Kbase P11906: What is the role/definition of a broker?
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/16/2008 |
|
Status: Unverified
GOAL:
what is the role/definition of a broker?
FIX:
In general, you can say the broker is the process that handles and enables the multi-user session. See the following part from the system Adminstration Guide, chapter 1:
1.3 Single- and Multiple-user Environments
PROGRESS running in single-user mode allows one user to access a specified database at a time. If another user is already accessing a database, you cannot connect to the database from a different PROGRESS session. PROGRESS uses a lock file (.lk) to lock out other users. Running PROGRESS in single-user mode is helpful when you perform system administration tasks that require exclusive access to the database. PROGRESS running in multi-user mode enables more than one user to access the database at the same time. A broker coordinates all the database requests from all the users using a single database. For example, the broker process locks the database to prevent any other broker or single-user process from opening it. Also, all users must request access from the broker to connect to the database.
1.5 Self-service and Network Clients
The PROGRESS database architecture supports self-service and remote clients. A self-service client is a multi-user PROGRESS session that runs on the same machine as the broker. Self-service clients access the database directly through shared memory and not through servers, because server code is part of the self-service client process. Self-service clients also perform server and client functions in one process, and they execute application logic. On shared-memory UNIX and Windows systems, PROGRESS provides self-service clients with nearly simultaneous access to the database. A network client can be local or remote but cannot connect to a database directly, rather it must use a server. A network client is a client process on a computer that does not contain the database or the broker process. The network client accesses the database through a server process that the broker usually starts over a network connection. The network client does not have access to shared memory, and it must communicate with a server process.