FeedLink.h

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// Copyright Onix Solutions Limited [OnixS]. All rights reserved.
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#pragma once

#include <string>

#include <OnixS/CME/MDH/Integral.h>

ONIXS_CMEMDH_NAMESPACE_BEGIN

ONIXS_CMEMDH_LTWT_CLASS_DECL(NetFeed);

/// Abstraction of a link used by the NetFeed
/// instances to cover transportation layer.
///
/// The actual implementations are provided by
/// a particular feed engine, whereas the NetFeed
/// class interacts with the feed engine through
/// the given abstraction.
class ONIXS_CMEMDH_EXPORTED NetFeedLink
{
public:
    /// Establishes connection for the given feed.
    ///
    /// The timeout parameter specifies amount of time
    /// allocated for the link to get into connected/linked
    /// state. The string parameter is used by the feed
    /// engine to report on non-critical issues which may
    /// take place while establishing communication link.
    virtual void link(const NetFeed&, UInt32, std::string&) = 0;

    /// Closes communication link for the given feed.
    virtual void unlink(const NetFeed&) = 0;

    /// Sends the given message to the counterpart.
    ///
    /// The given member is invoked by Handler only for the
    /// feeds assuming bi-directional communication like the
    /// historical ones. Multicast links aren't supposed to
    /// provide the given functionality and thus may raise
    /// an exception.
    virtual void send(const NetFeed&, const void*, size_t, UInt32) = 0;

    /// Releases the link used by the given feed.
    /// Once invoked, no other members are invoked
    /// afterwards any more.
    virtual void release(const NetFeed&) = 0;

protected:
    /// Instances are constructed through descendants.
    NetFeedLink() {}

    /// Instances aren't destructed in a regular way.
    /// The 'release()' member serves for that purpose.
    virtual ~NetFeedLink() {}

private:
    NetFeedLink(const NetFeedLink&);

    NetFeedLink& operator=(const NetFeedLink&);
};

ONIXS_CMEMDH_NAMESPACE_END