src/main/asciidoc/_chapters/external_apis.adoc

////
/**
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
////

[[external_apis]]
= Apache HBase External APIs
:doctype: book
:numbered:
:toc: left
:icons: font
:experimental:

This chapter will cover access to Apache HBase either through non-Java languages and
through custom protocols. For information on using the native HBase APIs, refer to
link:https://hbase.apache.org/apidocs/index.html[User API Reference] and the
<<hbase_apis,HBase APIs>> chapter.

== REST

Representational State Transfer (REST) was introduced in 2000 in the doctoral
dissertation of Roy Fielding, one of the principal authors of the HTTP specification.

REST itself is out of the scope of this documentation, but in general, REST allows
client-server interactions via an API that is tied to the URL itself. This section
discusses how to configure and run the REST server included with HBase, which exposes
HBase tables, rows, cells, and metadata as URL specified resources.
There is also a nice series of blogs on
link:http://blog.cloudera.com/blog/2013/03/how-to-use-the-apache-hbase-rest-interface-part-1/[How-to: Use the Apache HBase REST Interface]
by Jesse Anderson.

=== Starting and Stopping the REST Server

The included REST server can run as a daemon which starts an embedded Jetty
servlet container and deploys the servlet into it. Use one of the following commands
to start the REST server in the foreground or background. The port is optional, and
defaults to 8080.

[source, bash]
----
# Foreground
$ bin/hbase rest start -p <port>

# Background, logging to a file in $HBASE_LOGS_DIR
$ bin/hbase-daemon.sh start rest -p <port>
----

To stop the REST server, use Ctrl-C if you were running it in the foreground, or the
following command if you were running it in the background.

[source, bash]
----
$ bin/hbase-daemon.sh stop rest
----

=== Configuring the REST Server and Client

For information about configuring the REST server and client for SSL, as well as `doAs`
impersonation for the REST server, see <<security.gateway.thrift>> and other portions
of the <<security>> chapter.

=== Using REST Endpoints

The following examples use the placeholder server pass:[http://example.com:8000], and
the following commands can all be run using `curl` or `wget` commands. You can request
plain text (the default), XML , or JSON output by adding no header for plain text,
or the header "Accept: text/xml" for XML, "Accept: application/json" for JSON, or
"Accept: application/x-protobuf" to for protocol buffers.

NOTE: Unless specified, use `GET` requests for queries, `PUT` or `POST` requests for
creation or mutation, and `DELETE` for deletion.

.Cluster-Wide Endpoints
[options="header", cols="2m,m,3d,6l"]
|===
|Endpoint
|HTTP Verb
|Description
|Example

|/version/cluster
|GET
|Version of HBase running on this cluster
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/version/cluster"

|/status/cluster
|GET
|Cluster status
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/status/cluster"

|/
|GET
|List of all non-system tables
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/"

|===

.Namespace Endpoints
[options="header", cols="2m,m,3d,6l"]
|===
|Endpoint
|HTTP Verb
|Description
|Example

|/namespaces
|GET
|List all namespaces
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/namespaces/"

|/namespaces/_namespace_
|GET
|Describe a specific namespace
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/namespaces/special_ns"

|/namespaces/_namespace_
|POST
|Create a new namespace
|curl -vi -X POST \
  -H "Accept: text/xml" \
  "example.com:8000/namespaces/special_ns"

|/namespaces/_namespace_/tables
|GET
|List all tables in a specific namespace
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/namespaces/special_ns/tables"

|/namespaces/_namespace_
|PUT
|Alter an existing namespace. Currently not used.
|curl -vi -X PUT \
  -H "Accept: text/xml" \
  "http://example.com:8000/namespaces/special_ns

|/namespaces/_namespace_
|DELETE
|Delete a namespace. The namespace must be empty.
|curl -vi -X DELETE \
  -H "Accept: text/xml" \
  "example.com:8000/namespaces/special_ns"

|===

.Table Endpoints
[options="header", cols="2m,m,3d,6l"]
|===
|Endpoint
|HTTP Verb
|Description
|Example

|/_table_/schema
|GET
|Describe the schema of the specified table.
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/users/schema"

|/_table_/schema
|POST
|Update an existing table with the provided schema fragment
|curl -vi -X POST \
  -H "Accept: text/xml" \
  -H "Content-Type: text/xml" \
  -d '&lt;?xml version="1.0" encoding="UTF-8"?>&lt;TableSchema name="users">&lt;ColumnSchema name="cf" KEEP_DELETED_CELLS="true" />&lt;/TableSchema>' \
  "http://example.com:8000/users/schema"

|/_table_/schema
|PUT
|Create a new table, or replace an existing table's schema
|curl -vi -X PUT \
  -H "Accept: text/xml" \
  -H "Content-Type: text/xml" \
  -d '&lt;?xml version="1.0" encoding="UTF-8"?>&lt;TableSchema name="users">&lt;ColumnSchema name="cf" />&lt;/TableSchema>' \
  "http://example.com:8000/users/schema"

|/_table_/schema
|DELETE
|Delete the table. You must use the `/_table_/schema` endpoint, not just `/_table_/`.
|curl -vi -X DELETE \
  -H "Accept: text/xml" \
  "http://example.com:8000/users/schema"

|/_table_/regions
|GET
|List the table regions
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/users/regions
|===

