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https://issues.apache.org/jira/browse/ARROW-1047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16225530#comment-16225530
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ASF GitHub Bot commented on ARROW-1047:
---------------------------------------

elahrvivaz commented on a change in pull request #1259: ARROW-1047: [Java] Add 
Generic Reader Interface for Stream Format
URL: https://github.com/apache/arrow/pull/1259#discussion_r147799085
 
 

 ##########
 File path: 
java/vector/src/main/java/org/apache/arrow/vector/ipc/ArrowReader.java
 ##########
 @@ -216,9 +171,32 @@ private void initialize() throws IOException {
     this.root = new VectorSchemaRoot(schema, vectors, 0);
     this.loader = new VectorLoader(root);
     this.dictionaries = Collections.unmodifiableMap(dictionaries);
+
+    // Read and load all dictionaries from schema
+    for (int i = 0; i < dictionaries.size(); i++) {
 
 Review comment:
   yeah, an overloaded method would be fine. I agree that having to load a 
batch before reading dictionaries is a bit confusing for the general use case.

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> [Java] Add generalized stream writer and reader interfaces that are decoupled 
> from IO / message framing
> -------------------------------------------------------------------------------------------------------
>
>                 Key: ARROW-1047
>                 URL: https://issues.apache.org/jira/browse/ARROW-1047
>             Project: Apache Arrow
>          Issue Type: New Feature
>          Components: Java - Vectors
>            Reporter: Wes McKinney
>            Assignee: Bryan Cutler
>              Labels: pull-request-available
>
> cc [~julienledem] [~elahrvivaz] [~nongli]
> The ArrowWriter 
> https://github.com/apache/arrow/blob/master/java/vector/src/main/java/org/apache/arrow/vector/file/ArrowWriter.java
>  accepts a WriteableByteChannel where the stream is written
> It would be useful to be able to support other kinds of message framing and 
> transport, like GRPC or HTTP. So rather than writing a complete Arrow stream 
> as a single contiguous byte stream, the component messages (schema, 
> dictionaries, and record batches) would be framed as separate messages in the 
> underlying protocol. 
> So if we were using ProtocolBuffers and gRPC as the underlying transport for 
> the stream, we could encapsulate components of an Arrow stream in objects 
> like:
> {code:language=protobuf}
> message ArrowMessagePB {
>   required bytes serialized_data;
> }
> {code}
> If the transport supports zero copy, that is obviously better than 
> serializing then parsing a protocol buffer.
> We should do this work in C++ as well to support more flexible stream 
> transport. 



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