Question 1

How do I handle async middleware in Aleph?

Accepted Answer

Use Aleph's wrap-ring-async-handler helper or reimplement synchronous middleware with Manifold's let-flow operator, as the README warns that sync middleware can conflict with deferred responses. This ensures compatibility but requires extra coding effort.

Question 2

Aleph vs clj-http: which is better for HTTP clients?

Accepted Answer

Aleph is better for async, non-blocking requests with Manifold deferreds and HTTP/2 support, while clj-http is simpler for synchronous calls with features like cache support. Choose Aleph if you need high concurrency and can work around its missing clj-http features.

Question 3

How to set up HTTP/2 in an Aleph server?

Accepted Answer

Specify :http-versions [:http2 :http1] and provide an SSL context in the server options, as shown in the HTTP server example. Check the aleph.examples.http2 file for detailed configuration and awareness of limitations like no multipart uploads.

Question 4

Can Aleph handle WebSocket clients and servers?

Accepted Answer

Yes, Aleph provides duplex streams for WebSocket communication, allowing easy creation of servers and clients with messages as strings or byte arrays. The echo-handler example demonstrates bidirectional streaming using manifold.stream.

Question 5

What are the trade-offs of using Aleph over other Clojure web servers?

Accepted Answer

Aleph offers high performance via Netty and async patterns but adds complexity with Manifold and Netty dependencies. Servers like http-kit might be simpler for basic async needs, while Ring-jetty is more synchronous but easier for traditional setups.

Question 6

How to stream responses from an Aleph HTTP server?

Accepted Answer

Return a Manifold stream as the response body, where each message is sent as a chunk, enabling server-sent events or other streamed data. The README mentions this for precise control over chunked responses.

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