.Endpoints for `Get` Operations
[options="header", cols="2m,m,3d,6l"]
|===
|Endpoint
|HTTP Verb
|Description
|Example

|/_table_/_row_
|GET
|Get all columns of a single row. Values are Base-64 encoded. This requires the "Accept" request header with a type that can hold multiple columns (like xml, json or protobuf).
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/users/row1"

|/_table_/_row_/_column:qualifier_/_timestamp_
|GET
|Get the value of a single column. Values are Base-64 encoded.
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/users/row1/cf:a/1458586888395"

|/_table_/_row_/_column:qualifier_
|GET
|Get the value of a single column. Values are Base-64 encoded.
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/users/row1/cf:a"

curl -vi -X GET \
  -H "Accept: text/xml" \
   "http://example.com:8000/users/row1/cf:a/"

|/_table_/_row_/_column:qualifier_/?v=_number_of_versions_
|GET
|Multi-Get a specified number of versions of a given cell. Values are Base-64 encoded.
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/users/row1/cf:a?v=2"

|===

.Endpoints for `Scan` Operations
[options="header", cols="2m,m,3d,6l"]
|===
|Endpoint
|HTTP Verb
|Description
|Example

|/_table_/scanner/
|PUT
|Get a Scanner object. Required by all other Scan operations. Adjust the batch parameter
to the number of rows the scan should return in a batch. See the next example for
adding filters to your scanner. The scanner endpoint URL is returned as the `Location`
in the HTTP response. The other examples in this table assume that the scanner endpoint
is `\http://example.com:8000/users/scanner/145869072824375522207`.
|curl -vi -X PUT \
  -H "Accept: text/xml" \
  -H "Content-Type: text/xml" \
  -d '<Scanner batch="1"/>' \
  "http://example.com:8000/users/scanner/"

|/_table_/scanner/
|PUT
|To supply filters to the Scanner object or configure the
Scanner in any other way, you can create a text file and add
your filter to the file. For example, to return only rows for
which keys start with <codeph>u123</codeph> and use a batch size
of 100, the filter file would look like this:

[source,xml]
----
<Scanner batch="100">
  <filter>
    {
      "type": "PrefixFilter",
      "value": "u123"
    }
  </filter>
</Scanner>
----

Pass the file to the `-d` argument of the `curl` request.
|curl -vi -X PUT \
  -H "Accept: text/xml" \
  -H "Content-Type:text/xml" \
  -d @filter.txt \
  "http://example.com:8000/users/scanner/"

|/_table_/scanner/_scanner-id_
|GET
|Get the next batch from the scanner. Cell values are byte-encoded. If the scanner
has been exhausted, HTTP status `204` is returned.
|curl -vi -X GET \
  -H "Accept: text/xml" \
  "http://example.com:8000/users/scanner/145869072824375522207"

|_table_/scanner/_scanner-id_
|DELETE
|Deletes the scanner and frees the resources it used.
|curl -vi -X DELETE \
  -H "Accept: text/xml" \
  "http://example.com:8000/users/scanner/145869072824375522207"

|===

.Endpoints for `Put` Operations
[options="header", cols="2m,m,3d,6l"]
|===
|Endpoint
|HTTP Verb
|Description
|Example

|/_table_/_row_key_
|PUT
|Write a row to a table. The row, column qualifier, and value must each be Base-64
encoded. To encode a string, use the `base64` command-line utility. To decode the
string, use `base64 -d`. The payload is in the `--data` argument, and the `/users/fakerow`
value is a placeholder. Insert multiple rows by adding them to the `<CellSet>`
element. You can also save the data to be inserted to a file and pass it to the `-d`
parameter with syntax like `-d @filename.txt`.
|curl -vi -X PUT \
  -H "Accept: text/xml" \
  -H "Content-Type: text/xml" \
  -d '<?xml version="1.0" encoding="UTF-8" standalone="yes"?><CellSet><Row key="cm93NQo="><Cell column="Y2Y6ZQo=">dmFsdWU1Cg==</Cell></Row></CellSet>' \
  "http://example.com:8000/users/fakerow"

