Lecture Notes in Computer Science 3472

16 TTCN-3 493
possible locations where the components may be distributed; the homes reflect
the user constraints for distribution.
The next piece of XML code is an example of a component assembly file.
The special tag indicates the host where the MTC component is deployed. The
selector defines a filter to select all components of type ptcType. The selected
components can be deployed either on container1 or on container2. One can
define deployment constraints for each container (ex. do not allow deployment
of more than 100 components on container2). The user can constrain the memory
usage, the CPU load, the number of components etc.
Example to use TCDL language
ptcType
10
100
Usually, the definition of constraints is a difficult task; for complex setups it
may be very difficult to describe an efficient distribution. Therefore, the task of
hardware options and constraints should be realized by the execution environment.
It should provide services, which implement distribution algorithms that
are designed to be efficient for a certain type of problems. The task of the user
remains to select the algorithm which solves the problem best. The code below
shows a set which deploys the components of types ptcType2, ptcType3 and
the instances 1, 2 and 5 of type ptcType4 on the container2 and container3, according
with the mem50 algorithm. The mem50 is an example of an algorithm
which allows to deploy components on a container until the limit of 50 percent
of memory is reached.