Note that you allow services to directly call other services call do."
(That is, each service itself is a client of another service.)

As such, the content available to the business to reuse the service can be significantly reduced. sometimes to It seems that it is necessary to make a service a client of another service in its execution. By doing this you define a phase of the connection That will be a problem for you later. If you find yourself in this situation, use an orchestration technology ( harmony ) such as BPEL.
Also without Service Level Agreement (SLA) software monitoring and metrics to track how much service is being received at any location becomes; It can be difficult. Another problem in the field of summoning the service is that it is not allowed to see the tool Your topography adds complexity. Tools to show resources across resources related to services stored in Repositories are available from major SOA vendors. But it is very expensive.
The architectural solution to this problem is when we want to have a service that directly calls another service We can create an orchestration instead.
Just as a service covers a system or subsystem, an orchestration covers a set of services that flow together. It covers the But an orchestration acts like a service, just like any other service for clients It seams.
In every organization, SOAs are different and it is better that each organization according to the business and its elements and limitations for SOA. keep its own meaning in mind.