From 0a7d62c019404fe5ce48f3d39f143ed502ae06d9 Mon Sep 17 00:00:00 2001
From: Chris Lu <chrislusf@users.noreply.github.com>
Date: Fri, 5 Feb 2021 00:30:30 -0800
Subject: [PATCH] Updated SeaweedFS Java Client (markdown)

---
 SeaweedFS-Java-Client.md | 56 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/SeaweedFS-Java-Client.md b/SeaweedFS-Java-Client.md
index ead04f2..0eeca65 100644
--- a/SeaweedFS-Java-Client.md
+++ b/SeaweedFS-Java-Client.md
@@ -5,3 +5,59 @@ Here is an SeaweedFS Java API implementation refactored out of the existing code
 https://github.com/chrislusf/seaweedfs/tree/master/other/java/examples/src/main/java/com/seaweedfs/examples
 
 Basically this library will be able to read and write directly to the volume servers, and only use filer servers for meta data.
+If you use http to read or write directly via filer, the data still needs to go through filer, which is less efficient.
+
+## Read File
+
+```
+  FilerGrpcClient filerGrpcClient = new FilerGrpcClient("localhost", 18888);
+  SeaweedInputStream seaweedInputStream = new SeaweedInputStream(filerGrpcClient, "/test.zip");
+  // next, you can use seaweedInputStream as a normal InputStream
+```
+
+## Write File
+
+```
+  FilerGrpcClient filerGrpcClient = new FilerGrpcClient("localhost", 18888);
+  SeaweedOutputStream seaweedOutputStream = new SeaweedOutputStream(filerGrpcClient, "/test/"+filename);
+  // next, you can use seaweedOutputStream as a normal OutputStream
+```
+
+## Watch file changes
+
+This API streams meta data changes. 
+
+The following is one implementation. It just watch the folder "/buckets" and all the meta data changes under the folder and all sub folders recursively. A bit more code, but should be powerful and simple to use.
+
+```
+        FilerClient filerClient = new FilerClient("localhost", 18888);
+
+        long sinceNs = (System.currentTimeMillis() - 3600 * 1000) * 1000000L;
+
+        Iterator<FilerProto.SubscribeMetadataResponse> watch = filerClient.watch(
+                "/buckets",
+                "exampleClientName",
+                sinceNs
+        );
+
+        System.out.println("Connected to filer, subscribing from " + new Date());
+
+        while (watch.hasNext()) {
+            FilerProto.SubscribeMetadataResponse event = watch.next();
+            FilerProto.EventNotification notification = event.getEventNotification();
+            if (!event.getDirectory().equals(notification.getNewParentPath())) {
+                // move an entry to a new directory, possibly with a new name
+                if (notification.hasOldEntry() && notification.hasNewEntry()) {
+                    System.out.println("moved " + event.getDirectory() + "/" + notification.getOldEntry().getName() + " to " + notification.getNewParentPath() + "/" + notification.getNewEntry().getName());
+                } else {
+                    System.out.println("this should not happen.");
+                }
+            } else if (notification.hasNewEntry() && !notification.hasOldEntry()) {
+                System.out.println("created entry " + event.getDirectory() + "/" + notification.getNewEntry().getName());
+            } else if (!notification.hasNewEntry() && notification.hasOldEntry()) {
+                System.out.println("deleted entry " + event.getDirectory() + "/" + notification.getOldEntry().getName());
+            } else if (notification.hasNewEntry() && notification.hasOldEntry()) {
+                System.out.println("updated entry " + event.getDirectory() + "/" + notification.getNewEntry().getName());
+            }
+        }
+```