Java Reference
In-Depth Information
Recapping All the Stages
To summarize what has been said so far, each model step is detailed below. To complete this
subsection, all the stages are described later in reference Table 2.1.
Distribution
Given the importance and frequency of this subphase, we will describe its function in some
detail.
First of all, this phase depends on the kind of connection established between the client and the
Distributor. If this connection is a standard network connection, even one as temporary as that
of a home modem, the Distribution Phase will consist basically of a file transfer, using some
given protocol. This is almost always the case, so it is safe to refer to this situation. Despite
that, the model is abstract enough to handle other types of distribution means. The outcome of
this stage doesn't depend on the particular type of connection; at the end of any Distribution
step, we will have (mostly by the AH) the given item, freshly delivered from the Deployment
Servers. Note that eventually caching mechanisms will be handled explicitly by the AH.
Another important feature of this phase is the capability to conserve bandwidth by delivering
only the needed items. See the Resources Installation During AH Application Support Phase
that follows for details.
2
The AH Application Support Phase is composed of three steps.
1.
Connects back to the Deployment Server, possibly performing some form of authentica-
tion, if needed. We can assume that the client will always begin the deployment, even
when the AH operates as a background demon process, waking up as instructed by the
Deployment Policies and starting a server communication. We will see the rare cases
where this is not true when discussing the whole model.
2.
Resolves the items to transfer, involving the Deployment Policies and the other inputs in
the Resolution Phase described later.
3.
The transfer of the requested items takes place.
Development
The Development Phase is an important part of the whole deployment lifecycle, and is the
focus of the second part of this topic. Its outputs are the software resources to be deployed and
the Deployment Policies that define the deployment itself. Both resources and policies are rep-
resented in some meta-information format intelligible to the Distributor.
Publication
This stage is composed of the Removal step or, alternatively, the following two successive
steps:
