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Introduction

Storage Resource Managers (SRMs) are middleware components whose function is to provide dynamic space allocation and file management on shared storage components on the Grid. SRMs support protocol negotiation and a reliable replication mechanism. The SRM specification standardizes the interface, thus allowing for a uniform access to heterogeneous storage elements.

The SRM utilizes the Grid Security Infrastructure (GSI) for authentication. The SRM is a Web Service implementing a published WSDL document. Please visit the SRM Working Group Page to see the SRM Version 1.1 and SRM Version 2.2 protocol specification documents.

The SRM protocol uses HTTP over GSI as a transport. The dCache SRM implementation added HTTPS as a transport layer option. The main benefits of using HTTPS rather than HTTP over GSI is that HTTPS is a standard protocol and has support for sessions, improving latency in case a client needs to connect to the same server multiple times. The current implementation does not offer a delegation service. Hence srmCopy will not work with SRM over HTTPS. A separate delegation service will be added in a later release.