curl -vi -X PUT \
  -H "Accept: text/json" \
  -H "Content-Type: text/json" \
  -d '{"Row":[{"key":"cm93NQo=", "Cell": [{"column":"Y2Y6ZQo=", "$":"dmFsdWU1Cg=="}]}]}'' \
  "example.com:8000/users/fakerow"

|===

.Endpoints for `Check-And-Put` Operations
[options="header", cols="2m,m,3d,6l"]
|===
|Endpoint
|HTTP Verb
|Description
|Example

|/_table_/_row_key_/?check=put
|PUT
|Conditional Put - Change the current version value of a cell: Compare the current or latest version value (`current-version-value`) of a cell with the `check-value`, and if `current-version-value` == `check-value`, write new data (the `new-value`) into the cell as the current or latest version. The row, column qualifier, and value must each be Base-64 encoded. To encode a string, use the `base64` command-line utility. To decode the string, use `base64 -d`. The payload is in the `--data` or `-d` argument, with `the check cell name (column family:column name) and value` always at the end and right after `the new Put cell name (column family:column name) and value` of the same row key. You can also save the data to be inserted to a file and pass it to the `-d` parameter with syntax like `-d @filename.txt`.
|curl -vi -X PUT \
  -H "Accept: text/xml" \
  -H "Content-Type: text/xml" \
  -d '<?xml version="1.0" encoding="UTF-8" standalone="yes"?><CellSet><Row key="cm93MQ=="><Cell column="Y2ZhOmFsaWFz">T2xkR3V5</Cell><Cell column="Y2ZhOmFsaWFz">TmV3R3V5</Cell></Row></CellSet>' \
  "http://example.com:8000/users/row1/?check=put"

curl -vi -X PUT \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -d '{"Row":[{"key":"cm93MQ==","Cell":[{"column":"Y2ZhOmFsaWFz","$":"T2xkR3V5"},{"column":"Y2ZhOmFsaWFz", "$":"TmV3R3V5"}] }]}' \
  "http://example.com:8000/users/row1/?check=put"
|===
Detailed Explanation:

*** In the above json-format example:
1. `{"column":"Y2ZhOmFsaWFz", "$":"TmV3R3V5"}` at the end of `-d` option are `the check cell name and check cell value in Base-64` respectively: `"Y2ZhOmFsaWFz" for "cfa:alias"`, and `"TmV3R3V5" for "NewGuy"`
2. `{"column":"Y2ZhOmFsaWFz","$":"T2xkR3V5"}` are `the new Put cell name and cell value in Base-64` respectively: `"Y2ZhOmFsaWFz" for "cfa:alias"`, and `"T2xkR3V5" for "OldGuy"`
3. `"cm93MQ=="` is `the Base-64 for "row1"` for the checkAndPut `row key`
4. `"/?check=put"` after the `"row key" in the request URL` is required for checkAndPut WebHBase operation to work
5. The `"row key" in the request URL` should be URL-encoded, e.g., `"david%20chen"` and `"row1"` are the URL-encoded formats of row keys `"david chen"` and `"row1"`, respectively

  Note: "cfa" is the column family name and "alias" are the column (qualifier) name for the non-Base64 encoded cell name.

*** Basically, the xml-format example is the same as the json-format example, and will not be explained here in detail.

.Endpoints for `Check-And-Delete` Operations
[options="header", cols="2m,m,3d,6l"]
|===
|Endpoint
|HTTP Verb
|Description
|Example

|/_table_/_row_key_/?check=delete
|DELETE
|Conditional Deleting a Row: Compare the value of any version of a cell (`any-version-value`) with the `check-value`, and if `any-version-value` == `check-value`, delete the row specified by the `row_key` inside the requesting URL.The row, column qualifier, and value for checking in the payload must each be Base-64 encoded. To encode a string, use the base64 command-line utility. To decode the string, use base64 -d. The payload is in the --data argument. You can also save the data to be checked to a file and pass it to the `-d` parameter with syntax like `-d @filename.txt`.
|curl -vi -X DELETE \
  -H "Accept: text/xml" \
  -H "Content-Type: text/xml" \
  -d '<?xml version="1.0" encoding="UTF-8" standalone="yes"?><CellSet><Row key="cm93MQ=="><Cell column="Y2ZhOmFsaWFz">TmV3R3V5</Cell></Row></CellSet>' \
  "http://example.com:8000/users/row1/?check=delete"

curl -vi -X DELETE \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -d '{"Row":[{"key":"cm93MQ==","Cell":[{"column":"Y2ZhOmFsaWFz","$":"TmV3R3V5"}]}]}' \
  "http://example.com:8000/users/row1/?check=delete"

