---
title: Activation and hosting
summary: How each of the six services is activated, and how the internal/external deployment variants differ.
status: draft
owner: SAIF Doc Gen
last_reviewed: 2026-09-22
---

# Activation and hosting

This host publishes all six services through ASP.NET route registration in `Application_Start`; there is no `.svc` file anywhere in this host, and none anywhere in the repository. The build produces two deployment variants — Internal and External — from the same route table and service code.

## Activation mechanism

| Aspect | Finding |
| --- | --- |
| Mechanism | Route-based (`ServiceRoute`) |
| Registered in | `src/WCF/SAIF.Services.WCF.Host/Global.asax.cs` — `Global.Application_Start` |
| Host factory | `System.ServiceModel.Activation.ServiceHostFactory` — one instance created at `src/WCF/SAIF.Services.WCF.Host/Global.asax.cs:12` and reused for all six registrations |
| `.svc` files present | None — verified by recursive enumeration of `src/WCF` |
| Route table is authoritative | Yes |
| `<system.serviceModel><services>` entries | 6 service elements, no `<endpoint>` children |

`Web.Base.config` carries a `<system.serviceModel><services>` element listing the same six service classes the route table registers, and every one of those `<service>` elements is empty — there is not a single `<endpoint>` child in the file. The configuration therefore confirms service identity and supplies no operation, contract, or address information; the route table is the authoritative activation surface, and the binding comes from `ServiceHostFactory` defaults (`basicHttpBinding`, the .NET Framework default protocol mapping for `http`, picking up the unnamed `<basicHttpBinding>` binding in `Web.Base.config`).

## Route registrations

| Route | Service class | Address suffix | Registered at |
| --- | --- | --- | --- |
| `FileService` | `SAIF.Services.WCF.Services.FileService` (`src/WCF/SAIF.Services.WCF.Host/Services/FileService.cs`) | `~/FileService` | `src/WCF/SAIF.Services.WCF.Host/Global.asax.cs` |
| `PreferenceService` | `SAIF.Services.WCF.Services.PreferenceService` (`src/WCF/SAIF.Services.WCF.Host/Services/PreferenceService.cs`) | `~/PreferenceService` | `src/WCF/SAIF.Services.WCF.Host/Global.asax.cs` |
| `WebContext` | `SAIF.Services.WCF.Services.WebContextService` (`src/WCF/SAIF.Services.WCF.Host/Services/WebContextService.cs`) | `~/WebContext` | `src/WCF/SAIF.Services.WCF.Host/Global.asax.cs` |
| `Imaging` | `SAIF.Services.WCF.Services.ImagingService` (`src/WCF/SAIF.Services.WCF.Host/Services/ImagingService.cs`) | `~/Imaging` | `src/WCF/SAIF.Services.WCF.Host/Global.asax.cs` |
| `Fax` | `SAIF.Services.WCF.Services.FaxService` (`src/WCF/SAIF.Services.WCF.Host/Services/FaxService.cs`) | `~/Fax` | `src/WCF/SAIF.Services.WCF.Host/Global.asax.cs` |
| `Security` | `SAIF.Services.WCF.Services.Security.SecurityService` (`src/WCF/SAIF.Services.WCF.Host/Services/Security/SecurityService.cs`) | `~/Security` | `src/WCF/SAIF.Services.WCF.Host/Global.asax.cs` |

## Activation diagram

The following diagram visualizes how a request reaches a service instance.

```mermaid
flowchart TD
    START["Application_Start"] --> FACT["var factory =<br>new ServiceHostFactory()"]
    FACT --> ADD["RouteTable.Routes.Add<br>six ServiceRoute registrations"]
    ADD --> TABLE["Route table:<br>FileService, PreferenceService, WebContext,<br>Imaging, Fax, Security"]
    REQ["Caller request<br>/wcf/&lt;route-name&gt;"] --> TABLE
    TABLE --> HOST["ServiceHost created<br>for the matched service class"]
    HOST --> DISPATCH["Operation dispatched"]
```

## Configuration-declared services

| Service element | Class named | Endpoints declared | Effect |
| --- | --- | --- | --- |
| `<service name="SAIF.Services.WCF.Services.FileService"/>` | `SAIF.Services.WCF.Services.FileService` | None | Confirms service identity only; supplies no endpoint |
| `<service name="SAIF.Services.WCF.Services.PreferenceService"/>` | `SAIF.Services.WCF.Services.PreferenceService` | None | Confirms service identity only; supplies no endpoint |
| `<service name="SAIF.Services.WCF.Services.WebContextService"/>` | `SAIF.Services.WCF.Services.WebContextService` | None | Confirms service identity only; supplies no endpoint |
| `<service name="SAIF.Services.WCF.Services.ImagingService"/>` | `SAIF.Services.WCF.Services.ImagingService` | None | Confirms service identity only; supplies no endpoint |
| `<service name="SAIF.Services.WCF.Services.FaxService"/>` | `SAIF.Services.WCF.Services.FaxService` | None | Confirms service identity only; supplies no endpoint |
| `<service name="SAIF.Services.WCF.Services.Security.SecurityService"/>` | `SAIF.Services.WCF.Services.Security.SecurityService` | None | Confirms service identity only; supplies no endpoint |

## Host inventory

This repository contains more than one deployable WCF host project. Each one has its own document set; this table places this host among them.

