DISTRIBUTED COMPONENT OBJECT MODEL A STUDY OF ITS

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 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.

ARCHITECTURE OF DCOM

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 Co. Create. Instance. Ex, Co. Get. Class. Object, etc. to create a new instance of a component. • To specify the server on which a component resides, DCOM employs the notion of Remote. Server. Name

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 Overrun Vulnerability • TCP port 135 is 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/M S 03 -026. mspx.

DCOM SUPPORTERS All said and done DCOM is not without its supporters. • SAP • DUNN and BRADSTREET • SYBASE