|/_table_/_row_key_
/_column_family_
/?check=delete
|DELETE
|Conditional Deleting a Column Family of a Row: Compare the value of any version of a cell (`any-version-value`) with the `check-value`, and if `any-version-value` == `check-value`, delete the column family of a row specified by the `row_key/column_family` inside the requesting URL. Anything else is the same as those in `Conditional Deleting a Row`.
|curl -vi -X DELETE \
  -H "Accept: text/xml" \
  -H "Content-Type: text/xml" \
  -d '<?xml version="1.0" encoding="UTF-8" standalone="yes"?><CellSet><Row key="cm93MQ=="><Cell column="Y2ZhOmFsaWFz">TmV3R3V5</Cell></Row></CellSet>' \
  "http://example.com:8000/users/row1/cfa/?check=delete"

curl -vi -X DELETE \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -d '{"Row":[{"key":"cm93MQ==","Cell":[{"column":"Y2ZhOmFsaWFz","$":"TmV3R3V5"}]}]}' \
  "http://example.com:8000/users/row1/cfa/?check=delete"

|/_table_/_row_key_
/_column:qualifier_
/?check=delete
|DELETE
|Conditional Deleting All Versions of a Column of a Row: Compare the value of any version of a cell (`any-version-value`) with the `check-value`, and if `any-version-value` == `check-value`, delete the column of a row specified by the `row_key/column:qualifier` inside the requesting URL. The `column:qualifier` in the requesting URL is the `column_family:column_name`. Anything else is the same as those in `Conditional Deleting a Row`.
|curl -vi -X DELETE \
  -H "Accept: text/xml" \
  -H "Content-Type: text/xml" \
  -d '<?xml version="1.0" encoding="UTF-8" standalone="yes"?><CellSet><Row key="cm93MQ=="><Cell column="Y2ZhOmFsaWFz">TmV3R3V5</Cell></Row></CellSet>' \
  "http://example.com:8000/users/row1/cfa:alias/?check=delete"

curl -vi -X DELETE \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -d '{"Row":[{"key":"cm93MQ==","Cell":[{"column":"Y2ZhOmFsaWFz","$":"TmV3R3V5"}]}]}' \
  "http://example.com:8000/users/row1/cfa:alias/?check=delete"

|/_table_/_row_key_
/_column:qualifier_
/_version_id_/?check=delete
|DELETE
|Conditional Deleting a Single Version of a Column of a Row: Compare the value of any version of a cell (`any-version-value`) with the `check-value`, and if `any-version-value` == `check-value`, delete the version of a column of a row specified by the `row_key/column:qualifier/version_id` inside the requesting URL. The `column:qualifier` in the requesting URL is the `column_family:column_name`. The `version_id` in the requesting URL is a number, which equals to `the timestamp of the targeted version + 1`. Anything else is the same as those in `Conditional Deleting a Row`.
|curl -vi -X DELETE \
  -H "Accept: text/xml" \
  -H "Content-Type: text/xml" \
  -d '<?xml version="1.0" encoding="UTF-8" standalone="yes"?><CellSet><Row key="cm93MQ=="><Cell column="Y2ZhOmFsaWFz">TmV3R3V5</Cell></Row></CellSet>' \
  "http://example.com:8000/users/row1/cfa:alias/1519423552160/?check=delete"

curl -vi -X DELETE \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -d '{"Row":[{"key":"cm93MQ==","Cell":[{"column":"Y2ZhOmFsaWFz","$":"TmV3R3V5"}]}]}' \
  "http://example.com:8000/users/row1/cfa:alias/1519423552160/?check=delete"
|===
Detailed Explanation:

*** In the above 4 json-format examples:
1. `{"column":"Y2ZhOmFsaWFz", "$":"TmV3R3V5"}` at the end of `-d` option are `the check cell name and check cell value in Base-64` respectively: `"Y2ZhOmFsaWFz" for "cfa:alias"`, and `"TmV3R3V5" for "NewGuy"`
2. `"cm93MQ=="` is `the Base-64 for "row1"` for the checkAndDelete `row key`
3. `"/?check=delete"` at the end of `the request URL` is required for checkAndDelete WebHBase operation to work
4. `"version_id"` in the `request URL` of the last json-format example should be equivalent to the value of `"the timestamp number + 1"`
5. The `"row key"`, `"column family"`, `"cell name" or "column family:column name"`, and `"version_id"` in `the request URL` of a checkAndDelete WebHBase operation should be URL-encoded, e.g., `"row1"`, `"cfa"`, `"cfa:alias"` and `"1519423552160"` in the examples are the URL-encoded `"row key"`, `"column family"`, `"column family:column name"`, and `"version_id"`, respectively

*** Basically, the 4 xml-format examples are the same as the 4 corresponding json-format examples, and will not be explained here in detail.

