py-gemfire-rest

This library enables your python applications to use GemFire as a datastore. (GemFire is a distributed key-value store. A short tutorial can be found at http://goo.gl/rF93fn). This library exposes Spring's CrudRepository like methods in an effort to simplify GemFire's APIs while still giving access to advanced GemFire features (details below).

Installation

Using pip installation is simple

    $ sudo pip install gemfire-rest

or from source:

    $ sudo python setup.py install

Quick Start

1. Start the GemFire REST service by following the instructions
2. Create a Region on the server (Region is a distributed ConcurrentMap in which GemFire stores the data).

    gfsh>create region --name=orders --type=PARTITION

    >>> from gemfire import *
    >>> client = GemfireClient(hostname="localhost", port=8080)
    >>> myRepo = client.create_repository("orders")
    >>> myRepo.save(order)

where the order object has an "id" instance variable. The library handles converting the object to/from json.

API Reference

This library exercises GemFire's REST APIs for enabling your python application to use GemFire as its datastore. To get started, we create a client by providing a hostname and port for an already running endpoint.

    client = GemfireClient(hostname="localhost", port=8080)

For each type of Object that we want to store in GemFire, we create a repository (Please not that you will have to create a Region on the server with the same name as the repository).

    orders = client.create_repository("orders")

The client provides a method to look up all the Regions that have been created on the server already:

    client.list_all_regions()

GemfireClient also has methods for querying and function execution which we will see later.

Repository

Just like Spring's CrudRepository interface, the following methods are available on the Repository

    save(entities)   #saves one or more entities in GemFire
    find(ids)        #finds entities with the given ids
    find_all()       #returns all data in region
    exists(id)       #checks to see if an entity with the given id exists
    delete(entities) #deletes the given entities from GemFire
    delete_all()     #deletes all data in the GemFire region

As the naming suggests, intention of these methods is pretty clear. One thing that needs to be highlighted here is that all entities need an identity; this library uses "id" instance variable as identity. So all entities that are stored in GemFire need to have an instance variable named "id".

Region

For advanced operations, we also provide access to Region, which defines the following methods:

    create(key, value)  #will insert only if key does not exists
    update(key, value)  #will update only if the key exists
    keys()              # returns all keys in the region
    compare_and_set(key, oldvalue, newvalue) #sets the key to newvalue only if current value is equal ot oldvalue

Querying

GemfireClient provides API for running ad-hoc OQL queries on the server.

    adhoc_query(query_string)  #OQL query string

For faster performance, you will want to run prepared OQL queries. GemfireClient provides the following APIs for this:

    new_query(query_id, query_string) #registers and prepares the OQL query on the server
    run_query(query_id, query_args)   #runs the query with specified parameters