Architecture¶
This host is a two-layer pass-through: a WCF service facade (UC4Service) that owns the allow/deny rule gate and logging, and a thin outbound client (UC4Client) that resolves the downstream address from configuration and maps the result contract. There is no repository layer, no domain layer, no persistence, no unit of work, and no dependency-injection container.
Hosting model¶
The host runs in IIS. Global.asax instantiates a code-behind class declared in namespace SAIF.Services.WCF.Host (copy-paste residue from the main host, not a functional link — see Tech debt) deriving from System.Web.HttpApplication, whose Application_Start builds a ServiceHostFactory and registers the single UC4 route. The registration detail is on Activation and hosting; this page covers what happens once a message is dispatched.
| Aspect | Finding |
|---|---|
| Host | IIS (System.Web.HttpApplication) — no self-host, no Windows service host |
| Application class | Declared in Global.asax.cs, namespace SAIF.Services.WCF.Host (src/WCF/SAIF.Services.WCF.UC4.Host/Global.asax.cs) |
| Startup call chain | Application_Start → construct new ServiceHostFactory() → RouteTable.Routes.Add(new ServiceRoute("UC4", factory, typeof(UC4Service))) |
| ASP.NET compatibility | AspNetCompatibilityRequirementsMode.Allowed |
aspNetCompatibilityEnabled |
true |
| Target framework | .NET Framework 4.6.2 |
| Platform target | AnyCPU on Release/Prod; x64 on Debug/QA |
Classification resolution, stated once here: the pipeline's AppType marker for this host is api, while the sibling SAIF.Services.WCF.Host carries AppType: web — the two markers disagree inside one repository, and this host's own build template is the web template while its release template is the api template. None of these pipeline markers classifies the host. The decisive source marker is the RouteTable.Routes.Add(new ServiceRoute("UC4", factory, typeof(UC4Service))) call in Global.asax.cs, corroborated by [AspNetCompatibilityRequirements] on the service class and <system.serviceModel> in Web.config; on that evidence this host is documented as a WCF SOAP service, and the conflicting api/frontEndApp-style pipeline reading is recorded and overruled rather than silently discarded.
Message dispatch path¶
The following diagram shows how a SOAP request reaches an operation and how the operation reaches the downstream service.
flowchart TD
CALLER["SOAP caller"] --> IIS["IIS + HttpApplication"]
IIS --> ROUTETBL["RouteTable<br>UC4 route mapping"]
ROUTETBL --> FACTORY["ServiceHostFactory"]
FACTORY --> HOST["ServiceHost for<br>UC4Service"]
HOST --> BEHAVIOR["LogErrorBehavior<br>(external IServiceBehavior)"]
BEHAVIOR --> OPER["Operation dispatched"]
OPER --> SVC["UC4Service"]
SVC --> GATE["IsJobAllowed<br>uc4.rules evaluation"]
GATE -->|"blocked"| EMPTY["Return empty UC4Result<br>reason discarded"]
GATE -->|"allowed"| CLIENT["UC4Client<br>(host-internal collaborator)"]
CLIENT --> APICLIENTS["SAIF.Web.API.Clients<br>ClientInfo, Proxy"]
CLIENT --> UC4PKG["SAIF.Services.UC4<br>downstream IUC4Service"]
CLIENT --> DOWNSTREAM["Downstream UC4<br>scheduling service"]Layer responsibilities¶
| Layer | Type | Responsibility |
|---|---|---|
Application class in Global.asax.cs |
System.Web.HttpApplication |
Application start-up and the single UC4 route registration |
UC4Service |
Service implementation | Message handling, rule-based job gating, logging, parameter shaping |
UC4Client |
Host-internal collaborator | Resolves the downstream UC4 address from configuration, stamps caller/host identity, forwards the job, maps the downstream result |
SAIF.Services.UC4 / SAIF.Web.API.Clients |
External packages | Downstream client contract, transport, and identity types* |
There is no repository/DAO layer. See Faults and error pipeline for the error-handling behavior actually applied.
