Getting Started with RemObjects SDK for Delphi: A Beginner’s GuideRemObjects SDK for Delphi is a mature framework that simplifies building distributed applications and services in Delphi. It provides a structured way to expose Delphi classes and methods over the network, handle serialization, transport protocols, and security, and integrate with multi-tier architectures. This guide walks you through the core concepts, setup, a simple example, deployment considerations, and pointers for learning more.
What is RemObjects SDK?
RemObjects SDK is a component-based framework that enables RPC-style communication between clients and servers. It abstracts transport (TCP, HTTP, HTTPS), serialization formats (binary, JSON, XML), and service invocation so you can focus on application logic rather than low-level networking. In Delphi, RemObjects provides design-time components that integrate into the IDE and runtime libraries for both client and server sides.
Key concepts
- Service: A collection of exposed methods (operations). A service is the unit of functionality the client calls remotely.
- Server channel/transport: The mechanism by which requests and responses are sent (examples: TCP listener, HTTP listener).
- Client channel: Client-side counterpart for sending requests (e.g., TCP client, HTTP client).
- Message/Serializer: How data is encoded and decoded (BinaryMessage, JsonMessage, etc.).
- Invoker/Dispatcher: Components that map incoming requests to server-side service object methods and route responses back.
- Metadata: Optional service descriptions that facilitate proxy generation or dynamic clients.
Installing RemObjects SDK for Delphi
- Obtain RemObjects SDK for Delphi from RemObjects (commercial licensing). Ensure you download the edition compatible with your Delphi version.
- Run the installer or add the RemObjects packages (.bpl/.dcp) to the Delphi IDE:
- Install the design-time packages so components appear on the Tool Palette.
- Add runtime library paths to your Delphi project options if needed.
- Check the Samples folder included with the installer — it contains example client/server projects that are a great starting point.
Project structure and components
Typical RemObjects-based applications use a small set of components:
-
Server-side:
- TROIndyServerChannel / TROIndyHTTPServerChannel (or other channel implementations): accept and manage connections.
- TRORemoteService / custom service classes: implement business logic.
- TRORemoteDispatcher (or TROMessageRouter): maps incoming messages to service instances.
- TROMessage or specific serializer components: interpret the payload.
- TROAuth-related components (optional): implement authentication/authorization.
-
Client-side:
- TROIndyTCPChannel / TROIndyHTTPClientChannel: channel to connect to the server.
- TROMessage/serializer component: matching format used by the server.
- TRORemoteInvoker / generated proxy: calls remote methods as if they were local.
A simple example: Echo service over TCP
Below is a conceptual walkthrough (not exact copy-paste) of creating a minimal echo service.
- Create the server project
- Drop a TROIndyServerChannel onto a data module or form; configure the ListenPort (e.g., 8099).
- Drop a TROMessage (BinaryMessage or JsonMessage) and link it to the server channel.
- Add a TRORemoteService descendant to implement the service interface:
- Create a class TEchoService = class(TRORemoteService) with a published method function Echo(const AText: string): string; override mechanisms depend on your RemObjects version.
- Register the service with the dispatcher / server so incoming calls target TEchoService.
- Start the channel at runtime (Channel.Active := True).
- Create the client project
- Drop a TROIndyTCPChannel and set Host/Port to connect to the server.
- Drop a TROMessage (matching server serializer) and link to the channel.
- Create an invoker or use the dynamic call mechanism:
- Use TRORemoteInvoker and call invoker.Invoke(‘Echo’, [ ‘Hello’ ], ResultList) or use generated proxy methods if you created interface/metadata.
- Call the remote method and handle the response.
This flow hides many implementation details that vary across RemObjects versions and Delphi releases. Use shipped examples as the authoritative reference.
Serialization formats and interoperability
RemObjects supports multiple message formats:
- BinaryMessage: compact, fast, RemObjects-specific binary encoding.
- JSONMessage: interoperable with web clients and easy to inspect.
- XmlMessage: interoperable but larger and slower.
Choose Binary for performance within Delphi-only stacks. Choose JSON or XML when interacting with non-Delphi clients (web, Node.js, mobile).
Security and authentication
- For transport-level security use HTTPS (HTTP channel over TLS) or wrap Indy/TCP with TLS components where supported.
- Implement authentication via tokens, API keys, or username/password using middleware-like components or by validating credentials in service constructors.
- Use per-call or per-session access controls in your server service implementations.
Error handling and debugging
- Use try/except blocks in services and return structured error information to the client.
- RemObjects includes facilities to transmit exception details; consider limiting sensitive data in exceptions when sending to untrusted clients.
- For debugging, start with local TCP connections and use the JSONMessage to inspect payloads easily.
- Watch for version mismatches between client and server serializers or service metadata.
Performance considerations
- BinaryMessage is fastest; JSON is slower but useful for cross-platform.
- Keep payloads small and avoid sending large blobs inside RPC calls—consider separate file transfer endpoints or chunking strategies.
- Reuse channels/invokers when making many calls rather than creating a fresh connection per call.
- Profile the server under expected concurrency; increase thread pool sizes or listener limits as appropriate.
Deployment tips
- Run servers as Windows services (or systemd services on Linux via cross-platform builds) for production reliability.
- Configure logging and monitoring (request latency, error counts).
- Apply TLS and firewall rules, and consider rate-limiting or API gateways for public endpoints.
- Version your service API and provide backward-compatible changes where possible.
When to use RemObjects SDK
- You need tight integration with Delphi and Pascal code.
- You prefer a component-based, RPC-style approach rather than building REST endpoints from scratch.
- You want flexible transport/serialization options and built-in tooling for client proxies.
Consider REST/HTTP+JSON or gRPC if you need broad language-agnostic tooling or standard web API patterns, though RemObjects can interoperate by using JSONMessage over HTTP.
Learning resources and next steps
- Study the sample projects included with RemObjects — they show practical configurations (TCP vs HTTP, message formats, proxies).
- Read the product documentation for your RemObjects version to learn exact component names and API changes.
- Experiment: build a small CRUD service, expose it over JSON/HTTP, and access it from a simple web page to see cross-platform behavior.
- Investigate advanced features: metadata-driven proxy generation, multiplexing, authentication plug-ins, and integration with Data Abstract if you need database synchronization and ORM-like features.
Summary: RemObjects SDK for Delphi provides a powerful, componentized way to build remote services with flexible transports and serializations. Start by installing the SDK, study the included samples, implement a small echo or CRUD service using matching client/server channels and message components, and iterate toward production with attention to security, performance, and versioning.
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