I have blogged in the past about various web framework concepts in golang, and have also named some names articulating what dissuades me from using said frameworks but I have not yet reviewed an entire framework before. In this blog I will attempt to explain my sentiment about Vivid Cortex’s Siesta and explain my perceived pain points.
Context, oh my…
Firstly, there is nothing spectacularly new and exciting about this web framework
in my opinion, much like all new golang http web frameworks. Moreover post go1.7
many of these frameworks will die off as that is the slated release of built in
request net.Context. This should get everyone extremely excited, as finally we
will have a persistent cancel-able context built into the http.Request structure.
Basically removing 70% of what the droves of http frameworks offer to the public, a scheme for context passing from handler to handler.
Getting back to Siesta, it is clear they are following the “make your own” context approach as opposed to using the vastly superior stacking net.Context which will soon be in the standard library. Furthermore in looking at their context source code clearly the built in context isn’t safe for multiple goroutines, if you ever have the need to access the context variables in parallel.
As I have griped about in a previous blog entry siesta invented a new function signature for their handlers, which requires an implementation of their context from above to be passed in. The do however have a wrapping concept though in practice if you are using this framework, likely you are using all the features including the context in your handlers, so it seems silly to me (maybe the middlewares only need the context??) to not just implement the siesta standard handler func signature complete with the context.
I just have to say again… this style of framework, where you need to alter the function signature is merely a stop-gap until go1.7 comes out. When we get net.Context living within the request, all of this BS goes away. We can all go back to standard http.HandlerFunc signatures and all will be right in the world again. It almost feels like this last generation of web frameworks will be extinct in the very near future.
Another thing I have noticed, and maybe it is in progress, is that there is no built in concept of content negotiation. I feel that in order to call yourself a REST framework, as opposed to a Web Framework, you need to have that concept built into the ServeHTTP. If a REST client requests Accept: application/xml the REST framework needs to respond appropriately by performing the negotiation with the client.
As for the middleware composition, with siesta.Compose, I can’t seem to figure out how you are supposed to have wrapping middlewares. For example, lets look at the awesome negroni middleware handler definition:
As can be seen, we have the ability to fully wrap a handler, or a chain of handlers with negroni, so you can perform some action, call the next handler in the chain, then do some more stuff after the chain completes. I like how they implemented the quit signaling in the middleware chaining in siesta, but I really do not like how there is no way to clearly have precondition and postcondition operations within middlewares if I wanted.
Something Borrowed, Something Blue
Now to my favorite section of any web framework, the url routing. I have to say,
at least they picked a trie based router, by taking from HTTPRouter, and excellent
router. That being said, they are running into some more of my gripes
by having trees rooted in the request http method. Try hitting a resource that
exists under a different method. I promise you will get a “Not Found” message.
Then again the only golang router in existence that I know of that handles RFC 2616 correctly is vestigo.
Looking closer at this router bolt on, I have discovered this which pains me a bit to talk about. So not only does the HTTPRouter code alloc key value pair space on the heap for storing the URL parameters, but then siesta also allocs heap space to also store the parameters within the form data, like a Pat or vestigo does.
Credit Where Due
I will mention that I very much like like the “flag”-esc helper functions to get form and URL parameters based on type. It reminds me of viper/flag a lot, and that is a very useful aspect of this web framework.