[[xml_schema]]
=== REST XML Schema

[source,xml]
----
<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:tns="RESTSchema">

  <element name="Version" type="tns:Version"></element>

  <complexType name="Version">
    <attribute name="REST" type="string"></attribute>
    <attribute name="JVM" type="string"></attribute>
    <attribute name="OS" type="string"></attribute>
    <attribute name="Server" type="string"></attribute>
    <attribute name="Jersey" type="string"></attribute>
  </complexType>

  <element name="TableList" type="tns:TableList"></element>

  <complexType name="TableList">
    <sequence>
      <element name="table" type="tns:Table" maxOccurs="unbounded" minOccurs="1"></element>
    </sequence>
  </complexType>

  <complexType name="Table">
    <sequence>
      <element name="name" type="string"></element>
    </sequence>
  </complexType>

  <element name="TableInfo" type="tns:TableInfo"></element>

  <complexType name="TableInfo">
    <sequence>
      <element name="region" type="tns:TableRegion" maxOccurs="unbounded" minOccurs="1"></element>
    </sequence>
    <attribute name="name" type="string"></attribute>
  </complexType>

  <complexType name="TableRegion">
    <attribute name="name" type="string"></attribute>
    <attribute name="id" type="int"></attribute>
    <attribute name="startKey" type="base64Binary"></attribute>
    <attribute name="endKey" type="base64Binary"></attribute>
    <attribute name="location" type="string"></attribute>
  </complexType>

  <element name="TableSchema" type="tns:TableSchema"></element>

  <complexType name="TableSchema">
    <sequence>
      <element name="column" type="tns:ColumnSchema" maxOccurs="unbounded" minOccurs="1"></element>
    </sequence>
    <attribute name="name" type="string"></attribute>
    <anyAttribute></anyAttribute>
  </complexType>

  <complexType name="ColumnSchema">
    <attribute name="name" type="string"></attribute>
    <anyAttribute></anyAttribute>
  </complexType>

  <element name="CellSet" type="tns:CellSet"></element>

  <complexType name="CellSet">
    <sequence>
      <element name="row" type="tns:Row" maxOccurs="unbounded" minOccurs="1"></element>
    </sequence>
  </complexType>

  <element name="Row" type="tns:Row"></element>

  <complexType name="Row">
    <sequence>
      <element name="key" type="base64Binary"></element>
      <element name="cell" type="tns:Cell" maxOccurs="unbounded" minOccurs="1"></element>
    </sequence>
  </complexType>

  <element name="Cell" type="tns:Cell"></element>

  <complexType name="Cell">
    <sequence>
      <element name="value" maxOccurs="1" minOccurs="1">
        <simpleType><restriction base="base64Binary">
        </simpleType>
      </element>
    </sequence>
    <attribute name="column" type="base64Binary" />
    <attribute name="timestamp" type="int" />
  </complexType>

  <element name="Scanner" type="tns:Scanner"></element>

  <complexType name="Scanner">
    <sequence>
      <element name="column" type="base64Binary" minOccurs="0" maxOccurs="unbounded"></element>
    </sequence>
    <sequence>
      <element name="filter" type="string" minOccurs="0" maxOccurs="1"></element>
    </sequence>
    <attribute name="startRow" type="base64Binary"></attribute>
    <attribute name="endRow" type="base64Binary"></attribute>
    <attribute name="batch" type="int"></attribute>
    <attribute name="startTime" type="int"></attribute>
    <attribute name="endTime" type="int"></attribute>
  </complexType>

  <element name="StorageClusterVersion" type="tns:StorageClusterVersion" />

  <complexType name="StorageClusterVersion">
    <attribute name="version" type="string"></attribute>
  </complexType>

  <element name="StorageClusterStatus"
    type="tns:StorageClusterStatus">
  </element>

  <complexType name="StorageClusterStatus">
    <sequence>
      <element name="liveNode" type="tns:Node"
        maxOccurs="unbounded" minOccurs="0">
      </element>
      <element name="deadNode" type="string" maxOccurs="unbounded"
        minOccurs="0">
      </element>
    </sequence>
    <attribute name="regions" type="int"></attribute>
    <attribute name="requests" type="int"></attribute>
    <attribute name="averageLoad" type="float"></attribute>
  </complexType>

