On Sat, 2016-11-12 at 20:16 +0530, Nishant Kumar wrote:
> Hi,
>
> I am writing a singleton class (Object in scala) which uses apache
> httpclient(4.5.2) to send some file or some json content to a server and
> return status to caller. Here is my class -
>
> object HttpUtils{
> protected val retryHandler = new HttpRequestRetryHandler() {
> def retryRequest(exception: IOException, executionCount: Int,
> context: HttpContext): Boolean = {
> //retry logic
> true
> }
> }
> private val connectionManager = new
> PoolingHttpClientConnectionManager()
>
> // Reusing same client for each request that might be coming from
> different threads .
> // Is it correct ????
Yes.
> val httpClient = HttpClients.custom()
> .setConnectionManager(connectionManager)
> .setRetryHandler(retryHandler)
> .build()
>
> def restApiCall (url : String, rDD: RDD[SomeMessage]) : Boolean = {
> // Creating new context for each request
> val httpContext: HttpClientContext = HttpClientContext.create
> val post = new HttpPost(url)
>
> // convert RDD to text file using rDD.collect
>
> // add this file as MultipartEntity to post
>
> var response = None: Option[CloseableHttpResponse] // Is it correct
> way of using it ???
Not really. HttpClient never returns null response messages. The
'response' instance is non-optional.
> try {
> response = Some(httpClient.execute(post, httpContext))
> val responseCode = response.get.getStatusLine.getStatusCode
> EntityUtils.consume(response.get.getEntity) // Is it require ???
Not required but advised if you want to ensure re-use of persistent
connections.
> if (responseCode == 200) true
> else false
> }
> finally {
> if (response.isDefined) response.get.close
> post.releaseConnection() // Is it require ???
No, it is not.
> }
> }
> def onShutDown = {
> connectionManager.close()
> httpClient.close()
CloseableHttpClient#close also shuts down the connection pool associated
with it.
Oleg
> }
> }
>
>
> Multiple threads (More specifically from spark streaming context) are
> calling `restApiCall` method. I am relatively new to `scala` and `apache
> httpClient`. I have to make frequent connections to only few fixed server
> (i.e. 5-6 fixed URL's with different request parameters). I have also
> written comments in above code as question. Please address them as well.
>
> I went through multiple online resource but still not confident about it.
>
> - Is it the best way to use http client in multi-threaded environment?
> - Is it possible to keep live connections and use it for various requests
> ? Will it be beneficial in this case ?
> - Am i using/releasing all resources efficiently ? If not please suggest.
> - Is it good to use it in Scala or there exist some better library ?
>
> Thanks for your help in advance.
>
>
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