What is currently defined by a real-time FX trading environment?
Real-time in an FX trading environment means different things to different people. For the buy side, it can mean being able to trade electronically via a broker or direct with an ECN (Electronic Communication Network) whenever need be. This can be for covering FX exposure or moving FX risk from one currency to another. For the sell side, real-time will mean much more than simply being able to execute a single trade immediately; it might mean connecting to multiple liquidity sources to take advantage of arbitrage opportunities, being able to execute complex algorithms, high speed credit checking, risk management and being able to offer clients STP (Straight Through Processing) to ECN's.

What are different timeframes in which clients need to execute their trades?
Timeframes for completing a transaction (a transaction being generating one or a set of quotes/orders or trades) to meet a specific trading objective are clearly going to be different for the various parties involved in FX trading. Hedge funds with Black Box trading can be generating thousands of messages per second and looking for arbitrage opportunities across various execution venues. Fund managers or corporates might only be looking for a limited number of quotes/orders per second connecting from their Order Management System via an API. At the other extreme, clients carrying out large trades may still revert to voice broking; they would expect it to take several seconds to complete the deal. Even if using electronic trading, a corporate treasurer executing only a few trades per day might expect to be given VWAP (Volume-Weighted Average Price) over the day. Custodians moving dividends into local currencies or trade finance clients may be happy with a daily price fix.