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Security Scenarios

agers or to only users who work for a particular department. In short, all clients are

not equal in terms of their permissions to access or use services or resources. 

Because a service endpoint also needs to interact with other components and

resources, the endpoint needs some way to control access to them. That is, the

endpoint needs to be able to specify resources that have restricted access, to group

clients into logical roles and map those roles to an established identity, and, while

processing a service request, to decide whether clients with a particular identity

can access a particular resource. 

7.1.1.3

Secure Channel for Message Exchange

A client's utilization of a Web service entails numerous message exchanges, and

such messages may contain documents, input parameters, return values, and so

forth. Since not all messages require security, an application needs to identify those

messages requiring security and ensure that they are properly protected.

Some message exchanges, such as passing credit card information, require

confidentiality. For these messages, the interaction between a client and a Web

service must be encrypted so that unintended parties, even if they manage to inter 

cept the message, cannot read the data. 

Interactions between a client and a Web service might require integrity con 

straints. That is, message exchanges between a client and a service might require a

digital signature to verify that the message was not altered in transit. The message

recipient, by validating a signature bound to a message, verifies the integrity of

the message.

To handle interactions requiring integrity and confidentiality, it is important to

establish secure channels for exchanging messages. Applications use HTTPS and

digital certificates to establish such secure channels. HTTPS provides a secure

message exchange for one hop between two parties.

7.1.1.4

Message Level Security

Besides creating a secure communication channel between a client and a Web ser 

vice, some Web service message exchanges might require that security information

be embedded within the SOAP message itself. This is often the case when a

message needs to be processed by several intermediary nodes before it reaches the

target service or when a message must be passed among several services to be

processed.