160 likes | 336 Views
DISTRIBUTED COMPONENT OBJECT MODEL -. A STUDY OF ITS ARCHITECTURE AND WHY IT IS CONSIDERED A FAILURE BY EXPERTS. DISTRIBUTED COMPUTING PROTOCOLS. CORBA Java’s RMI DCOM. ADVANTAGES OF DISTRIBUTED COMPUTING. Speeding up development processes Improving deployment flexibility
E N D
DISTRIBUTED COMPONENT OBJECT MODEL - A STUDY OF ITS ARCHITECTURE AND WHY IT IS CONSIDERED A FAILURE BY EXPERTS.
DISTRIBUTED COMPUTINGPROTOCOLS • CORBA • Java’s RMI • DCOM
ADVANTAGES OF DISTRIBUTED COMPUTING • Speeding up development processes • Improving deployment flexibility • Lowering maintenance costs • Improving scalability • Load balancing
REGISTRIES AND KEYS • A Registry is the place where the components installed in a machine store their settings. • The ‘registry’ contains many sections called keys. The keys contain value data such as Class ID and Application ID.
THE FIVE COMPONENTS OF DCOM • Object Instantiation Process • Data transferring between clients and components • Security in DCOM • The DCE RPC component • The low-level protocol stack
OBJECT INSTANTIATION PROCESS • Clients use COM’s "create instance" functions such as CoCreateInstanceEx, CoGetClassObject, etc. to create a new instance of a component. • To specify the server on which a component resides, DCOM employs the notion of RemoteServerName
Data transferring between clients and components • Marshaling : is the process of reading parameters from the stack into a flat memory buffer (that will be transferred across "the wire" later.) • Unmarshaling :it reads the memory buffer and re-creates the stack that is the same as the caller’s stack.
Security in DCOM • Access Security • Launch Security • Identity Security • Connection Policy
IS DCOM AN UNQUALIFIED SUCCESS? • Initially, DCOM was a major competitor to CORBA. • There were difficulties in getting them to work over internet firewalls. • DCOM and CORBA lost out to web browsers combined with http requests.
THE MS-BLASTER WORM • DCOM RPC Interface Buffer OverrunVulnerability • TCP port 135is overrun by a large amount of data • This allows the remote system to gain local system privileges on tcp port 4444. • In essence it causes a ‘DENIAL OF SERVICE’ error for microsoftupdate.com. • Microsoft did come up with a patch to rectify the ‘buffer overrun in msrpc’. The patch is available at http://www.microsoft.com/technet/security/bulletin/MS03-026.mspx.
DCOM SUPPORTERS All said and done DCOM is not without its supporters. • SAP • DUNN and BRADSTREET • SYBASE