System Integration: Key Considerations

• System Integration Lesson 2 covers key considerations for integration, interfacing with customers, database integration, types of communication (synchronous vs. asynchronous), and remote procedure calls (RPC).

Considerations in Integration

• When integrating systems, find the ideal integration technology.
• Avoid breaking changes to minimize customer impact.
• Keep APIs technology-agnostic, ensuring integration technology doesn't dictate the technology stack.
• Make the service simple for consumers and hide internal implementation details.

Interfacing with Customers

• Interfacing is more than CRUD operations, and includes extra processes, like customer enrollment.
• Customer enrollment involves steps such as setting up financial payments, establishing communication channels, and managing transactions.

Shared Database

• Database integration stands as the most common form of integration.
• Entities are bound together to a single storage location in a database.
• Specified technologies should remain compatible with storage.
• Shared databases often face problems like tight coupling and lack of cohesion.
• Database integration facilitates easy data sharing but lacks inherent sharing behavior management.

Synchronous vs. Asynchronous

• Synchronous communication involves a call to a remote server that consumes the server's operation until completion.
• Asynchronous communication means the caller doesn't wait for the operation to complete, and it may not care about the operation's completion status.
• Request/Response involves a client initiating a request and waiting for a response.
• Event-Based operations occur based on the events they are designed for.

Remote Procedure Calls (RPC)

• RPC refers to making a local call that executes on a remote service.
• A procedure call is also referred to as as function call or a subroutine call.
• RPCs are synchronous operations.
• The basic RPC operation flow contains the Client, Network, and the Server.
• The client invokes a client stub procedure, and passes the parameters. The client stub remains within the client's address space.
• The client stub packages the parameters into a message by converting the parameters into a standard format and copying each parameter into the message.
• The client stub passes the message to the transport layer, which sends it to the remote server machine.
• The transport layer on the server passes the message to a server stub, which unpacks the parameters and calls the designated server routine using a regular procedure call mechanism.
• When the server procedure is complete, it returns to the server stub, which marshalls the return values into a message.
• The server stub then hands the message to the transport layer, which sends the result message back to the client transport layer, which then hands the message back to the client stub.
• The client stub unpacks the return parameters, and the execution returns to the caller.

Types of RPC:

• Callback RPC allows processes to act as both clients and servers, aiding in remote processing of interactive applications.
  • The server gains a handle to the client and enables peer-to-peer communication between processes.
• Broadcast RPC sends a client's request to all servers on the network capable of handling it.
  • This specify a client's message should be broadcast and can create special broadcast ports.
  • This RPC helps reduce the load on the network.
• Batch-mode RPC collects multiple RPC requests on the client side and sends them to the server in batches.
  • This reduces the overhead of sending many separate requests and works best for applications that don't often need to make calls, which requires a reliable way to send data.