Hi Shashikant,

I think you are trying to do too much at once in your helper class.
Spark's RDD API is functional, it is meant to be used by writing many
little transformations that will be distributed across a cluster.

Appart from that, `rdd.pipe` seems like a good approach. Here is the
relevant doc comment (in RDD.scala) on how to use it:

 Return an RDD created by piping elements to a forked external
process. The resulting RDD
   * is computed by executing the given process once per partition. All elements
   * of each input partition are written to a process's stdin as lines
of input separated
   * by a newline. The resulting partition consists of the process's
stdout output, with
   * each line of stdout resulting in one element of the output
partition. A process is invoked
   * even for empty partitions.
   * [...]
Check the full docs here

This is how you could use it:

    productRDD=//get from cassandra
    processedRDD=productsRDD.map(STEP1).map(STEP2).pipe(C binary of step 3)
    STEP4 //store processed RDD

hope this gives you some pointers,


On Thu, Sep 22, 2016 at 2:10 AM, Shashikant Kulkarni (शशिकांत
कुलकर्णी) <shashikant.kulka...@gmail.com> wrote:
> Hello Jakob,
> Thanks for replying. Here is a short example of what I am trying. Taking an
> example of Product column family in Cassandra just for explaining my
> requirement
> In Driver.java
> {
>          JavaRDD<Product> productsRdd = Get Products from Cassandra;
>          productsRdd.map(ProductHelper.processProduct());
> }
> in ProductHelper.java
> {
>         public static Function<Product, Boolean> processProduct() {
> return new Function< Product, Boolean>(){
> private static final long serialVersionUID = 1L;
> @Override
> public Boolean call(Product product) throws Exception {
> //STEP 1: Doing some processing on product object.
> //STEP 2: Now using few values of product, I need to create a string like
> "name id sku datetime"
> //STEP 3: Pass this string to my C binary file to perform some complex
> calculations and return some data
> //STEP 4: Get the return data and store it back in Cassandra DB
> }
> };
> }
> }
> In this ProductHelper, I cannot pass and don't want to pass sparkContext
> object as app will throw error of "task not serializable". If there is a way
> let me know.
> Now I am not able to achieve STEP 3 above. How can I pass a String to C
> binary and get the output back in my program. The C binary reads data from
> STDIN and outputs data to STDOUT. It is working from other part of
> application from PHP. I want to reuse the same C binary in my Apache SPARK
> application for some background processing and analysis using JavaRDD.pipe()
> API. If there is any other way let me know. This code will be executed in
> all the nodes in a cluster.
> Hope my requirement is now clear. How to do this?
> Regards,
> Shash
> On Thu, Sep 22, 2016 at 4:13 AM, Jakob Odersky <ja...@odersky.com> wrote:
>> Can you provide more details? It's unclear what you're asking
>> On Wed, Sep 21, 2016 at 10:14 AM, shashikant.kulka...@gmail.com
>> <shashikant.kulka...@gmail.com> wrote:
>> > Hi All,
>> >
>> > I am trying to use the JavaRDD.pipe() API.
>> >
>> > I have one object with me from the JavaRDD

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