  <complexType name="Node">
    <sequence>
      <element name="region" type="tns:Region"
   maxOccurs="unbounded" minOccurs="0">
      </element>
    </sequence>
    <attribute name="name" type="string"></attribute>
    <attribute name="startCode" type="int"></attribute>
    <attribute name="requests" type="int"></attribute>
    <attribute name="heapSizeMB" type="int"></attribute>
    <attribute name="maxHeapSizeMB" type="int"></attribute>
  </complexType>

  <complexType name="Region">
    <attribute name="name" type="base64Binary"></attribute>
    <attribute name="stores" type="int"></attribute>
    <attribute name="storefiles" type="int"></attribute>
    <attribute name="storefileSizeMB" type="int"></attribute>
    <attribute name="memstoreSizeMB" type="int"></attribute>
    <attribute name="storefileIndexSizeMB" type="int"></attribute>
  </complexType>

</schema>
----

[[protobufs_schema]]
=== REST Protobufs Schema

[source,json]
----
message Version {
  optional string restVersion = 1;
  optional string jvmVersion = 2;
  optional string osVersion = 3;
  optional string serverVersion = 4;
  optional string jerseyVersion = 5;
}

message StorageClusterStatus {
  message Region {
    required bytes name = 1;
    optional int32 stores = 2;
    optional int32 storefiles = 3;
    optional int32 storefileSizeMB = 4;
    optional int32 memstoreSizeMB = 5;
    optional int32 storefileIndexSizeMB = 6;
  }
  message Node {
    required string name = 1;    // name:port
    optional int64 startCode = 2;
    optional int32 requests = 3;
    optional int32 heapSizeMB = 4;
    optional int32 maxHeapSizeMB = 5;
    repeated Region regions = 6;
  }
  // node status
  repeated Node liveNodes = 1;
  repeated string deadNodes = 2;
  // summary statistics
  optional int32 regions = 3;
  optional int32 requests = 4;
  optional double averageLoad = 5;
}

message TableList {
  repeated string name = 1;
}

message TableInfo {
  required string name = 1;
  message Region {
    required string name = 1;
    optional bytes startKey = 2;
    optional bytes endKey = 3;
    optional int64 id = 4;
    optional string location = 5;
  }
  repeated Region regions = 2;
}

message TableSchema {
  optional string name = 1;
  message Attribute {
    required string name = 1;
    required string value = 2;
  }
  repeated Attribute attrs = 2;
  repeated ColumnSchema columns = 3;
  // optional helpful encodings of commonly used attributes
  optional bool inMemory = 4;
  optional bool readOnly = 5;
}

message ColumnSchema {
  optional string name = 1;
  message Attribute {
    required string name = 1;
    required string value = 2;
  }
  repeated Attribute attrs = 2;
  // optional helpful encodings of commonly used attributes
  optional int32 ttl = 3;
  optional int32 maxVersions = 4;
  optional string compression = 5;
}

message Cell {
  optional bytes row = 1;       // unused if Cell is in a CellSet
  optional bytes column = 2;
  optional int64 timestamp = 3;
  optional bytes data = 4;
}

message CellSet {
  message Row {
    required bytes key = 1;
    repeated Cell values = 2;
  }
  repeated Row rows = 1;
}

message Scanner {
  optional bytes startRow = 1;
  optional bytes endRow = 2;
  repeated bytes columns = 3;
  optional int32 batch = 4;
  optional int64 startTime = 5;
  optional int64 endTime = 6;
}
----

== Thrift

Documentation about Thrift has moved to <<thrift>>.

[[c]]
== C/C++ Apache HBase Client

FB's Chip Turner wrote a pure C/C++ client.
link:https://github.com/hinaria/native-cpp-hbase-client[Check it out].

C++ client implementation. To see link:https://issues.apache.org/jira/browse/HBASE-14850[HBASE-14850].

[[jdo]]

== Using Java Data Objects (JDO) with HBase

link:https://db.apache.org/jdo/[Java Data Objects (JDO)] is a standard way to
access persistent data in databases, using plain old Java objects (POJO) to
represent persistent data.

.Dependencies
This code example has the following dependencies:

. HBase 0.90.x or newer
. commons-beanutils.jar (https://commons.apache.org/)
. commons-pool-1.5.5.jar (https://commons.apache.org/)
. transactional-tableindexed for HBase 0.90 (https://github.com/hbase-trx/hbase-transactional-tableindexed)

.Download `hbase-jdo`
Download the code from http://code.google.com/p/hbase-jdo/.

.JDO Example
====

This example uses JDO to create a table and an index, insert a row into a table, get
a row, get a column value, perform a query, and do some additional HBase operations.

