Object Storage Service:Manage symbolic links

Usage notes

• In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions and endpoints.

• In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient by using custom domain names or Security Token Service (STS), see Create an OSSClient instance.

• To create a symbolic link, you must have the oss:PutObject permission. To query a symbolic link, you must have the oss:GetObject permission. For more information, see Attach a custom policy to a RAM user.

• After you delete the object to which a symbolic link points, the symbolic link still exists, but the object cannot be accessed by using the symbolic link.

Create a symbolic link

The following sample code provides an example on how to create a symbolic link:

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
            
    /* Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. */
    std::string Region = "yourRegion";
    /* Specify the name of the bucket. Example: examplebucket. */
    std::string BucketName = "examplebucket";
    /* Specify the full path of the object. Example: exampledir/exampleobject.txt. Do not include the bucket name in the full path. */
    std::string ObjectName = "exampledir/exampleobject.txt";
    /* Specify the full path of the symbolic link. Example: shortcut/myobject.txt. */
    std::string LinkName = "shortcut/myobject.txt";

    /* Initialize resources, such as network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);



    /* Configure the HTTP headers. */
    auto meta = ObjectMetaData();
    meta.setContentType("text/plain");

    /* Configure the user metadata of the object. */
    meta.UserMetaData()["meta"] = "meta-value";

    /* Create the symbolic link. */
    CreateSymlinkRequest request(BucketName, ObjectName, meta);
    request.SetSymlinkTarget(LinkName);
    auto outcome = client.CreateSymlink(request);

    if (!outcome.isSuccess()) {
        /* Handle exceptions. */
        std::cout << "CreateSymlink fail" <<
        ",code:" << outcome.error().Code() <<
        ",message:" << outcome.error().Message() <<
        ",requestId:" << outcome.error().RequestId() << std::endl;
        return -1;
    }

    /* Release resources, such as network resources. */
    ShutdownSdk();
    return 0;
}

Query a symbolic link

To query a symbolic link, you must have read permissions on the symbolic link. The following sample code provides an example on how to query the symbolic link and the name of the object to which the symbolic link points:

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
            
    /* Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Specify the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the region to cn-hangzhou. */
    std::string Region = "yourRegion";
    /* Specify the name of the bucket. Example: examplebucket. */
    std::string BucketName = "examplebucket";
    /* Specify the full path of the symbolic link. Example: shortcut/myobject.txt. */
    std::string LinkName = "shortcut/myobject.txt";

    /* Initialize resources, such as network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);

    /* Obtain the name of the object to which the symbolic link points. */
    GetSymlinkRequest request(BucketName, LinkName);
    auto outcome = client.GetSymlink(request);

    if (!outcome.isSuccess()) {
        /* Handle exceptions. */
        std::cout << "GetSymlink fail" <<
        ",code:" << outcome.error().Code() <<
        ",message:" << outcome.error().Message() <<
        ",requestId:" << outcome.error().RequestId() << std::endl;
        return -1;
    }
    else { 
        std::cout << " GetSymlink success Symlink name:" << outcome.result().SymlinkTarget() << std::endl;
    }

    /* Release resources, such as network resources. */
    ShutdownSdk();
    return 0;
}

References

• For more information about the API operation that you can call to create a symbolic link, see PutSymlink.

• For more information about the API operation that you can call to query a symbolic link, see GetSymlink.