NEW YORK — Online spending is expected to rise a robust 17 percent this year, despite a sluggish economy that has bruised many brick-based retailers, according to an annual survey to be released today.

Retail sales online, excluding travel purchases, are set to grow to $204 billion in 2008 from $174.5 billion last year, fueled by sales of apparel, computers and autos, according to a survey conducted by Internet analysis firm Forrester Research for www.Shop.org, the online arm of the National Retail Federation trade group. That projection is below the 21 percent increase seen in the prior year, but industry officials attribute it to the maturing of the business, not the sluggish economy.

E-commerce "is clearly the bright spot in retailing," said Scott Silverman, executive director of www.Shop.org.

The upbeat report contrasts with the outlook for many traditional retailers, which have been paring down store growth and closing shops as they struggle with consumers who don't feel like spending amid higher gas and food costs, a housing slump and a weaker job market. The exceptions are discounters and wholesale clubs, as shoppers turn to less expensive stores.

On Thursday, the nation's retailers are expected to report at best flat sales growth in March, according to the International Council of Shopping Centers. Same-stores sales are sales at stores open at least a year and are considered a key indicator of a retailer's health.