--- title: Model Contracts slug: devicepark/sdk-documentation/reference/model-contracts description: Review request, response and nullable field contracts. docTags: createdAt: 2026-08-10T08:03:44.631Z --- These contracts describe the Device Park public API request and response payloads used by the official SDKs. Java response models expose fields through record-style accessors such as `device.serial()` and `allocation.allocationId()`. In the .NET SDK every field below maps to a read-only property with the same name in PascalCase, for example `device.Serial` and `allocation.AllocationId`. Request models are built through a nested `Builder` type, for example `new ListDevicesRequest.Builder()`. ## Page ```typescript interface PageDto { size: number; page: number; totalPages: number; totalElements: number; data: T[]; } ``` ```json { "size": 20, "page": 0, "totalPages": 1, "totalElements": 1, "data": [] } ``` ## Device and Pool ```typescript interface Device { id: number | null; serial: string | null; marketName: string | null; model: string | null; manufacturer: string | null; platform: string | null; platformVersion: string | null; version: string | null; state: string | null; isSimulator: boolean | null; isPublic: boolean | null; } interface DeviceApp { id: number | null; bundleIdentifier: string | null; installedAt: string | null; updatedAt: string | null; isDefault: boolean | null; } interface Pool { id: string | null; name: string | null; isDefault: boolean | null; } interface CreatePoolRequest { name: string; } ``` `Device.state` is represented as a string by the SDK. Use the documented API constants such as `HEALTHY`, `ALLOCATED` and `RUNNING`, not interface labels such as `Online` or `Busy`. See [Device State Values](docId\:T2lFRSsG2mhohPOA4K26-) for the complete list and meanings. `DeviceApp` and `ListDeviceAppsRequest` are available in the Node.js and .NET SDKs; the Java SDK does not expose this operation. See [List Device Apps](docId\:JOQ1A2pU5ih-Rqb7TDx_4) for filters, pagination and response behavior. `isSimulator` and `isPublic` were added to the Java and Node.js `Device` models for master parity. They are also present in the .NET model. They remain nullable because older or environment-specific responses may omit them. `Pool.isDefault` is also nullable response metadata. `true` means Device Park marks the pool as default, `false` means it does not and `null` means the response omitted the status. It is not an availability flag. Use `pool.id` as `devicePoolId` when creating an allocation. For default-only listing behavior, see [Understanding isDefault](docId\:fmKLq2CPwGu4aurSboUFg). `CreatePoolRequest.name` is required, must not be blank and must be unique within the authenticated account. Pool membership methods accept a non-empty list of device serials and return the serials present after the operation. See [Manage Pools](docId\:ObX8hTXvKifuvFe9uTuit). ## Allocation Request: ```typescript interface DeviceAllocationRequest { serial?: string; manufacturer?: string; model?: string; platform?: string; platformVersion?: string; devicePoolId?: string; priority: number; removeApps: RemoveAppSelectionType; } ``` Response: ```typescript interface Allocation { allocationId: string | null; deviceSerial: string | null; requestId: string | null; position: number | null; expiresAt: string | null; } ``` ```json { "allocationId": "allocation-123", "deviceSerial": null, "requestId": "request-456", "position": 2, "expiresAt": "2026-07-14T12:30:00Z" } ``` `priority` defaults to `3` and accepts `1` through `5`. `removeApps` defaults to `NO_REMOVE`; use `REMOVE_WITHOUT_IS_DEFAULT_APPS` to remove non-default applications before allocation. A `null` `deviceSerial` means the allocation response does not yet identify an assigned device. Keep the same `allocationId` while waiting. ## Session Request: ```typescript interface DeviceStartSessionRequest { allocationId: string; companyPoolId?: string; videoRecording?: boolean; videoRecordingScope?: "FULL_SESSION" | "APPIUM_SESSION"; userId: number; userEmail: string; companyId: number; companyName: string; customVideoRecordingPath?: string; appiumVersion?: string; } ``` The Java, Node.js and .NET SDKs send `videoRecordingScope`. It accepts `FULL_SESSION` or `APPIUM_SESSION` and defaults to `FULL_SESSION`. The Java builder includes that default in the JSON body. Read it from a session with `session.videoRecordingScope()`. `Session` responses carry the same field. It can be absent on environments that predate the feature, so Java and .NET expose it as a nullable value. Device Park generates `sessionId`; it is present in the `Session` response and is not accepted as a Start Session request field. Response: ```typescript interface Session { id: number | null; state: string | null; client: string | null; sessionId: string | null; allocationId: string | null; startDate: string | null; endDate: string | null; latestInteractionTime: string | null; userId: number | null; userEmail: string | null; companyId: number | null; companyName: string | null; deviceSerial: string | null; deviceName: string | null; deviceModel: string | null; deviceManufacturer: string | null; devicePlatform: string | null; deviceVersion: string | null; videoRecording: boolean | null; videoRecordingScope: "FULL_SESSION" | "APPIUM_SESSION" | null; videoRecordUrl: string | null; appiumVersion: string | null; createdAt: string | null; updatedAt: string | null; dataAccessEndDate: string | null; } ``` `Session.state` is represented as a string by the SDK. Use `ACTIVE`, `CLOSING`, `CLOSED` or `FAILED_TO_CLOSE` when filtering. See [Session State Values](docId\:yDnbFyoHkKjGUefb_-6rf) for their meanings. ## Application and Screen Record ```typescript interface Application { revision: number | null; sizeInBytes: number | null; version: string | null; fileKey: string | null; filePath: string | null; downloadUrl: string | null; createdAt: string | null; bundleId: string | null; title: string | null; ipaVersion: string | null; enterprise: boolean | null; minimumOsVersion: string | null; minSdkVersion: number | null; } interface ScreenRecord { fileKey: string | null; filePath: string | null; downloadUrl: string | null; createdAt: string | null; updatedAt: string | null; duration: number | null; } ``` Download URLs can expire. Persist `fileKey`, not `downloadUrl`, when a stable application or recording identifier is required. The last six `Application` members are artifact metadata read during upload and returned by both the upload and the list operation. `bundleId`, `title`, `ipaVersion`, `enterprise` and `minimumOsVersion` are populated for IPA artifacts, `minSdkVersion` for APK artifacts, and every one of them is `null` when it cannot be read from the artifact. The Java, Node.js and .NET SDKs expose them as typed members. See [List Applications](docId\:SPDXnMADbDctpaPsO1gbH) for details. Each `ScreenRecord` describes one stored recording segment. The complete RFC 8216 HLS stream is exposed separately as `Session.videoRecordUrl`; it is not a field of `ScreenRecord`. See [List Screen Records](docId:9voFjQy3NQ7olg4uHLhTK) for readiness, authorization and browser playback guidance. ## Published Constants ```typescript const SortDirection = { ASC: "ASC", DESC: "DESC" } as const; const SearchOperation = { EQUAL: "EQUAL", NOT_EQUAL: "NOT_EQUAL", GREATER_THAN: "GREATER_THAN", LESS_THAN: "LESS_THAN" } as const; const RemoveAppSelection = { NO_REMOVE: "NO_REMOVE", REMOVE_WITHOUT_IS_DEFAULT_APPS: "REMOVE_WITHOUT_IS_DEFAULT_APPS" } as const; ``` Java and .NET expose the same values as `SortDirection`, `SearchOperation` and `RemoveAppSelection` enums. Filter-key constants and compatibility are documented on each list-operation page and summarized in [Pagination and Filtering](docId\:dGs4iHB5eEr5U28AOL8T_).