OP-008: Resolve a user's default printer from Active Directory¶

GetDefaultPrinter is invoked over the PreferenceService route on SAIF.Services.WCF.Services.PreferenceService; this page documents the process end to end, from route dispatch to the message the caller receives.

Field	Value
Operation ID	OP-008
Trigger	Caller invokes `GetDefaultPrinter` over the `PreferenceService` route.
Entry operation	`GetDefaultPrinter`
Owning component	`SAIF.Services.WCF.Services.PreferenceService.GetDefaultPrinter`
Inputs	Request message parts listed below
Outputs	The AD `extensionAttribute2` value for the SAIF-domain principal matching `user`.
Failure behavior	Generic SOAP fault, per Faults and error pipeline

Request and response¶

Direction	Element	Type	Declared in	Notes
Request	`user`	`string`	BCL (`System`)	User whose default printer is requested. (Yes)
Response	`string`	`string`	BCL (`System`)	The AD `extensionAttribute2` value for the SAIF-domain principal matching `user`.

Steps¶

Open a PrincipalContext(ContextType.Domain, SaifUserPrincipal.DOMAIN) where DOMAIN is the constant "SAIF".
SaifUserPrincipal.FindByIdentity(context, user); a null principal returns string.Empty (BR-WCF-012).
Otherwise return principal.DefaultPrinter, backed by the AD attribute extensionAttribute2 (BR-WCF-013).
On failure: a directory exception is logged by the installed error handler and surfaced as a generic SOAP fault with exception detail included.

Process flow¶

The following diagram visualizes this process's control flow.

flowchart TD
    A["Open PrincipalContext for<br>SAIF domain"]
    B["SaifUserPrincipal.FindByIdentity(context, user)"]
    B1{"Principal found?"}
    B2["Null principal: return string.Empty"]
    C["Return DefaultPrinter from<br>AD extensionAttribute2"]
    A --> B
    B --> B1
    B1 -->|"No"| B2
    B1 -->|"Yes"| C

Transaction and side effects¶

Aspect	Finding
Unit of work	None
Commit point	Not applicable
Records written	None
Downstream calls	Active Directory (`SAIF` domain)
Shared state touched	None
Repeat-call behavior	Idempotent read

Logging¶

Surface	Written content
`ErrorLogErrorHandler` → `LogService`	Failure-path exception logging only, carrying method signature, calling user and exception detail; see Faults and error pipeline

Faults and error handling¶

Failure	Fault type the caller receives	Produced by	Source
Directory exception	`Generic SOAP fault`	The `ErrorLogErrorHandler` installed by `[LogErrorBehavior]`	src/WCF/SAIF.Services.WCF.Host/Services/Security/SaifUserPrincipal.cs

Authorization¶

Requirement	Enforced by	Source	Applies to
None in code	IIS authentication on the deployment (see Activation and hosting)	`src/WCF/SAIF.Services.WCF.Host/Services/PreferenceService.cs`	This operation

Note: Statements marked with * were inferred from code structure, naming conventions, or contextual evidence where direct confirmation was not available in source artifacts. Statements marked with ** could not be confirmed; treat as unknown until verified.

Sources¶

src/WCF/SAIF.Services.WCF.Host/Services/PreferenceService.cs
src/WCF/SAIF.Services.WCF.Host/Services/Security/SaifUserPrincipal.cs