| Host project | Services registered | Platform | Document set |
| --- | --- | --- | --- |
| `SAIF.Services.WCF.Host` | `FileService`, `PreferenceService`, `WebContextService`, `ImagingService`, `FaxService`, `SecurityService` | x64 | This set |
| `SAIF.Services.WCF32.Host` | `ImagingService` (a different class/contract) | x86 | Not documented — SOAP-typed (`ServiceRoute` activation) but no pipeline reference and no `.nuspec` reference; see `docgen-manifest.md` |
| `SAIF.Services.WCF.PDF.Host` | `PdfService` | x64 | Not documented — SOAP-typed (`ServiceRoute` activation) but no pipeline reference and no `.nuspec` reference; see `docgen-manifest.md` |
| `SAIF.Services.WCF.UC4.Host` | `UC4Service` | x64 | [SAIF.Services.WCF.UC4.Host](../saif-services-wcf-uc4-host/index.md) |

## Services hosted in more than one host

| Service class | Also registered by | Implementation shared | Primary document set |
| --- | --- | --- | --- |
| `ImagingService` | `SAIF.Services.WCF32.Host` | Separate copy — `src/WCF/SAIF.Services.WCF.Host/Services/ImagingService.cs` implements `SAIF.Services.WCF.Contracts.IImagingService` (`QueueImage`/`ReserveImageId`, Oracle-backed) while `src/WCF/SAIF.Services.WCF32.Host/ImagingService.cs` implements the distinct `SAIF.Services.WCF.Imaging.WCF32.IImagingService` (`GetImageFilePath`/`GetImageRelativePath`/`GetImageFileType`); they are different classes with different operation surfaces, distinguished by platform target (this host x64, WCF32 x86) | This set (`contracts/imaging-service.md`); `SAIF.Services.WCF32.Host` is not documented — no pipeline reference, no `.nuspec` reference |

The route name `Imaging` is registered by both hosts, but the two are not two deployments of one class — see [Tech debt](tech-debt.md) for the duplication finding.

## Deployment variants

| Variant | Build configuration | Artifact | Config transform | Audience | Notes |
| --- | --- | --- | --- | --- | --- |
| Internal | `Release` (`BuildConfigurationInternal`) | `app-internal` (`ArtifactNameInternal`) | `Web.Base.config` + `Web.Release.config` | Internal callers | IIS auth via `IISWindowsAuthInternal`/`IISAnonymousAuthInternal` (values defined outside this repository) |
| External | `ReleaseExternal` (`BuildConfigurationExternal`) | `app-external` (`ArtifactNameExternal`) | `Web.Base.config` + `Web.ReleaseExternal.config` | External callers | IIS auth via `IISWindowsAuthExternal`/`IISAnonymousAuthExternal`; `LangVersion 7.3` set only for this configuration |

Both variants are produced by the same `pipelines/build.yml` job over the same `src/wcf/SAIF.Services.WCF.Hosts.sln` — once with `IsPrimary: true` for the internal artifact and once with `IsPrimary: false` for the external artifact. `pipelines/release.yml` then deploys both artifacts with independent `DeployInternal`/`DeployExternal` switches.

### Variant differences

| Setting or behavior | Internal | External | Source |
| --- | --- | --- | --- |
| `system.webServer/modules` | Replaced with an empty element | `<remove name="clsSecurityModule" />` and `<remove name="ContextLogger" />` added | `Web.Release.config`, `Web.ReleaseExternal.config` |
| `system.web/httpModules` | Left empty | Same two modules removed | Same two files |
| `LangVersion` | Project default | `7.3` | `WCF.csproj` |
| `appSettings` | Identical to the base file | Identical to the base file | `Web.Base.config` and both transforms |
| Services exposed | All six | All six | `src/WCF/SAIF.Services.WCF.Host/Global.asax.cs` (route table is not transformed) |

The externally-facing build explicitly removes the `clsSecurityModule` and `ContextLogger` HTTP modules that the internal deployment environment would otherwise inject; that is the one functional difference between the two variants beyond IIS authentication settings.

## IIS configuration

| Aspect | Finding |
| --- | --- |
| Site / virtual directory | Development root `http://localhost/wcf` (`<IISUrl>` in `WCF.csproj`); deployed host names come from the release pipeline's external `EnvironmentSettings\settings.yml`, which is not readable from this repository ** |
| Application pool | Identity `$(wcf.svc.username)`/`$(wcf.svc.password)` from the `Architecture.ServiceAccounts.IIS` variable group; .NET version `$(IISAppPoolDotNetVersion)`, both resolved by the release pipeline and not confirmable from this repository ** |
| `multipleSiteBindingsEnabled` | true |
| `httpErrors` mode | `Detailed` |
| Custom modules or handlers | `clsSecurityModule`, `ContextLogger` (removed only in the External variant) |

## Related documentation
- [Index](index.md)
- [Overview](overview.md)
- [Architecture](architecture.md)
- [Operations](operations.md)
- [Faults and error pipeline](faults.md)
- [Authentication and authorization](authentication-authorization.md)
- [Dependencies](dependencies.md)
- [Configuration](configuration.md)
- [Operations and processes](operations-processes.md)
- [Business rules](business-rules.md)
- [Data model](data-model.md)
- [Operational runbook](operational-runbook.md)
- [Tech debt](tech-debt.md)

> **Note:** Statements marked with `**` could not be confirmed; treat as unknown
> until verified.

## Sources
- src/WCF/SAIF.Services.WCF.Host/Global.asax.cs
- src/WCF/SAIF.Services.WCF.Host/WCF.csproj
- src/WCF/SAIF.Services.WCF.Host/Web.Base.config
- src/WCF/SAIF.Services.WCF.Host/Web.Release.config
- src/WCF/SAIF.Services.WCF.Host/Web.ReleaseExternal.config
- pipelines/build.yml
- pipelines/build-vars.yml
- pipelines/release.yml