Service contracts¶
The [ServiceContract] interface source is not in scope. IUC4Service is not declared anywhere in this repository; it is resolved only through using IUC4Service = SAIF.Services.WCF.Contracts.IUC4Service; (src/WCF/SAIF.Services.WCF.UC4.Host/UC4Service.cs:12-13), and is not a <Reference>, a <ProjectReference> (the project has none), or a packages.config entry. This is the normal state for this host, not a gap: operations are enumerated below from the ServiceRoute registration plus the public members of the implementing class, never from an unread contract interface.
| Service class | Declared contract | Contract location | Resolved how |
|---|---|---|---|
UC4Service |
IUC4Service (SAIF.Services.WCF.Contracts.IUC4Service) |
External — SAIF.Services.WCF.Contracts, assembly identity not resolvable from this project |
using-alias only; the assembly arrives transitively via SAIF.Framework.Core 2.0.23079.1* |
| Aspect | Finding |
|---|---|
| Contract assembly | SAIF.Services.WCF.Contracts (namespace) — assembly identity not resolvable from this project* |
| Present in repository | No — external |
| Arrives via | SAIF.Framework.Core 2.0.23079.1 (transitive)* |
| Operation surface derived from | Implementing class public members + the UC4 route registration |
| Consequence for this document set | Operation names, parameters, and return types are read entirely from UC4Service.cs. Which public members carry [OperationContract] on the external IUC4Service, any [OperationContract] name-override attribute, and any [FaultContract] declarations cannot be confirmed from this repository.** |
Composition root¶
| Field | Value |
|---|---|
| Container present | No — collaborators constructed directly in each operation |
| Project | — |
| File | — |
| Entry method | — |
| Invoked from | — |
| Instance provider | WCF default (parameterless constructor) |
| Additional registration files | None |
A search of this project's sources for the Autofac API surface (new ContainerBuilder(, RegisterType<, RegisterAssemblyTypes(, RegisterModule, builder.Build(, : Autofac.Module, and the bare token Autofac) returned zero matches, even though Autofac 3.5.2 is a packages.config entry and project reference — it is packaged and unused. UC4Service() (parameterless) builds WcfEnvironmentService(OperationContext.Current.RequestContext) and LogService(envSvc) directly; UC4Client is constructed inline inside each execute path.
Instancing and concurrency¶
| Aspect | Finding |
|---|---|
InstanceContextMode |
Not declared — WCF default PerSession |
ConcurrencyMode |
Not declared — WCF default Single |
| Declared in | Not declared — no [ServiceBehavior] attribute on UC4Service |
| Shared mutable state | None found in code |
Fault pipeline (summary)¶
UC4Service carries [LogErrorBehavior], an IServiceBehavior whose type arrives from an unresolved external SAIF.* package (namespace SAIF.Services.WCF.Common.Extensions) — it is not the in-repository SAIF.Services.WCF.Extensions.LogErrorBehaviorAttribute used by the sibling WCF host, since this project carries no reference to that project.** No throw new FaultException exists anywhere in this host's source, so every failure surfaces as WCF's default fault for the thrown exception, carrying exception detail because includeExceptionDetailInFaults="true". Full detail is on Faults and error pipeline.
Integration points¶
| System | Type | Purpose |
|---|---|---|
| Downstream UC4 scheduling service | External service, package-mediated | Target of every job forwarded by UC4Client.ScheduleJob; address resolved from uc4coreapi.url |
| Environment settings service | Configuration source | Supplies uc4.rules (allow/deny document), uc4coreapi.url, uc4coreapi.schedulejobroute, and the environment tier resolved per request from OperationContext.RequestContext |
SAIF.Framework.Core (SAIF.Core.Services, SAIF.Core.Contracts.UC4, SAIF.Services.WCF.Contracts) |
NuGet package | Supplies IEnvironmentService, ILogService, UC4Result, UC4Environment, and the IUC4Service contract* |
SAIF.Services.UC4 / SAIF.Web.API.Clients |
NuGet packages | Downstream IUC4Service client surface, ClientInfo, and the Proxy type used by UC4Client* |
Related documentation¶
- Index
- Overview
- Activation and hosting
- Operations
- Faults and error pipeline
- Authentication and authorization
- Dependencies
- Configuration
- Operations and processes
- Business rules
- Operational runbook
- Tech debt
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.UC4.Host/Global.asax.cssrc/WCF/SAIF.Services.WCF.UC4.Host/UC4Service.cssrc/WCF/SAIF.Services.WCF.UC4.Host/Uc4Client.cssrc/WCF/SAIF.Services.WCF.UC4.Host/Web.configsrc/WCF/SAIF.Services.WCF.UC4.Host/SAIF.Services.WCF.UC4.Host.csprojsrc/WCF/SAIF.Services.WCF.UC4.Host/packages.configpipelines/build-vars.UC4.ymlpipelines/release.UC4.ymlpipelines/build-vars.yml(comparison only)