OrderBook

Simple price-time priority order book. Supports multiple clients connecting concurrently from different computers (See: Adittional parameters - Server).

Work in progress! 👷

=== ##How to run:

The project is uses Java 1.8 and Maven and rmiregistry, make sure they are present by running:

$> java -version

$> mvn -v

$> which rmiregistry #Should Ouput /usr/bin/rmiregistry

###Install Maven (If missing) Download unzip and mv to /opt/, run

$> export PATH=/opt/apache-maven-3.3.9/bin:$PATH

validate again:

$> mvn -v.

###Compiling Define the env variable ROOT (for every console window), pointing to where you cloned this repo:

$> export ROOT="<path_to_repo_clone>"

Once in "$ROOT" , and stepped into this repository's extract location run:

$> mvn clean install

###Setting it up to browse with eclipse (optional) While in the "$ROOT" folder run:

$> mvn eclipse:eclipse -DdownloadSources=true

or simply import as a maven project through the eclipse-maven's plugin wizard.

===

Showtime

We will need at least 3 console windows open for this when running local server & clients. For conviniency use the scripts rabbitmq.sh server.sh client-joe.sh client-pete.sh all in different console windows will provide a server and 2 valid clients for live testing.

Steps 1-2-3 can be ignored if you decide to use the scripts.

1 - RabbitMQ

$> rabbitmq-server

2 - Server

$> java -jar orderbook-server/target/orderbook-server-1.0-SNAPSHOT.jar

####Aditional parameters (Server)

Aditional parameters to host for clients on other computers should be set (optional).

Current defaults are:

HOSTNAME=localhost PORT=1099 SERVICE=OrderBookService

change as you please and pass as command line argument.

The server supports a session start & end time (i.e Market operates during a given time interval).

To set that use:

• START = A delayed start date in the format yyyy-MM-dd HH:mm:ss, default is current time.

• END = A session expiration date in the format yyyy-MM-dd HH:mm:ss, default is never expire.

for example:

START="2016-08-24 01:34:30" END="2016-08-24 01:36:00"

3 - Client

We support many clients running concurrently over the net. If your server is running on a different computer make sure you're passing the optional paramters:

$> java -jar orderbook-client/target/orderbook-client-1.0-SNAPSHOT.jar CLIENT=myClientId

Passing the clientId over CLI simulates the authentication of a user. That would be the place where the server could prompt for a password and authenticate against a secure database.

=== ##Trading

###Placing Orders

Clients prompt you to enter a transaction in the following single-line format:

SECURITY=GOOG AMOUNT=500 VALUE=430.0 ISBUYING=YES

SECURITY: The security that you want to trade.

AMOUNT: The number of units for that security that you want to place.

VALUE: The limit value.

ISBUYING: YES if it is a buying order, NO if it is a selling order.

####Note: A client is not allowed to buy and sell the same security. This is a design desition made to allow the matching algorithm to be general for buy & sell side.

###Listing Orders

Client's transaction log can be accessed through.

LIST

	It shows a Transaction log for that client, meaning all matches (buy & sell) that happened over the session for that current client. This would be something the client can have access to, since it's their own transactions and can't affect the market in any way.
	Aditionally ,It trirggers a dump of the server's (on it's console) book to inspect it's internal state. This is for debugging purposes and would never be something the client can see.

###Updating orders

Once an order is placed, through the server output console or in the client through LIST a unique ORDERID can be retrieved. Subsequent updates of that order can happen in the following format:

ORDERID=0 SECURITY=GOOG AMOUNT=500 VALUE=430.0 ISBUYING=YES

Where 0 is the number retrieved under the above instructions.

When doing so the following considerations take place:

1. If price changes, you lose priority regardless of the rest of the values.
2. If quantity increases, even if price remains the same, you lose priority.
3. ONLY If quantity decreases and price remains the same, you keep priority.

===

Tests

An OrderBook has several rules that it needs to apply, for that reason there are Unit Tests the comments should aid to understand the behavior expected for this service.

Given that the project is client-server we only test our PriorityOrderBook where the logic rules are actually enforced. Any remote objects are mocked using the Mockito Java tool.

###About RabbitMQ

RabbitMQ is a message queue supported in many languages and backed by Pivotal. By using this technology we enable multiple clients to query a single server with the posibility of spinning multiple instances of the server on demand, if for example trade increased at a particular time of day. This would happen with very little code change and having each instance address a particular type of security.

Nota that if deploying on a real-life envirorment the file-descriptor limit for RabbitMQ should be higher than the default OS' as per this article