another layer of information to your deployment diagram by specifying how artifacts are to be deployed. If for example an artifact requires an initialization command or a connection information you can specify this using a deployment specification. And a deployment specification looks like what you see on the screen right here, it's a rectangular classifier box that is stereotyped with deployment spec, it needs that, it's the name of the specification and you may or may not see another compartment beneath the specifications name and I'll say more about that, the second compartment in just moment. To show that this deployment specification specifies the parameters for this artifact use a dependency arrow and that arrow should point from the deployment specification to the artifact whose parameters it specifies. So to look at an example we might have an artifact named printer driver dot dll and the deployment specification for that artifact could be something like deploy dot dat. So now we know that this deployment specification specifies the parameters or parameterizes this artifact. But we don't have a lot of information in this diagram about what those parameters are, what are the deployment requirements that are being specified in the specification and that's where the second compartment comes into play. You can expand this compartment in a deployment specification and use it to list deployment requirements as attributes. So in our example a deployment requirement for the printer driver might be something like test data and that's string and you can list as many deployment requirements as you want or need to in this compartment. So that's a useful to make sure its clear right in your diagram what the parameters, what the deployment requirements are for a particular artifact. Now the next question is how you do link these to nodes and one way you might do that, we'll have a device here and we'll just call it desktop PC. One way to do that as you've seen in other diagrams is simply to move you're artifact and your deployment specification inside the node. Let me bring that forward so we can see it. So this says that within this node we've got this artifact that is parameterized by this deployment specification. You can also show this with the artifact and the deployment specification outside of the node and that might look something like this, we want the deployment dependency arrow going from the artifact up to the node, let's do that like that, move this over and then we can hitch the deployment specification to that dependency arrow. So I'm going to draw a dependency arrow from the deployment specification to the node and then snap those together. So this also shows the same thing that you saw in the previous style where the artifact and the deployment specification are contained in the desktop pc symbol. This shows the same thing that this artifact deploys to this node and this deployment specification goes along with the artifact. Now one more thing that I'd like to mention about deployment specification is that you can also put an artifact together with its deployment specification inside of a bigger artifact. So you can bundle them together inside another artifact and here's an example of when you might want to do this. Let's say that you've got an artifact that is a web archive and will call it account server and we'll make this bigger so it can hold an artifact and its specification. So inside this web archive you might have account server dot jar and in this context you might have a deployment specification web dot xml and we'll draw our dependency arrow. So this is an example of when you might want to show an artifact and its deployment specification inside of a bigger artifact. So as you can see from the examples we've looked at deployment specifications are very useful at giving the details of the deployment requirements or the parameters that are required by some artifact so that artifact will be able to execute.