Retreiving image through JPA and displaying it

[Shayan Shah]

Hi

I am storing users data in a table along with pictures using JPA. I have successfully stored the images in data base. I have to display the data on a JSF page in data table along with the pictures. Now I am facing the problem of how to display the pictures. When I retrieve the data, all the records are fetched along with the pictures in form of byte arrays. I am only stuck on how to display the images.

I found several programs on Internet which used to pass Id of the image to a servlet which will retrieve the image and process it and send as a response which means for 10 pics, there will be 10 seperate full cycle requests to database when I am already having all the pics loaded to memory. I don't want to make a separate request for each image of each record. Reason being its a distributed application. Every call means a remote call and serialization and all that other stuff.

Is there any possible solution to this.

Regards

[Ulf Dittmer]

I don't want to make a separate request for each image of each record.

There's no way around that if we're talking about an HTML/HTTP client.

Reason being its a distributed application. Every call means a remote call and serialization and all that other stuff.

What do you mean by "serialization" in this context? You mentioned JSF, which implies HTTP/HTML; if you're using something else, then TellTheDetails.

[Shayan Shah]

Well, I have two servers A and B. The core application is installed on server B. HTTP requests are received to server A which then queries server B and returns result. So there will be remote calls from server A to server B.

Now when serve A requests from server B all the list of users, server B will return the list along with the Images. When server A all the records in hand, I want that server A should make the images and return it as HTTP response. Not like that it make separate remote request again for each image again from server B.

[Ulf Dittmer]

An HTTP request can only be for a single page, or for a single image. Once the images arrive at A from B (as the result of a page being requested), you need to store them on A somehow, either on disk or in memory. Then you need to make sure that the page being sent back from A to the client contains image URLs that point to A in a way so that A can be sure that the image is present there (and doesn't need to be retrieved from B).

[Shayan Shah]

Yeah. Its the only way. Now I create temporary images on server A when I get the list, and send its paths in response. But now I have another problem.
As according to JPA recommendations, I am using the @Lob on the ''image' field which is of type byte[] and fetch type is lazy.

public class Member implements Serializable {
    
     ...........

    @Lob 
    @Basic(fetch=FetchType.LAZY,optional=true)
    @Column(name = "image")
    private byte[] image;
    
    ...........

}

According to this, when I query, the images must not be loaded into memory as its Lazy fetch but still they are loaded.
I am using Hibernate as persistence provider. What can be the problem??

Thanks