[source, java]
----
package com.apache.hadoop.hbase.client.jdo.examples;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.Hashtable;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.client.tableindexed.IndexedTable;

import com.apache.hadoop.hbase.client.jdo.AbstractHBaseDBO;
import com.apache.hadoop.hbase.client.jdo.HBaseBigFile;
import com.apache.hadoop.hbase.client.jdo.HBaseDBOImpl;
import com.apache.hadoop.hbase.client.jdo.query.DeleteQuery;
import com.apache.hadoop.hbase.client.jdo.query.HBaseOrder;
import com.apache.hadoop.hbase.client.jdo.query.HBaseParam;
import com.apache.hadoop.hbase.client.jdo.query.InsertQuery;
import com.apache.hadoop.hbase.client.jdo.query.QSearch;
import com.apache.hadoop.hbase.client.jdo.query.SelectQuery;
import com.apache.hadoop.hbase.client.jdo.query.UpdateQuery;

/**
 * Hbase JDO Example.
 *
 * dependency library.
 * - commons-beanutils.jar
 * - commons-pool-1.5.5.jar
 * - hbase0.90.0-transactionl.jar
 *
 * you can expand Delete,Select,Update,Insert Query classes.
 *
 */
public class HBaseExample {
  public static void main(String[] args) throws Exception {
    AbstractHBaseDBO dbo = new HBaseDBOImpl();

    //*drop if table is already exist.*
    if(dbo.isTableExist("user")){
     dbo.deleteTable("user");
    }

    //*create table*
    dbo.createTableIfNotExist("user",HBaseOrder.DESC,"account");
    //dbo.createTableIfNotExist("user",HBaseOrder.ASC,"account");

    //create index.
    String[] cols={"id","name"};
    dbo.addIndexExistingTable("user","account",cols);

    //insert
    InsertQuery insert = dbo.createInsertQuery("user");
    UserBean bean = new UserBean();
    bean.setFamily("account");
    bean.setAge(20);
    bean.setEmail("ncanis@gmail.com");
    bean.setId("ncanis");
    bean.setName("ncanis");
    bean.setPassword("1111");
    insert.insert(bean);

    //select 1 row
    SelectQuery select = dbo.createSelectQuery("user");
    UserBean resultBean = (UserBean)select.select(bean.getRow(),UserBean.class);

    // select column value.
    String value = (String)select.selectColumn(bean.getRow(),"account","id",String.class);

    // search with option (QSearch has EQUAL, NOT_EQUAL, LIKE)
    // select id,password,name,email from account where id='ncanis' limit startRow,20
    HBaseParam param = new HBaseParam();
    param.setPage(bean.getRow(),20);
    param.addColumn("id","password","name","email");
    param.addSearchOption("id","ncanis",QSearch.EQUAL);
    select.search("account", param, UserBean.class);

    // search column value is existing.
    boolean isExist = select.existColumnValue("account","id","ncanis".getBytes());

    // update password.
    UpdateQuery update = dbo.createUpdateQuery("user");
    Hashtable<String, byte[]> colsTable = new Hashtable<String, byte[]>();
    colsTable.put("password","2222".getBytes());
    update.update(bean.getRow(),"account",colsTable);

    //delete
    DeleteQuery delete = dbo.createDeleteQuery("user");
    delete.deleteRow(resultBean.getRow());

    ////////////////////////////////////
    // etc

    // HTable pool with apache commons pool
    // borrow and release. HBasePoolManager(maxActive, minIdle etc..)
    IndexedTable table = dbo.getPool().borrow("user");
    dbo.getPool().release(table);

    // upload bigFile by hadoop directly.
    HBaseBigFile bigFile = new HBaseBigFile();
    File file = new File("doc/movie.avi");
    FileInputStream fis = new FileInputStream(file);
    Path rootPath = new Path("/files/");
    String filename = "movie.avi";
    bigFile.uploadFile(rootPath,filename,fis,true);

    // receive file stream from hadoop.
    Path p = new Path(rootPath,filename);
    InputStream is = bigFile.path2Stream(p,4096);

  }
}
----
====

[[scala]]
== Scala

=== Setting the Classpath

To use Scala with HBase, your CLASSPATH must include HBase's classpath as well as
the Scala JARs required by your code. First, use the following command on a server
running the HBase RegionServer process, to get HBase's classpath.

[source, bash]
----
$ ps aux |grep regionserver| awk -F 'java.library.path=' {'print $2'} | awk {'print $1'}

/usr/lib/hadoop/lib/native:/usr/lib/hbase/lib/native/Linux-amd64-64
----

Set the `$CLASSPATH` environment variable to include the path you found in the previous
step, plus the path of `scala-library.jar` and each additional Scala-related JAR needed for
your project.

