m4_comment([$Id: progmodel.so,v 10.27 2001/03/01 15:57:54 bostic Exp $])m4_ref_title(Architecture, Programming model,, arch/bigpic, arch/apis)m4_p([dnlm4_db is a database library, in which the library is linked into theaddress space of the application using it.  The code using m4_db may bea standalone application or it may be a server providing functionalityto many clients via inter-process or remote-process communication(IPC/RPC).])m4_p([dnlIn the standalone application model, one or more applications link them4_db library directly into their address spaces.  There may be manythreads of control in this model because m4_db supports locking for bothmultiple processes and for multiple threads within a process.  Thismodel provides significantly faster access to the databasefunctionality, but implies trust among all threads of control sharingthe database environment because they will have the ability to read,write and potentially corrupt each other's data.])m4_p([dnlIn the client-server model, developers write a database serverapplication that accepts requests via some form of IPC/RPC, and issuescalls to the m4_db interfaces based on those requests.  In this model,the database server is the only application linking the m4_db libraryinto its address space.  The client-server model trades performance forprotection because it does not require that the applications share aprotection domain with the server, but IPC/RPC is slower than a functioncall.  Of course, this model also greatly simplifies the creation ofnetwork client-server applications.])m4_page_footer