[FIXED] Building a web service: what options do I have?

Issue

I'm looking to build my first web service and I would like to be pointed in the right direction right from the start.

Here are the interactions that must take place:

• First, a smartphone or computer will send a chunk of data to my web service.
• The web service will persist the information to the database.
• Periodically, an algorithm will access and modify the database.
• The algorithm will periodically bundle data and send it out to smartphones or computer (how?)

The big question is: What basic things do I need to learn to in order to implement something like this?

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Now here are the little rambling questions that I've also got rolling around in my head. Feel free to answer these if you wish. (...maybe consider them extra credit?)

• I've heard a lot of good things about RESTful services, I've read the wiki article, and I've even played around with the Twitter's webservice which is RESTful. Is this the obvious way to go? Or should I still consider something else?
• What programming language do I use to persist things to the database? I'm thinking php will be the first choice for this.
• What programming language do I use to interact with the database? I'm thinking anything is probably acceptable, right?
• Do I have to worry about concurrent access to the database, or does MySQL handle that for me? (I'm fairly new to databases too.)
• How on earth do I send information back? Obviously, if it's a reply to an HTTP request that's no problem, but there will be times when the reply may take quite a long time to compute. Should I just let the HTTP request remain outstanding until I have the answer?
• There will be times when I need to send information to a smartphone regardless of whether or not information has been sent to me. How can I push information to my users?

Other information that may help you know where I'm coming from:

• I am pretty familiar with Java, C#, C++, and Python. I have played around with PHP, Javascript, and Ruby.
• I am relatively new to databasing, but I get the basic idea.
• I've already set up my server and I'm using a basic LAMP stack. My understanding of L, A, M and P is fairly rudimentary.

Solution

Language: Python for it's ease of use assuming the GIL is not a particular concern for your requirements (e.g. multi-threading). It has drivers for most databases and supports numerous protocols. There are several web frameworks for it - the most popular probably being Django.

Protocols: if you are HTTP focused study SOAP and REST. Note, SOAP tends to be verbose, which causes problems moving volumes of data. On the other hand, if you are looking at other options study socket programming and perhaps some sort of binary format such as Google's protocol buffers. Flash is also a possibility (see: Flash Remoting). Note, binary options require users install something onto their machine (e.g. applet or standalone app).

Replies: if the process is long running, and the client should be notified when it's done, I would recommend developing an app for the client. Browser's can be programmed with JavaScript to periodically poll, or a Flash movie can be embedded to real time updates, but these are somewhat tricky bits of browser programming. If you're dealing with wireless phones, look at SMS. Otherwise I would just provide a way for clients to get status, but not send out notification (e.g. push vs. pull). As @jcomea_ictx wrote, AJAX is an option if it's a browser based solution - study jQuery.

Concurrency: understand what ACID means with regards to databases. Think about what should happen if you receive multiple writes to the same data - database may not necessarily solve this problem the way you'd want.

Answered By - orangepips