[source, bash]
----
$ export CLASSPATH=$CLASSPATH:/usr/lib/hadoop/lib/native:/usr/lib/hbase/lib/native/Linux-amd64-64:/path/to/scala-library.jar
----

=== Scala SBT File

Your `build.sbt` file needs the following `resolvers` and `libraryDependencies` to work
with HBase.

----
resolvers += "Apache HBase" at "https://repository.apache.org/content/repositories/releases"

resolvers += "Thrift" at "https://people.apache.org/~rawson/repo/"

libraryDependencies ++= Seq(
    "org.apache.hadoop" % "hadoop-core" % "0.20.2",
    "org.apache.hbase" % "hbase" % "0.90.4"
)
----

=== Example Scala Code

This example lists HBase tables, creates a new table, adds a row to it, and gets the value of the row.

[source, scala]
----
import org.apache.hadoop.hbase.{HBaseConfiguration, TableName}
import org.apache.hadoop.hbase.client.{Admin, Connection, ConnectionFactory, Get, Put}
import org.apache.hadoop.hbase.util.Bytes

val conf = HBaseConfiguration.create()
val connection = ConnectionFactory.createConnection(conf);
val admin = connection.getAdmin();

// list the tables
val listtables = admin.listTables()
listtables.foreach(println)

// let's insert some data in 'mytable' and get the row
val table = connection.getTable(TableName.valueOf("mytable"))

val theput = new Put(Bytes.toBytes("rowkey1"))

theput.addColumn(Bytes.toBytes("ids"),Bytes.toBytes("id1"),Bytes.toBytes("one"))
table.put(theput)

val theget = new Get(Bytes.toBytes("rowkey1"))
val result = table.get(theget)
val value = result.value()
println(Bytes.toString(value))
----

[[jython]]
== Jython


=== Setting the Classpath

To use Jython with HBase, your CLASSPATH must include HBase's classpath as well as
the Jython JARs required by your code.

Set the path to directory containing the `jython.jar` and each additional Jython-related JAR needed for
your project. Then export HBASE_CLASSPATH pointing to the $JYTHON_HOME env. variable.

[source, bash]
----
$ export HBASE_CLASSPATH=/directory/jython.jar
----

Start a Jython shell with HBase and Hadoop JARs in the classpath:
$ bin/hbase org.python.util.jython

=== Jython Code Examples

.Table Creation, Population, Get, and Delete with Jython
====
The following Jython code example checks for table,
if it exists, deletes it and then creates it. Then it
populates the table with data and fetches the data.

[source,jython]
----
import java.lang
from org.apache.hadoop.hbase import HBaseConfiguration, HTableDescriptor, HColumnDescriptor, TableName
from org.apache.hadoop.hbase.client import Admin, Connection, ConnectionFactory, Get, Put, Result, Table
from org.apache.hadoop.conf import Configuration

# First get a conf object.  This will read in the configuration
# that is out in your hbase-*.xml files such as location of the
# hbase master node.
conf = HBaseConfiguration.create()
connection = ConnectionFactory.createConnection(conf)
admin = connection.getAdmin()

# Create a table named 'test' that has a column family
# named 'content'.
tableName = TableName.valueOf("test")
table = connection.getTable(tableName)

desc = HTableDescriptor(tableName)
desc.addFamily(HColumnDescriptor("content"))

# Drop and recreate if it exists
if admin.tableExists(tableName):
    admin.disableTable(tableName)
    admin.deleteTable(tableName)

admin.createTable(desc)

# Add content to 'column:' on a row named 'row_x'
row = 'row_x'
put = Put(row)
put.addColumn("content", "qual", "some content")
table.put(put)

# Now fetch the content just added, returns a byte[]
get = Get(row)

result = table.get(get)
data = java.lang.String(result.getValue("content", "qual"), "UTF8")

print "The fetched row contains the value '%s'" % data
----
====

.Table Scan Using Jython
====
This example scans a table and returns the results that match a given family qualifier.

[source, jython]
----
import java.lang
from org.apache.hadoop.hbase import TableName, HBaseConfiguration
from org.apache.hadoop.hbase.client import Connection, ConnectionFactory, Result, ResultScanner, Table, Admin
from org.apache.hadoop.conf import Configuration
conf = HBaseConfiguration.create()
connection = ConnectionFactory.createConnection(conf)
admin = connection.getAdmin()
tableName = TableName.valueOf('wiki')
table = connection.getTable(tableName)

cf = "title"
attr = "attr"
scanner = table.getScanner(cf)
while 1:
    result = scanner.next()
    if not result:
       break
    print java.lang.String(result.row), java.lang.String(result.getValue(cf, attr))
----
====