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javaphpipcanti-patterns

Database as IPC antipattern

I've written a layered web application that consists of a rich-web client (PHP) that interacts with a java service. The web client is hosted on an apache server, and the java service runs on the same physical machine (to reiterate: the entire app, client and service, are running on the same physical machine).

User Request --> DB <-- Poller --> RequestHandler --> StoreResult in DB --> Web Client updates page with the result (AJAX).

Communication between the client and service uses a relational database to pass messages. The java service has a single-thread poller, which looks for and then processes any messages/requests from the client. The system works, but I am not confident in my design choice.

Does anyone have any comments about this strategy? I've read that using a Database as IPC antipattern is poor practice, or at least an inappropriate one. However, the alternatives--XMLRPC, named pipes--seem to involve additional dependencies.

Thanks for looking.

Solution

  • If it were me, and I needed PHP to grab/consume data from a java service, i'd dump the DB.

    Have the java service w/ HTTP listening on 127.0.0.1, port 5544 (or some random #). Have a servlet/jsp take RESTful requests, and spit out JSON results. So if its a search, the URL would be:

    h ttp://127.0.0.1:5544/search_zip_code/80203

    and the result would be simple json:

    { "city": "Denver", "state": "Colorado" }

    and then on the PHP side do a curl request - build the URL with the parameters from the user input, do the curl request, get the data back and json_decode it ( $result_array = json_decode($curl_result); ).

    It'd be simple. This way, you can test either component easily (do a curl/wget from command line to test the java service, or check the access_logs on the server side to see the search parameters and the connection from the client).

    For the PHP side, use curl_exec and json_decode (search for those functions in the PHP manual).

    Here's a random link I found for the java side:

    Parsing JSON data with java servlet struts

    This way would be scalable (its easy to separate the services), modular (easy to test either component), and a lot faster for delivering results back to the client.