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From Shuyi Chen <suez1...@gmail.com>
Subject [DISCUSS] Adding new interfaces in [Stream]ExecutionEnvironment
Date Mon, 14 May 2018 06:14:33 GMT
Hi Flink devs,

In an effort to support loading external libraries and creating UDFs from
external libraries using DDL in Flink SQL, we want to use Flink’s Blob
Server to distribute the external libraries in runtime and load those
libraries into the user code classloader automatically.

However, the current [Stream]ExecutionEnvironment.registerCachedFile
interface limits only to registering executable or non-executable blobs.
It’s not possible to tell in runtime if the blob files are libraries and
should be loaded into the user code classloader in RuntimeContext.
Therefore, I want to propose to add an enum called *BlobType* explicitly to
indicate the type of the Blob file being distributed, and the following
interface in [Stream]ExecutionEnvironment to support it. In general, I
think the new BlobType information can be used by Flink runtime to
preprocess the Blob files if needed.

** Registers a file at the distributed cache under the given name. The file
will be accessible*
** from any user-defined function in the (distributed) runtime under a
local path. Files*
** may be local files (as long as all relevant workers have access to it),
or files in a distributed file system.*
** The runtime will copy the files temporarily to a local cache, if needed.*
** <p>The {@link org.apache.flink.api.common.functions.RuntimeContext} can
be obtained inside UDFs via*
** {@link
org.apache.flink.api.common.functions.RichFunction#getRuntimeContext()} and
provides access*
** {@link org.apache.flink.api.common.ca
<http://org.apache.flink.api.common.ca>che.DistributedCache} via*
** {@link
** @param filePath The path of the file, as a URI (e.g. "file:///some/path"
or "hdfs://host:port/and/path")*
** @param name The name under which the file is registered.*
** @param blobType indicating the type of the Blob file*

*public void registerCachedFile(String filePath, String name,
DistributedCache.BlobType blobType) {...}*

Optionally, we can add another interface to register UDF Jars which will
use the interface above to implement.

*public void registerJarFile(String filePath, String name) {...}*

The existing interface in the following will be marked deprecated:

*public void registerCachedFile(String filePath, String name, boolean
executable) {...}*

And the following interface will be implemented using the new interface
proposed above with a EXECUTABLE BlobType:

*public void registerCachedFile(String filePath, String name) { ... }*

Thanks a lot.

"So you have to trust that the dots will somehow connect in your future."

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